Method, system, and apparatus for providing enhanced steering pull compensation
First Claim
1. A method of providing compensation for steering pull in a vehicle steering system that includes a handwheel, the method including:
- monitoring the vehicle to determine whether the vehicle is heading forward along a substantially linear straight-ahead path and, if so;
measuring handwheel torque, as a sensed torque signal, to determine an amount of steering pull existing at the handwheel;
generating a torque assist signal in response to the sensed torque signal;
calculating an offset signal for reducing the amount of steering pull to substantially zero by;
integrating the sensed torque signal to produce a short term compensation signal;
integrating a sum of the sensed torque signal and the short term compensation signal to produce a long term compensation signal; and
summing the short term compensation signal and the long term compensation signal to produce the offset signal;
producing a modified torque assist signal by adding the offset signal to the torque assist signal; and
applying the modified torque assist signal to the vehicle steering system.
9 Assignments
0 Petitions
Accused Products
Abstract
A method, system, and apparatus for providing enhanced steering pull compensation are provided. The method compensates for steering pull in a vehicle steering system that includes a handwheel. The method includes monitoring the vehicle to determine whether the vehicle is heading forward along a substantially linear straight-ahead path and, if so, measuring handwheel torque, as a sensed torque signal, to determine an amount of steering pull existing at the handwheel. The method also includes generating a torque assist signal in response to the sensed torque signal and calculating an offset signal for reducing the amount of steering pull to substantially zero. The method further includes producing a modified torque assist signal by adding the offset signal to the torque assist signal, and applying the modified torque assist signal to the vehicle steering system.
254 Citations
16 Claims
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1. A method of providing compensation for steering pull in a vehicle steering system that includes a handwheel, the method including:
monitoring the vehicle to determine whether the vehicle is heading forward along a substantially linear straight-ahead path and, if so; measuring handwheel torque, as a sensed torque signal, to determine an amount of steering pull existing at the handwheel; generating a torque assist signal in response to the sensed torque signal; calculating an offset signal for reducing the amount of steering pull to substantially zero by;
integrating the sensed torque signal to produce a short term compensation signal;
integrating a sum of the sensed torque signal and the short term compensation signal to produce a long term compensation signal; and
summing the short term compensation signal and the long term compensation signal to produce the offset signal;producing a modified torque assist signal by adding the offset signal to the torque assist signal; and applying the modified torque assist signal to the vehicle steering system. - View Dependent Claims (2, 3, 4, 5, 6, 7, 15)
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8. A controller for a vehicular steering system that includes a handwheel for steering the vehicle, a torque sensing mechanism for sensing torque applied to the handwheel and providing a sensed torque signal in response thereto, an angular position sensor for sensing an angular position of the handwheel and providing an angular position sensor output in response thereto, a vehicle speed sensor capable of acquiring vehicle speed, and a motor which provides assist torque to the steering system, the controller including:
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a torque assist function responsive to the sensed torque signal for providing a torque assist command to the motor; and a steering pull compensator for modifying the torque assist command to the motor by an offset signal corresponding to a detected steering pull condition; wherein the steering pull compensator includes a first lowpass filter operatively coupled to a first integrator for generating a short term compensation signal from the sensed torque signal passing through the first lowpass filter and the first integrator, a second lowpass filter operatively coupled to a second integrator for generating a long term compensation signal from a sum of the short term compensation signal and the sensed torque signal passing through the second lowpass filter and the second integrator, and a combiner for combining the short term compensation signal and the long term compensation signal to generate the offset signal; wherein the first lowpass filter has a first time constant, and the second lowpass filter has a second time constant longer than the first time constant; wherein the first integrator has a first gain, and the second integrator has a second gain less than the first gain; and wherein the first and second lowpass filters are enabled in response to the vehicle traveling forward along a substantially linear straight-ahead path as determined by at least one of the sensed torque signal, the angular position sensor output, and the acquired vehicle speed. - View Dependent Claims (9, 10, 11, 12, 13, 14, 16)
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Specification