DYNAMIC GROUNDHOOK CONTROL IN A VEHICLE USING AN ACTIVE SUSPENSION SYSTEM
20260091635 ยท 2026-04-02
Assignee
Inventors
Cpc classification
B60G2400/1062
PERFORMING OPERATIONS; TRANSPORTING
B60G17/0165
PERFORMING OPERATIONS; TRANSPORTING
B60G2400/202
PERFORMING OPERATIONS; TRANSPORTING
International classification
Abstract
A vehicle may include a vehicle body, a plurality of wheels, an active suspension system operatively coupled to the plurality of wheels and the vehicle body, and at least one processor configured to control the active suspension system. The at least one processor may be configured to determine a first force command based on a vehicle body parameter, determine a second force command based on the vehicle body parameter and a suspension parameter, determine a blend ratio based on the first force command, determine a third force command based at least partly on the blend ratio, the first force command, and the second force command, and command the at least one actuator to apply force between at least one of the plurality of wheels and the vehicle body based at least partly on the third force command.
Claims
1. A vehicle comprising: a vehicle body; a plurality of wheels; an active suspension system operatively coupled to the plurality of wheels and the vehicle body, wherein the active suspension system comprises at least one actuator configured to apply active forces to at least one of the plurality of wheels in at least one mode of operation; and at least one processor configured to control the active suspension system, wherein the at least one processor is configured to: determine a first force command based on a vehicle body parameter, determine a second force command based on the vehicle body parameter and a suspension parameter, determine a blend ratio based at least partly on the first force command, determine a third force command based at least partly on the blend ratio, the first force command, and the second force command, and command the at least one actuator to apply force between at least one of the plurality of wheels and the vehicle body based at least partly on the third force command.
2. The vehicle of claim 1, wherein the vehicle body parameter is a vehicle body velocity, and wherein the suspension parameter is a suspension velocity.
3. The vehicle of claim 1, further comprising at least one first sensor and at least one second sensor, wherein the at least one processor is further configured to: receive vehicle information from the at least one first sensor; determine the vehicle body parameter based on the vehicle information; receive suspension information from the at least one second sensor; and determine the suspension parameter based on the suspension information.
4. The vehicle of claim 3, wherein the at least one first sensor comprises a first accelerometer disposed on the vehicle body, and wherein the at least one second sensor comprises an accelerometer disposed on the active suspension system.
5. The vehicle of claim 1, wherein determining the third force command comprises: determining a first portion of the third force command based on the blend ratio and the first force command; and determining a second portion of the third force command based on the blend ratio and the second force command.
6. The vehicle of claim 5, wherein the first portion of the third force command is proportional to the blend ratio and the first force command, and wherein the second portion of the third force command is proportional to the blend ratio and the second force command.
7. The vehicle of claim 5, wherein the at least one processor is further configured to: determine if a road event is longer than a threshold duration is occurring; and upon determining the road event longer than the threshold duration is occurring, maintain the blend ratio greater than a threshold blend ratio for a predetermined time period.
8. The vehicle of claim 5, wherein the first portion of the third force command is proportional to an antecedent of the blend ratio, and wherein the second portion of the third force command is proportional to a consequent of the blend ratio.
9. The vehicle of claim 8, wherein the antecedent of the blend ratio is between 0 and 1, wherein the consequent of the blend ratio is between 0 and 1, and wherein the antecedent and consequent sum to 1.
10. The vehicle of claim 5, wherein the at least one processor is further configured to: apply a low-pass filter to the blend ratio to obtain a filtered blend ratio, wherein the first portion of the third force command is determined based on the filtered blend ratio, and wherein the second portion of the third force command is determined based on the filtered blend ratio.
11. The vehicle of claim 1, wherein the first force command is configured to isolate the vehicle body from movement, and wherein the second force command is configured to move the vehicle body with a road surface.
12. The vehicle of claim 1, wherein the third force command is configured to control a heave and/or pitch of the vehicle.
13. The vehicle of claim 1, further comprising a user interface, wherein the user interface is configured to receive input from a user, and wherein the at least one processor is further configured to determine the blend ratio based at least partly on the input from the user.
14. The vehicle of claim 1, further comprising a forward-looking sensor configured to obtain forward-looking road information, wherein the at least one processor is further configured to determine the blend ratio based at least partly on the forward-looking road information.
15. The vehicle of claim 1, wherein the first force command is a first output from a first control module, and wherein the second force command is a second output from a second control module.
16. The vehicle of claim 1, wherein the at least one processor is further configured to determine the blend ratio to avoid exceeding a wheel travel threshold of the plurality of wheels.
17. A method of controlling a vehicle comprising: determining a first force command based on a vehicle body parameter, determining a second force command based on the vehicle body parameter and a suspension parameter, determining a blend ratio based on the first force command, determining a third force command based at least partly on the blend ratio, the first force command, and the second force command, and commanding at least one actuator of an active suspension system to apply active force between at least one of a plurality of wheels of the vehicle and a vehicle body of the vehicle based at least partly on the third force command.
18. The method of claim 17, wherein the vehicle body parameter is a vehicle body velocity, and wherein the suspension parameter is a suspension velocity.
19. The method of claim 17, further comprising: receiving vehicle information from at least one first sensor; determining the vehicle body parameter based on the vehicle information; receiving suspension information from at least one second sensor; and determining the suspension parameter based on the suspension information.
20. The method of claim 19, wherein the at least one first sensor comprises a first accelerometer disposed on the vehicle body, and wherein the at least one second sensor comprises an accelerometer disposed on the active suspension system.
21. The method of claim 17, wherein determining the third force command comprises: determining a first portion of the third force command based on the blend ratio and the first force command; and determining a second portion of the third force command based on the blend ratio and the second force command.
22. The method of claim 21, wherein the first portion of the third force command is proportional to the blend ratio and the first force command, and wherein the second portion of the third force command is proportional to the blend ratio and the second force command.
23. The method of claim 21, further comprising: determining if a road event is longer than a threshold duration is occurring; and upon determining the road event longer than the threshold duration is occurring, hold the blend ratio greater than a threshold blend ratio for a predetermined time period.
24. The method of claim 21, wherein the first portion of the third force command is proportional to an antecedent of the blend ratio, and wherein the second portion of the third force command is proportional to a consequent of the blend ratio.
