Dr. Ashish Dutta

Indian Institute of Technology

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Dr. Ashish Dutta
Professor, Dept. of Mechanical Engineering
Head, Computer Centre
Email:adutta@iitk.ac.in
Office: Faculty Building Room 338
Phone:91-512-2597562 (Off.), 2598710 (Res)
Fax:91-512-2597408
Research Associate: Biswanath Panda, Anupam Sana
Affiliated Center(s):
1 Centre for Mechatronics

Design of an optimal
finger exoskeleton based on human motion data

 

Outline:

 

Objective : understanding synergy between: hand kinematics - muscles - brain.

 

§ Human finger motion biomechanics.

 

§ Optimal design of a hand exoskeleton.

 

§ Hybrid control (EEG+EMG+Dynamics)

 

Finger biomechanics:

 

•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:

Ellipsoid calculations:

 

•Activity of each finger :

•Ellipsoid volume

•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

 

 

Hybrid control:

 

•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: