Design characterization of 3D printed compliant gripper

This paper introduces a novel compliant gripper composed of multiplicity of continuum linkage mechanism with fingers configured in symmetrical pattern. The proposed gripper can be classified by a compliant multi-finger grasper with two modes of actuations: independent or underactuated parallel manipulation of fingers. The structural performances are analyzed in terms of the relationship between the performance of the mechanism, its topology, material properties, actuation methods, and the boundary conditions. Topology based kinematic analysis is developed by using Stiffness Matrix Method to evaluate the ratio between the fingertip displacement output to the step displacement input. Simulation case studies examined how the variation of modules of elasticity of the fixed support beam affect the fingertip displacement: for example, it was found that the deflection of fingertip, for a specified geometry, has nonlinear relationship. Interestingly, the deflection is sensitive to the change in elastic properties when the material ratio is small. Moreover, experimental analysis is performed to measure both the contact force and displacement of fingertip due to step displacement input, step force input, and electromagnetic force input. One finding is that the characteristics of the input load applied to soft polymer manipulator influences the linearity of its static-structural response. Quasi-static actuation, such as force generated by electromagnetic coil actuator, tends to allow nonlinear elongation to take place; which contrasts with the linear responses obtained from step input force. The proposed methodologies will facilitate the design of mechanism based on additive polymer manufacturing.