A Lightweight Force-Controllable Wearable Arm Based on Magnetorheological-Hydrostatic Actuators

Supernumerary Robotic Limbs (SRLs) are wearable robots augmenting human capabilities by acting as a co-worker, reaching objects, support human arms, etc. However, existing SRLs lack the mechanical backdrivability and bandwidth required for tasks where the interaction forces must be controlled such a...

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Bibliographic Details
Main Authors: Veronneau, Catherine, Denis, Jeff, Lebel, Louis-Philippe, Denninger, Marc, Plante, Jean-Sebastien, Girard, Alexandre
Format: Conference Proceeding
Language:English
Subjects:
Backdrivability
Bandwidth
Force
Force-Control
Friction
High-Bandwidth
Hydraulic systems
Hydrostatic Transmission
Lightweight
Magnetorheological
Manipulators
Supernumerary robotic limbs
Task analysis
Wearable robotic
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Summary:Supernumerary Robotic Limbs (SRLs) are wearable robots augmenting human capabilities by acting as a co-worker, reaching objects, support human arms, etc. However, existing SRLs lack the mechanical backdrivability and bandwidth required for tasks where the interaction forces must be controlled such as painting, drilling, manipulating fragile objects, etc. Being highly backdrivable with a high bandwidth while minimizing weight presents a major technological challenge imposed by the limited performances of conventional electromagnetic actuators. This paper studies the feasibility of using magnetorheological (MR) clutches coupled-to a low-friction hydrostatic transmission to provide a highly capable, but yet lightweight, force-controllable SRL. A 2.7 kg 2-DOFs wearable robotic arm is designed and built. Shoulder and elbow joints are designed to deliver 39 and 25 Nm, with 115 and 180 ° of range of motion. Experimental studies conducted on a one-DOF test bench and validated analytically demonstrate a high force bandwidth (>25 Hz) and a good ability to control interaction forces even when interacting with an external impedance. Furthermore, three force-control approaches are studied and demonstrated experimentally: open-loop, closed-loop on force, and closed-loop on pressure. All three methods are shown to be effective. Overall, the proposed MR-Hydrostatic actuation system is well-suited for a lightweight SRL interacting with both human and environment that add unpredictable disturbances.
ISSN:2577-087X
DOI:10.1109/ICRA.2019.8793978