Dynamic Behavior and Motion Planning of a Robot Arm with Non-Rigid Transmission

In this paper some aspects of the dynamical behavior of manipulators with non-rigid transmissions between servomotors and links are reported. The dynamical effects related with transmission elasticity are analysed by means of a mathematical model and some dedicated software. The simulation results show how different laws of motion can induce end-effector vibrations, sometimes quite wide caused by occurrence of resonance. These vibrations can be reduced by means of an appropriate computing of the servomotors laws of motion; in this paper an algorithm is described to determine the above-mentioned laws of motions. The authors propose a method to compute servomotors laws of motion that permit to the end-effector to describe a planned trajectory with a robot arm having non rigid transmission between motors and links; this technique just needs the knowledge of a simple manipulator mathematical model and is apart from the control system. This method has been validated using a virtual prototype realized by co-simulations between ADAMS code, for the mechanical model, and SIMULINK code, for the control and actuator systems.