Design of a Soft, Pneumatic, Robotic Hand End Effector with Variable Stiffness Via Differential Layer Jamming
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Publisher:The Ohio State University
Series/Report no.:The Ohio State University. Department of Mechanical and Aerospace Engineering Honors Theses
Soft robotic grippers have become an increasingly popular solution for pick and place tasks involving both rigid and deformable payloads while maintaining a human safe environment. To avoid damage from rigid, motorized linkages and unchangeable stiffnesses, compliant materials and tunable stiffness have been introduced in a variety of proposed grippers in the form of layer jamming. Independent use of either positive or negative pneumatic layer jamming in existing designs, however, has provided varied tunable stiffness profiles that often require unreasonably large gripper volumes to achieve complete actuation of a payload. This research proposes the design, manufacturing, and testing of a differential jamming soft robotic gripper that utilizes the effects of both positive and negative layer jamming. A multi-chamber pneumatic system is designed to reduce the necessary volume of compliant pneumatic systems while maintaining an increased upper limit of tunable stiffness. The gripper is developed for use in home living assistance through a multi-fingered hand operable by a UR5 robotic arm. The results of this work show absolute stiffness increase of differential jamming in actuators of volume comparable to humanoid digits. The design demonstrates a maximum single finger differential stiffness of 0.1840 N/mm at 20 PSI jamming pressure. Stiffness of an individual finger was increased by up to a maximum of 110.63% when switching from linearly combined positive and negative jamming to differential jamming. The multi-fingered design with reduced-size pneumatic actuators provides a more approachable and implementable actuator design for non-expert user applications. The integration of combined jamming techniques allows for the use of existing stiffness methods in applications previously considered too small to benefit.
Academic Major: Mechanical Engineering
National Science Foundation Grant CMMI2019648
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