SYSTEMS AND METHODS FOR CONTROLLING STEERING OF A MARINE DRIVE

Abstract

A steering system for a marine drive includes a marine drive, wherein the marine drive is steerable about a steering axis, a steering actuator configured to steer the marine drive to a range of steering positions within a permitted steering range, a first steering sensor configured to sense the steering position of the marine drive and output a first sensed value, a second steering sensor configured to sense the steering position of the marine drive and output a second sensed value and a controller. The controller is configured to calculate a measured steering position for the marine drive based on the first sensed value and the second sensed value, and control the steering actuator based on the measured steering position.

Claims

1. A steering system for a marine drive, the steering system comprising; a marine drive, wherein the marine drive is steerable about a steering axis; a steering actuator configured to steer the marine drive to a range of steering positions within a permitted steering range; a first steering sensor configured to sense the steering position of the marine drive and output a first sensed value; a second steering sensor configured to sense the steering position of the marine drive and output a second sensed value; a controller configured to: calculate a measured steering position for the marine drive based on the first sensed value and the second sensed value; and control the steering actuator based on the measured steering position.

2. The system of claim 1, wherein the measured steering position is calculated as an average of the first sensed value and the second sensed value.

3. The system of claim 1, wherein the measured steering position is a value between the first sensed value and the second sensed value.

4. The system of claim 1, wherein the controller is further configured to detect a fault condition if a difference between the first sensed value and the second sensed value exceeds a difference threshold, wherein the difference threshold is based on a predetermined maximum tolerated uncommanded steering change effectuated in response to the fault condition.

5. The system of claim 1, wherein the controller is further configured to: in response to detecting a fault condition of the first steering sensor or the second steering sensor, redetermine the measured steering position based on only the first sensed value or the second sensed value; and adjust the steering position of the marine drive based on the redetermined measured steering position.

6. The system of claim 5, wherein the controller is configured such that a difference between the first sensed value and the second sensed value does not exceed a difference threshold, wherein the difference threshold is configured such that the steering position of the marine drive is not adjusted by more than a predetermined maximum tolerated uncommanded steering change in response to the fault condition.

7. The system of claim 6, wherein the difference threshold is based on a predetermined maximum tolerated uncommanded steering change effectuated in response to a fault condition.

8. The system of claim 7, wherein the difference threshold is two times the predetermined maximum tolerated uncommanded steering change.

9. The system of claim 7, wherein the predetermined maximum tolerated uncommanded steering change is a 3-degree change in steering angle.

10. The system of claim 1, wherein the controller is further configured to: determine a difference between the first sensed value and the second sensed value; compare the difference to a difference threshold; and detect a fault condition if the difference exceeds the difference threshold.

11. The system of claim 10, wherein the controller is further configured to disable the steering actuator in response to the detection of the fault condition.

12. The system of claim 10, in response to the detection of the fault condition, redetermine the measured steering position based on only one of the first steering sensor or the second steering sensor, operate the steering actuator to automatically change the steering position of the marine drive based on the redetermined measured steering position, wherein the difference threshold is associated with a predetermined maximum tolerated uncommanded steering change in response to the detection of the fault condition.

13. The system of claim 1, wherein each of the first steering sensor and the second steering sensor is a Hall Effect sensor.

14. A method of controlling steering of a marine drive configured to propel a marine vessel, the method comprising: sensing the steering position of the marine drive with a first steering sensor to output a first sensed value; sensing the steering position of the marine drive with a second steering sensor to output a second sensed value; calculating a measured steering position for the marine drive based on the first sensed value and the second sensed value; and steering the marine drive based on the measured steering position.

15. The method of claim 14, wherein the measured steering position is calculated as an average of the first sensed value and the second sensed value.

16. The method of claim 14, wherein the measured steering position is a value between the first sensed value and the second sensed value.

17. The method of claim 14, further comprising detecting a fault condition if a difference between the first sensed value and the second sensed value exceeds a difference threshold, wherein the difference threshold is based on a predetermined maximum tolerated uncommanded steering change effectuated in response to the fault condition.

