CPC B62D 15/025 (2013.01) [B62D 5/0463 (2013.01); B62D 6/003 (2013.01); B62D 5/0421 (2013.01)] | 12 Claims |
1. A vehicle steering system comprising
a power assisted steering module including
a steering motor and
a motor controller for:
receiving a signal representing a target steering angle to automatically maintain a position of the vehicle on a road;
calculating, from the target steering angle, a motor torque value to be applied to the steering motor for controlling the steering motor;
maintaining the motor torque value while a driver-applied steering input parameter is below a non-zero first threshold;
limiting the motor torque value to reduce an influence of the signal in linear proportion to an increase in the driver-applied steering input parameter when the driver-applied steering input parameter is above the first threshold and below a second threshold that is higher than the first threshold; and
reducing the motor torque value substantially to zero when the driver-applied steering input parameter reaches or exceeds the second threshold,
wherein limiting the motor torque value is further dependent on a steering angle error comprising a difference between the target steering angle and an actual steering angle provided to a steering wheel of the steering system.
|