Method and apparatus for controlling an electric assist steering system using an adaptive blending torque filter

Claim 1

An apparatus for controlling a steering assist system, said steering assist system providing assist in response to a steering control signal, said apparatus comprising: torque sensing means operatively connected to a vehicle hand wheel for providing a torque signal indicative of applied steering torque; blending filter means connected to said torque sensing means for providing a blended filtered torque signal having a first functional characteristic at torque frequencies less than a blending frequency and a second functional characteristic at torque frequencies greater than said blending frequency; steering assist means for providing steering assist in response to a control signal; and control means operatively connected to said blending filter means for providing said control signal to said steering assist means in response to said blended filtered torque signal, said blending filtering means filtering said torque signal so as to maintain a selectable system bandwidth during system operation.

Claim 2

An apparatus for controlling a steering assist system, said steering assist system providing assist in response to a steering control signal, said apparatus comprising: torque sensing means operatively connected to a vehicle hand wheel for providing a torque signal indicative of applied steering torque; blending filter means connected to said torque sensing means for providing a blended filtered torque signal having a first functional characteristic at torque frequencies less than a blending frequency and a second functional characteristic at torque frequencies greater than said blending frequency; steering assist means for providing steering assist in response to a control signal; and control means operatively connected to said blending filter means for providing said control signal to said steering assist means in response to said blended filtered torque signal, said blending filtering means filtering said torque signal so as to maintain a selectable system bandwidth during system operation.

Claim 6

An apparatus for controlling a steering assist system, said steering assist system providing assist in response to a steering control signal, said apparatus comprising: vehicle speed sensing means for sensing vehicle speed and for providing a speed signal having a value indicative of the sensed vehicle speed; torque sensing means operatively connected to a vehicle hand wheel for providing a torque signal indicative of applied steering torque; blending filter means connected to said torque sensing means and to said vehicle speed sensing means for providing a blended filtered torque signal having a first functional characteristic at torque frequencies less than a blending frequency and a second functional characteristic at torque frequencies greater than said blending frequency, said blending filter means further establishing said blending frequency at a value functionally related to vehicle speed; steering assist means for providing steering assist in response to a control signal; and control means operatively connected to said blending filter means for providing said control signal to said steering assist means in response to said blended filtered torque signal, said blending filtering means filtering said torque signal so as to maintain a selectable system bandwidth during system operation.

Claim 7

An apparatus for controlling a steering assist system, said steering assist system providing assist in response to a steering control signal, said apparatus comprising: vehicle speed sensing means for sensing vehicle speed and for providing a speed signal having a value indicative of the sensed vehicle speed; torque sensing means operatively connected to a vehicle hand wheel for providing a torque signal indicative of applied steering torque; blending filter means connected to said torque sensing means and to said vehicle speed sensing means for providing a blended filtered torque signal having a first functional characteristic at torque frequencies less than a blending frequency and a second functional characteristic at torque frequencies greater than said blending frequency, said blending filter means further establishing said blending frequency at a value functionally related to vehicle speed; steering assist means for providing steering assist in response to a control signal; and control means operatively connected to said blending filter means for providing said control signal to said steering assist means in response to said blended filtered torque signal, said blending filtering means filtering said torque signal so as to maintain a selectable system bandwidth during system operation.

Claim 12

A method for controlling a steering assist system that provides steering assist in response to a steering control signal, said method comprising the steps of: measuring applied steering torque and providing a torque signal indicative of the measured applied steering torque; filtering said torque signal so as to have a first functional characteristic at torque frequencies less than a blending frequency and a second functional characteristic at torque frequencies greater than said blending frequency so as to maintain a selectable system bandwidth during system operation; providing steering assist in response to a steering control signal; and providing the control signal in response to the filtered torque signal.

Claim 13

A method for controlling a steering assist system that provides steering assist in response to a steering control signal, said method comprising the steps of: measuring applied steering torque and providing a torque signal indicative of the measured applied steering torque; filtering said torque signal so as to have a first functional characteristic at torque frequencies less than a blending frequency and a second functional characteristic at torque frequencies greater than said blending frequency so as to maintain a selectable system bandwidth during system operation; providing steering assist in response to a steering control signal; and providing the control signal in response to the filtered torque signal.

Claim 17

An apparatus for controlling a steering assist system, said steering assist system providing assist in response to a steering control signal, said apparatus comprising: torque sensing means operatively connected to a vehicle hand wheel for providing a torque signal indicative of applied steering torque; blending filter means connected to said torque sensing means for providing a blended filtered torque signal having a first functional characteristic at torque frequencies less than a blending frequency and a second functional characteristic at torque frequencies greater than said blending frequency; steering assist means for providing steering assist in response to a control signal; and control means operatively connected to said blending filter means for providing said control signal to said steering assist means in response to said blended filtered torque signal, said blending filtering means filtering said torque signal so as to maintain a selectable system bandwidth during system operation; wherein said blending filter means includes means for establishing a blending frequency value one decade lower than the system's open loop zero db crossover frequency.

