Gain-scheduled L2-gain based control of a flexible parameter-varying robot link

High-precision manufacturing tasks such as circuit-board assembly are often carried out with the use of gantry robots. One possible design allows motion along two axes, namely a beam moving along a frame and a head sliding along the beam. This configuration can be modeled as a linear parameter-varying system where the head position is the time-varying parameter. In this paper, a modified gain-scheduled H_∞ control design method with parameter-dependent Lyapunov function is applied for motion control of an industry-grade flexible gantry robot beam with moving head. Availability of online head position measurements and knowledge about head velocity limits are incorporated in the control design process. The overall control objective is minimal settling time regarding beam positioning within a ±10 μm range of the desired location. Simulation results show achievable performance for a detailed simulation model, and verify attenuation of beam vibrations and friction disturbances. Special considerations in the control design due to some major difficulties of the problem are presented