A non-contact gesture sensor is mounted within a vehicle for vehicle occupants to enter control commands by using hand gestures. The effects of vehicle motion and vibration are stabilized by an electronic circuit that includes an inertial motion sensor (IMU) in rigidly fixed relation to the gesture sensor. An adaptive filter processes the gesture sensor signal and the IMU sensor signal by modeling the arm and hand as a semi-rigid articulated body using a transfer function that relates accelerations measured by the IMU with vehicle motion-induced accelerations of the hand. The filter calculates a noise-reduced gesture signal by subtracting out the motion-induced accelerations and measurement noise. The filter also outputs a confidence measure that controls a threshold circuit that inhibits use of the filtered gesture signal when confidence in the filter's system estimation is low.