Suspension control system for controlling suspension of automotive vehicle based on wheel speed data
First Claim
1. A suspension control system for controlling a suspension of an automotive vehicle, said suspension control system comprising:
- wheel speed detection means for detecting a wheel speed of the vehicle;
extraction means for extracting at least one of a sprung resonance frequency component of the suspension and an unsprung resonance frequency component of the suspension that are contained in a wheel speed signal detected by said wheel speed detection means; and
altering means for altering the stiffness of the suspension on the basis of said at least one resonance frequency component.
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Accused Products
Abstract
A suspension control system capable of controlling a suspension of an automotive vehicle in such a manner as to improve the riding comfort and maneuverability of the vehicle without the need for many sensors is disclosed, in which a speed difference signal obtained by subtracting an estimated vehicle speed from a wheel speed is filtered with band-pass filters which pass sprung resonance frequency components and unsprung resonance frequency components, respectively. After amplification, the filtered speed difference are compared with a reference value so that a damping force of a shock absorber is set in accordance with a road surface condition. Since the damping force of the shock absorber is shifter by using only information based on the wheel speed detected by a wheel speed sensor, a total number of sensor to be mounted on the vehicle for controlling the suspension can be considerably reduced. The suspension control system is simple in construction and can be manufactured at a relatively low cost.
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Citations
61 Claims
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1. A suspension control system for controlling a suspension of an automotive vehicle, said suspension control system comprising:
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wheel speed detection means for detecting a wheel speed of the vehicle; extraction means for extracting at least one of a sprung resonance frequency component of the suspension and an unsprung resonance frequency component of the suspension that are contained in a wheel speed signal detected by said wheel speed detection means; and altering means for altering the stiffness of the suspension on the basis of said at least one resonance frequency component. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59)
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60. A suspension control system for controlling a suspension of an automotive vehicle, said suspension control system comprising:
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wheel speed detection means for detecting a wheel speed of the vehicle; extraction means for extracting at least one of a sprung resonance frequency component of the suspension and an unsprung resonance frequency component of the suspension that are contained in a wheel speed signal detected by said wheel speed detection means; altering means for altering the stiffness of the suspension on the basis of said at least one resonance frequency component; and processing means for estimating a long-term vibration of the vehicle and a road surface condition on which the vehicle is running on the basis of the wheel speed, said sprung resonance frequency component, and said unsprung resonance frequency component, and combining the estimated long term vibration and the estimated road surface condition for setting a proper stiffness of the suspension, wherein said processing means includes; first means for computing an estimated vehicle speed on the basis of said wheel speed detected by said wheel speed detection means; second means for computing a sprung vibration estimation signal on the basis of said wheel speed detected by said wheel speed detection means, said second means including a first filter which passes said sprung resonance frequency component contained said wheel speed signal detected by said wheel speed detection means; third means for computing a wheel acceleration on the basis of said wheel speed detected by said wheel speed detection means; fourth means for computing a filtered wheel acceleration on the basis of said wheel acceleration computed by said third means, said fourth means including a second filter which passes frequency components having frequencies at least the same as a frequency of said unsprung resonance frequency component; fifth means for computing a fitered wheel acceleration absolute value on the basis of said filtered wheel acceleration, and a road surface condition signal on the basis of said filtered wheel acceleration absolute value; sixth means for determining whether or not said sprung vibration estimation signal exceeds a first level range provided for detecting the degree of a long-term vibration of the vehicle and for outputting a first determination result; seventh means for determining whether or not said road surface condition signal exceeds a second level range provided for detecting the degree of roughness of the road surface on which the vehicle is running and for outputting a second determination result; eighth means for setting a proper damping force for the suspension on the basis of said first and second determination results; ninth means for determining whether or not the vehicle is an accelerated/decelerated condition and for outputting a determination result; and tenth means for changing the characteristic of said first filter when said ninth means determines that the vehicle is in accelerated/decelerated condition, wherein said tenth means increases a cut-off frequency of said first filter.
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61. A suspension control system for controlling a suspension of an automotive vehicle, said suspension control system comprising:
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wheel speed detection means for detecting a wheel speed of the vehicle; extraction means for extracting at least one of a sprung resonance frequency component of the suspension and an unsprung resonance frequency component of the suspension that are contained in a wheel speed signal detected by said wheel speed detection means; altering means for altering the stiffness of the suspension on the basis of said at least one resonance frequency component; and processing means for estimating a long-term vibration of the vehicle and a road surface condition on which the vehicle is running on the basis of the wheel speed, said sprung resonance frequency component, and said unsprung resonsance frequency component, and combining the estimated long term vibration and the estimated road surface condition for setting a proper stiffness of the suspension, wherein said processing means includes; first means for computing an estimated vehicle speed on the basis of said wheel speed detected by said wheel speed detection means; second means for computing a sprung vibration estimation signal on the basis of said wheel speed detected by said wheel speed detection means, said second means including a first filter which passes said sprung resonance frequency component contained said wheel speed signal detected by said wheel speed detection means; third means for computing a wheel acceleration on the basis of said wheel speed detected by said wheel speed detection means; fourth means for computing a filtered wheel acceleration on the basis of said wheel acceleration computed by said third means, said fourth means including a second filter which passes frequency components having frequencies at least the same as a frequency of said unsprung resonance frequency component; fifth means for computing a filtered wheel acceleration absolute value on the basis of said filtered wheel acceleration, and a road surface condition signal on the basis of said filtered wheel acceleration absolute value; sixth means for determining whether or not said sprung vibration estimation signal exceeds a first level range provided for detecting the degree of a long-term vibration of the vehicle and for outputting a first determination result; seventh means for determining whether or not said road surface condition signal exceeds a second level range provided for detecting the degree of roughness of the road surface on which the vehicle is running and for outputting a second determination result; and eighth means for setting a proper damping force for the suspension on the basis of said first and second determination results; and means for correcting the characteristic of said first filter on the basis of said road surface condition signal computed by said fifth means before said second means computes said sprung vibration estimation signal.
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Specification