Design and additive manufacturing of compliant grippers: modeling and experimental characterization

Abstract

Here the design and analytical modeling of a 2D compliant gripper are developed. For this, the formulation that describes the behavior of a Flexure-Based Compliant Parallel Mechanisms (FBCPM) is considered, as well as the integration of a blade-type flexure to complete the opening and closing motion of the compliant gripper. Due to its use in precision and fracture resistance tasks, this monolithic mechanism is being analyzed. By adapting an existing compliant gripper design, the expected displacement in the flexures is obtained and the occurrence of stressed elements is reduced, achieving separation between rigid and bending elements. The use of the Compliance Matrix Method (CMM) allows to evaluate the kinetostatic analysis that relates the input force and output displacement in our selected design. A coordinate frame is considered in each blade-type flexure to establish the connection between the fixed elements and those that will experience displacement. The results obtained analytically are validated via Finite Element Method (FEM) models and experimental approach. The displacement of the fingers in the simulation is evaluated in the plane and contrasted with the analytical prediction obtaining a 5% error using the force as a input parameter. For experimental validation, the output displacement is compared with the analytical model using displacement as input value, the behaviour of the compliant gripper is validated by all three methods (analytical, FEM and experimental) with an error rate of less than 5%. Finally, the design of Architected Fingers is evaluated qualitatively to demonstrate the grip of objects with different shapes as well as the difference in printing materials.