18. The method of claim 14, further comprising: in response to detecting a fault condition of the first steering sensor or the second steering sensor, redetermining the measured steering position based on only the first sensed value or the second sensed value; and adjusting the steering position of the marine drive based on the redetermined measured steering position.

19. The method of claim 14, further comprising continuing to control steering of the marine drive based on the measured steering position provided that a difference between the first sensed value and the second sensed value does not exceed a difference threshold, wherein the difference threshold is based on a predetermined maximum tolerated uncommanded steering change effectuated in response to a fault condition.

20. The method of claim 19, wherein the difference threshold is two times the predetermined maximum tolerated uncommanded steering change.

21. The method of claim 19, wherein the predetermined maximum tolerated uncommanded steering change is a 3-degree change in steering angle.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0039] The present disclosure is described with reference to the following Figures.

[0040] FIG. 1A is a schematic depiction of a marine propulsion system on a marine vessel according to one embodiment of the present disclosure.

[0041] FIG. 1B is a schematic illustration of another embodiment of a marine propulsion system for a marine vessel according to the present disclosure.

[0042] FIG. 2 is a schematic illustration of measured steering position calculation using two steering sensors indicating two sensed values according to one embodiment of the present disclosure.

[0043] FIG. 3 is a schematic illustration of controlling steering of a marine vessel using two steering sensors according to one embodiment of the present disclosure.

[0044] FIGS. 4-6 are flow charts exemplifying methods of controlling steering of at least one marine drive according to the present disclosure.

DETAILED DESCRIPTION

[0045] The inventor has recognized a need for vessel control systems and methods that provide improved control over steering of the marine vessel when the quality of the steering sensor(s) is poor or when a steering sensor fails. Some steering systems include a primary sensor and a backup sensor so that when a sensor failure occurs and the controller switches from the failed steering sensor to second, backup, steering sensor to control steering. However, switching from the primary sensor to the backup sensor causes a step change in steering position to be effectuated based on a difference between the last valid steering position value outputted by the failed sensor and the steering position value outputted by the backup steering sensor. In some embodiments, the step change when switching between steering sensors can approach an intolerable magnitude, and thus systems may be configured to generate a steering fault when the difference between outputs of the main steering sensor and the backup steering sensor diverge by more than a threshold amount.

[0046] The inventor has endeavored to develop a steering system that utilizes two steering position sensors, where the output of both sensors is utilized for steering control and fault diagnostic purposes unless one of the sensors is faulted. For example, both the first and second sensors may be Hall Effect sensors, potentiometers, or some other sensor type, and in some embodiments the first and second sensors may be different sensor types. The disclosed system and method includes two steering sensors configured to sense the steering position of a single steered element, such as a steerable marine drive, and is configured to calculate a measured steering position for the steerable element based on a first sensed value outputted by a first steering sensor and a second sensed value outputted by a second steering sensor. The measured steering position is then used as a feedback value for controlling steering, where the steering actuator is controlled based on a comparison between a commanded steering position and the measured steering position that is calculated based on the output of the two steering sensors. For example, the measured steering position output may be calculated as an average of the first and second sensed values. In other embodiments, the measured steering position may be determined as a value between the first and second sensed values, which may be calculated or otherwise generated in various ways, such as the output of a filter receiving both sensed inputs.

[0047] The method of combining both sensors improves fault tolerance and resilience of the system while avoiding an increase in steering change magnitude when one of the sensors fails. In response to detecting a fault condition in one of the two steering sensors, the controller redetermines the measured steering position of the marine drive based on only the output of the remaining steering sensor and adjusts the steering position of the marine drive based on the redetermined measured steering position. Since the measured steering position is a value between the first and second sensed positions, the step change in sensed steering position will be less than the step change that would be induced by switching from reliance on only one sensor to reliance on only the other steering sensor. For example, if the measured steering position is an average of the first and second sensed positions, then the step change will be half of that caused by switching from one sensor to the other. Therefore, the inventive system and method have the benefit of increasing the fault tolerance of the system by decreasing the step change in sensed steering position when one of the two sensors experiences a faultand thus reducing the uncommanded steering change effectuated in response to the fault condition.

