The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Jul. 09, 1991
Filed:
Apr. 06, 1990
Joseph M Raad, Sterling Heights, MI (US);
Geoffrey F Bridges, Belleville, MI (US);
Ford Motor Company, Dearborn, MI (US);
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.