2020 Volume 33 Issue 3 Pages 87-94
This paper proposes, for two-inertia system of low stiffness and high inertia ratio, a design method of a proportional controller that minimizes the closed-loop H∞ norm from the disturbance torque applied to the driven-side inertia to the driven-side angular velocity. The controller is to generate the driving-side torque by using the driving- and driven-side angular velocities, and is composed of two proportional coefficients configured by a simple calculation law which explicitly depends on the physical parameters. The method is based on the fact that the optimal H∞ controller is analytically derived for the case with infinite inertia ratio, and the controller for finite-inertia-ratio case is similarly given along with the derivation process by introducing an approximation due to high inertia ratio. Numerical examples show that the degradation in H∞ norm from the optimal solution is less than 0.02 dB for high inertia ratio of 10 or more. Control experiments show the validity of the proposed method.