A vehicle control device includes a sensor and a controller. The sensor detects wheel speed. The controller estimates sprung mass state based on detected information in a prescribed frequency range. The controller controls a variable-damping force shock absorber to bring the estimated sprung mass state to a target sprung mass state. The controller estimates wheel rim braking/drive torque acting on a wheel. The controller determines the estimation accuracy of the sprung mass state has deteriorated when a rate of change of a stationary component extracted from components of wheel rim braking/drive torque acting on a wheel is detected to equal or exceed a prescribed value. The controller controls the variable-damping force shock absorber to a more limited extent than when the estimation accuracy has not deteriorated.

A method is described for determining multiplicative faults of a sensor installed in a system comprising a plurality of sensors, comprising the steps of:detecting an effective target signal (s) from a target sensor, representative of a target quantity of the system;detecting one or more auxiliary signals respectively from one or more auxiliary sensors of the system besides the target sensor, representative of auxiliary quantities of the system;determining an estimated target signal (s*) representative of the target quantity from the one or more auxiliary signals;determining a first quadratic difference (r+) between the effective target signal (s) multiplied by a multiplicative positive factor (cr+) greater than 1, and the estimated target signal (s*);determining a second quadratic difference (r) between the effective target signal (s) and estimated target signal (s*);determining a third quadratic difference (r) between the effective target signal (s) multiplied by a positive multiplicative factor (c) smaller than 1, and the estimated target signal (s*);determining a first ratio (r/r+) between the second (r) and lirst quadratic differences (r+);determining a second ratio (r/r) between the second (r) and third quadratic differences (r);comparing the first (r/r+) and second ratios (r/r) with a first comparison factor (Kf);determining the square of the effective target signal (s); determining the square of the estimated target signal (s*); comparing the square of the effective target signal (s) and square of estimated target signatl (s*) with a second comparison factor (Ke); establishing the presence of multiplicative faults of target sensor if at least one between the first (r/r+) and second ratios (r/r) is greater than the first comparison factor (Kf), and at least one between the square of the effective target signal (s) and square of the estimated target signal (s*) is greater than said second comparison factor (Ke).

Aspects of the present invention relate to a control system (100, 200) for a vehicle suspension system of a vehicle (800). The control system is configured to perform a test for testing operation of an isolation switch (430). The vehicle suspension system comprises an actuator power supply (450) configured to supply power to the vehicle suspension system. The actuator power supply is configured to be electrically connected to the vehicle suspension system via the isolation switch. The control system is configured to: receive a shutdown indicator signal indicating that the vehicle is in a shutdown state (530); output an open isolation switch signal (524) configured to open the isolation switch in dependence on the shutdown indicator signal; receive an open isolation switch confirmation signal (516) indicative of the isolation switch being open; determine whether the open isolation switch confirmation signal is received within a predetermined time period; and output a test pass signal or a test failure signal in dependence on the determination.