A Two-Loop Performance-Oriented Tip-Tracking Control of a Linear-Motor-Driven Flexible Beam System With Experiments

In this paper, a two-loop control structure for the constrained tip regulation of a linear-motor-driven flexible beam is developed to achieve high performance. Specifically, in the inner loop, a feedback control law with freely assignable closed-loop poles is designed to achieve an arbitrarily good disturbance rejection capability at steady state. In the outer loop, an online trajectory replanning unit is constructed so that the tip-position output of the beam converges to its desired target as fast as possible while all the constraints of the system are satisfied. Theoretically, it is shown that the proposed approach can achieve a sufficiently fast transient converging speed of the tracking error and a guaranteed steady-state tracking accuracy. The proposed strategy is tested on a HIWIN linear-motor-driven stage system with a flexible beam clamped. Experimental results obtained demonstrate the effectiveness and applicability of the proposed approach.