Uni-drive modular robots with pulse width modulation control

In this paper a newly developed concept and design in modular robots and relevant control methodology are introduced. This new class is called "uni-drive modular robots" whose design employs only a single drive for operating all the joints. The drive is mounted at the robot base and all joints tap power from a central rotating shaft inside each module using spring wrap clutches (SWC). This technique can effectively reduce the mass of each module which is the most important setback in design and applications of modular robots. From the control point of view, the uni-drive modular robot is controlled based upon the application of pulse width modulation (PWM) technique. By controlling the engagement time of the clutches, the position and velocity of the joints are regulated. In this work, we study the overall design of a planar uni-drive modular robot and obtain a self expansion formula which can automatically generate all equations of motion only based upon the number of modules. We further model SWCs and self locking mechanism which are parts of the proposed robot.