HYDRAULIC CYLINDER POSITION CONTROL FOR LIFTING AND LOWERING TOWED IMPLEMENTS
20240044346 ยท 2024-02-08
Inventors
Cpc classification
F15B21/08
MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
F15B2211/6656
MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
A01B63/002
HUMAN NECESSITIES
F15B2211/7052
MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
F15B15/14
MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
F15B9/09
MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
F15B2211/7656
MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
F15B2211/6336
MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
F15B2211/328
MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
F15B2211/634
MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
F15B2211/6343
MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
F15B21/087
MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
F15B2211/7128
MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
F15B2211/782
MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
F15B11/22
MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
International classification
F15B21/08
MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
F15B15/14
MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
Abstract
The disclosed apparatus, systems and methods relate to a hydraulic control system, comprising, the control system having a control unit configured to be in operational communication with a plurality of gauge wheel assemblies, a plurality of cylinders in operational communication with the plurality of gauge wheel assemblies, and a plurality of position sensors in operational communication with the plurality of cylinders, wherein the control unit comprises a feedback position command loop configured to calculate cylinder position error and issue valve commands.
Claims
1. A hydraulic control system, comprising, the control system comprising: a. a control unit configured to be in operational communication with a plurality of gauge wheel assemblies; b. a plurality of cylinders in operational communication with the plurality of gauge wheel assemblies; and c. a plurality of position sensors in operational communication with the plurality of cylinders.
2. The hydraulic control system of claim 1, wherein the control unit comprises a feedback position command loop configured to calculate cylinder position error and issue valve commands.
3. The hydraulic control system of claim 2, wherein the control unit is configured to calculate position error from a measured cylinder position error and a target cylinder position.
4. The hydraulic control system of claim 3, wherein the calculated position error is compared to threshold.
5. The hydraulic control system of claim 2, wherein the feedback position command loop comprises a proportional integral (PI) control loop
6. The hydraulic control system of claim 2, wherein the feedback position command loop is configured to calculate velocity error.
7. The hydraulic control system of claim 2, wherein the feedback position command loop is configured to direct increased relative flow rate via a change in pulse-width modulation (PWM) command.
8. A hydraulic control system comprising: a) a plurality of gauge wheel assemblies, each of the plurality of gauge wheel assemblies comprising: i) a cylinder in fluidic communication with a PMV valve; and ii) a position sensor in operational communication with the cylinder configured to generate position data; b) a control unit in operational communication with the position sensors and PMV valves, the control unit comprising a feedback position control system configured to: define a target position; receive position sensor data from the position sensor to measure actual position; calculate a position error from the target position; compare the position error to a threshold; and command PMV valves if the position error exceeds the threshold.
9. The hydraulic control system of claim 8, wherein the control unit comprises a processor, memory and software configured to execute the feedback position control system.
10. The hydraulic control system of claim 8, wherein the feedback position control system is comprises one or more of a position control PI loop and a nested velocity control PI loop.
11. The hydraulic control system of claim 8, wherein the feedback position control system is configured to calculate velocity error from actual velocity and target velocity.
12. The hydraulic control system of claim 8, further comprising a performance model.
13. The hydraulic control system of claim 12, wherein the performance model is configured to identify potential failures, modify thresholds or adjust control loop parameters.
14. The hydraulic control system of claim 12, wherein the feedback position command loop is configured to calculate velocity error.
15. A hydraulic control system comprising: a) a control unit in operational communication with a gauge wheel assembly comprising: i) a cylinder in fluidic communication with a valve; and ii) a position sensor in operational communication with the cylinder configured to generate position data; and b) a feedback position control system configured to: define a target position; measure actual position; calculate a position error from the target position; and command the valve to increase or decrease flow to the cylinder from the position error.
16. The hydraulic control system of claim 15, the feedback position control system is configured to execute one or more of a position control PI loop and a nested velocity control PI loop.
17. The hydraulic control system of claim 15 comprising a plurality of gauge wheel assemblies.
18. The hydraulic control system of claim 17, wherein the feedback position control system is configured to regulate hydraulic flow between the plurality of gauge wheel assemblies by determining one or more lagging cylinders.
