Kinematic analysis of a 3D printable 4-DOF desktop robot actuated exclusively by Revolute Pairs

Abstract

This paper describes the kinematic structure of Yondy, a desktop robot with three rotational DOFs and one translational DOF. The kinematic structure comprises only rotational joints, easing its construction using off-the-shelf rotational actuators like servomotors. No pinion-rack or other mechanical elements are required for its construction, permitting its realization even with low-accuracy 3D printers. The robot is realized as a hybrid 4-DOF mechanism, with a planar 2-DOF parallel manipulator connected in series with other 2 DOFs. Particular focus is given to the parallel manipulator, which is interesting from a theoretical point of view because it is able to undergo nonsingular assembly mode transitions.