25. The method of claim 24, wherein the antecedent of the blend ratio is between 0 and 1, wherein the consequent of the blend ratio is between 0 and 1, and wherein the antecedent and consequent sum to 1.
26. The method of claim 21, further comprising applying a low-pass filter to the blend ratio to obtain a filtered blend ratio, wherein the first portion of the third force command is determined based on the filtered blend ratio, and wherein the second portion of the third force command is determined based on the filtered blend ratio.
27. The method of claim 17, wherein the first force command is configured to isolate the vehicle body from movement, and wherein the second force command is configured to move the vehicle body with a road surface.
28. The method of claim 17, wherein the third force command is configured to control a heave and/or pitch of the vehicle.
29. The method of claim 17, further comprising receive input from a user at a user interface, wherein determining the blend ratio is based at least partly on the input from the user.
30. The vehicle of claim 17, further comprising obtaining forward-looking road information with a forward-looking sensor, wherein determining the blend ratio is based at least partly on the forward-looking road information.
31. The vehicle of claim 17, wherein the first force command is a first output from a first control module, and wherein the second force command is a second output from a second control module.
32. The vehicle of claim 17, further comprising determining the blend ratio to avoid exceeding a wheel travel threshold of the plurality of wheels.
33. At least one non-transitory computer-readable medium comprising instructions thereon that, when executed by at least one processor, perform the method of claim 17.
Description
BRIEF DESCRIPTION OF DRAWINGS
[0007] The accompanying drawings are not intended to be drawn to scale. In the drawings, each identical or nearly identical component that is illustrated in various figures may be represented by a like numeral. For purposes of clarity, not every component may be labeled in every drawing. In the drawings:
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DETAILED DESCRIPTION
[0015] In conventional vehicles, a vehicle suspension may be responsible for control of a plurality of vehicle motion parameters. Such vehicle motion parameters may include, but are not limited to, roll, heave, pitch, and twist. In some cases, an active suspension may be employed in a vehicle to provide for active control of one or more of these or other vehicle motion parameters. In some cases, active suspension systems that deliver excellent comfort isolation control on small road inputs can suffer poor performance on large road events (e.g., hills, dips, large bumps, etc.) where, for example, a magnitude of the road event exceeds the capacity of the suspension travel. In some cases, an active suspension system may be employed to isolate the vehicle body from external disturbances (e.g., skyhook control), such that a center of mass of the vehicle body remains at a substantially constant or effectively substantially constant elevation despite external disturbances. Such vehicle control may sometimes result in a wheel of the vehicle reaching end of travel (e.g., exceeding a wheel travel threshold), because the isolation control uses an excessive amount of suspension travel to compensate for the large magnitude road event. Reaching the end of travel may result in noise or an abrupt transfer of force to the vehicle body, which may be undesirable. Accordingly, the inventors have recognized that there is a need for isolation control of a vehicle body using an active suspension system to adapt to the conditions present on a road surface to avoid reaching end of suspension travel. The inventors have further recognized the benefits of a vehicle body isolation control methodology that is robust to work effectively on a wide range road surfaces and for a wide variety of road events to maintain user comfort while avoiding the suspension system reaching an end of travel.
[0016] In addition to the above, the inventors have appreciated the challenges of trying to predict and compensate future movement of a vehicle, for example, with limited to no forward-looking information. Conventional suspension systems may apply a constant control methodology that may reduce the overall performance of the suspension system while remaining applicable to effectively all conditions that may be encountered on a road network. In contrast, the inventors of the instant application have recognized the benefits of a control methodology that adapts to different road conditions using current information (e.g., with limited to no forward-looking information) to improve suspension performance. In particular, the inventors have recognized the benefits of providing enhanced vehicle body isolation for a greater variety of road conditions, for example, by using previously measured information related to a road surface. For example, the inventors have recognized that a suspension system control methodology that operates well for isolating small bumps may not work well when encountering, e.g. hills or inclines. According to this example, an isolation control module, operating without forward-looking information, may initially mistakenly conclude the hill is a small bump based on current information, resulting in a suspension response that is ultimately not appropriate for a hill (e.g., reaching end of travel, upsetting the vehicle body, etc.). The inventors have recognized this problem, and the systems and methods of exemplary embodiments herein provide a technical solution to suspension control for improved isolation control in a variety of road conditions. However, it should be understood that instances in which the systems and methods disclosed herein are implemented with vehicles aided by forward-looking sensors during a current traverse of a road, or by information about the road ahead of the vehicle collected during previous traverses of the road, are also contemplated.
[0017] In view of the foregoing, the inventors have recognized the benefits of a vehicle control system that dynamically blends vehicle body isolation and road tracking control outputs of the vehicle control system. On road surfaces with small magnitude road events (e.g., events causing a suspension response less than reaching an end of travel) the blend may be biased towards vehicle body isolation control (e.g., skyhook control), which may increase passenger comfort by reducing or eliminating overall vehicle body motion due to vibrations applied to the vehicle body by disturbances from various types of road events. On road surfaces with large magnitude road events (e.g., events which may cause a suspension response equal to or greater than reaching an end of travel) the blend may be biased towards road tracking control (e.g., groundhook control). Road tracking control may aim to maintain the vehicle body at a determined elevation relative to the road surface profile. Road tracking control may prevent end of travel events within the active suspension. The blend between vehicle body isolation control (e.g., skyhook) and road tracking control (e.g., groundhook), may result in a controller that may dynamically shift between stiff vehicle body isolation control (e.g., stiff skyhook) where vehicle body isolation is favored more heavily and weak vehicle body isolation control (e.g., weak skyhook) where road tracking control is favored more heavily. Such a vehicle control system may deliver robust comfort control on a range of road surfaces and may help to avoid the occurrence of end of suspension travel events without significantly diminishing user comfort. Additionally, such a vehicle control system may be simple to implement and, in some embodiments, may not necessarily require direct monitoring of the position of the suspension system relative its range of motion to achieve the desired reduction in the number and/or intensity of end of travel events.
