Document Type : Full Research Paper

Authors

• Amir Homayoun Jafari
• Seyed Mohammad Reza Hashemi Golpayegani
• Farzad Towhidkhah
• Ali Fallah

Department of Biomedical Engineering, Amir Kabir University of Technology

Abstract

A hierarchical structure model with three levels is presented for modeling motor control in skill movements. At each level, based on accuracy and quality of control, a specific controller is activated. At first level, control concepts are qualitative. The duty of the first level is to provide stability of system, based on the received qualitative information from second level such as the decrement or increment of error. A self-organized controller at first level is used to generate qualitative control commands, and it plays an encouragement-punishment role to keep the stability of system by sending discrete commands to the second level. This controller only contributes at control action when the controller of second level can not preserve stability individually. At second level, control concepts are quantitative. The duty of the second level is adaptation and control of system accurately. The received information at this level generally comes from sensory and visual feedbacks, and it includes more accurate concepts of control action - like the amount of movement error. A model based on the predictive controller at second level generates quantitative control commands and indeed, determines trajectory of movement accurately. A fuzzy switch combines the control commands of first and second levels, based on the sliding mode strategy, to provide a robust control. At third level, this command is interpreted and then is applied to the involved muscles in movement. The received information at this level is generally the contribution of muscles in performing movement and the effects of environment on the movement, which comes from sensory feedbacks. The presented model with this hierarchical structure has a proper ability to control and keep the stability of system. The simulation results confirm this subject. 

Keywords

• hierarchical structure
• Self-organized control
• sliding mode control
• model predictive control
• Skill movements

Main Subjects

• Gait Analysis
• Biomechanical Motor Control / Motor Control of Human Movement
• Neuro-Muscular Engineering