Method and system for improving motor vehicle stability incorporating an electric power steering system

Claim 2

A stabilizing system for a vehicle employing an electric power steering system which generates a desired torque command, the system comprising: a vehicle speed sensor, wherein said vehicle speed sensor measures a vehicle speed and transmits a vehicle speed signal representative of said vehicle speed; an assist mechanism configured apply an assist torque to said electric power steering system, wherein said assist torque is responsive to an assist torque command; an acceleration sensor, wherein said acceleration sensor measures vehicle acceleration and transmits an acceleration signal representative of said vehicle acceleration; a controller configured to receive signals including: a steering wheel torque signal from a torque sensor; a steering wheel position signal from a steering wheel position sensor; said vehicle speed signal from said vehicle speed sensor; said acceleration signal from said acceleration sensor; said controller further configured to generate said assist torque command comprising a combination of said desired torque command with a compensating torque command; and wherein said acceleration sensor measures vehicle yaw acceleration and transmits a yaw acceleration signal.

Claim 3

The electric power steering system of claim 1 further including a second acceleration sensor, which measures a second vehicle acceleration.

Claim 4

The electric power steering system of claim 2 wherein: said second acceleration sensor generates a second acceleration signal representative of said second vehicle acceleration; said second acceleration signal is a lateral acceleration signal representative of vehicle lateral acceleration; and said compensating torque command is responsive to said vehicle speed signal, said yaw acceleration, and said lateral acceleration signal.

Claim 5

A stabilizing system for a vehicle employing an electric power steering system which generates a desired torque command, the system comprising: a vehicle speed sensor, wherein said vehicle speed sensor measures a vehicle speed and transmits a vehicle speed signal representative of said vehicle speed; an assist mechanism configured apply an assist torque to said electric power steering system, wherein said assist torque is responsive to an assist torque command; an acceleration sensor, wherein said acceleration sensor measures vehicle acceleration and transmits an acceleration signal representative of said vehicle acceleration; a controller configured to receive signals including: a steering wheel torque signal from a torque sensor; a steering wheel position signal from a steering wheel position sensor; said vehicle speed signal from said vehicle speed sensor; said acceleration signal from said acceleration sensor; said controller further configured to generate said assist torque command comprising a combination of said desired torque command with a compensating torque command; wherein said acceleration sensor measures vehicle yaw acceleration and transmits a yaw acceleration signal; and wherein said compensating torque command is the resultant of frequency based compensation applied via a yaw acceleration compensator to said yaw acceleration signal.

Claim 6

A stabilizing system for a vehicle employing an electric power steering system which generates a desired torque command, the system comprising: a vehicle speed sensor, wherein said vehicle speed sensor measures a vehicle speed and transmits a vehicle speed signal representative of said vehicle speed; an assist mechanism configured apply an assist torque to said electric power steering system, wherein said assist torque is responsive to an assist torque command; an acceleration sensor, wherein said acceleration sensor measures vehicle acceleration and transmits an acceleration signal representative of said vehicle acceleration; a controller configured to receive signals including: a steering wheel torque signal from a torque sensor; a steering wheel position signal from a steering wheel position sensor; said vehicle speed signal from said vehicle speed sensor; said acceleration signal from said acceleration sensor; said controller further configured to generate said assist torque command comprising a combination of said desired torque command with a compensating torque command; wherein said acceleration sensor measures vehicle yaw acceleration and transmits a yaw acceleration signal; and wherein said compensating torque command is the resultant of frequency based compensation applied via a yaw acceleration compensator to said yaw acceleration signal.

Claim 7

The electric power steering system of claim 4 wherein said yaw acceleration compensator modifies and shapes the spectral content of said yaw acceleration signal to maintain the stability of said vehicle.

Claim 8

The electric power steering system of claim 5 wherein said yaw acceleration compensator is characterized by a second order band pass filter arrangement with a pass band between about 0.15 Hz and about 15.0 Hz.