19. The hydraulic control system of claim 18, wherein the feedback position control system is configured to increase pressure in the on or more lagging cylinders.
20. The hydraulic control system of claim 18, further comprising a model-based feed-forward control system configured to determine a predicted load.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
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DETAILED DESCRIPTION
[0055] This disclosure relates to the devices, systems and methods for a control system 10 and the use of one or more gauge wheel/lift wheel assemblies 12 mounted on a toolbar 14 that are coupled with hydraulic cylinder(s) 16, a position sensor 18, and electronically controlled hydraulic valve(s) 20. In various implementations, these hydraulic cylinder(s) 16 are in operational communication or fluidic with the control system 10, position sensor(s) 18 and valve(s) 20 so as to allow the control system 10 to monitor the position of the individual cylinder(s) 16 to direct hydraulic flow via the valve(s) 20 to individually control the position of the assemblies 12 relative to the toolbar 14 and ground. In various implementations, the position sensor(s) 18 are configured to determine cylinder position sensor data from the cylinder, which can include actual position, actual velocity and the like, as described herein. This position sensor data may variously be referred to herein as actual position, actual velocity and the like.
[0056] That is, in various implementations, the system 10 allows for the individual control of the assemblies 12 to account for real-world conditions and execute specified commands on a row-by-row level. In certain implementations, for example, the system 10 is able to identify individual assemblies that have not extended or retracted as commanded via the position sensor(s) 18 and direct hydraulic flow to those assemblies 12 to bring all of the assemblies 12 into alignment, as will be explained further herein.
[0057] Certain of the disclosed implementations can be used in conjunction with any of the devices, systems or methods taught or otherwise disclosed in U.S. Pat. No. 10,684,305 issued Jun. 16, 2020, entitled Apparatus, Systems and Methods for Cross Track Error Calculation From Active Sensors, U.S. patent application Ser. No. 16/121,065, filed Sep. 4, 2018, entitled Planter Down Pressure and Uplift Devices, Systems, and Associated Methods, U.S. Pat. No. 10,743,460, issued Aug. 18, 2020, entitled Controlled Air Pulse Metering apparatus for an Agricultural Planter and Related Systems and Methods, U.S. Pat. No. 11,277,961, issued Mar. 22, 2022, entitled Seed Spacing Device for an Agricultural Planter and Related Systems and Methods, U.S. patent application Ser. No. 16/142,522, filed Sep. 26, 2018, entitled Planter Downforce and Uplift Monitoring and Control Feedback Devices, Systems and Associated Methods, U.S. Pat. No. 11,064,653, issued Jul. 20, 2021, entitled Agricultural Systems Having Stalk Sensors and/or Data Visualization Systems and Related Devices and Methods, U.S. Pat. No. 11,297,768, issued Apr. 12, 2022, entitled Vision Based Stalk Sensors and Associated Systems and Methods, U.S. patent application Ser. No. 17/013,037, filed Sep. 4, 2020, entitled Apparatus, Systems and Methods for Stalk Sensing, U.S. patent application Ser. No. 17/226,002 filed Apr. 8, 2021, and entitled Apparatus, Systems and Methods for Stalk Sensing, U.S. Pat. No. 10,813,281, issued Oct. 27, 2020, entitled Apparatus, Systems, and Methods for Applying Fluid, U.S. patent application Ser. No. 16/371,815, filed Apr. 1, 2019, entitled Devices, Systems, and Methods for Seed Trench Protection, U.S. patent application Ser. No. 16/523,343, filed Jul. 26, 2019, entitled Closing Wheel Downforce Adjustment Devices, Systems, and Methods, U.S. patent application Ser. No. 16/670,692, filed Oct. 31, 2019, entitled Soil Sensing Control Devices, Systems, and Associated Methods, U.S. patent application Ser. No. 16/684,877, filed Nov. 15, 2019, entitled On-The-Go Organic Matter Sensor and Associated Systems and Methods, U.S. Pat. No. 11,523,554, issued Dec. 13, 2022, entitled Dual Seed