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:
Aug. 21, 1990
Filed:
Nov. 16, 1987
John C Whitehead, Davis, CA (US);
Other;
Abstract
A steering system for a vehicle has a torque actuator under automatic control which applies transient steering torque during rapid maneuvers in addition to any power-assist torque. The transient active torque acts without delay in response to steer angle changes, thereby opposing steering overshoot and stabilizing emergency lateral maneuvers at high speed. A means for estimating natural restoring torque expected during steady-state cornering receives signals indicating vehicle speed and the steer angle. A further measurement means produces a signal proportional to instantaneous natural steering torque, which is a lateral acceleration signal in the preferred embodiments. The difference between the signal proportional to instantaneous torque and a signal proportional to expected steady-state torque is large during and immediately after rapid steering motions, because vehicles have a delay between any change in steer angle and the resulting change in natural restoring steering torque. The transient active torque supplements or opposes the natural torque according to said difference, to effectively reduce said delay. The result is that the sum of natural and active steering torques acts to restore the steered wheels to the straight-ahead position, with reduced overshoot. An additional means for damping high frequency steering system oscillations is included. The main benefit of the invention is to stabilize the free control oscillation at approximately 1 Hz which is a whole vehicle mode rather than a steering system oscillation. This free control weave mode can result in steering overshoot when the driver of a vehicle without the invention performs a rapid emergency maneuver. The stabilizing apparatus thus has a different purpose from conventional power assisted steering systems which amplify steering torque applied by the driver of a vehicle. The stabilizing apparatus can operate on front wheel steering or rear wheel steering vehicles, with or without power steering.