Triple Scissor Extender Robot Arm: A Solution to the Last One Foot Problem of Manipulation

Final assembly, inspection, and maintenance of aircrafts, automobiles, and industrial equipment often requires a robot to reach confined areas that are difficult to access. While a robot can move freely in open space, the last one foot to a target site in a manufacturing environment is typically cluttered with complex obstacles. Here, we present a novel solution to the last one foot problem. Inspired by plant stem growth, a new design concept for an expandable arm, the triple scissor extender robot arm (TSERA), is developed to access a confined area through a narrow channel. The robot consists of a series of expandable segments each of which is able to extend and tilt. Thus, the robot can elongate its structure along a narrow, winding space. The novel design concept is accompanied by a new algorithm for path planning, the sequential expansion algorithm. Unlike traditional algorithms for articulated robot path planning, TSERA's sequential expansion algorithm reduces the otherwise computationally expensive multibody path planning problem to a single rigid body kinematics problem. Exploiting the serial nature of expandable structure, we can compute arm motion by sequentially solving a simple inverse kinematics problem for each segment.