Meter and Related Systems and Methods, U.S. patent application Ser. No. 16/891,812, filed Jun. 3, 2020, entitled Apparatus, Systems and Methods for Row Cleaner Depth Adjustment On-The-Go, U.S. Pat. No. 11,678,607, issued Jun. 20, 2023, entitled Apparatus, Systems, and Methods for Eliminating Cross-Track Error, U.S. patent application Ser. No. 16/921,828, filed Jul. 6, 2020, entitled Apparatus, Systems and Methods for Automatic Steering Guidance and Visualization of Guidance Paths, U.S. patent application Ser. No. 16/939,785, filed Jul. 27, 2020, entitled Apparatus, Systems and Methods for Automated Navigation of Agricultural Equipment, U.S. patent application Ser. No. 16/997,361, filed Aug. 19, 2020, entitled Apparatus, Systems and Methods for Steerable Toolbars, U.S. patent application Ser. No. 16/997,040, filed Aug. 19, 2020, entitled Adjustable Seed Meter and Related Systems and Methods, U.S. patent application Ser. No. 17/011,737, filed Sep. 3, 2020, entitled Planter Row Unit and Associated Systems and Methods, U.S. patent application Ser. No. 17/060,844, filed Oct. 1, 2020, entitled Agricultural Vacuum and Electrical Generator Devices, Systems, and Methods, U.S. patent application Ser. No. 17/105,437, filed Nov. 25, 2020, entitled Devices, Systems and Methods For Seed Trench Monitoring and Closing, U.S. patent application Ser. No. 17/127,812, filed Dec. 18, 2020, entitled Seed Meter Controller and Associated Devices, Systems and Methods, U.S. patent application Ser. No. 17/132,152, filed Dec. 23, 2020, entitled Use of Aerial Imagery For Vehicle Path Guidance and Associated Devices, Systems, and Methods, U.S. patent application Ser. No. 17/164,213, filed Feb. 1, 2021, entitled Row Unit Arm Sensor and Associated Systems and Methods, U.S. patent application Ser. No. 17/170,752, filed Feb. 8, 2021, entitled Planter Obstruction Monitoring and Associated Devices and Methods, U.S. patent application Ser. No. 17/225,586, filed Apr. 8, 2021, entitled Devices, Systems, and Methods for Corn Headers, U.S. patent application Ser. No. 17/225,740, filed Apr. 8, 2021, entitled Devices, Systems, and Methods for Sensing the Cross Sectional Area of Stalks, U.S. patent application Ser. No. 17/323,649, filed May 18, 2021, entitled Assisted Steering Apparatus and Associated Systems and Methods, U.S. patent application Ser. No. 17/369,876, filed Jul. 7, 2021, entitled Apparatus, Systems, and Methods for Grain Cart-Grain Truck Alignment and Control Using GNSS and/or Distance Sensors, U.S. patent application Ser. No. 17/381,900, filed Jul. 21, 2021, entitled Visual Boundary Segmentations and Obstacle Mapping for Agricultural Vehicles, U.S. patent application Ser. No. 17/461,839, filed Aug. 30, 2021, entitled Automated Agricultural Implement Orientation Adjustment System and Related Devices and Methods, U.S. patent application Ser. No. 17/468,535, filed Sep. 7, 2021, entitled Apparatus, Systems, and Methods for Row-by-Row Control of a Harvester, U.S. patent application Ser. No. 17/526,947, filed Nov. 15, 2021, entitled Agricultural High Speed Row Unit, U.S. patent application Ser. No. 17/566,678, filed Dec. 20, 2021, entitled Devices, Systems, and Method For Seed Delivery Control, U.S. patent application Ser. No. 17/576,463, filed Jan. 14, 2022, entitled Apparatus, Systems, and Methods for Row Crop Headers, U.S. patent application Ser. No. 17/724,120, filed Apr. 19, 2022, entitled Automatic Steering Systems and Methods, U.S. patent application Ser. No. 17/742,373, filed May 11, 2022, entitled Calibration Adjustment for Automatic Steering Systems, U.S. patent application Ser. No. 17/902,366, filed Sep. 2, 2022, entitled Tile Installation System with Force Sensor and Related Devices and Methods, U.S. patent application Ser. No. 17/939,779, filed Sep. 7, 2022, entitled Row-by-Row Estimation System and Related Devices and Methods, U.S. patent application Ser. No. 18/081,432, filed Dec. 14, 2022, entitled Seed Tube Guard and Associated Systems and Methods of Use, U.S. patent application Ser. No. 18/087,413, filed Dec. 22, 2022, entitled Data Visualization and Analysis for Harvest Stand Counter and Related Systems and