[0018] In some embodiments, a vehicle may include a vehicle body, a plurality of wheels, and an active suspension system operatively coupled to the plurality of wheels and the vehicle body. The active suspension system may include at least one actuator configured to apply active forces to at least one of the plurality of wheels in at least one mode of operation. The vehicle may include at least one processor configured to control the active suspension system, and in particular the active and/or damping forces applied by the active suspension system between the wheel(s) and the vehicle body to affect the response of the vehicle chassis or body while driving along a road surface. In some embodiments, the at least one processor may operate a first suspension control module and a second suspension control module. The suspension control modules may be operated based on one or more inputs, where an output of each suspension control module is a force command usable to command the at least one actuator to apply active and/or damping forces between the vehicle body and wheel(s). The first suspension control module may be an isolation control module and may provide a first force command based at least in part on an input including a vehicle body parameter (e.g., vehicle body velocity). Accordingly, the first force command may be a force command intended to avoid vehicle body motion as the vehicle encounters road features (e.g., bumps, potholes, etc.) that may cause motion of the vehicle body (e.g., skyhook control). The second suspension control module may be a tracking control module and may provide a second force command based at least in part on an input including vehicle body parameter(s) and/or suspension parameter(s) (e.g., suspension velocity). Accordingly, the second force command may be a force command intended to maintain the vehicle body at a fixed position (in the vertical direction) relative to the ground with limited isolation relative to external disturbances (e.g., groundhook control or weak skyhook control).
[0019] The inventors have recognized that multiple force commands (e.g., the above noted first force command and second force command) may be blended by the at least one processor according to a blend ratio to produce a blended (e.g., third) force command that may be used to operate the at least one actuator of the active suspension system. In some embodiments, the blend ratio may be varied based on the output of the first suspension control module to vary a relative weighting of e.g., the first and second forces used to provide the blended (e.g., third) force. For example, a large increase in the output of the first force controller module may be associated with a large magnitude disturbance like a hill rather than a lesser magnitude disturbance like a bump, and accordingly the blend ratio may be adjusted to more heavily weight the output second force from the second suspension control module to provide the blended force command. In this manner, a combination of isolation control and ground tracking control may be employed dynamically and automatically based on the output of an isolation control module to increase overall isolation performance while helping to avoid, or eliminate, undesirable events like reaching end of wheel travel (e.g., exceeding a threshold wheel travel).
[0020] According to exemplary embodiments disclosed herein, an isolation control module (e.g., a first control module) may be tuned to provide a first level (e.g., a maximum) isolation of the vehicle chassis or body from road inputs. The control goal of the isolation control module may be to avoid the vertical acceleration of the vehicle body for one or more motion parameters of the vehicle body (e.g., heave, pitch, roll, etc.). Such isolation control may be known as skyhook control. Skyhook control may be implemented to keep the vehicle body flat while absorbing road inputs with the suspension travel. In some implementations, when there is sufficient suspension travel to allow for the force commands requested by the isolation control module, this control strategy may work well in an active suspension system. However, as discussed above, during large road inputs this type of control module may result in excessive suspension travel, creating vulnerability to end stop impacts (e.g., a wheel reaching an end of suspension travel). In some embodiments, a suspension travel range for a vehicle may be 7 cm (a total of 14 cm suspension travel from end to end). In other embodiments, any suspension travel range may be employed on a vehicle including travel ranges greater than or less than 7 cm. A tracking control module (e.g., a second control module) may be tuned to include some groundhook control, providing reduced levels of isolation of road inputs for the vehicle body as compared to the isolation control module. In contrast, groundhook control may work to keep the vehicle body at a set distance from the underlying road surface. Thus, in some embodiments, the tracking control module may be configured to deliver a moderate level of vehicle body isolation to road inputs, but with reduced suspension travel. In some embodiments, to avoid abrupt transitions in suspension control, the contribution of the groundhook control may be made less abrupt by use of a non-linear gain curve. Additionally, in some embodiments, the tracking control module may have greater damping provided in rebound, compared to compression.
[0021] It should be noted that while an isolation control module and tracking control module may be described herein as implementing skyhook control or groundhook control, respectively, in some embodiments control modules may implement a blend of skyhook control and groundhook control. In some such embodiments, an isolation control module may more heavily weight skyhook control compared to groundhook control. In some embodiments, a tracking control module may more heavily weight groundhook control compared to skyhook control.
[0022] To help implement the relative weighting of the different suspension control modules, the inventors have recognized the benefits of a blending module including appropriate decision logic that blends the outputs of the isolation and tracking controller modules. The blend of the outputs of the two control modules may be, for example, determined by monitoring the magnitude and frequency characteristics of the isolation control force. This methodology relies on the property that the output of the isolation control module is strongly correlated with suspension travel. When the isolation control module outputs (e.g., force commands) are small or short in duration full isolation control may be implemented. However, when the isolation control module outputs (e.g., force commands are large, a prolonged period of tracking control may be implemented according to a blend ratio. The blend ratio may be, for example, formulaic and computed automatically, based on the information from the isolation control module and/or other inputs regarding the vehicle. In this manner, the overall control of an active suspension of a vehicle may change in real time to adjust to isolating small road features (e.g., bumps, potholes, etc.) or compensating for large road features (e.g., hills) while avoiding undesirable events like reaching end of wheel travel (e.g., exceeding a wheel travel threshold). While embodiments herein describe an isolation control module and a tracking control module, the methodology described herein may be applicable to combining any plurality of control module outputs. That is, embodiments described herein may be applicable to a wide variety of control module combinations associated with various parameters.
[0023] In some embodiments, to represent transitioning between an isolation control module and a tracking control module, a blend ratio may be employed. In some embodiments, the blend ratio may be a value representing the contributions of the outputs from one or more of the control modules to an overall force command. For example, a blend ratio may be a ratio of tracking control to isolation control, where the blend ratio may be between or equal to 0 and 1 in some embodiments. In such an embodiment, 0 may indicate full isolation module control (e.g., an overall force command output is equal to the isolation control module force command output) while 1 indicates full tracking module control (e.g., an overall force command output is equal to the tracking control module force command output). Of course different ranges for a blend ratio both greater and less than those noted above may also be used.
[0024] In some embodiments, a blend ratio may be tuned via a notch filter, PI filter and/or dead-zone parameters described further herein. Such modifiers may shape the desired sensitivity to different frequency and magnitude content for the different control modules. In some embodiments, the blend ratio may be employed to create a linear blend of tracking control module and isolation control module output forces to generate an overall force command. In some cases, this may create a composite force signal that delivers a robust comfort mode on a variety of road surfaces, while reducing or minimizing end of travel events. In other embodiments, the blend ratio may be non-linear, polynomial, or represent another relationship to combine the outputs of two controllers into an overall output. For example, in some embodiments the blend ratio may represent a weighting or scale between the force commands of two controllers to generate an overall force command. The blend ratio value may vary linearly based on a first control module output, may vary non-linearly based on a first control module output, and/or may vary based on another function of the first control module output.
