Stator-Free RPM Sensor Using Accelerometers—A Statistical Performance Simulation by Monte Carlo Method

This paper presents an statistical performance simulation for rigid-body revolutions per minute (RPM) measurement based on two uni-axial accelerometers mounted on rotor. In comparison with other existing sensing methods that are based on two coupled parts, namely stator and rotor and which include conventional electro-magnetic RPM sensors and photo-electric RPM sensors, this new stator-free inertial sensing principle has the advantage of high bandwidth at low RPM, true contact-free sensing and flexible installation. The paper first focuses on the description of the operating principle and the common mode rejection (CMR) method of the stator-free RPM sensor, and then its error model is developed and the error sources are statistically simulated based on Monte Carlo method. The simulation result presents a most interesting property of this sensor, that is, it gives lower precision at lower RPM and higher precision at higher RPM. The conclusion summarizes the modeling analysis result and motivates potential application for this new RPM sensing method.