A flexible joints microassembly robot with metamorphic gripper

摘要

Purpose The purpose of this paper is to report research which led to the realization of a robot for miniaturized assembly endowed with high‐accuracy and high‐operative flexibility. Design/methodology/approach The proposed solution is a microassembly system composed of a Cartesian parallel robot with flexure revolute joints and a modular gripper with metamorphic fingertips, capable of adapting their shape to different micro‐objects. The fingertips are realized by electro‐discharge machining from a sheet of superelastic alloy. Thanks to its modularity, the gripper can be arranged with two opposite fingers or three fingers placed at 120°. The fingers are actuated by a piezoelectric linear motor with nanometric accuracy. Findings The experimental results on the prototype are very interesting. The measured positioning accuracy of the linear motors is 0.5 μ m; the end‐effector positioning accuracy is lower, due to the non‐perfect kinematics and hysteresis of the flexure joints; however, these effects can be compensated by the direct measurement of the end effector position or by visual feedback. The metamorphic design of the fingertips remarkably increases the grasping force; moreover, the grasping is more stable and reliable. Practical implications The introduction of this microassembly system can fulfil the needs of a wide range of industrial applications, thanks to its accurate positioning in a relatively large workspace. The cost of the machine is relatively low, thanks to its modularity. Originality/value The combination of Cartesian parallel kinematics, cog‐free linear motors and superelastic flexure revolute joints allows one to obtain high‐positioning accuracy; the metamorphic fingertips enhance the grasping effectiveness and flexibility.