Tip Position Control of a Flexible Robot Arm Considering the Reduction Gear’s Friction
Yasuo Yoshida and Masato Tanaka
System Control Division, Government Industrial Research Institute, Shikoku, AIST, MITI 2-3-3, Hananomiya, Takamatsu 761, Japan
The reduction gear’s friction strongly affects the dynamic characteristics of a one-link flexible robot arm. Experiments of open loop response by motor torque were performed in two cases of large and small values of the reduction gear’s friction, and compared with simulation. The reduction gear’s friction has both viscous and Coulomb aspects and can be approximately treated as an equivalent viscous friction. However, tip position control was very difficult in the case of large friction with an equivalent viscous friction. Experiments indicated that tip position feedback control was possible by using a dither signal and linearizing the non-linear friction.