Steering control method and control system for wheeled vehicles
First Claim
1. In a vehicle steering system including a handwheel, a method for controlling a flow control valve and an electric actuator for operating the valve to control a flow of control fluid in the vehicle steering system, the flow of control fluid being utilized by the system to provide a power assist steering force, the method comprising steps of:
- generating an initial control signal, the initial control signal being representative of a power steering assist level desired, wherein the improvement comprises;
generating a feedback signal based on actual current of the electric actuator, said step of generating the feedback signal including steps of measuring the actual current and averaging the measured actual current to obtain an average current signal representative of average current through the actuator; and
generating a final control signal as a function of the initial control signal and the feedback signal to control the electric actuator as a function of the actual current of the electric actuator to compensate for varying system operating conditions.
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Accused Products
Abstract
A feedback control method and system are provided to accurately control the steering assist level in a vehicle steering system. An electric actuator, such as a solenoid, operates a flow control valve that controls the flow of control fluid in a vehicle steering system in relation to driver and vehicle inputs such as vehicle speed and the angular position and velocity of a hand-wheel of the steering system. The flow of the control fluid is utilized by the steering system to provide a power assist steering force. A feedback signal based on the actual measured current of the solenoid is generated after a hardware filter filters the measured current. There is a time lag associated with the filtered feedback signal. A software filter filters an initial control signal which represents the desired steering assist level to maintain a similar time relationship between the feedback signal and the initial control signal. An error signal is generated by comparing the feedback signal and the filtered initial control signal. The initial control signal is then modified by the error signal to obtain a final control signal which compensates for varying system operating conditions.
45 Citations
15 Claims
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1. In a vehicle steering system including a handwheel, a method for controlling a flow control valve and an electric actuator for operating the valve to control a flow of control fluid in the vehicle steering system, the flow of control fluid being utilized by the system to provide a power assist steering force, the method comprising steps of:
- generating an initial control signal, the initial control signal being representative of a power steering assist level desired, wherein the improvement comprises;
generating a feedback signal based on actual current of the electric actuator, said step of generating the feedback signal including steps of measuring the actual current and averaging the measured actual current to obtain an average current signal representative of average current through the actuator; and generating a final control signal as a function of the initial control signal and the feedback signal to control the electric actuator as a function of the actual current of the electric actuator to compensate for varying system operating conditions. - View Dependent Claims (2, 3, 4, 5, 6, 7)
- generating an initial control signal, the initial control signal being representative of a power steering assist level desired, wherein the improvement comprises;
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8. In a vehicle steering system including a handwheel, a control system for controlling a flow control valve to control a flow of control fluid in the steering system, the flow of control fluid being utilized by the steering system to provide a power assist steering force, the control system including means for generating an initial control signal to control the control valve, the initial control signal being representative of a power steering assist level desired;
- an electric actuator coupled to the fluid control valve for driving the flow control valve as a function of a final control signal, wherein the improvement comprises;
feedback means for generating a feedback signal representative of actual current of the actuator, said feedback means including current averaging means coupled to the actuator for providing an average current signal representative of average current through the actuator; and control means for generating the final control signal as a function of the initial control signal and the feedback signal to control the actuator as a function of the actual current of the actuator to compensate for varying system operating conditions. - View Dependent Claims (9, 10, 11, 12, 13, 14, 15)
- an electric actuator coupled to the fluid control valve for driving the flow control valve as a function of a final control signal, wherein the improvement comprises;
Specification