Methods, U.S. patent application Ser. No. 18/097,804, filed Jan. 17, 2023, entitled Agricultural Mapping and Related Systems and Methods, U.S. patent application Ser. No. 18/101,394, filed Jan. 25, 2023, entitled Seed Meter with Integral Mounting Method for Row Crop Planter and Associated Systems and Methods, U.S. patent application Ser. No. 18/102,022, filed Jan. 26, 2023, entitled Load Cell Backing Plate and Associated Devices, Systems, and Methods, U.S. patent application Ser. No. 18/116,714, filed Mar. 2, 2023, entitled Cross Track Error Sensor and Related Devices, Systems, and Methods, U.S. patent application Ser. No. 18/203,206, filed May 30, 2023, entitled Seed Tube Camera and Related Devices, Systems and Methods, U.S. patent application Ser. No. 18/209,331, filed Jun. 13, 2023, entitled Apparatus, Systems and Methods for Image Plant Counting, U.S. patent application Ser. No. 18/215,721, filed Jun. 28, 2023, entitled Seed Tube Guard and Associated Systems, Devices, and Methods of Use, U.S. Patent Application 63/394,843, filed Aug. 3, 2022, entitled Hydraulic Cylinder Position Control for Lifting and Lowering Towed Implements, U.S. Patent Application 63/395,061, filed Aug. 4, 2022, entitled Seed Placement in Furrow, U.S. Patent Application 63/400,943, filed Aug. 25, 2022, entitled Combine Yield Monitor, U.S. Patent Application 63/406,151, filed Sep. 13, 2022, entitled Hopper Lid with Magnet Retention and Related Systems and Methods, U.S. Patent Application 63/427,028, filed Nov. 21, 2022, entitled Stalk Sensors and Associated Devices, Systems and Methods, U.S. Patent Application 63/445,960, filed Feb. 15, 2023, entitled Ear Shelling Detection and Related Devices, Systems, and Methods, U.S. Patent Application 63/445,550, filed Feb. 14, 2023, entitled Liquid Flow Meter and Flow Balancer, U.S. Patent Application 63/466,144, filed May 12, 2023, entitled Devices, Systems, and Methods for Providing Yield Maps, and U.S. Patent Application 63/466,560, filed May 15, 2023, entitled Devices, Systems, and Methods for Agricultural Guidance and Navigation, U.S. Patent Application 63/524,065, filed Jun. 29, 2023, entitled Ring Assembly, and U.S. Patent Application 63/525,525, filed Jul. 7, 2023, entitled Assisted Steering Systems and Associated Devices and Methods for Agricultural Vehicles, each of which is incorporated herein by reference.
[0058] Returning to the disclosed control system 10, the various implementations described herein utilize real-time or near-real-time position sensor data to control the application of hydraulic pressure to the gauge wheel assemblies of an implement to control the extension and retraction of those wheel assemblies. It is understood that as the overall hydraulic system pressure is established by the tractor and is normally equal at all cylinders and control valves, and that the various implementations of the system 10 are configured to utilize the various control valves to adjust the flow rate at system pressure to increase or decrease the discrete pressure applied to, and correspondingly the travel speed of, individual cylinders based on position sensor feedback. Discussion of changes in pressure contained herein should be understood as such.
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[0060] In the prior art, master/slave hydraulic systems like the one shown in
[0061] In contrast, and as shown in
[0062] In an exemplary implementation of the system,
[0063] Transport folding functions can be simplified and the transition could be made to know if the machine in is an elevated or lowered position at the start so the proper sequence can be implemented. For example, consider a simple wing fold planter with four center tires and the wing tires that must be retracted for transport. If the planter is lowered at the start of the transport sequence, the wing wheels would stay retracted because the electronically controlled valve on those cylinders would remain closed while the center four cylinders are extended. If the planter is raised at the beginning of the transport sequence, the center four cylinders 16 would remain extended while the wing wheels could be retracted.
