Abstract
Robotic grippers have been used in industry as end-effectors but are usually limited to operations in pre-defined workspace. However, few devices can capture irregularly shaped dynamic targets in space, underwater and other unstructured environments. In this paper, a novel continuum arm group mechanism inspired by the morphology and motions of sea anemones is proposed. It is able to dissipate and absorb the kinetic energy of a fast moving target in omni-direction and utilize multiple arms to wrap and lock the target without accurate positioning control. Wire-driven actuation systems are implemented in the individual continuum arms, achieving both bending motion and stiffness regulation. Through finite element method, the influence of different configurations of the continuum arm group on the capture performance is analyzed. A robotic prototype is constructed and tested, showing the presented arm group mechanism has high adaptability to capture targets with different sizes, shapes, and incident angles.
Highlights
Traditional grippers with rigid links and joints, usually adopt two-finger or three-finger configurations to pick and hold objects, taking the advantages of high precision and stiffness
Bolboe and Staretu [4] developed a gripper with two symmetrical fingers that can grasp objects within a certain size range by placing sensors on the articulated modules
2 Design of the Capture Mechanism In order to deal with non-cooperative targets that are irregularly shaped and moving fast in omni-direction, the following requirements for the capture mechanism should be satisfied
Summary
Traditional grippers with rigid links and joints, usually adopt two-finger or three-finger configurations to pick and hold objects, taking the advantages of high precision and stiffness. We presented a capture mechanism using a number of flexible continuum arms to form an arm group to intercept and capture non-cooperative targets. The movement of sliding plate 1 will simultaneously apply tension to all driving wires 1 and initiate a bending motion to all arms to grasp an object. Even if failures occur to a single continuum arm, the rest arms can still complete the task This mechanism provides significant tolerance, compliance and adaptability required by the capture operation for non-cooperative targets. If the microswitches detect vibration on any of the arms, the stepper motor 1 will be activated to pull the driving wires 1, making all arms bend toward the center of the arm group to grasp the target.
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