[0025] In some embodiments, a raw blend ratio may vary rapidly as it is a function of the instantaneous isolation force command. Accordingly, the inventors have recognized the benefits of suppressing repeated cycling between full tracking and full isolation control with a hit/hold module. In some embodiments, the hit/hold module may set the blend ratio to a predetermined level for a threshold period of time when a threshold output from a first control module is detected. For example, a hit/hold module may set a blend ratio to provide for full tracking state (e.g., with zero contribution from the isolation control module) for a suitable period of time during larger events (e.g., greater than or equal to 1 second). In some embodiments, the blend ratio may be further smoothed to avoid repeated cycling by implementing a low-pass filter. The low-pass filter may remove high frequency content that may be undesirable to obtain a filtered blend ratio that is used to determine the overall blended force output.
[0026] In some embodiments, inputs to various control modules described herein may be provided by one or more sensors onboard a vehicle or from on-board or remote databases. In some cases, multiple sensors and/or redundant sensors may be employed to provide information (e.g., current and/or preview information) from which a force command may be determined by a control module (e.g., via proportional, integral, and/or derivative control). Sensors may provide information associated with different components of the vehicle, including e.g., wheels, suspension components, vehicle body components, user interface components, transmission components, engine components, etc. In some embodiments, one or more accelerometers may be employed to provide acceleration information regarding a vehicle component. For example, an accelerometer may be disposed on the vehicle body which may be provide vehicle body acceleration information or vehicle body velocity information (e.g., via the integral of the acceleration). In some embodiments, information from one or more accelerometers on the vehicle body may be employed to determine inertial heave, pitch and roll velocity of the vehicle body, each of which are parameters that may be employed for skyhook control. As another example, one or more accelerometers may be disposed on one or more components of a vehicle suspension and/or wheel assembly and may be configured to provide suspension acceleration information (e.g., in a direction of travel such as a vertical direction) and suspension velocity information (e.g., via the integral of the acceleration). In some embodiments, information from one or more accelerometers on the suspension may be employed to determine suspension heave, pitch and roll velocity with respect to the road surface, each of which are parameters that may be employed for groundhook control. Other sensors may also be employed, including encoders, potentiometers, and/or other appropriate types of sensors on any appropriate portion of a vehicle to sense position, velocity, and/or acceleration information of the associated portion of the vehicle. In some embodiments, a suspension actuator may provide feedback information to a control module regarding its force output, position, velocity, and/or acceleration. In view of the above, any suitable inputs and sensors may be employed as inputs for controllers described herein, as the present disclosure is not so limited.
[0027] In some embodiments, control modules described herein may be vehicle level control modules. That is, the control modules may output an overall force command for the suspension system to execute. A suspension may include one or more actuators, and this overall force command may be allocated to individual actuators to achieve the overall force command and desired overall response of the vehicle body. In some embodiments, methodologies described herein may be applicable to control of a vehicle at a per-corner or per-actuator level following the blending process described according to exemplary embodiments herein. Corresponding to the described vehicle level control, in some embodiments inputs to the control modules described herein may also be at the vehicle level. For example, in some embodiments, information from individual sensors (e.g., associated with an individual wheel or actuator) may be combined with information from other sensors to provide overall information regarding the motion of the overall vehicle body or overall vehicle suspension system. For example, individual inputs regarding a suspension system associated with a single wheel may be averaged with the other wheels of the vehicle to obtain a per-corner average input that is provided to a vehicle level controller. Any suitable method of combining information from multiple sensors may be employed to obtain overall information provided to a control module, including, but not limited to, summing, averaging or other matrix multiplication. According to some embodiments herein, a control methodology including a blend ratio may be implemented for controlling heave and/or pitch of a vehicle body. In some embodiments, an overall force command may be configured to modify the heave and/or pitch motion of the vehicle body, and the overall force command may be allocated to individual actuators to achieve the overall control objective. In other embodiments control methodologies described herein may be employed to control other vehicle motion parameters, such as vehicle body roll, as the present disclosure is not so limited.
[0028] In some embodiments, a vehicle may include a user interface through which the user may provide user input to affect the control of the vehicle. For example, a user interface may include a touch screen, buttons, switches, microphone (e.g., for receiving voice commands), etc. In some embodiments, the user interface may be configured to receive input from a user that may be employed to update one or more parameters for control of the vehicle. For example, in some embodiments, the user interface may be configured to receive user input. The blend ratio may then be determined at least in part using the user input as discussed herein. According to such an example, a user may provide input regarding an operating mode selection (e.g., comfort, sport, etc.). Based on the mode selection, the determination of the blend ratio may change. In a comfort mode, for example, the blend ratio determination may be set to favor more of an isolation control mode to increase vehicle body isolation. In a sport mode, for example, the blend ratio determination may be set to favor more of a tracking control mode to introduce increased motion to the vehicle body to more closely track variations in the road surface height to provide increased driving feedback, e.g., more of a sports car feel. In some cases, a formula for the blend ratio determination may be updated and/or one or more parameters in a formula for the blend ratio determination may be updated based on the received user input. In some embodiments, a formula for the blend ratio determination may be updated and/or one or more parameters in a formula for the blend ratio determination may be updated based on information from a user and/or an identification of a driver and/or occupants of a vehicle. For example, an occupant may be prone to motion sickness such that the formula is updated when the occupant is identified to favor a control strategy that avoids motions of the vehicle body associated with motion sickness. In some embodiments, a vehicle control system may determine an identity of a driver or occupant by detecting a credential (e.g., key, phone, RFID etc.) associated with a particular driver or occupant. In some embodiments, a driver or occupant may identify themselves (e.g., via user input at a graphical user interface). In some embodiments, a driver or occupant my be identified by detection of a biometric by a biometric sensor (e.g., facial recognition by camera, fingerprint by fingerprint sensor, etc.). Other methods of identifying a driver and/or occupant may also be implemented in some embodiments.
