Development of a Stabilized Wideband Pendulum-Type Gravity Direction Sensor Utilizing Electromagnetic Clutch and Brake for Anti-Swing

This paper proposes the usefulness of combining an electromagnetic clutch and brake with a pendulum for antiswing for developing a stabilized wideband pendulum-type gravity direction sensor. The pendulum-type sensor is high in response to direction change but liable to swing even when the change stops, in general. Therefore, anti-swing control without degrading sensitivity of direction measurement is important. Continuous damping of the pendulum motion causes an error in a stationary condition unless the pendulum is free from damping repetitively in an appropriate term. To develop a quick response direction sensor without error, we use a magnetic device. Based on motion analysis of a double pendulum, we simulate behaviours of the pendulum-type sensor by actuating the magnetic device by using different signals in form, frequency and magnitude. Also, we fabricate a motion simulator having two rotation joints to evaluate the anti-swing effect of the magnetic device. In the experiment we demonstrate that the device is beneficial for suppressing pendulum vibration over a wideband for measuring resultant direction of the acceleration compound with motion and gravity on such a platform moving randomly. Also, we show that a triangular signal is better than a sinusoidal signal for making the settling time short; however difference is within a narrow margin.