Helical Actuator–Driven Inchworm Robot Design and Prototype

Abstract

Bio-inspired robots provide solutions in many applications. Robots that can traverse and transport materials through confined areas are useful in disaster response, mining, mapping, and tunneling. The proposed robot is an inchworm-inspired robot that contracts and expands its body segments to move. It has spiky feet that are angled to only allow each foot to slide forward. It has a small frontal area compared to its length, and this allows it to travel through tight gaps or tunnels. Each segment uses two helical actuators as prismatic linkages to drive both forward movement and turning movement. These helical actuators transform the rotation of stepper motors into linear motion. Many linkage configurations were considered in designing this robot, and one without continuous singularities was selected. The robot stride consists of an extension phase and a contraction phase. In each phase, one foot is stationary, and one foot is moving. When each of the feet is in motion, the ground reaction force is assumed to be zero. The motion planning of the robot is designed so that the velocity and acceleration of each of the robot's rigid bodies are zero at the beginning and end of each movement phase. A 3D-printed prototype of the robot has been manufactured, and initial testing has shown that the foot spike design successfully allows the inchworm to shuffle forward. Testing the turning capabilities of this robot is ongoing.