[0029] Alternatively or additionally, in some embodiments, a vehicle may include at least one forward-looking sensor. The at least one forward-looking sensor may be configured to obtain forward-looking information regarding upcoming road conditions, road events, or road features. In some embodiments, at least one forward-looking sensor may include one or more of a LIDAR sensor, camera, radar sensor, ultrasonic sensor, terrain-based navigation system and/or any other suitable forward-looking sensor. In some embodiments, a blend ratio may be determined based on forward-looking information obtained by a forward-looking sensor. For example, the forward-looking information may be indicative of a small road feature (e.g., bump or pothole) that can be fully compensated for by an isolation control module. According to this example, the blend ratio may be determined to favor the isolation control module. As an alternative example, the forward-looking information may be indicative of a large road feature (e.g., a hill) that cannot be fully compensated for by the isolation control module. According to this example, the blend ratio may be determined to incorporate additional output from a tracking control module into an overall output (e.g., force command). In this manner, forward-looking information may be optionally incorporated into the methodologies described herein to improve the amount of vehicle body isolation that may be provided while still adapting to changing road conditions that cannot be fully compensated for by an isolation control module.
[0030] According to exemplary embodiments herein, skyhook may refer to control seeking to isolate a vehicle body from external disturbances regardless of the profile of the underlying road surface. For example, under perfect or effectively perfect skyhook control a vehicle body may experience no accelerations or effectively no accelerations in roll, pitch, and/or heave. It should be understood that when skyhook control is implemented by an actual active suspension system, depending on the magnitude and frequency of a road input to a vehicle from a corresponding feature on a road surface, the active suspension system may only mitigate a portion of the road input such that the vehicle body is still subject to some force/acceleration due to the road input. However, this force/acceleration may be reduced as compared to situations in which the skyhook control is not applied.
[0031] According to exemplary embodiments herein, groundhook may refer to control seeking to maintain a fixed distance or an effectively fixed distance between a vehicle body and the underlying road surface. For example, the distance between a wheel and the vehicle body under perfect groundhook control may remain constant. It should be understood that when groundhook control is implemented by an actual active suspension system, depending on the magnitude and frequency of a road input to a vehicle from a corresponding feature on a road surface, the active suspension system may not maintain a constant distance between the vehicle body and road surface. Instead, some variations from the target distance may be experienced, though these variations from the target distance may be mitigated as compared to situations in which the groundhook control is not applied.
[0032] Variations of skyhook and groundhook may be implemented in some embodiments. For example, stiff may refer to the control module tending more toward the perfect form of its control goal, whereas weak may refer to the controller being weaker and tending more toward the other form of control. For example, a stiff skyhook controller may attempt to implement perfect skyhook control as much as possible for a given active suspension system (e.g., provide a maximum level of vehicle body isolation for the active suspension system). In some embodiments, stiff skyhook may implement skyhook control down to frequencies as low as 0.2 Hz. As an alternative example, a weak skyhook controller may implement some skyhook control but may also implement some groundhook control. In some embodiments, weak skyhook may implement skyhook control down to frequencies as low as 1 Hz with gains less than those of the stiff skyhook controller. In some embodiments a tracking control module may be a weak skyhook controller, implementing some groundhook control while retaining some isolation of the vehicle body. Skyhook and groundhook control and their variations may be implemented for at least partially controlling heave and/or pitch of the vehicle, in some embodiments. In some embodiments, skyhook and groundhook control may also at least partially control roll of the vehicle as well.
[0033] According to embodiments herein, a vehicle may include a vehicle body and one or more wheels (e.g., four wheels) supporting the vehicle body. The vehicle may include an active suspension system operatively interposed between the one or more wheels and the vehicle body. The active suspension system may be configured to adjust a normal force between any one or more of the wheels of the vehicle and the ground (e.g., via a tire) by applying force between the wheel and a chassis or body of the vehicle. The active suspension system may be configured to generate extension or compression of a suspension assembly main spring, in some embodiments. The forces applied between the wheels and the vehicle body may be transferred to the vehicle body through the active suspension system, allowing the active suspension system to control one or more motion parameters of the vehicle body. Vehicle motion parameters, may include, but are not limited to, rotations about various axes (e.g., roll and pitch). Vehicle motion parameters may also include, but are not limited to, translation along various axes (e.g., translation along a vertical z-axis otherwise referred to as heave). In some embodiments, three Cartesian principal axes may be established relative to a supporting surface underneath a vehicle (e.g., a plane). In some embodiments, the three cartesian principal axes may be established relative to a direction of local gravity when the vehicle is disposed on level ground. As discussed further below, the active suspension system may control one or more vehicle motion parameters of the vehicle body of the vehicle by applying active or passive forces between the vehicle body and one or more wheels. Changing the force output by the active suspension system may alter the one or more vehicle motion parameters. In some embodiments, a vehicle may include at least one processor configured to execute computer readable instructions stored in associated volatile or non-volatile memory that when executed perform any of the methods disclosed herein. In some embodiments, the at least one processor may be configured to control the active suspension system to control the one or more vehicle motion parameters of the vehicle body. In some embodiments, the at least one processor may be operated as a part of one or more control modules of the vehicle.
[0034] In some embodiments, an active suspension system is operatively interposed between one or more wheels and a vehicle body of a vehicle. The active suspension system may include one or more actuators associated with the one or more wheels. For example, the active suspension system may include at least one actuator at each wheel of the vehicle. In some embodiments, an actuator of an active suspension system comprises a hydraulic device operatively coupled with an electric motor/generator. The term hydraulic device may refer to either a hydraulic motor, a hydraulic pump, a hydraulic motor being operated as a pump, and/or a hydraulic pump being operated as a hydraulic motor. A hydraulic device may be capable of providing fixed displacements, variable displacements, fixed velocities, and/or variable velocities as the disclosure is not limited to any particular device. Appropriate types of hydraulic devices may include, but are not limited to, gerotor pumps, vane pumps, gear pumps, screw pumps, and/or any other appropriate type of hydraulic device. The term electric motor/generator may refer to either an electric motor and/or an electric generator. In either case, in some embodiments, an associated hydraulic device may drive the electric motor/generator such that it functions as a generator to provide damping to a hydraulic actuator while also generating electrical energy in at least one mode of operation. The electric motor/generator may also drive the hydraulic device as a pump to create a flow of fluid to drive operation of the actuator and/or resist movement of a piston of the actuator in at least one mode of operation. Depending on the particular embodiment, an electric motor/generator may be operated only as a generator, only as a driven motor, and/or as both depending on the particular application. Appropriate types of electric motor/generators may include, but are not limited to, a brushless DC motor, a brushed DC motor, an induction motor, a dynamo, or any other type of device capable of converting electricity into rotary motion and/or vice-versa. The actuator may be configured to apply active forces and/or passive forces (which may also be referred to as damping forces herein) between a wheel of the vehicle and the chassis or body of the vehicle. The application of active and/or passive forces may be employed to control a motion of the vehicle body and/or wheel. In some embodiments, an active suspension system may include one or more physical springs or dampers, which may apply passive forces to the one or more wheels and the chassis or the body of the vehicle.
