Characterization and Experimental Verification of the Nonlinear Distortion in a Technique for Measuring the Relative Velocity Between Micromachined Structures in Normal Translational Motion

Applications exist for microelectromechanical systems (MEMS) devices where the measurement or estimation of the relative velocity, or at least the direction of instantaneous relative velocity, between two microstructures in normal translational motion is required. A technique for directly measuring the relative velocity has not been available. This paper presents a technique for directly measuring the relative velocity between two microstructures in normal translational motion. The technique consists of measuring the current flowing into the capacitance formed between the two microstructures when a constant voltage is applied across them. The technique and the resulting nonlinear distortion in the velocity measurement are characterized. A prototype relative velocity sensor is fabricated and evaluated to verify the measurement technique