Data processing: vehicles – navigation – and relative location – Vehicle control – guidance – operation – or indication – Vehicle subsystem or accessory control
Reexamination Certificate
1999-05-18
2001-10-09
Zanelli, Michael J. (Department: 3661)
Data processing: vehicles, navigation, and relative location
Vehicle control, guidance, operation, or indication
Vehicle subsystem or accessory control
C701S042000
Reexamination Certificate
active
06301534
ABSTRACT:
TECHNICAL FIELD OF THE INVENTION
The present invention relates to steering control systems, and in particular to a method and system for vehicle directional control by commanding lateral acceleration.
BACKGROUND OF THE INVENTION
A number of efforts have been made to develop servo steering mechanisms associated with a joystick servo steering concept. A steering system was developed in the late nineteen-sixties that could make a vehicle automatically follow an antenna cable buried in the road. This system used an electronic proportional and derivative controller which regulated a hydraulic steering valve to turn the front wheels. A joystick steering system for a van was later developed that used a computer to automatically decrease the steering gain in proportion to the square of the vehicle speed in order to make the van safe to drive at higher speeds. The system was reported to be acceptable for use with test drivers. Recently, hydraulically powered joystick systems have been designed specifically for handicapped drivers. One joystick steering system (now marketed as the EMC Digidrive) uses an electric stepper motor to turn the steering wheel instead of regulating a power steering hydraulic valve. This system has a joystick input that decreases gain sensitivity with speed and steering wheel angle. All of these systems faced the common problem of having to compensate for steering gain when a vehicle travels at high speeds. These systems also involve a driver directly commanding the front wheel turn angle using a joystick.
SUMMARY OF THE INVENTION
Accordingly, a need has arisen in the art for a method and system for vehicle directional control by commanding lateral acceleration. The present invention provides a method and system for vehicle directional control by commanding lateral acceleration that substantially reduces problems associated with prior systems and methods.
In one embodiment of the described invention, a directional control system for a vehicle is disclosed that includes a driver input device being operable to receive a driver input corresponding to a desired lateral acceleration of the vehicle. The system also includes a controller in communication with the driver input device, the controller being operable to generate a control signal in response to comparing the received desired lateral acceleration and an actual lateral acceleration of the vehicle. The system further includes an actuator in communication with the controller, the actuator being operable to effect a change in the direction of travel of the vehicle in response to the control signal.
In another embodiment of the present invention, a system includes a driver input device that is operable to generate a first signal indicative of a desired lateral acceleration of an automobile and an accelerometer that is operable to generate a second signal indicative of an actual lateral acceleration of the automobile. The system further includes a tachometer being operable to generate a third signal indicative of a rate of change in the actual lateral acceleration of the automobile. The system also includes a controller in communication with the driver input device, the accelerometer, and the tachometer, the controller being operable to generate a drive current in response to comparing the first signal and the second signal and further in response to the third signal. The system also includes an actuator in communication with the controller and the tachometer, the actuator being operable to adjust the orientation of at least one wheel of the automobile in response to the drive current.
Embodiments of the described invention offer one or more of the following advantages. A technical advantage is to provide a steering control that can be used by handicapped drivers. A further advantage is to provide control of both acceleration or braking and steering using a single control input. Another advantage is to allow a driver who has limited hand or arm function to operate the primary control (steering, acceleration, and braking) of a vehicle with one hand, for example, leaving the other hand free for secondary controls. As yet a further advantage, at least one embodiment of the present invention enables the elimination of a hard steering column directly in front of the driver's chest. Utilizing lateral acceleration may also alleviate difficulties in compensating for high vehicle speed while controlling a vehicle's direction. Additionally, embodiments of the present invention avoid the gain compensation problems of present systems when a vehicle is traveling at high speeds.
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Kenny Andrew
McDermott, Jr. Make
Baker & Botts L.L.P.
The Texas A&M University System
Zanelli Michael J.
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