[0035] While an actuator of an active suspension system disclosed above is described as including a hydraulic device and an electric motor/generator, the current disclosure is not limited to any particular type of active suspension system. Accordingly, other appropriate types of active suspension systems including different types of actuators may also be used. For example, electrical actuators such as solenoid-based actuators, actuators using linear electric motors, hydraulic actuators associated with a central pressure source (e.g., a pump) and associated valves, and/or any other appropriate type of actuator capable of being used to operate an active suspension system may be used with the various embodiments disclosed herein as the disclosure is not so limited.
[0036] As used herein an active force is a force that is generated by a vehicle suspension system, and that is oriented at least partially in the direction of motion at the point of application of the force on an associated structure. For example, an active force may include applying force to a wheel in a direction of motion of the wheel via an active suspension system actuator. As used herein a passive force, damping force, or other similar term may be a force that may be applied on a structure in a direction that at least partially opposes the motion at the point of application of the force. For example, a suspension system actuator may generate a damping force (e.g., forces that resist movement of a wheel and/or vehicle body) in response to a wheel being moved by a road feature, though it is noted that an active suspension system may also apply damping forces that resist motion of an associated mass. For example, in some embodiments an actuator may apply a damping force in a direction that is at least partially opposite a direction of motion of the component being damped. According to exemplary embodiments described herein, certain vehicle systems (e.g., active suspension systems) may apply active and/or passive forces depending on a mode of operation of the vehicle system. For example, an active suspension system may be operated in a first mode where an actuator is employed to apply active forces to one or more portions of the vehicle (e.g., a vehicle body and wheel of the vehicle) and in a second mode where only passive forces are applied in response to external force inputs on the vehicle. In some operational modes, vehicle systems, including active suspension systems, may generate both active and passive forces.
[0037] As used herein, a road event is any event that may occur while a vehicle is traveling on a roadway. In some embodiments, a road event may include encountering a road feature. A road feature is any non-nominal road condition that may be encountered by a vehicle while traveling on a road surface. For example, a road feature may include, but is not limited to rough pavement, potholes, manhole covers, storm drains, bumps, uneven lanes, variable road materials (e.g., dirt, gravel, pavement, concrete, metal, etc.), road coverings (e.g., snow, ice, salt, sand, dirt, water, etc.), and/or any other appropriate feature that may involve changes in the forces applied to a vehicle traversing a road surface. In some embodiments, a road event may include a turn (e.g., traversing a corner). In some embodiments, a road event may include a braking event. A braking event is any instance or period of time in which one or more brakes of a vehicle are applied, e.g., to decelerate or stop the vehicle or the vehicle is decelerated by applying a drag to one or more rotating components in the drive. A braking event may have any duration, as the present disclosure is not so limited. In some embodiments, a braking event may include a single application of the brakes or multiple applications of the brakes, as the present disclosure is not so limited.
[0038] According to exemplary embodiments described herein, a vehicle control system, control module, or other appropriate system may be operated by one or more processors. The one or more processors may be configured to execute computer readable instructions stored in volatile or non-volatile memory. The one or more processors may communicate with one or more actuators associated with various systems of the vehicle (e.g., braking system, active suspension system, steering system, rear steering system, driver assistance system, etc.) to control activation and movement of the various systems of the vehicle. The one or more processors may receive information from one or more sensors that provide feedback regarding the various systems of the vehicle. For example, the one or more processors may receive position information regarding the vehicle from a Global Navigation Satellite System (GNSS) or other positioning system. The sensors on board the vehicle may include, but are not limited to, wheel rotation speed sensors, accelerometers, inertial measurement units (IMUs), optical sensors (e.g., cameras, LIDAR), radar, suspension position sensors, gyroscopes, and/or any other appropriate type of sensor. In this manner, the vehicle control system may implement proportional control, integral control, derivative control, a combination thereof (e.g., PID control), or other control strategies of various systems of the vehicle. Other feedback or feedforward control schemes are also contemplated, and the present disclosure is not limited in this regard. Any suitable sensors in any desirable quantities may be employed to provide feedback information to the one or more processors. Information from sensors may be employed in coordination with desirable processing techniques (e.g., machine vision). The one or more processors may also communicate with other controllers, computers, and/or processors on a local area network, a controller area network (CAN), wide area network, a cloud-based database, or internet using an appropriate wireless or wired communication protocol. It should be noted that while exemplary embodiments described herein are described with reference to a single processor, any suitable number of processors may be employed as a part of a vehicle, as the present disclosure is not so limited.
[0039] It should be understood that as used herein a vehicle body may refer to any appropriate type of vehicle body construction including but not limited to: unitary, unibody, or monocoque vehicle body constructions; vehicle bodies including a separately formed vehicle chassis attached to the other potions of the vehicle body; and/or any other appropriate type of vehicle body construction that functions as a sprung mass attached to a suspension system of a vehicle. Additionally, it should be understood that references to a vehicle body disclosed herein may be replaced with a vehicle chassis and that, where context allows, references to operating parameters and physical characteristics of the vehicle body and vehicle chassis may be used interchangeably with one another in any of the embodiments disclosed herein as the disclosure is not so limited.
[0040] Turning to the figures, specific non-limiting embodiments are described in further detail. It should be understood that the various systems, components, features, and methods described relative to these embodiments may be used either individually and/or in any desired combination as the disclosure is not limited to only the specific embodiments described herein.
