Position accuracy improvement by using feed forward torque in regulation structure of servo drive

The paper describes a way of control of a serial mechatronic chain (electric servodrive + gearbox + cam mechanism + load) in the sense of SW tools usage. The goal of the control law is to reach the maximum position accuracy. The driving motor is set in the position mode which allows a definition of the displacement law (table of predefined position values). The control law uses position-speed-torque cascade with speed feed forward loop applied and torque feed forward loop applied as well. It is possible to couple and to uncouple the different parts of the cascade and investigate the effect of the particular loops. The load of the mechatronic chain was realized by servo drive set in torque mode which enables to keep the constant applied torque. The measured data were recorded using the programming tools of Yaskawa. Firstly the position accuracy was monitored at the constant speed of the drive when the torque of the load was changing. Secondly the displacement law for the driving motor was strictly defined and the accuracy of positioning was monitored again. The experiment results show the beneficial impact of feed forward loops on the position accuracy of a kinematic excitation.