Claim 9

A stabilizing system for a vehicle employing an electric power steering system which generates a desired torque command, the system comprising: a vehicle speed sensor, wherein said vehicle speed sensor measures a vehicle speed and transmits a vehicle speed signal representative of said vehicle speed; an assist mechanism configured apply an assist torque to said electric power steering system, wherein said torque is responsive to an assist torque command; an acceleration sensor, wherein said acceleration sensor measures vehicle acceleration and transmits an acceleration signal representative of said vehicle acceleration; a controller configured to receive signals including: a steering wheel torque signal from a torque sensor; a steering wheel position signal from a steering wheel position sensor; said vehicle speed signal from said vehicle speed sensor; said acceleration signal from said acceleration sensor; said controller further configured to generate said assist torque command comprising a combination of said desired torque command with a compensating torque command; wherein said acceleration signal is a lateral acceleration signal; and wherein said compensating torque command is the resultant of frequency based compensation applied via a lateral acceleration compensator to said lateral acceleration signal.

Claim 10

A stabilizing system for a vehicle employing an electric power steering system which generates a desired torque command, the system comprising: a vehicle speed sensor, wherein said vehicle speed sensor measures a vehicle speed and transmits a vehicle speed signal representative of said vehicle speed; an assist mechanism configured apply an assist torque to said electric power steering system, wherein said torque is responsive to an assist torque command; an acceleration sensor, wherein said acceleration sensor measures vehicle acceleration and transmits an acceleration signal representative of said vehicle acceleration; a controller configured to receive signals including: a steering wheel torque signal from a torque sensor; a steering wheel position signal from a steering wheel position sensor; said vehicle speed signal from said vehicle speed sensor; said acceleration signal from said acceleration sensor; said controller further configured to generate said assist torque command comprising a combination of said desired torque command with a compensating torque command; wherein said acceleration signal is a lateral acceleration signal; and wherein said compensating torque command is the resultant of frequency based compensation applied via a lateral acceleration compensator to said lateral acceleration signal.

Claim 11

The electric power steering system of claim 7 wherein said lateral acceleration compensator modifies the spectral content of said lateral acceleration signal to maintain the stability of said electric power steering system.

Claim 12

The electric power steering system of claim 8 wherein said lateral acceleration compensator is characterized by a second order band pass filter arrangement with a pass band between about 0.25 Hz and about 6.25 Hz.

Claim 13

A stabilizing system for a vehicle employing an electric power steering system which generates a desired torque command, the system comprising: a vehicle speed sensor, wherein said vehicle speed sensor measures a vehicle speed and transmits a vehicle speed signal representative of said vehicle speed; an assist mechanism configured apply an assist torque to said electric power steering system, wherein said assist torque is responsive to an assist torque command; an acceleration sensor, wherein said acceleration sensor measures vehicle acceleration and transmits an acceleration signal representative of said vehicle acceleration; a controller configured to receive signals including: a steering wheel torque signal from a torque sensor; a steering wheel position signal from a steering wheel position sensor; said vehicle speed signal from said vehicle speed sensor; said acceleration signal from said acceleration sensor; said controller further configured to generate said assist torque command comprising a combination of said desired torque command with a compensating torque command; and wherein said compensating torque command is characterized by a scheduling of an acceleration scale factor which is the resultant of a speed stability look up table indexed by vehicle speed.

Claim 14

A stabilizing system for a vehicle employing an electric power steering system which generates a desired torque command, the system comprising: a vehicle speed sensor, wherein said vehicle speed sensor measures a vehicle speed and transmits a vehicle speed signal representative of said vehicle speed; an assist mechanism configured apply an assist torque to said electric power steering system, wherein said assist torque is responsive to an assist torque command; an acceleration sensor, wherein said acceleration sensor measures vehicle acceleration and transmits an acceleration signal representative of said vehicle acceleration; a controller configured to receive signals including: a steering wheel torque signal from a torque sensor; a steering wheel position signal from a steering wheel position sensor; said vehicle speed signal from said vehicle speed sensor; said acceleration signal from said acceleration sensor; said controller further configured to generate said assist torque command comprising a combination of said desired torque command with a compensating torque command; and wherein said compensating torque command is characterized by a scheduling of an acceleration scale factor which is the resultant of a speed stability look up table indexed by vehicle speed.

