Variable Tracking Active Suspension System

Abstract

An active suspension system for a sprung mass that is supported and movable relative to an unsprung mass. The active suspension system has a suspension that comprises an electromagnetic actuator that is adapted to produce an arbitrary force on the sprung mass that is independent of the position, velocity and acceleration of the sprung mass, a control system that provides control signals that cause the suspension to exert force on the sprung mass, to control the position of the sprung mass relative to the unsprung mass, wherein the control system implements a control algorithm with one or more constants, and a user interface that is operable to cause a change of one or more of the control algorithm constants so as to vary how closely motion of the sprung mass follows motion of the unsprung mass.

What is claimed is: 
     
         1 . An active suspension system for a sprung mass that is supported and movable relative to an unsprung mass, the active suspension system comprising:
 a suspension comprising an electromagnetic actuator to produce an arbitrary force on the sprung mass that is independent of the position, velocity and acceleration of the sprung mass;   a control system to provide control signals to cause the suspension to exert force on the sprung mass and control the position of the sprung mass relative to the unsprung mass, wherein the control system implements a control algorithm with one or more constants; and   a user interface operable to cause a change of one or more of the control algorithm constants that allows the user to tradeoff between an amount of relative motion between the sprung mass and the unsprung mass provided by the active suspension system and an amount of vibration isolation of the sprung mass provided by the active suspension system;   wherein the active suspension system is operative to provide vibration isolation of the sprung mass over an operating frequency range,   wherein operation of the user interface causes a frequency dependent change over the operating frequency range in the vibration isolation of the sprung mass, and;   wherein the frequency dependent change in vibration isolation is larger in a lower frequency portion of the operating frequency range than it is in a higher frequency portion of the operating frequency range.   
     
     
         2 . The active suspension system of  claim 1  wherein the suspension further comprises a bias force eliminator. 
     
     
         3 . The active suspension system of  claim 2  wherein the bias force eliminator comprises a dynamically-adjustable low stiffness spring element. 
     
     
         4 . The active suspension system of  claim 1  wherein the sprung mass comprises a seat of a motor vehicle and the unsprung mass comprises a floor of the motor vehicle. 
     
     
         5 . The active suspension system of  claim 1  wherein the user interface is operable to cause a variation in the degree to which a motion of the sprung mass follows a motion of the unsprung mass in the lower frequency portion of the operating frequency range. 
     
     
         6 . The active suspension system of  claim 1  wherein the low frequency portion of the operating frequency range comprises frequencies of no more than about 10 Hz. 
     
     
         7 . The active suspension system of  claim 1  wherein the low frequency portion of the operating frequency range comprises frequencies of no more than about 2 Hz. 
     
     
         8 . The active suspension system of  claim 1  wherein the suspension system further comprises a first sensor that senses a position of the sprung mass relative to the unsprung mass and provides a position signal to the control system. 
     
     
         9 . The active suspension system of  claim 8  wherein the suspension system further comprises a second sensor that senses an acceleration of the sprung mass relative to the unsprung mass and provides an acceleration signal to the control system. 
     
     
         10 . The active suspension system of  claim 8  wherein the control system comprises a position loop that is involved in controlling the position of the sprung mass relative to the unsprung mass. 
     
     
         11 . The active suspension system of  claim 10  wherein the control algorithm comprises proportional and derivative constants in the position loop. 
     
     
         12 . The active suspension system of  claim 11  wherein the user interface is operable to change the proportional and derivative constants in the position loop. 
     
     
         13 . The active suspension system of  claim 1  wherein the user interface defines at least two presets, where the presets are operable to change the control signals such that;
 for a first preset, for a quantity with a value computed as the ratio of motion of the sprung mass to road perturbation, a first transition frequency range within the operating frequency range is set where the quantity transitions between a value close one and a value close to zero, and; 
 for a second preset, a second transition frequency range within the operating frequency is set for the quantity, 
 wherein the first and second transition frequency ranges are different. 
 
     
     
         14 . The active suspension system of  claim 13  wherein the user interface defines three presets, each preset operable to change the control signals such that each preset sets a different transition frequency range for the quantity. 
     
     
         15 . The active suspension system of  claim 13  wherein the user interface comprises a separate user-operable button for each preset. 
     
     
         16 . An active suspension system to provide vibration isolation for a sprung mass that is supported and movable relative to an unsprung mass, the active suspension system comprising:
 a suspension that comprises an electromagnetic actuator to produce an arbitrary force on the sprung mass that is independent of the position, velocity and acceleration of the sprung mass;   a control system to provide control signals that cause the suspension to exert force on the sprung mass, to control the position of the sprung mass relative to the unsprung mass, wherein the control system implements a control algorithm with one or more constants; and   a user interface that is operable to cause a change of one or more of the control algorithm constants that allows the user to reduce the amount of vibration isolation of the sprung mass provided by the active suspension system over a low frequency portion of an operating frequency range of the active suspension, to provide a more comfortable tradeoff between an amount of relative motion between the sprung mass and the unsprung mass provided by the active suspension system and the vibration isolation of the sprung mass provided by the active suspension system.   
     
     
         17 . The active suspension system of  claim 16  wherein the sprung mass comprises a seat of a motor vehicle and the unsprung mass comprises a floor of the motor vehicle. 
     
     
         18 . The active suspension system of  claim 16  wherein the user interface is operable to cause variation in a transition frequency range within the operating frequency of a quantity with a value computed as the ratio of a motion of the sprung mass relative to road perturbation, where the quantity transitions between a value close to one and a value close to zero over the transition frequency range. 
     
     
         19 . The active suspension system of  claim 16  wherein the low frequency portion of the operating frequency range comprises frequencies of no more than about 10 Hz. 
     
     
         20 . The active suspension system of  claim 16  wherein the low frequency portion of the operating frequency range comprises frequencies of no more than about 2 Hz.