Hybrid Open-Loop Closed-Loop Control of Coupled Human-Robot Balance During Assisted Stance Transition with Extra Robotic Legs
This work addresses the challenge of stable human-robot interaction for operators in hazardous environments like nuclear decommissioning, though it appears incremental as it builds on existing wearable robotics and control methods.
The paper tackles the problem of controlling a wearable robotic leg system (XRL) to assist human balance during stance transitions, such as moving from standing to crawling, by introducing a hybrid open-loop/closed-loop control architecture that allows constrained motion in some directions and free movement in others, and demonstrates its application in a simulated nuclear waste decommissioning task.
A new approach to the human-robot shared control of the Extra Robotic Legs (XRL) wearable augmentation system is presented. The XRL system consists of two extra legs that bear the entirety of its backpack payload, as well as some of the human operator's weight. The XRL System must support its own balance and assist the operator stably while allowing them to move in selected directions. In some directions of the task space the XRL must constrain the human motion with position feedback for balance, while in other directions the XRL must have no position feedback, so that the human can move freely. Here, we present Hybrid Open-Loop / Closed-Loop Control Architecture for mixing the two control modes in a systematic manner. The system is reduced to individual joint feedback control that is simple to implement and reliable against failure. The method is applied to the XRL system that assists a human in conducting a nuclear waste decommissioning task. A prototype XRL system has been developed and demonstrated with a simulated human performing the transition from standing to crawling and back again while coupled to the prototype XRL system.