Development of a vehicle height sensor for active suspension

This paper describes development method of a vehicle height sensor for active suspension controlled by using magnetic rheological fluid. Most of the current vehicle height sensors have been installed at external place of the damper and connected to that by linkage structures so far. This mechanism has disadvantage of instability and inaccuracy. The proposed sensor could be installed at inside of the MR CDC dampers so that there is no misalignment between the center axis of the damper and the vehicle height measuring position. The sensor mechanism has been designed based upon the well known magnetic field induced position sensor principle used in LVDT(linear variable displacement transducer). Dimensional parameters of the sensor could be determined by analyzing the magnetic phenomena around a sensor coil assembly and a sensor rod. Sensor output signal processing circuits have been also developed in order to have fast response and communicate with an active damper ECU. A series of experiments have been conducted to evaluate the steady state as well as the transient state performances. As the results, the developed sensors show that the accuracy is under plusmn0.5%, the resolution is 0.1 mm and the response time is up to 0.2 msec.