An approach to object-level stiffness regulation of hand-arm systems subject to under-actuation constraints

Ruiz Garate, Virginia; Ajoudani, Arash

Abstract

When using a tool with a robotic hand-arm system, the stiffness at the grasped object plays a key role in the interaction with the environment, allowing the successful execution of the task. However, the rapidly increasing use of under-actuated hands in robotic systems due to their robustness and simplicity of control, pose limitations to the achievable object-level stiffness. Indeed, due to the serial coupling of the hand and the arm, the resulting object-level stiffness is determined by the most compliant of both elements. To address this problem, we propose a novel controller that takes into account the limited achievable geometry of the object stiffness ellipsoid given by a hand with under-actuation constraints, and exploits the contribution of the robotic arm in reshaping the final stiffness towards the desired profile. The under-actuation is illustrated by a coordinated stiffening of the hand fingers. The proposed method is experimentally validated by a hand-arm system performing a peg-in-hole task.

• Journal Article Type: Article
• Acceptance Date: Aug 12, 2020
• Online Publication Date: Aug 27, 2020
• Publication Date: Nov 1, 2020
• Deposit Date: Mar 10, 2021
• Journal: Autonomous Robots
• Print ISSN: 0929-5593
• Electronic ISSN: 1573-7527
• Publisher: Springer (part of Springer Nature)
• Peer Reviewed: Peer Reviewed
• Volume: 44
• Issue: 8
• Pages: 1505-1517
• DOI: https://doi.org/10.1007/s10514-020-09942-9
• Keywords: Artificial Intelligence
• Public URL: https://uwe-repository.worktribe.com/output/7033342
• Additional Information: Received: 2 July 2019; Accepted: 12 August 2020; First Online: 27 August 2020