An assembly including a hollow outer tube, and a hollow inner tube fitted within the outer tube and adapted to be slidably engageable with the outer tube, and a sensor-less measurement system adapted to measure the capacitance between the inner tube and the outer tube, where relative movement between the inner tube and the outer tube is derived from the change in measured capacitance between the inner tube and the outer tube.

A calibration device includes: a first coefficient calculation unit, a first output unit, an ideal value calculation unit, a second coefficient calculation unit configured to calculate a second coefficient by dividing a second output value by the ideal value, the second output value being an actual output value of the detector when the extension/contraction amount of the suspension device is the first extension/contraction amount, and a calibration unit configured to calculate a calibration value which is an output value after calibration of the detector when the suspension device has the minimum extension/contraction amount, by using the second output value, the first extension/contraction amount, the operation amount, the first output value, and the second coefficient.

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).