Torque Minimization of Dynamically Decoupled 3R Spatial Serial Manipulators via Optimal Motion Generation

This paper proposes an analytically tractable solution for minimizing input torques in decoupled three-degrees-of-freedom spatial serial manipulators. The solution relies on the generation of motion using a «bang-bang» profile. The problem is solved in two stages. Firstly, the dynamic decoupling of the manipulator is accomplished through the redistribution of the moving masses and the relocation of one of the actuators. This leads to the decoupling of the equations of motion for different degrees of mobility. It is worth mentioning that this solution represents a symbiosis of two distinct approaches: the redistribution of link masses and the relocation of one of the manipulator actuators. This innovative approach to dynamic decoupling has not been previously proposed. At the second stage, the input torques of the actuators are reduced by generating motion profiles for the manipulator's links using the «bang-bang» law. Thus, thanks to the developed methodology, it becomes possible to reduce the energy consumption of high-speed manipulators by choosing the optimal planned motion of their links. To evaluate the effectiveness of this approach, numerical simulations are carried out using the ADAMS software. A comparative analysis of the trajectories generated by the fifth-order polynomial profile, widely used in industrial robots, and the «bang-bang» profile has been performed. The simulation results show act, the use of the «bang-bang» profile allows one to reduce the maximum values of the input torques. The developed technique allows designers to create high-speed manipulators featuring decoupled dynamics and diminished energy consumption.