[0048] In one embodiment, the controller is further configured to detect a fault condition if a difference between the first sensed value and the second sensed value exceeds a difference threshold, wherein the difference threshold is based on a predetermined maximum tolerated uncommanded steering change effectuated in response to the fault condition. In embodiments, where both sensors have a fault and are unusable, the controller may preserve limited navigational capacity wherein steering adjustment is manual.

[0049] Similarly, the disclosed dual sensor system may be incorporated in other types of control systems for controlling rotatable devices to control vessel roll, pitch, and/or yaw. The disclosed method and control system for controlling roll, pitch, and/or yaw of a marine vessel includes sensing a position of the rotatable device with a first sensor to output a first sensed value, sensing the position of the rotatable device with a second sensor to output a second sensed value, calculating a measured position for the rotatable device on the first sensed value and the second sensed value, and controlling movement of the rotatable device based on the measured position. The rotatable device may be a steerable drive, such as an outboard drive, a stern drive, a tolling motor, or the like. In other implementations, the rotatable device may be a steerable rudder, or other steerable device, or may be a trimmable device such as a trim tab, a trim plate, or a trimmable drive. Although the invention is illustrated herein with respect to steering position sensors associated with a steerable marine drive, the inventive system and method with dual position sensors may be applied to sensing and controlling the position of any of the forgoing marine steering and/or trim devices.

[0050] FIGS. 1A and 1B are schematic representations of a propulsion system 100 for a marine vessel 10. The embodiment shown in FIG. 1A includes one rear marine drive 21 positioned at the stern 24, such as attached to the transom of the vessel 10. The single rear marine drive 21 may be mounted along a centerline CL of vessel 10. The single rear marine drive 21 may be, for example, an outboard drive, a stern drive, a pod drive, a jet drive, or any other type of steerable drive. The rear marine drive 21 is steerable to a range of steering angles within a permitted steering range, having a steering actuator 13 configured to rotate the drive 21 about its vertical steering axis 31. The steering axis 31 is positioned at a distance X from the center of turn (COT) 30, which could also be the effective center of gravity (COG). A first steering sensor 44 and a second steering sensor 45 are configured to sense the steering position of the marine drive and each output a sensed value. The first steering sensor 44 outputs a first sensed value and the second steering sensor 45 outputs a second sensed value. The sensed values are communicatively connected to a controller that calculates a measured steering position for the marine drive based on the first and second sensed values and controls the steering actuator 13 to rotate the marine drive 21 based on the measured steering position. Rotating the rear marine drive 21 and effectuating thrust thereby causes rotation of the marine vessel 10 about the effective COT 30.

[0051] The marine vessel 10 is maneuvered, such as according to a user-inputted steering command, by causing the marine drive to rotate about its steering axis 31. The marine drive 21 is rotated in response to an operator's manipulation of the steering wheel 12 or joystick 40, wherein the rotational position of the marine drive 21 is sensed by the first and second steering sensors 44 and 45. The propulsion system 100 may include one or more alternative or additional user input device(s) 40, such as a joystick or a keypad, operable by a user to provide steering input, such as a lateral movement demand input and/or rotational movement demand input.

[0052] The user steering inputs provided at the user input device 40 and/or the steering wheel 12 are received by the control system 33, which may include multiple control devices communicatively connected via a communication link, such as a CAN bus (e.g., a CAN Kingdom Network), to control the propulsion system 100 as described herein. In the embodiment of FIGS. 1A-1B, the control system 33 includes a central controller 34 communicatively connected to the drive control module (DCM) 41, 42 of each marine drive 21, 22 and may also include other control devices. Thereby, the controller 34 can communicate instructions to the DCM 41, 42 of each drive 21, 22, or may otherwise communicate directly to each steering actuator(s) 13a, 13b, to effectuate a steering action based on user input at the steering input device 12, 40. At least two steering sensors 44 and 45, 46 and 47 are configured to sense the steering angle, or steering position, of each drive 21, 22. The control system 33, such as by the central controller 14 or each DCM 41, 42, is configured to determine the measured steering position for each drive 21, 22 based on the outputs of the two or more steering sensors associated with that drive, as is disclosed herein. The steering actuators 13a, 13b are then controlled accordingly, such as based on a comparison of the commanded steering position and the measured steering position.

