Design Analysis of a Novel Belt-Driven Manipulator for Fast Movements

In this work, we propose a new four-degree-of-freedom (4-DOF) manipulator design involving belt transmissions and direct drives at the proximal end of the manipulator. This results into a backlash free, low-inertia arm that enables fast movements. Additionally, the belt routing inside the arm distributes actuator torques beneficially to the joints and allows the use of identical motors under dissimilar joint torque requirements. While the kinematics of the arm and the separation of actuation and joint space are discussed in detail, we also demonstrate beneficial properties for dynamic movements of the manipulator. To obtain optimal motion trajectories, an iterative Linear-Quadratic Regulator (iLQR) was implemented and is compared against a traditional trajectory creation in joint- and actuation space. Furthermore, a stiffness model of the belts in joint- and actuation-space is given to assess a modal analysis in the early design phase.