[0064] In various implementations, the toolbar 14 lift height can also be set by stopping the extension of the lift cylinder before it is fully extended, thereby reducing the lift/lower time at turn arounds. Further, in certain implementations, the lift position switch needed on most implements to turn operations on and off can be eliminated.
[0065] It is also appreciated that in certain implementations the lift circuit according to certain implementations can be paired to other hydraulic circuits and reduce the need for a tractor remote hydraulic connection, as would be readily understood. An additional valve can optionally be added to reverse the hydraulic flow for the up/down function, as would also be understood.
[0066]
[0067] Additionally, the control unit 50 can be optionally in operational communication with various additional data sources for the operations discussed herein, such as optionally any implement control unit(s) 58, hydraulic temperature sensor(s) 60, and/or valve sensor(s) 62. Further inputs are of course possible and would be readily understood, such as gyroscopes and accelerometers and the like, which can be used in conjunction with a GPS/GNSS technologies for precise location or separately for implement orientation, as has been previously-described. Historical data such as previous tractor/cylinder performance can also be utilized by the system, as described elsewhere herein.
[0068] Continuing with
[0069] As is appreciated, in exemplary implementations of the system 10, the control unit is in operational communication with the various position sensors 18 so as to receive provided position sensor data to determine the actual position of the various assemblies 12 and cylinders 16 being commanded by the system 10.
[0070] As shown in
[0071] In the exemplary implementation of
[0072] Further, in this implementation of the system 10 the electronic control valves 24 are installed at the extend port of each cylinder 16, along the raise 26 side (and opposite the lower side 28) of the system 10. In turn, the position sensors (shown, for example, at 18 in
[0073] In various implementations, the control system 10 is thus configured to monitor the extension and retraction position of each actuating cylinder 16 and adjust the flow rate or applied pressure to each cylinder 16 via the various valves 24 so all the cylinders 16 in the lifting system either extend and/or retract at the same rate regardless of the weight on various parts of the machine and regardless of the terrain or are otherwise moved into the commanded position or arrangement efficiently and smoothly.
[0074] It is appreciated that in these implementations, the various tolerances can be defined, set by the user and/or adjusted over a defined period, as described herein.
[0075] In certain implementations, combinations of controlled position hydraulic cylinders 16 and uncontrolled position assist cylinders 16 can be used to reduce the overall number of position sensors and control valves. It is appreciated that this could be determined by needs to control the cylinder position during transport functions and the need to monitor the system during operation.
[0076] As shown generally in
[0077] Thus, when the position of each cylinder 16 is always known, there are several features that can be added to the operation of the toolbar function. For example, the toolbar 14 operation height can be set by stopping the retraction of the lift cylinder before it is fully retracted eliminating the need for a mechanical adjustment. This can be important if changing field conditions cause the toolbar to run out of level. Further explanation of exemplary implementations is described in detail in
[0078]
[0079] In the implementation of
[0080] In the implementation of
[0081] It is understood that in the event that there is no position error, or if it is within a defined deadband or threshold established by the system and/or user (shown at line 99), no change in action (box 97) will be commanded. It is further understood that the calculation of position error (box 106) in these and other implementations is performed continuously overtime such that while the implement is being activated, the position error may change continually.
[0082] In use according to these implementations, in the event that a position error is present (line 98), the PI control loop 101 is able to direct increased relative flow rate via a change in pulse-width modulation (PWM) command to the lagging assembly 12 and increase the cylinder's rate of extension or retraction via proportional (box 110) and integral (box 112) control commands that are combined (box 114) and issued to command a change in PWM valve signal to the cylinders (shown in real-time execution as Process, box 116). It is understood that actual cylinder position (box 108) continues to be recorded and that the control system 10 and feedback position command loop 100 both continue to proceed as described. Those of skill in the art will appreciate that the combination of proportional and integral control can provide both immediate and persistent adjustment to lagging cylinders in certain implementations, but in further implementations additional feedback control systems and approaches can also be incorporated as appropriate.
[0083] That is, while these implementations utilize one version of a PI control loop, it is well-appreciated that other implementations can use alternate PI control configurations, proportional integral derivative (PID) loop configurations, and other control loop feedback mechanisms as would be well-appreciated in the art.