[0053] In one embodiment, the central controller 34 also communicates a command instruction to the DCM 41, 42 for the marine drive, which includes a steering position instruction, and wherein the commands to the various drives 21, 22 are coordinated such that the total of the thrusts yields the user's propulsion demand input. A person of ordinary skill in the art will understand in view of the present disclosure that other control arrangements could be implemented and are within the scope of the present disclosure, and that the control functions described herein may be combined into a single controller or divided into any number of a plurality of distributed controllers that are communicatively connected.

[0054] Also referencing FIG. 1B, a schematic representation of a propulsion system 100 is shown including two marine drives 21 and 22 configured to be positioned at the stern 24, such as attached to the transom. Each marine drive 21, 22, whether in a single drive arrangement or an arrangement of two or more rear drives, includes a powerhead 111, 112 configured to rotate a propeller 23 in each of a forward rotational direction to effectuate a forward thrust on the vessel 10 tending to move it in the forward direction and a reverse rotational direction to effectuate a reverse thrust on the vessel 10 tending to move it backward. The powerhead 111, 112 may comprise, for example, an electric motor, an internal combustion engine, or a hybrid arrangement of an electric motor or motor/generator and an internal combustion engine. The number of marine drives is exemplary and a person having ordinary skill in the art will understand in light of the present disclosure that any number of one or more marine drives steerable to a range of steering angles may be utilized in the disclosed system and method. A rotational speed sensor 123, 124 is associated with each powerhead 111, 112 and configured to sense a rotational speed thereof. A person having ordinary skill in the art will understand in view of the present disclosure that the disclosed propulsion system 100 may include other types and locations of marine drives, which may be an alternative to or in addition to the one or more rear marine drives 21, 22. Where one or more of the marine drives 21, 22 is an electric drivei.e., having a powerhead being an electric motor-the propulsion system 100 will include a power storage device (e.g., battery) powering the motor(s) thereof.

[0055] Each marine drive 21, 22 is individually and separately steerable, each having a respective steering actuator 13a, 13b configured to rotate the drive 21, 22 about its respective steering axis 31, as is standard. In some examples, the entire drive is a steerable drive (such as with certain outboard drive arrangements) and in some examples, the portion of the drive containing the propeller steers independent of the powerhead (such as with certain stern drive arrangements or steerable gearcase arrangements). The steering axes 31 are separated by a dimension along the Y axis and at a distance X from the center of turn 30 (COT), which could also be the effective center of gravity (COG). The marine vessel 10 is maneuvered by causing the first and second marine drives to rotate about their respective steering axis. The marine drives 21 and 22 are rotated in response to an operator's manipulation of the joystick 40 or steering wheel 12, which are each communicatively connected to the steering actuators 13a, 13b that rotate the marine drives 21 and 22. Rotating the rear marine drives 21 and 22 and effectuating thrusts thereby causes turn of the marine vessel 10, which may include turn about the effective COT 30 (which may alternatively be the center of pressure (COP) or center of gravity (COG)).

[0056] Each rear marine drive 21, 22 is steerable to a range of steering angles, such as 30 degrees from a centered steering position or about 45 degrees from a centered steering position each of a clockwise rotation and counterclockwise rotation direction. In some embodiments, one or more of the marine drives may be steerable to enable rotation of the propeller to 90 degrees or more of steering in at least one direction from a centered steering position (e.g., parallel to the centerline CL).

[0057] FIG. 2 illustrates an exemplary calculation of a measured steering position based on first and second sensed values. The graph in FIG. 2 shows two sensed values, including a first sensed value 62 being the output of a first position sensor and a second sensed value 68 being the output of a second position sensor. The measured steering position 51 is a value between the first and second sensed values 62 and 68 and is determined based thereon. In the depicted embodiment, the measured steering position 51 is calculated as an average of the first sensed value 62 and the second sensed value 68.

