State-space speed control of two-mass mechanical systems: Analytical tuning and experimental evaluation

This paper proposes a model-based two-degrees-of-freedom (2DOF) state-space speed controller design for a two-mass mechanical system. Analytical tuning rules for a feedback gain, a reduced-order state observer, a full-order state observer, and a prefilter are derived. The proposed design rules enable automatic tuning of the controller if the mechanical parameters are known. The prefilter is designed for step, ramp, and parabolic command tracking. It is shown by Nyquist diagrams and noise-transfer functions that the full-order observer based controller is a preferable choice if the feedback loop is delayed and noisy. Time-domain simulations and experimental results verified the Nyquist-diagram analysis and showed that the proposed controller gives good reference tracking for step and dynamic commands as well as robust and fast load-torque rejection.