Design and control of a magnetic pendulum actuator

Most magnetic pendulums are driven at the bottom of the pendulum arm as they cross through the lowest point of their swing. The present design had to be driven close to the anchor point of the arm because of operational constraints. With a mass up to 12 kg, the actuator was required to increase the swing gradually until the arm reached a maximum ±18° swing, then keep it swinging at that angle. Additional requirements include detection of the mass, adjustment of forces to the mass and control of overshoot. As a safety mechanism, the swing is started by hand, by moving the mass a certain distance from the rest point and a shutoff mechanism in case the arm swings more than 25° in either direction. Operation is from a low voltage source and may also operate from rechargeable batteries requiring power optimization.