Dynamic formulation, identification and energy-saving control for an LCD glass-handling robot system

In this paper, dynamic formulation, system identification and motion control for a liquid crystal display (LCD) glass-handling robot system are studied. Hamilton’s principle is employed to derive Lagrange’s equations of both flexible and rigid models for an LCD glass-handling robot driven by a permanent magnet synchronous motor (PMSM). The real-coded genetic algorithm is adopted to identify all the parameters of the robot and PMSM simultaneously, and to search for the unknown coefficients of polynomials for the point-to-point trajectories by minimizing the input absolute electrical energy (IAEE). In this paper, variable structure controller (VSC) is realized to track the minimum IAEE point-to-point trajectory with a sliding-mode observer. In numerical simulations, vibrations due to flexibility of the timing belts are investigated for the angular displacements, speeds, accelerations of arms, and the horizontal and vertical displacements of the robot. In comparisons of numerical simulations and experimental results, it is demonstrated that identification results of the dynamic model present well matching with the system. Finally, the VSC tracking control based on the minimum IAEE trajectory is realized and its robustness and energy-saving performance is demonstrated simultaneously. The proposed methodology to design the minimum IAEE trajectory can also be applied to any other mechatronic system driven by a PMSM.