Claims
- 1. A method for operating a steer-by-wire power steering system for a materials handling vehicle comprising the steps of:
monitoring angular position of a steering tiller for said materials handling vehicle; monitoring angular position of a steered wheel for said materials handling vehicle; determining a difference between the position of said steering tiller and the position of said steered wheel; and generating a counter rotation force that opposes turning of said steering tiller by an operator of said materials handling vehicle in response to said difference.
- 2. A method for operating a steer-by-wire power steering system for a materials handling vehicle as claimed in claim 1 wherein said counter rotation force is linearly related to said difference.
- 3. A method for operating a steer-by-wire power steering system for a materials handling vehicle as claimed in claim 1 wherein said counter rotation force is exponentially related to said difference.
- 4. A method for operating a steer-by-wire power steering system for a materials handling vehicle as claimed in claim 1 further comprising the step of generating a normal drag counter rotation force.
- 5. A method for operating a steer-by-wire power steering system for a materials handling vehicle as claimed in claim 1 further comprising the step of initially moving at least one of said steering tiller and said steered wheel to bring said steering tiller and said steered wheel into synchronization with one another.
- 6. A method for operating a steer-by-wire power steering system for a materials handling vehicle as claimed in claim 5 wherein said step of initially moving at least one of said steering tiller and said steered wheel comprises the step of moving said steered wheel.
- 7. A method for operating a steer-by-wire power steering system for a materials handling vehicle as claimed in claim 1 wherein said step of generating a counter rotation force that opposes turning of said steering tiller by an operator of said materials handling vehicle comprises the step of operating a motor coupled to said steering tiller to move said steering tiller.
- 8. A method for operating a steer-by-wire power steering system for a materials handling vehicle as claimed in claim 7 further comprising the step of synchronizing the positions of said steering tiller and said steered wheel to one another.
- 9. A method for operating a steer-by-wire power steering system for a materials handling vehicle as claimed in claim 8 wherein said step of synchronizing the positions of said steering tiller and said steered wheel to one another comprises the step of operating said motor coupled to said steering tiller in a direction to reduce said difference.
- 10. A method for operating a steer-by-wire power steering system for a materials handling vehicle as claimed in claim 9 wherein said step of synchronizing the positions of said steering tiller and said steered wheel to one another further comprises the step of moving said steered wheel in a direction to reduce said difference.
- 11. A method for operating a steer-by-wire power steering system for a materials handling vehicle as claimed in claim 8 wherein said step of synchronizing the positions of said steering tiller and said steered wheel to one another comprises the step of moving said steered wheel in a direction to reduce said difference.
- 12. A method for operating a steer-by-wire power steering system for a materials handling vehicle as claimed in claim 8 wherein said step of synchronizing the positions of said steering tiller and said steered wheel to one another comprises the step of applying a small bias to drive current for said motor in a direction which reduces offset error between said steering tiller and said steered wheel.
- 13. A method for operating a steer-by-wire power steering system for a materials handling vehicle as claimed in claim 1 wherein said step of generating a counter rotation force that opposes turning of said steering tiller by an operator of said materials handling vehicle comprises the step of braking said steering tiller.
- 14. A method for operating a steer-by-wire power steering system for a materials handling vehicle as claimed in claim 13 further comprising the step of synchronizing the positions of said steering tiller and said steered wheel to one another.
- 15. A method for operating a steer-by-wire power steering system for a materials handling vehicle as claimed in claim 14 wherein said step of synchronizing the positions of said steering tiller and said steered wheel to one another comprises the steps of:
slipping said steering system for movements of said system in a direction which reduces offset error between said steering tiller and said steered wheel; and preventing slip of said steering system for movements of said system in a direction which increases offset error between said steering tiller and said steered wheel.
- 16. A method for operating a steer-by-wire power steering system for a materials handling vehicle comprising the steps of:
monitoring angular position of a steering tiller for said materials handling vehicle; monitoring angular position of a steered wheel for said materials handling vehicle; moving said steering tiller to a position preferred by an operator of said materials handling vehicle to correspond to a defined steered wheel position; moving said steered wheel to said defined steered wheel position; and setting said preferred tiller position and said defined steered wheel position to correspond to one another so that movements of said steered wheel are made from said defined steered wheel position in correspondence with movement of said steering tiller from said operator preferred position.
- 17. A method for operating a steer-by-wire power steering system for a materials handling vehicle as claimed in claim 16 wherein said step of moving said steering tiller is performed at key on prior to startup of said materials handling vehicle and said step of moving said steered wheel is performed upon startup of said materials handling vehicle.
- 18. A method for operating a steer-by-wire power steering system for a materials handling vehicle as claimed in claim 17 wherein said step of moving said steering tiller is performed manually by said operator.
- 19. A method for operating a steer-by-wire power steering system for a materials handling vehicle as claimed in claim 16 wherein said defined steered wheel position corresponds to straight ahead movement for said materials handling vehicle.
- 20. A method for operating a steer-by-wire power steering system for a materials handling vehicle comprising the steps of:
monitoring angular position of a steering tiller for said materials handling vehicle; monitoring angular position of a steered wheel for said materials handling vehicle; moving said steered wheel toward the position of said defined steering tiller; and synchronizing said steered wheel and said steering tiller upon the position of said steered wheel substantially matching the position of said steering tiller.
- 21. A method for operating a steer-by-wire power steering system for a materials handling vehicle as claimed in claim 20 further comprising the step of operating a motor to move said steering tiller toward the position of said steered wheel.
- 22. A method for operating a steer-by-wire power steering system for a materials handling vehicle as claimed in claim 20 wherein said defined steered wheel position corresponds to straight ahead movement for said materials handling vehicle.
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application claims the benefit of U.S. Provisional Patent Application No. 60/186,160 filed Feb. 29, 2000, and entitled SYNCHRONIZED/VARIABLE FORCE FEEDBACK POWER STEERING, which is incorporated herein by reference.
Provisional Applications (1)
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Number |
Date |
Country |
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60186160 |
Feb 2000 |
US |