Claim 15

A stabilizing system for a vehicle employing an electric power steering system which generates a desired torque command, the system comprising: a vehicle speed sensor, wherein said vehicle speed sensor measures a vehicle speed and transmits a vehicle speed signal representative of said vehicle speed; an assist mechanism configured apply an assist torque to said electric power steering system, wherein said assist torque is responsive to an assist torque command; an acceleration sensor, wherein said acceleration sensor measures vehicle acceleration and transmits an acceleration signal representative of said vehicle acceleration; a controller configured to receive signals including: a steering wheel torque signal from a torque sensor; a steering wheel position signal from a steering wheel position sensor; said vehicle speed signal from said vehicle speed sensor; said acceleration signal from said acceleration sensor; said controller further configured to generate said assist torque command comprising a combination of said desired torque command with a compensating torque command; wherein said compensating torque command is the resultant of application of a compensating torque limit function to a composite feedback signal; and said compensating torque limit function is responsive to limiting established by a compensating torque limit look up table which is indexed by vehicle speed to generate a limit value for said compensating torque limit function.

Claim 16

A stabilizing system for a vehicle employing an electric power steering system which generates a desired torque command, the system comprising: a vehicle speed sensor, wherein said vehicle speed sensor measures a vehicle speed and transmits a vehicle speed signal representative of said vehicle speed; an assist mechanism configured apply an assist torque to said electric power steering system, wherein said assist torque is responsive to an assist torque command; an acceleration sensor, wherein said acceleration sensor measures vehicle acceleration and transmits an acceleration signal representative of said vehicle acceleration; a controller configured to receive signals including: a steering wheel torque signal from a torque sensor; a steering wheel position signal from a steering wheel position sensor; said vehicle speed signal from said vehicle speed sensor; said acceleration signal from said acceleration sensor; said controller further configured to generate said assist torque command comprising a combination of said desired torque command with a compensating torque command; wherein said compensating torque command is the resultant of application of a compensating torque limit function to a composite feedback signal; and said compensating torque limit function is responsive to limiting established by a compensating torque limit look up table which is indexed by vehicle speed to generate a limit value for said compensating torque limit function.

Claim 17

The electric power steering system of claim 11 wherein said compensating torque limit function limits the compensating torque command magnitude to decreasing values of said composite feedback signal as said vehicle speed increases.

Claim 18

The electric power steering system of claim 11 wherein said composite feedback signal is generated as a result of a combination of one or more feed back signals.

Claim 19

The electric power steering system of claim 13 wherein said one or more feed back signals includes a yaw feed back signal and a lateral feed back signal.

Claim 20

The electric power steering system of claim 13 wherein said one or more feed back signals is characterized by the scheduling of a compensated acceleration signal by an acceleration scale factor.

Claim 21

The electric power steering system of claim 15 wherein said acceleration scale factor is the resultant of a speed stability look up table indexed by vehicle speed.

Claim 22

The electric power steering system of claim 15 wherein said compensated acceleration signal is the resultant of frequency based compensation applied via an acceleration compensator to said acceleration signal.

Claim 23

The electric power steering system of claim 17 wherein said acceleration compensator modifies the spectral content of said acceleration signal to maintain the stability of said electric power steering system.

Claim 24

The electric power steering system of claim 18 wherein said acceleration compensator is characterized by a second order band pass filter.

Claim 27

The method of claim 20 further including acquiring a second acceleration signal representative of a second vehicle acceleration.

Claim 28

The method of claim 21 wherein: said second acceleration signal is generated by a second acceleration sensor that measures said second vehicle acceleration; said second acceleration signal is a lateral acceleration signal representative of vehicle lateral acceleration; and wherein said compensating torque command is responsive to said vehicle speed signal, said yaw acceleration, and said lateral acceleration signal.

Claim 31

The method of claim 23 wherein said yaw acceleration compensator modifies and shapes the spectral content of said yaw acceleration signal to maintain the stability of said vehicle.

Claim 32

The method of claim 24 wherein said yaw acceleration compensator is characterized by a second order band pass filter arrangement with a pass band between about 0.15 Hz and about 15.0 Hz.

Claim 35

The method of claim 26 wherein said lateral acceleration compensator modifies the spectral content of said lateral acceleration signal to maintain the stability of said vehicle.

Claim 36

The method of claim 27 wherein said lateral acceleration compensator is characterized by a second order band pass filter arrangement with a pass band between about 0.25 Hz. and about 6.25 Hz.

Claim 41

The method of claim 30 wherein said compensating torque limit function limits the compensating torque command magnitude to decreasing values of said composite feedback signal as said vehicle speed increases.

Claim 42

The method of claim 30 wherein said composite feedback signal is generated as a result of a combination of one or more feed back signals.

Claim 43

The method of claim 32 wherein said one or more feed back signals includes a yaw feed back signal and lateral feed back signal.