[0084] In the exemplary implementation of
[0085] In the velocity control loop 101B, the proportional of the velocity control loop (box 128) and integral of the velocity control loop (box 134) are combined (box 136) to command a PWM signal to the control valve to minimize velocity error. In this control system 10 implementation, it is appreciated that larger position errors will correspond to larger target velocity and accordingly higher PMV signals. And in turn, these higher velocities will more quickly eliminate the position error.
[0086] As an illustrative example of the application of the use of such a feedback position command loop 100, take a given cylinder currently at the desired cylinder position of 1 extension at zero velocity. Under these conditions, the cylinder has zero position error (box 106) and zero velocity error (box 132), and as such no change is required to the command. Subsequently, the operator issues a command (such as from the display or other in-cab system) defining the target position (box 104) to 10 of extension for this cylinder. As the cylinder is at 1, the position error is now instantly at of 9. This error (box 106) passes to a P-gain action at the proportional (box 110) that generates a proportional target velocity. In this instance, assume a P-gain of 2?. Accordingly, the target velocity is 9*2=18. Actual velocity is still zero, so the velocity error is 18?0=18. The velocity P and I actions (boxes 128 and 134) will therefore generate a corresponding PWM signal for the valve to increase hydraulic flow or pressure maximally.
[0087] After a period of time, the cylinder is now moving toward the defined target position. It's currently at 4 and the target is still 10. Position error is 10?4=6. Target velocity is position error*P-gain. 6*2=12. Assume current velocity is 13, so velocity error is 12?13=?1. So the PWM signal will be reduced accordingly. As the cylinder continues to approach the target position, the target velocity will steadily reduce, until target velocity drops to zero when the cylinder reaches 10. It is thus appreciated that in a population with a relatively limited overall hydraulic capacity, such differences in commands at the individual cylinders thus results an efficient allocation of pressure and more immediate response in the system. It is further appreciated that this is given to demonstrate one illustrative example according to an application of the implementation of
[0088] Returning to the figures, in the implementation of
[0089] In the implementation of
[0090] In the implementation of
[0091]
[0092]
[0093] In the implementation of
[0094] In various implementations, and as also shown in
[0095]
[0096]
[0097] As shown in
[0098] In certain optional implementations, the system 10 can delay (box 308) or otherwise hold and/or cycle the operation.
[0099] In another optional step, the system 10 addresses lag by identifying (box 310) one or more lagging cylinders and commanding the system to direct flow to those lagging cylinders, such as via the operations unit.
[0100] In a further optional step, the non-lagging control valve duty cycles can be proportionally adjusted (box 312) so as to balance flow to account for lagging cylinders, as is explained above and would be appreciated.
[0101] The system 10, in a further optional step, can query whether the detected positions/position errors (via the position sensors) are within defined tolerances (box 314); if yes, the system 10 proceeds as follows: it queries whether the cylinder is nearing the end of travel (box 316), if yes, it reduces the position error tolerance (box 318) and returns to box 314, if no, it directly returns to box 314.
[0102] Returning to box 314, if the position error is not within tolerances, the system determines whether the difference in position is below a critical value (box 320). If yes, the system executes a timer sequence 321, shown by optionally querying whether there is a timer (box 322) and starting a timer (box 324); and then running the timer, shown by querying whether the timer has expired (box 326), subsequently closing the control valves (box 328) and terminating the sequence (box 330).
[0103] If the difference in position is not below a critical value (box 320), the system according to these implementations returns to box 314 and proceeds. While
[0104] It is appreciated that according to certain implementations, no mechanical or hydraulic approach for splitting the hydraulic flow to each cylinder 16 is required. This is advantageous and can simplify the design, make it more modular, and be more efficient by making use of all the mechanical force generated by the cylinders 16. Further, the cylinders 16 can be made of a smaller bore and can all be the same design, as opposed to typical prior art approaches.
[0105] Although the disclosure has been described with reference to preferred embodiments, persons skilled in the art will recognize that changes may be made in form and detail without departing from the spirit and scope of the disclosed apparatus, systems and methods.