[0058] The sensed values are assessed to detect the presence of one or more fault conditions, such as to detect a fault with one or both sensors. The sensed values are compared to one or more thresholds, such as maximum and minimum range thresholds and/or a difference threshold to confirm their reliability. If the sensed values are outside of one of the threshold ranges, then a fault is detected, wherein the fault indicates that the respective steering sensor is unable to provide reliable values for detecting the steering position of the marine drive.

[0059] In one embodiment, the sensed values may be compared to one or more range thresholds, the range thresholds for the steering sensors may be stored values representing the appropriate range of outputs for the sensor when it is operating properly. For example, upper and lower range thresholds may be set representing a maximum valid sensor output and a minimum valid sensor output. In one example, the range thresholds may be a number of analog-digital conversion (ADC) counts, such as the counts representing a voltage output of a Hall Effect sensor. Confirmation that the sensed value is within the range thresholds establishes that the sensed value is within a valid range for measuring the steering position. For example, an output value from a sensor that is outside of the minimum and maximum range thresholds indicates that the steering sensor is either overvoltage or undervoltage and is therefore unusable. Thus, a range fault will be generated. The controller will then shift to reliance on only the non-faulted sensor for steering control.

[0060] The control system may also be configured to detect when the difference 52 between the first sensed value 62 and the second sensed value 68 exceeds a difference threshold, which would indicate that one of the sensors is faulted. For example, a difference fault may occur in an instance where a sensor fails in range and is stuck such that it continually outputs a value that is within the minimum and maximum range values, but is not reflective of the current steering position. In FIG. 2, the first sensed value 62 and the second sensed value 68 are illustrated at the outer bounds of the difference threshold, wherein any higher of a sensed value (for the first sensed value 62) or lower of a sensed value (for the second sensed value 68) would exceed the difference 52 to exceed a difference threshold of 60 counts. If the difference threshold is exceeded, a difference fault is detected. In one embodiment, the difference fault may render both sensors unusable since the controller may not be able to detect which of the two sensors is faulted, provided that both sensors are in range. Where the source of the fault is not determinable, then the digital control of the steering actuator is disabled. In some instances where the source of the fault is identifiable, such as where a difference fault is immediately followed by detection of a range fault in one of the sensors, then the faulted sensor can be identified and the system can shift to reliance on only the non-faulted sensor.

[0061] In one embodiment, the difference threshold is based on a maximum tolerated uncommanded steering change. When one sensor is faulted, the controller shifts to reliance only on the non-faulted sensor and the measured steering position becomes equal to output value of the non-faulted sensor. Since the measured steering position is utilized as feedback for controlling the steering actuator, the shift in the measured steering position causes a change in the steering position command effectuated by the steering actuator. This change in steering position effectuated in response to a faulted sensor is not associated with any change in commanded steering positioni.e., it is an uncommanded steering change. This steering change may be surprising to an operator and it is desirable to minimize the commanded steering change effectuated in response to a fault condition. Accordingly, the difference threshold may be based on a predetermined maximum tolerated uncommanded steering change, which is the maximum value determined to be acceptable, such as not overly disruptive to the user's steering control and not effectuating a substantial change in heading. Namely, the difference threshold may be calibrated such that the difference between the measured steering position and either one of the first or second sensed values does not exceed a value equivalent to the predetermined maximum tolerated uncommanded steering change. Thus, in an embodiment where the measured steering position is calculated as the average of the first and second sensed values, the difference threshold is equivalent to two times the predetermined maximum tolerated uncommanded steering change. In one embodiment, the predetermined maximum tolerated uncommanded steering change is a 3-degree change in steering angle. In such an embodiment, the difference threshold may be a sensor output magnitude equivalent to 6 degrees of steering change.

