Trajectory Control of Compliant Parallel-Arm Mechanisms

In this paper, a compliant parallel-arm mechanism design with a desired trajectory control is investigated. The compliant parallel-arm mechanism consists of two large-deflecting initially straight beams and a rigid coupler. The coupler is assumed to be actuated by a magnetic force drive with an obtainable force history. This compliant parallel-arm mechanism can be used as an indexing mechanism or a dwell mechanism if the rigid coupler horizontal trajectory includes stops at a certain horizontal displacement (rise) and it also includes waiting periods at the specified rise for a desired duration. This trajectory is achieved by using a conventional proportional-integral-derivative type trajectory controller that uses position, velocity, and acceleration information. The theory and the presented results are checked by several methods, including geometrically nonlinear finite element analysis, then a simulation based method, and finally an experimental method. The experimental setup is constructed based on a reverse engineering concept to validate the theory and to confirm the simulation results.