A Swash Mass Pendulum with Passivity-Based Control

We propose a mechanical system named swash mass pendulum (SMP) with application in robotics, and we develop a passivity-based control approach. The SMP is a pendulum made of a rigid shaft connected to a pair of cross-shafts where four swash masses can move under the action of servo mechanisms. The control objective is to stabilize the pendulum at a desired rest orientation. The regulation at the desired orientation is obtained via energy shaping that prevents the solution of partial differential equations. The derivation of the control law consists of a) partial feedback linearization under input coupling, b) a proportional plus integral (PI) controller acting on two new passive outputs. The performance of the controller is assessed by both simulations and experimental results, showing the effectiveness of the control design for the novel proposed pendulum.