Blend of independent joint control and variable structure systems for uni-drive modular robots

In this paper, a control design methodology for a new class of modular robots, so-called "uni-drive modular robots" is introduced. Uni-drive modular robots have a substantial advantage over regular modular robots in terms of the mass of each module since then employ only a single drive for powering all the joints. The drive is mounted at the robot base and all joints tap power from this single drive using clutches. By controlling the engagement time of the clutches, the position and velocity of the joints are regulated. After reviewing the structure of the uni-drive modular robot, a self-expansion formula to generate the dynamics of the robot is introduced. The control of uni-drive n-module robots is realized by blending independent joint control and theory of variable structure systems via a pulse width modulation technique. A uni-drive modular robot is used to conduct simulations and validate the control design technique.