[0041]
[0042] As shown in
[0043] As shown in the embodiment of
[0044] As shown in
[0045] According to the embodiment of
[0046] It should be noted that the vehicle of
[0047] In some embodiments as shown in
[0048] In some embodiments an active suspension system 107 may sense several parameters relating to the road, wheel, vehicle body movement, and other parameters that may benefit other vehicle subsystems. Such information may be transmitted from the active suspension system to the vehicle control system 200 and the other subsystems via the communication system 201. Other vehicle subsystems may alter their control based on information from the active suspension system. As such, bidirectional information may be communicated between the active suspension system 107 and other subsystems, and control of both the active suspension system and the other vehicle systems may be provided based at least partially on this information transfer. In some embodiments, the communication system 201 may include a transceiver configured to send or receive information. In some embodiments, the transceiver may be configured to receive the reference road information from another vehicle or cloud service (e.g., one or more servers). The transceiver may be configured to communicate wirelessly via any suitable wireless protocol, as the present disclosure is not so limited.
[0049] In some embodiments, the vehicle control system 200 may include a forward-looking sensor 116. The forward-looking sensor may sense road characteristics, road features, or objects in front the vehicle 100, which may be provided to the vehicle control system (e.g., at least one processor of the vehicle control system) as forward-looking road information. In some embodiments, the forward-looking sensor 116 may include one or more of a LIDAR sensor, camera, radar sensor, ultrasonic sensor, or any other suitable forward-looking sensor. In some embodiments, the forward-looking information obtained by the forward-looking sensor may be provided to a processor to be used in control of the vehicle (e.g., determination of a blend ratio). In the embodiment of
[0050] In some embodiments, a vehicle may include a user interface 118 through which the user may provide user input to affect the control of the vehicle. In the embodiment of
[0051] In some embodiments, the vehicle control system 200 is configured to control the various vehicle subsystems including the active suspension system 107. In particular, as will be discussed further below with reference to
[0052]
[0053] As shown in
[0054] According to the example of
[0055] As shown in
[0056]
[0057] In the embodiment of
[0058] As discussed previously, the inventors have recognized the benefits of a vehicle control system that dynamically blends the isolation control shown in
[0059]
[0060]
[0061] The output of the isolation control module 208 may be employed by the vehicle control system 200 to determine a blend ratio in block 212. In some embodiments, a blend ratio may be a value between 0 and 1, where the value represents a relative contribution of the tracking control module 210 to an overall blended output. As shown in block 216, an overall blended force 218 may be determined according to the formula F1*(1k)+F2*k, where k is the blend ratio, F1 is the output of the isolation control module 208, and F2 is the output of the tracking control module 210. For example, a blend ratio of 0 may represent full control by the isolation control module 208 (e.g., 100% of the blended force output is contributed by the output of the isolation control module). Alternatively, a blend ratio of 1 may represent full control by the tracking control module 210 (e.g., 100% of the blended force output is contributed by the output of the tracking control module). In some embodiments, the blend ratio may be represented as an antecedent and a consequent. In such an embodiment, the antecedent may be between 0 and 1, and the consequent may be between 0 and 1, where the antecedent and consequent sum to 1. The antecedent of the blend ratio may be proportional to a contribution of the isolation control module 208 (or another controller in other embodiments). The consequent may be proportional to a contribution of the tracking control module 210 (or another controller in other embodiments). For example, the blend ratio may be represented as an antecedent of 0.25 and a consequent of 0.75. In such an example, the isolation control module 208 may contribute 25% of an overall blended output, and the tracking control module 210 may contribute 75% of an overall blended output. A blend ratio may be represented as any appropriate value or relationship that may be applied to determine a combined overall output, as the present disclosure is not so limited.
[0062] According to some embodiments as shown in
[0063] In some embodiments as shown in
[0064] In some embodiments as shown in
[0065] In some cases, the inventors have recognized that the raw blend ratio determined in block 212 may vary rapidly, as it is a function of the instantaneous isolation force command from the isolation control module 208. To suppress repeated cycling between full tracking and full isolation control, in some embodiments in block 214 a hit/hold module may be applied to the raw blend ratio determined in block 212. The hit/hold module may enforce a predetermined blend ratio if a road event longer than a threshold duration is detected. In some embodiments, the hit/hold module may maintain the blend ratio greater than a threshold blend ratio for a predetermined time period (e.g., the hit/hold module may enforce a floor for the blend ratio for the predetermined time period). For example, the hit/hold module may assign the blend ratio a value of 1 if a road event longer than a threshold duration is detected. In some embodiments, the threshold duration may be one second. In some embodiments, the predetermined time period may be approximately one second, though time periods both greater and less than one second may also be used as the disclosure is not so limited. Relating to prior examples herein, the road features of
[0066] The blended force 218 output of the process described with reference to
[0067]
[0068] In block 406, a blend ratio is determined by a blending module, for example, based on the vehicle body isolation force command. In some embodiments, the blend ratio may be proportional to the vehicle body isolation force command from block 402 as described previously above. In some embodiments, the blend ratio may vary between 0 and 1, and may represent a ratio or weighting factor. In block 408, an overall force command is determined based at least partly on the blend ratio, vehicle body isolation force command, and road tracking force command. For example, in some embodiments, the vehicle body isolation force command and the road tracking force command may each make of a percentage component of the overall force command based on the blend ratio. For example, if the blend ratio were 0.25, the overall force command would be a sum composed of 25% of the road tracking force command and 75% of the vehicle body isolation force command. According to this example, the overall force command may include a first portion and a second portion, where the first portion is based on the blend ratio and the vehicle body isolation force command, and the second portion is based on the blend ratio and the road tracking force command. In some embodiments, the first portion may be proportional to the blend ratio and the vehicle body isolation force command, and the second portion may be proportional to the blend ratio and the road tracking force command. The overall force command may be representative of a force requested by the vehicle control system to achieve a desired motion of the vehicle body (e.g., a blend of isolation control and tracking control). In block 410, at least one actuator of the active suspension system may be commanded to apply an intervening force between at least one of a plurality of wheels of the vehicle and a vehicle body of the vehicle based at least partly on the overall force command.
