Selected Methods for a Robust Control of Direct Drive with a Multi-mass Mechanical Load

Mechanical vibrations represent one of the key issues in the development of direct drives with a complex mechanical structure, i.e., with non-stiff connections between motor and driven mechanisms and with variable moments of inertia. A solution for motion control in relation to a direct drive, with highly dynamic performance, coupled with multi-mass mechanical load is proposed in the chapter. Due to high resonance frequencies that are difficult to be actively damped by the control system, an original solution is proposed, which is based on damping the highest resonance frequencies with a specially selected and tuned filter, leaving the damping of the lowest frequencies to the control system. In the first part of this chapter, the identification method is presented, along with robust notch filters, which are tuned for the whole range of parameter variability. Due to variable moment of inertia, two robust control methods are proposed in the second and third parts of this chapter: one is based on an adaptive neural speed controller, while the other is based on a terminal sliding mode control (SMC). The online learning neural speed controller is based on the resilient back propagation (RPROP) algorithm. A modified terminal sliding control law is proposed for a system with delays and unmodelled dynamics. The advantages of both solutions are verified on the basis of experiment investigations.