A NEW METHOD FOR THE MEASUREMENT OF LOW-SPEED USING A MULTIPLE-ELECTRODE CAPACITIVE SENSOR

A novel method for the measurement of low speeds by using a few-cost c apacitive sensor is presented, Its main advantages are its simplicity, low cost and the very low speed (as low as 0.02 rad/s), which can be measured with a relatively high resolution in a short measurement time , The multiple capacitors, whose values are piece-wise linearly relate d to the position in a periodic way, are used as the sensing elements of the low-speed sensor, A capacitance-controlled oscillator is used i n the processing circuit to convert the capacitance to a period modula ted signal which can be read directly out by a microcontroller, An alg orithm, which is used to calculate the speed from the measured periods , either eliminates or strongly reduces the influence of most errors, The measurement time is relatively short for low speeds, Meanwhile, th e direction of movement can be indicated.