[0062] FIG. 3 depicts exemplary logic steps for calculating a measured steering position for the marine drive based on a first sensed value outputted by a first steering sensor and the second sensed value outputted by a second steering sensor. At steps 202, 204, and 206 fault status values are received for each of the first and second sensors, including indicating whether a range fault or a difference fault has occurred. The fault status information is passed to comparator logic step 208, which each passes through a 1 if any fault condition is detected. Logic block 210 then generates an output engaging different logic for calculating the measured steering position based on which sensors are faulted, if any. If no fault is detected in any sensor, then logic block 218 is utilized, which calculates the measured steering position based on both the first and second sensed values 162, 168. If a fault condition is detected with sensor 2 only, then logic block 216 is engaged which calculates the measured steering position based only on the output of the first position sensor (e.g., passes through the first sensed value 162 as the measured steering position). If a fault condition is detected with sensor 1 only, then logic block 214 is engaged which calculates the measured steering position based only on the output of the second position sensor (e.g., passes through the second sensed value 168 as the measured steering position). If the difference fault is detectedi.e., between the sensed values 162, 168 of the first and second steering sensors exceeds the difference thresholdthen both sensors are considered unfit to be used to calculate the measured steering position. In that case, logic block 212 is engaged, which generates an error and passes through a null or other default value indicating that no steering position can be measured and that the electronic steering control must be disabled.

[0063] At step 222, the measured steering position is then converted into an angular measured steering position, such as into degrees or radians. At step 224, the controller generates a measured steering position command to control the steering actuator to steer the marine drive.

[0064] Referring now to FIG. 4, exemplary method steps for controlling steering of a marine drive are illustrated. At 405, the steering position of the marine drive is sensed with a first steering sensor to output a first sensed value. At 410, the steering position of the marine drive is sensed with a second steering sensor to output a second sensed value. In one embodiment, the first and second sensors may each be a Hall Effect sensor. At 415, a measured steering position is calculated based on the first sensed value and the second sensed value. In one embodiment, the measured steering position is calculated as an average of the first sensed value and the second sensed value. At 420, the marine drive is steered based on the measured steering position. For example, the measured steering position may be provided as feedback for controlling the steering actuator based on a commanded steering position, and thus the steering actuator is controlled to minimize the difference between the measured steering position and the commanded steering position.

[0065] Referring now to FIG. 5, a flow chart exemplifying a method of controlling steering of at least one marine drive steerable to a range of steering angles is illustrated. At 505, the steering position of the marine drive is sensed with a first steering sensor to output a first sensed value. At 510, the steering position of the marine drive is sensed with a second steering sensor to output a second sensed value. At 515, a difference is determined between the first and second sensed values. At 520, a measured steering position is calculated based on the first sensed value and the second sensed value. Step 525 is then executed to determine whether the difference exceeds a difference threshold, and thus whether a difference fault is detected. If not, then the steering actuator is controlled based on the measured steering position at step 535. If the difference fault is detected, an error is generated wherein the steering sensors are determined to be unusable for calculating the measured steering position.

[0066] Referring now to FIG. 6, a flow chart exemplifying a method of controlling steering of at least one marine drive steerable to a range of steering angles is illustrated. At 445, the steering position of the marine drive is sensed with a first steering sensor to output a first sensed value. At 610, the steering position of the marine drive is sensed with a second steering sensor to output a second sensed value. At 615, a measured steering position is calculated based on the first sensed value and the second sensed value. At 620, the marine drive is steered based on the measured steering position.

[0067] At 625, the controller determines if the first or second steering sensor has failed, such as whether a fault condition is generated for only one of the sensors. If one steering sensor has failed, the measured steering position is redetermined at step 630 based on the sensed value from the nonfailed sensor. At 635, the steering position of the marine drive is adjusted based on the redetermined measured steering position. At 640, the controller continues to steering the marine drive using only one steering sensor.

[0068] This written description uses examples to disclose the invention, including the best mode, and also to enable any person skilled in the art to make and use the invention. Certain terms have been used for brevity, clarity, and understanding. No unnecessary limitations are to be inferred therefrom beyond the requirement of the prior art because such terms are used for descriptive purposes only and are intended to be broadly construed. The patentable scope of the invention is defined by the claims and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they have features or structural elements that do not differ from the literal language of the claims, or if they include equivalent features or structural elements with insubstantial differences from the literal languages of the claims.