A benchmark study on the planning and control of industrial robots with elastic joints

In this paper, we perform a comparative study of methods for improving motion performance of industrial robots. The compared methods address trajectory planning, trajectory preshaping, and feedforward control. Simulations are performed using a realistic 2DOF dynamic model with elastic joints. The simulation results demonstrate that the trajectory improvements may not be sufficient to obtain the required motion accuracy for industrial robots operating at high speeds due to the high nonlinearity of the system. We show that an improved performance may be achieved through nonlinear feedforward control even if the reference trajectory is planned using a trapezoidal velocity profile generator.