Polynomial Input Trajectory Functions for Improved Energy Efficiency in 3 DOF Impedance Controlled Robots

This study investigates the energy consumption of different input trajectory functions on a 3 degree-of-freedom (DOF) robot controlled by impedance controller. Industrial applications of robot manipulators, such as painting, often require only arm position control. However, in situations where obstacles may be present between the robot and the environment, the robot needs to avoid causing harm to itself and other entities. Impedance control allows for the dynamic relationship between the robot and the environment to be controlled. The force applied by the robot to the environment depends on the position of the robot endpoint and the corresponding impedance. The input trajectory function used in impedance control affects the interaction distance of the impedance force and thus the interaction force and torques in the joints. Therefore, it directly affects the energy consumption of the robot. To optimize the impedance controller parameters, the Bees Algorithm was employed to minimize positioning errors for three input trajectory functions: step, ramp, and polynomial. The energy consumption of each input trajectory function was compared, and the results were presented numerically and graphically. The study found that the input trajectory function had a significant impact on the energy consumption of the robot. The advantages and disadvantages of each trajectory function were also discussed. The step function was found to have the simplest implementation, but it caused the highest energy consumption. Overall, this study contributes to the understanding of how input trajectory functions affect the energy consumption of robots controlled by impedance controllers. The findings can be useful for selecting the most energy-efficient trajectory function for a given robot manipulation task.