Claim 44

The method of claim 32 wherein said one or more feed back signals is characterized by the scheduling of a compensated acceleration signal by an acceleration scale factor.

Claim 45

The method of claim 34 wherein said acceleration scale factor is the resultant of a speed stability look up table indexed by vehicle speed.

Claim 46

The method of claim 34 wherein said compensated acceleration signal is the resultant of frequency based compensation applied via an acceleration compensator to said acceleration signal.

Claim 47

The method of claim 36 wherein said acceleration compensator modifies the spectral content of said acceleration signal to maintain the stability of said electric power steering system.

Claim 48

The method of claim 37 wherein said acceleration compensator is characterized by a second order band pass filter.

Claim 49

A storage medium encoded with a machine-readable computer program code for stabilizing a vehicle employing an electric power steering system said storage medium including instruction for causing a computer to implement a method comprising: receiving a desired torque command representative of a steering wheel torque desired in said electric power steering system; receiving a vehicle speed signal representative of a forward speed of said vehicle; acquiring an acceleration signal representative of vehicle acceleration; generating an assist torque command comprising a combination of said desired torque command with a compensating torque command; applying said assist torque command to an assist mechanism; wherein said acceleration signal is generated by an acceleration sensor that measures said vehicle acceleration and transmit said acceleration signal; wherein said compensating torque command is responsive to said vehicle speed signal and said acceleration signal; and wherein said compensating torque command is the resultant of application of a compensating torque limit function to a composite feedback signal; and said compensating torque limit function is responsive to limiting established by a compensating torque limit look up table which is indexed by vehicle speed to generate a limit value for said compensating torque limit function.

Claim 50

A storage medium encoded with a machine-readable computer program code for stabilizing a vehicle employing an electric power steering system said storage medium including instruction for causing a computer to implement a method comprising: receiving a desired torque command representative of a steering wheel torque desired in said electric power steering system; receiving a vehicle speed signal representative of a forward speed of said vehicle; acquiring an acceleration signal representative of vehicle acceleration; generating an assist torque command comprising a combination of said desired torque command with a compensating torque command; applying said assist torque command to an assist mechanism; wherein said acceleration signal is generated by an acceleration sensor that measures said vehicle acceleration and transmit said acceleration signal; wherein said compensating torque command is responsive to said vehicle speed signal and said acceleration signal; and wherein said compensating torque command is the resultant of application of a compensating torque limit function to a composite feedback signal; and said compensating torque limit function is responsive to limiting established by a compensating torque limit look up table which is indexed by vehicle speed to generate a limit value for said compensating torque limit function.

Claim 51

A computer data signal for stabilizing a vehicle employing an electric power steering system said computer data signal comprising code for causing a computer to implement a method comprising: receiving a desired torque command representative of a steering wheel torque desired in said electric power steering system; receiving a vehicle speed signal representative of a forward speed of said vehicle; acquiring an acceleration signal representative of vehicle acceleration; generating an assist torque command comprising a combination of said desired torque command with a compensating torque command; applying said assist torque command to assist mechanism; wherein said acceleration signal is generated by an acceleration sensor that measures said vehicle acceleration and transmit said acceleration signal; wherein said compensating torque command is responsive to said vehicle speed signal and said acceleration signal; and wherein said compensating torque command is the resultant of application of a compensating torque limit function to a composite feedback signal; and said compensating torque limit function is responsive to limiting established by a compensating torque limit look up table which is indexed by vehicle speed to generate a limit value for said compensating torque limit function.

Claim 52

A computer data signal for stabilizing a vehicle employing an electric power steering system said computer data signal comprising code for causing a computer to implement a method comprising: receiving a desired torque command representative of a steering wheel torque desired in said electric power steering system; receiving a vehicle speed signal representative of a forward speed of said vehicle; acquiring an acceleration signal representative of vehicle acceleration; generating an assist torque command comprising a combination of said desired torque command with a compensating torque command; applying said assist torque command to assist mechanism; wherein said acceleration signal is generated by an acceleration sensor that measures said vehicle acceleration and transmit said acceleration signal; wherein said compensating torque command is responsive to said vehicle speed signal and said acceleration signal; and wherein said compensating torque command is the resultant of application of a compensating torque limit function to a composite feedback signal; and said compensating torque limit function is responsive to limiting established by a compensating torque limit look up table which is indexed by vehicle speed to generate a limit value for said compensating torque limit function.