Vehicle guidance system
A vehicle guidance system is disclosed where the vehicle includes a steering wheel assembly including a steering wheel and a hub, the hub connected to a steering shaft rotatable about a steering wheel axis within a steering column for steering the vehicle. The vehicle guidance system includes a receiver for receiving a position indication signal, a steering controller for generating a steering control signal based on the position indication signal and a drive assembly to directly drive the steering wheel assembly responsive to the steering control signal. The drive assembly generates a torque about a drive axis to rotate the steering wheel assembly, wherein the drive axis of the drive assembly is coaxial to the steering wheel axis.
1. A method of disengaging a drive assembly in a vehicle guidance system, the vehicle guidance system having a steering controller and a motor controller, and the vehicle guidance system operable on a steering wheel assembly including a steering wheel and a hub, the hub connected to a steering shaft rotatable about a steering wheel axis within a steering column for steering the vehicle and the drive assembly operable to generate a torque about a drive axis to rotate the steering wheel assembly, wherein the drive axis of the drive assembly is coaxial to the steering wheel axis, the method including the steps of:
commanding, using a signal from the steering controller, the drive assembly to achieve a prescribed value of a performance parameter;
monitoring, by the motor controller, the drive assembly to determine an actual value of the performance parameter;
determining a difference measure between the prescribed value and the actual value and disengaging, using a signal from the motor controller, the drive assembly based on the difference measure.
2. The method of disengaging a drive assembly as claimed in claim 1 , wherein the drive assembly includes an electric motor.
3. The method of disengaging a drive assembly as claimed in claim 2 , wherein the performance parameter is electric motor speed.
4. The method of disengaging a drive assembly as claimed in claim 2 , wherein the performance parameter is a direction of rotation of the electric motor.
5. The method of disengaging a drive assembly as claimed in claim 2 , wherein the performance parameter is electric motor torque.
6. The method of disengaging a drive assembly as claimed in claim 2 , wherein the performance parameter is electric motor position.
7. The method of disengaging a drive assembly as claimed in claim 2 , wherein the performance parameter is steered wheel angle position.
8. The method of disengaging a drive assembly as claimed in claim 2 , wherein the performance parameter is the position of the vehicle.
9. The method of disengaging a drive assembly as claimed in claim 2 , wherein the commanded performance parameter and the monitored performance parameter are different.
10. The method of disengaging a drive assembly as claimed in claim 9 , wherein the commanded performance parameter is a direction of applied torque and the monitored performance parameter is an acceleration of the electric motor.
11. The method of disengaging a drive assembly as claimed in claim 1 , wherein the difference measure is evaluated over a predetermined time period.