Rolling Contact Dynamics and Optimal Feedforward Control for the Modular Distributed Manipulator

The Modular Distributed Manipulator System (MDMS) is an array of actuators that is capable of manipulating objects in the plane [1]. This paper derives equations of motion for the coupled dynamics of the MDMS actuators and objects riding upon it, and it derives feedforward control strategies for this multi-input, three-output system. Unlike previous work in which traction forces were generated using viscous friction caused by sliding contact between the manipulated object and the actuators, this paper considers traction forces generated by no-slip rolling contact. This approach allows more precise manipulation, because object positions and orientations and their time derivatives can be determined by wheel encoder information. The dynamic equations account for the electromechanical dynamics of each actuator and the coupling between them and the translational and rotational dynamics of the manipulated object. This paper then presents two different feedforward control strategies based on minimizing the sum of the squares of the inputs or minimizing the total system power.