Performing overhead tasks with supernumerary robotic limbs

Abstract

Overhead tasks such as those frequently found in aircraft manufacturing pose health risks to the workers due to the strain imposed on the shoulders. To reduce the risk of injury, a set of supernumerary robotic limbs (SRL) were designed to perform these overhead tasks. The SRL is designed with limits in the hardware and software to protect the human and prevent collisions between robot and operator. The arms are designed to have a workspace above and in front of the head of the user free from singular configurations so the robot is free to operate where the tasks will be performed. To further protect the human, the mount that attaches the SRL to the shoulders was redesigned to be lighter and to better distribute the load. In this manner, the shoulders will become less fatigued from the static load of carrying the SRL To complete the task of positioning cables and routing them through the ceiling of an airplane, a winch end effector was designed to latch onto the fuselage arches and pull the cable through these arches. In order to control the SRL, the concept of principal components analysis was used to reduce the input space. This concept was specifically used to map the motion of the operator's hands onto the appropriate speed for the winch motor to operate. In this manner, the winch would pull the cable at the same rate that the human fed the cable. The human would then be able to control the speed of the winch simply by executing the task at whatever pace they so desired.