A passive form-sensing gripper featuring a mechanically adaptive variable torque joint

Abstract Robot grippers have drawn a lot of attention due to their various applications in the fields of manufacturing, agriculture, etc . The shape and mass of the workable objects have been considerable issues. For effective gripping, many studies have sought to control gripping forces; however, force control often requires complex external control structures. Here, it is aimed to develop a gripper of simple structure that resists moments, grasps object edges in the absence of complete object envelopment, and does not tilt the object. Moment resistance and edge grasping are key capabilities in ensuring stable object gripping. To ensure an energy-efficient, simple structure, a mechanical trigger and a variable torque joint link the output torque to the finger actuation angle without electrical sensing. The variable torque joint creates different torques for each finger, thus ensuring the sufficient reactive moments required for stable gripping without tilting the object. To implement the output torque profile, a mechanical cam was designed and utilized in the torque joint. The developed gripper effectively resists moments and grasps object edges without the need for electrical components such as sensors, wires, or batteries. This study shows that form-sensing data can be used in various scenarios to ensure successful gripping.