Indian Institute of Technology
Design of an optimal
Objective : understanding synergy between: hand kinematics - muscles - brain.
§ Human finger motion biomechanics.
§ Optimal design of a hand exoskeleton.
§ Hybrid control (EEG+EMG+Dynamics)
•How do humans perform simple object manipulation (rotation + translation) ?
Simple task of moving a coin and its motion analysis(NAIST Japan):
- 30 subjects performed this task.
Axes notation for each joint:
Manipulability calculation based on joint positions:
•Activity of each finger :
•Direction of major axis of ellipsoid
•Ratio of axes
Rotations and 3D motion:
Design of finger exoskeleton:
•Three finger exoskeleton (index-middle-thumb).
•Grasping and simple manipulation ability.
•Control using EMG / EEG, Inverse kinematics.
•Use in stroke rehabilitation, assistive robot, physical therapy.
Thumb and middle finger:
Links made by rapid prototyping and actuated by ultrasonic motors:
Fabrication of the exoskeleton: Rapid prototyping:
Three finger exoskeleton for exact finger motion emulation:
- 10 DOF actuated by ultrasonic motors.
- Both translations and rotations are possible.
- Control : NN and Inverse Kinematics
•Only EEG ? EEG as a switch.
•Inverse kinematics model
•EEG (switch) +EMG (muscle activation) + system behavior (kinematics/dynamics
Augment EMG with EEG for Control
Flow chart of the control strategy: EMG signal recording - Feature extraction and classification - control of joint motors.
Design & Simulation of Exoskeleton:
Design of optimal exoskeleton using 4-bars to model each finger joint as follows
Simulation of exoskeleton to test controller design: