Sébastien Mick1, Effie Segas2, Lucas Dure2, Christophe Halgand2, Jenny Benois-Pineau3, Gerald E Loeb4, Daniel Cattaert2, Aymar de Rugy2,5. 1. Institut de Neurosciences Cognitives et Intégratives d'Aquitaine, UMR 5287, CNRS and Univ. Bordeaux, 146 rue Léo Saignat, 33076, Bordeaux, France. sebastien.mick@u-bordeaux.fr. 2. Institut de Neurosciences Cognitives et Intégratives d'Aquitaine, UMR 5287, CNRS and Univ. Bordeaux, 146 rue Léo Saignat, 33076, Bordeaux, France. 3. Laboratoire Bordelais de Recherche en Informatique, UMR 5800, CNRS, Univ. Bordeaux and Bordeaux INP, 351 cours de la Libération, 33405, Talence, France. 4. Department of Biomedical Engineering, Univ. Southern California, 1042 Downey Way, Los Angeles, CA, 90089, USA. 5. Centre for Sensorimotor Performance, School of Human Movement and Nutrition Sciences, Univ. Queensland, Blair Drive, Brisbane, QLD, 4059, Australia.
Abstract
BACKGROUND: Prosthetic restoration of reach and grasp function after a trans-humeral amputation requires control of multiple distal degrees of freedom in elbow, wrist and fingers. However, such a high level of amputation reduces the amount of available myoelectric and kinematic information from the residual limb. METHODS: To overcome these limits, we added contextual information about the target's location and orientation such as can now be extracted from gaze tracking by computer vision tools. For the task of picking and placing a bottle in various positions and orientations in a 3D virtual scene, we trained artificial neural networks to predict postures of an intact subject's elbow, forearm and wrist (4 degrees of freedom) either solely from shoulder kinematics or with additional knowledge of the movement goal. Subjects then performed the same tasks in the virtual scene with distal joints predicted from the context-aware network. RESULTS: Average movement times of 1.22s were only slightly longer than the naturally controlled movements (0.82 s). When using a kinematic-only network, movement times were much longer (2.31s) and compensatory movements from trunk and shoulder were much larger. Integrating contextual information also gave rise to motor synergies closer to natural joint coordination. CONCLUSIONS: Although notable challenges remain before applying the proposed control scheme to a real-world prosthesis, our study shows that adding contextual information to command signals greatly improves prediction of distal joint angles for prosthetic control.
BACKGROUND: Prosthetic restoration of reach and grasp function after a trans-humeral amputation requires control of multiple distal degrees of freedom in elbow, wrist and fingers. However, such a high level of amputation reduces the amount of available myoelectric and kinematic information from the residual limb. METHODS: To overcome these limits, we added contextual information about the target's location and orientation such as can now be extracted from gaze tracking by computer vision tools. For the task of picking and placing a bottle in various positions and orientations in a 3D virtual scene, we trained artificial neural networks to predict postures of an intact subject's elbow, forearm and wrist (4 degrees of freedom) either solely from shoulder kinematics or with additional knowledge of the movement goal. Subjects then performed the same tasks in the virtual scene with distal joints predicted from the context-aware network. RESULTS: Average movement times of 1.22s were only slightly longer than the naturally controlled movements (0.82 s). When using a kinematic-only network, movement times were much longer (2.31s) and compensatory movements from trunk and shoulder were much larger. Integrating contextual information also gave rise to motor synergies closer to natural joint coordination. CONCLUSIONS: Although notable challenges remain before applying the proposed control scheme to a real-world prosthesis, our study shows that adding contextual information to command signals greatly improves prediction of distal joint angles for prosthetic control.
Entities:
Keywords:
Arm prosthesis; Joint angle prediction; Movement-based control
Authors: Katherine A Raichle; Marisol A Hanley; Ivan Molton; Nancy J Kadel; Kellye Campbell; Emily Phelps; Dawn Ehde; Douglas G Smith Journal: J Rehabil Res Dev Date: 2008