Path-constrained trajectory planning for robot service life optimization

The return-on-investment (ROI) of robotization is defined as the difference between the money earned through robotization and the investment put on the robotic system. In industrial practice, the ROI is often prioritized over other factors. There are two ways to help increase the ROI, namely, 1) improving robot productivity and 2) maximizing the robot service life. In fact, faster robot motion (i.e., higher productivity as preferred) with larger joint torque would lead to a higher chance of hardware failure. Therefore, it is of interest to develop a method that can maximize the robot service life without sacrificing the productivity. This paper presents a trajectory re-planning algorithm for this purpose. The idea is to increase the time duration for some periods of motion to extend the reducer life, while reduce the time duration for some other periods of motion to shorten the cycle time. The performance of the proposed method is evaluated on the FANUC M16iB robot system. The results show that the method can improve the expected worst-case service life by approximately 10%. Computation issues of the proposed algorithm are discussed.