KGripper: A Push-On Lift-Twist-Off Passive Perching Mechanism

Perching by grasping or landing on a branch or surface enables aerial vehicles to extend operation time. Existing perching devices either require an actuator or only support loads in one direction. We present the KGripper, a novel passive perching mechanism that is able to resist loads that both press into and pull away from the vehicle while perched. The design is based on the Kresling origami pattern, which exhibits coupled axial compression and twisting. We design a bistable Kresling dipole that drives a linkage to grasp a cylindrical object. Pushing the gripper into the object causes it to close, and twisting the gripper against the object causes it to open. The 122.5 g KGripper is able to support a vehicle over 6 kg, giving it a strength to weight ratio of at least 49. Compression tests indicate that a quadrotor using the gripper must be able to provide 11 N of thrust beyond hover and 0.3 Nm of yaw torque. We demonstrate successful perching on a quadrotor with a total system weight of 1.5 kg. Across both quadrotor and robot arm tests, successful grasping occurs in 96% of trials with objects of diameters up to 58 mm.