Claim 18

An apparatus for controlling a steering assist system, said steering assist system providing assist in response to a steering control signal, said apparatus comprising: torque sensing means operatively connected to a vehicle hand wheel for providing a torque signal indicative of applied steering torque; blending filter means connected to said torque sensing means for providing a blended filtered torque signal having a first functional characteristic at torque frequencies less than a blending frequency and a second functional characteristic at torque frequencies greater than said blending frequency; steering assist means for providing steering assist in response to a control signal; and control means operatively connected to said blending filter means for providing said control signal to said steering assist means in response to said blended filtered torque signal, said blending filtering means filtering said torque signal so as to maintain a selectable system bandwidth during system operation; wherein said blending filter means includes means for establishing a blending frequency value one decade lower than the system's open loop zero db crossover frequency.

Claim 19

An apparatus for controlling a steering assist system, said steering assist system providing assist in response to a steering control signal, said apparatus comprising: torque sensing means operatively connected to a vehicle hand wheel for providing a torque signal indicative of applied steering torque; blending filter means connected to said torque sensing means for providing a blended filtered torque signal having a first functional characteristic at torque frequencies less than a blending frequency and a second functional characteristic at torque frequencies greater than said blending frequency, and including high pass filter means for passing the torque signal with frequencies greater than said blending frequency; steering assist means for providing steering assist in response to a control signal; and control means operatively connected to said blending filter means for providing said control signal to said steering assist means in response to said blended filtered torque signal, said blending filtering means filtering said torque signal so as to maintain a selectable system bandwidth during system operation.

Claim 20

An apparatus for controlling a steering assist system, said steering assist system providing assist in response to a steering control signal, said apparatus comprising: torque sensing means operatively connected to a vehicle hand wheel for providing a torque signal indicative of applied steering torque; blending filter means connected to said torque sensing means for providing a blended filtered torque signal having a first functional characteristic at torque frequencies less than a blending frequency and a second functional characteristic at torque frequencies greater than said blending frequency, and including high pass filter means for passing the torque signal with frequencies greater than said blending frequency; steering assist means for providing steering assist in response to a control signal; and control means operatively connected to said blending filter means for providing said control signal to said steering assist means in response to said blended filtered torque signal, said blending filtering means filtering said torque signal so as to maintain a selectable system bandwidth during system operation.

Claim 21

An apparatus for controlling a steering assist system, said steering assist system providing assist in response to a steering control signal, said apparatus comprising: vehicle speed sensing means for sensing vehicle speed and for providing a speed signal having a value indicative of the sensed vehicle speed; torque sensing means operatively connected to a vehicle hand wheel for providing a torque signal indicative of applied steering torque; blending filter means connected to said torque sensing means and to said vehicle speed sensing means for providing a blended filtered torque signal having a first functional characteristic at torque frequencies less than a blending frequency and a second functional characteristic at torque frequencies greater than said blending frequency, said blending filter means further establishing said blending frequency at a value functionally related to vehicle speed and one decade lower than the system's open loop zero db crossover frequency; steering assist means for providing steering assist in response to a control signal; and control means operatively connected to said blending filter means for providing said control signal to said steering assist means in response to said blended filtered torque signal, said blending filtering means filtering said torque signal so as to maintain a selectable system bandwidth during system operation; wherein said blending filter means further includes means for establishing said blending frequency value.

Claim 22

An apparatus for controlling a steering assist system, said steering assist system providing assist in response to a steering control signal, said apparatus comprising: vehicle speed sensing means for sensing vehicle speed and for providing a speed signal having a value indicative of the sensed vehicle speed; torque sensing means operatively connected to a vehicle hand wheel for providing a torque signal indicative of applied steering torque; blending filter means connected to said torque sensing means and to said vehicle speed sensing means for providing a blended filtered torque signal having a first functional characteristic at torque frequencies less than a blending frequency and a second functional characteristic at torque frequencies greater than said blending frequency, said blending filter means further establishing said blending frequency at a value functionally related to vehicle speed and one decade lower than the system's open loop zero db crossover frequency; steering assist means for providing steering assist in response to a control signal; and control means operatively connected to said blending filter means for providing said control signal to said steering assist means in response to said blended filtered torque signal, said blending filtering means filtering said torque signal so as to maintain a selectable system bandwidth during system operation; wherein said blending filter means further includes means for establishing said blending frequency value.