Minimizing the Energy Consumption of a Delta Robot by Exploiting the Natural Dynamics

It is known that when performing high-speed pick-and-place motions in robot manipulators, an enormous amount of energy is dissipated in order to stop the robot during the braking phase. Typically, this energy is lost as heat in the braking resistances of the motor drivers, leading to increase the energetic losses in the actuation chain. In order to improve the energy efficiency while ensuring accuracy at high-speeds, this paper proposes the use of variable stiffness springs (VSS) in parallel configuration with the motors. This actuation chain is combined with a motion generator which seeks to exploit the robot natural dynamics by adjusting the equilibrium position of the VSS so that the robot is put in near resonance, thus decreasing the energetic losses. Simulations of the suggested approach on a Delta robot are performed and show the drastic reduction of energy consumption.