Workspace Determination and Feedback Control of a Pick-and-Place Parallel Robot: Analysis and Experiments

The authors report on the analysis and experimental evaluation of a parallel Schönflies-motion generator (SMG) intended for fast pick-and-place operations and actuated with cylindrical drives (C-drives). Its CRRHHRRC isostatic architecture offers high rotability of the moving platform and a reduced number of limbs, as compared to robots available on the market. A simulation model using the dynamics of the robot as well as an experimental prototype are described. The results obtained are used to assess the pros and cons of two alternative C-drive architectures.A workspace analysis including the feasible wrenches is conducted. The industry standard Adept test cycle is used to evaluate the performance of the prototype. The data obtained prove that C-drives augmented with strain-wave gears give the SMG significantly better wrench capabilities and lower trajectory-tracking error, compared to their alternative C-drives based on cables.