Novel Method for Designing High Precision Parallel Kinematic Machines Based on the Smart Structure

Improvements in the accuracy of the parallel kinematic machine (PKM) have proved challenging and are crucial for its practical application and industrialization. The present study proposes a novel idea that introduces smart structures into the PKM's kinematic chains to improve its accuracy rather than focusing on enhancing the performances of the PKM's hardware. A 2-degrees of freedom planar PKM is taken as the application object. Its geometric parameters are first optimized based on the dexterity index. The design scheme of the smart structure chains is then discussed in detail. The piezoceramic actuator is adopted as the actuation element and the compliant mechanism is used to construct the basic structure of the chain. Three smart structure chains are developed based on the design scheme and experimental tests suggest the presence of adequate motion stroke, high positioning resolution, and excellent dynamic performance, which provide a solid foundation for its application to improve the PKM's accuracy. Finally, a novel precision PKM based on the smart structure chains is developed, and experimental tests validate its high positioning and contour accuracies. Except for the PKM, the proposed method is also applicable in improving the accuracy of the other types of machines through the insertion of smart structures into their crucial components.