Design of a Parallel-Type Gripper Mechanism

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Abstract
A new parallel-type gripper mechanism is proposed in this work. This device has a parallelogramic platform that can be flexibly folded. Therefore, this mechanism not only can be used to grasp an object having irregular shape or large volume, but also can be utilized as a micro-positioning device after grasping objects. Forward position analysis and platform kinematics are investigated to deal with motion tracking and force control. Kinematic optimization is performed to design a parallel-type gripping mechanism so that it can reach the specified workspace, span the given range of the specified configuration parameters, and generate a desired force to grasp an object. A pneumatic rotator is employed for actuation and a miniaturized proportional 4/3 -way directional valve is specially developed to deal with feedback-based dynamic control. The proportional valve allows indirect force control by measuring the offset-load pressure raised by the contact between the grasped object and the parallel platform. In experimental work, the performance of the motion tracking and indirect force control has been shown to be successful.