tailieunhanh - Báo cáo hóa học: " The role of feed-forward and feedback processes for closed-loop prosthesis control"

Tuyển tập báo cáo các nghiên cứu khoa học quốc tế ngành hóa học dành cho các bạn yêu hóa học tham khảo đề tài: The role of feed-forward and feedback processes for closed-loop prosthesis control | Saunders and Vijayakumar Journal of NeuroEngineering and Rehabilitation 2011 8 60 http content 8 1 60 Iril JOURNAL OF NEUROENGINEERING NCR AND REHABILITATION RESEARCH Open Access The role of feed-forward and feedback processes for closed-loop prosthesis control Ian Saunders and Sethu Vijayakumar Abstract Background It is widely believed that both feed-forward and feed-back mechanisms are required for successful object manipulation. Open-loop upper-limb prosthesis wearers receive no tactile feedback which may be the cause of their limited dexterity and compromised grip force control. In this paper we ask whether observed prosthesis control impairments are due to lack of feedback or due to inadequate feed-forward control. Methods Healthy subjects were fitted with a closed-loop robotic hand and instructed to grasp and lift objects of different weights as we recorded trajectories and force profiles. We conducted three experiments under different feed-forward and feed-back configurations to elucidate the role of tactile feedback i in ideal conditions ii under sensory deprivation and iii under feed-forward uncertainty. Results i We found that subjects formed economical grasps in ideal conditions. ii To our surprise this ability was preserved even when visual and tactile feedback were removed. iii When we introduced uncertainty into the hand controller performance degraded significantly in the absence of either visual or tactile feedback. Greatest performance was achieved when both sources of feedback were present. Conclusions We have introduced a novel method to understand the cognitive processes underlying grasping and lifting. We have shown quantitatively that tactile feedback can significantly improve performance in the presence of feed-forward uncertainty. However our results indicate that feed-forward and feed-back mechanisms serve complementary roles suggesting that to improve on the state-of-the-art in prosthetic hands we must develop .