[0069] Optionally, the method of
[0070]
[0071] In block 508, a blend ratio is determined based on the first output. In some embodiments, the blend ratio may be proportional to the first output from block 504. In some embodiments, the blend ratio may vary between 0 and 1, and may represent a ratio or weighting factor. In block 510, a force command is determined based at least partly on the blend ratio, first output, and road second output. For example, in some embodiments, the first output and the second output may each make of a percentage component of the force command based on the blend ratio. For example, if the blend ratio were 0.50, the force command would be a sum composed of 50% of the first output and 50% of the second output. According to this example, the force command may include a first portion and a second portion, where the first portion is based on the blend ratio and the first output, and the second portion is based on the blend ratio and the second output. In some embodiments, the first portion may be proportional to the blend ratio and the first output, and the second portion may be proportional to the blend ratio and the second output. The force command may be representative of a force requested by the vehicle control system to achieve a desired motion of the vehicle body (e.g., a blend of the two controllers). In block 512, at least one actuator of the active suspension system may be commanded to apply active force between at least one of a plurality of wheels of the vehicle and a chassis or body of the vehicle based at least partly on the force command.
[0072] Optionally, the method of
[0073] The above-described embodiments of the technology described herein can be implemented in any of numerous ways. For example, the embodiments may be implemented using hardware, software or a combination thereof. When implemented in software, the software code can be executed on any suitable processor or collection of processors, whether provided in a single computer or distributed among multiple computers. Such processors may be implemented as integrated circuits, with one or more processors in an integrated circuit component, including commercially available integrated circuit components known in the art by names such as CPU chips, GPU chips, microprocessor, microcontroller, or co-processor. Alternatively, a processor may be implemented in custom circuitry, such as an ASIC, or semicustom circuitry resulting from configuring a programmable logic device. As yet a further alternative, a processor may be a portion of a larger circuit or semiconductor device, whether commercially available, semi-custom or custom. As a specific example, some commercially available microprocessors have multiple cores such that one or a subset of those cores may constitute a processor. Though, a processor may be implemented using circuitry in any suitable format.
[0074] Further, it should be appreciated that a computer may be embodied in any of a number of forms, such as a rack-mounted computer, a desktop computer, a laptop computer, or a tablet computer. Additionally, a computer may be embedded in a device not generally regarded as a computer but with suitable processing capabilities, including a Personal Digital Assistant (PDA), a smart phone or any other suitable portable or fixed electronic device.
[0075] Also, a computer may have one or more input and output devices. These devices can be used, among other things, to present a user interface. Examples of output devices that can be used to provide a user interface include printers or display screens for visual presentation of output and speakers or other sound generating devices for audible presentation of output. Examples of input devices that can be used for a user interface include keyboards, and pointing devices, such as mice, touch pads, and digitizing tablets. As another example, a computer may receive input information through speech recognition or in other audible format.
[0076] Such computers may be interconnected by one or more networks in any suitable form, including as a local area network or a wide area network, such as an enterprise network or the Internet. Such networks may be based on any suitable technology and may operate according to any suitable protocol and may include wireless networks, wired networks or fiber optic networks.
[0077] Also, the various methods or processes outlined herein may be coded as software that is executable on one or more processors that employ any one of a variety of operating systems or platforms. Additionally, such software may be written using any of a number of suitable programming languages and/or programming or scripting tools, and also may be compiled as executable machine language code or intermediate code that is executed on a framework or virtual machine.
[0078] In this respect, the embodiments described herein may be embodied as a computer readable storage medium (or multiple computer readable media) (e.g., a computer memory, one or more floppy discs, compact discs (CD), optical discs, digital video disks (DVD), magnetic tapes, flash memories, circuit configurations in Field Programmable Gate Arrays or other semiconductor devices, or other tangible computer storage medium) encoded with one or more programs that, when executed on one or more computers or other processors, perform methods that implement the various embodiments discussed above. As is apparent from the foregoing examples, a computer readable storage medium may retain information for a sufficient time to provide computer-executable instructions in a non-transitory form. Such a computer readable storage medium or media can be transportable, such that the program or programs stored thereon can be loaded onto one or more different computers or other processors to implement various aspects of the present disclosure as discussed above. As used herein, the term computer-readable storage medium encompasses only a non-transitory computer-readable medium that can be considered to be a manufacture (i.e., article of manufacture) or a machine. Alternatively, or additionally, the disclosure may be embodied as a computer readable medium other than a computer-readable storage medium, such as a propagating signal.
[0079] The terms program or software are used herein in a generic sense to refer to any type of computer code or set of computer-executable instructions that can be employed to program a computer or other processor to implement various aspects of the present disclosure as discussed above. Additionally, it should be appreciated that according to one aspect of this embodiment, one or more computer programs that when executed perform methods of the present disclosure need not reside on a single computer or processor but may be distributed in a modular fashion amongst a number of different computers or processors to implement various aspects of the present disclosure.
[0080] Computer-executable instructions may be in many forms, such as program modules, executed by one or more computers or other devices. Generally, program modules include routines, programs, objects, components, data structures, etc. that perform particular tasks or implement particular abstract data types. Typically, the functionality of the program modules may be combined or distributed as desired in various embodiments.
[0081] Also, data structures may be stored in computer-readable media in any suitable form. For simplicity of illustration, data structures may be shown to have fields that are related through location in the data structure. Such relationships may likewise be achieved by assigning storage for the fields with locations in a computer-readable medium that conveys relationship between the fields. However, any suitable mechanism may be used to establish a relationship between information in fields of a data structure, including through the use of pointers, tags or other mechanisms that establish relationship between data elements.
[0082] Various aspects of the present disclosure may be used alone, in combination, or in a variety of arrangements not specifically discussed in the embodiments described in the foregoing and is therefore not limited in its application to the details and arrangement of components set forth in the foregoing description or illustrated in the drawings. For example, aspects described in one embodiment may be combined in any manner with aspects described in other embodiments.
[0083] Also, the embodiments described herein may be embodied as a method, of which an example has been provided. The acts performed as part of the method may be ordered in any suitable way. Accordingly, embodiments may be constructed in which acts are performed in an order different than illustrated, which may include performing some acts simultaneously, even though shown as sequential acts in illustrative embodiments.
[0084] Further, some actions are described as taken by a user. It should be appreciated that a user need not be a single individual, and that in some embodiments, actions attributable to a user may be performed by a team of individuals and/or an individual in combination with computer-assisted tools or other mechanisms.
[0085] While the present teachings have been described in conjunction with various embodiments and examples, it is not intended that the present teachings be limited to such embodiments or examples. On the contrary, the present teachings encompass various alternatives, modifications, and equivalents, as will be appreciated by those of skill in the art. Accordingly, the foregoing description and drawings are by way of example only.