Design and Modelling of a Minimally Actuated Serial Robot

In this letter we present a minimally actuated overly redundant serial robot (MASR). The robot is composed of a planar arm comprised of ten passive rotational joints and a single mobile actuator that travels over the links to reach designated joints and rotate them. The joints remain locked, using a worm gear setup, after the mobile actuator moves to another link. A gripper is attached to the mobile actuator thus allowing it to transport objects along the links to decrease the actuation of the joints and the working time. A linear stepper motor is used to control the vertical motion of the robot in 3D space. Along the letter, we present the mechanical design of the robot with 10 passive joints and the automatic actuation of the mobile actuator. We also present an optimization algorithm and simulations designed to minimize the working time and the travelled distance of the mobile actuator. Multiple experiments conducted using a robotic prototype depict the advantages of the MASR robot: its very low weight compared to similar robots, its high modularity and the ease of replacement of its parts since there is no wiring along the arm, as shown in the accompanying video.