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Thesis defense

Tilt simulation: A virtual reality based upper extremity stroke rehabilitation. This Prezi was created by Harish Damodaran for his Masters Thesis defense. Any questions regarding the content can be directed to Harish at hd23@njit.edu

harish damodaran

on 8 December 2010

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Transcript of Thesis defense

Stroke or a cerebrovascular accident(CVA) is the rapid loss of brain function caused due to interruption of the blood supply to the brain. That makes stroke a leading cause of
death & disability About 6,400,000 stroke survivors are alive today; Studies show that about 795,000 people suffer a new or recurrent stroke each year. Leakage of blood : Hemorrhage Stroke Due to blockage: Ischemic Stroke Overview Thesis objective
Neuroplasticity in stroke victims
Virtual reality as a rehabilitation tool NJIT RAVR SYSTEM
Library of Virtual Reality(VR) simulations.
Measurments and training results. Tilt Simulation
Demo of the simulation
Design of the VR world
Algorithms and their purposes Design Validation - Two step validation
Questionnaire results
Similarity to real life training By
Harish Damodaran

Advisor: Dr. Sergei Adamovich image source:http://dr-lokku.com/docblog/files/2009/09/stroke-2.jpg Neuroplasticity refers to the ability of the brain to reorganize, recruit and / or reinforce existing pathways to produce the same functional results as the damaged pathways. On average, every 40 seconds someone in the United States has a stroke. Source: AHA computation Heart Disease and Stroke Statistics — 2010 Update, American Heart Association Stroke is a leading cause of serious, long-term disability in the United States. Source: SIPP; MMWR Morb Mortal Wkly Rep. 2001;50:120-125. Source: AHA computation Heart Disease and Stroke Statistics — 2010 Update, American Heart Association Stroke can cause

Cognitive deficits
Language deficits
Motor deficits At NJIT the research focuses on

Hemiparetic stroke patients

Upper extremity motion NJIT Robot Assisted Virtual Rehabilitation (NJIT RAVR)
System Quantity and duration of training Massed practice refers to patients performing repetitive, behaviorally relevant arm movements with short intertrial and intertask rest periods. Future Directions
Acknowledgements CUPS game
Haptically rendered shelves and cups
Time score after placement of each cup
Global damping, antigravity support
upper extremity range and smoothness of motion in the context of a functional reaching movement Haptic Master
3 DOF, Admittance- Controlled Robot
1000 Hz Measurements
Haptic Effects Hardware Simulations Isolated Movements
Measurements Tilt Simulation: Virtual Reality Based
Upper Extremity Stroke Rehabilitation
Objective of this thesis Neuroplasticity & Massed Practice Intro and background To develop an engaging virtual reality simulation that can assist in rehabilitative training of the upper extremity as a single functional unit. Duration
Path Length of reaching trajectory
Stroke Statistics relating to stroke Dynamic and adaptive training paradigms Change in neural architecture Rich and complex multimodal sensory information can be presented to the user with the help of Virtual Reality(VR) simulations. Virtual Reality Simulations Virtual Reality (VR) can be defined as an approach to user-computer interface that involves real-time simulation of an environment, scenario or activity that allows for user interaction via multiple sensory channels. Burdea,2003 VR systems can be classified as: Fully immersive systems Semi immersive systems Non immersive systems
Individualized intensive and repetitive training.

Precision and automatic adaptability based on subjects performance.

Easy change in environments and the amount and type of feedback tailoring it to meet therapeutic goals

Use of adaptive learning algorithms and graded rehabilitation activities Advantages of using VR systems Trackstar
Pulsed DC magnetic technology
Ultra fast trackers of small magnetic sensors. The CyberGrasp
Lightweight force –reflecting exoskeleton that fits over a CyberGlove
Resistive force feedback to each finger. The CyberGlove
Proprietary resistive bend sensing technology
Measures 22 joint angles using Flock of Birds
Pulsed DC magnetic technology that can measure six degrees of freedom.
X, Y and Z values give position and orientation of the users hand in the real world three dimensional spaces.
The pitch, roll and yaw would then determine the angle and orientation of the user’s wrist in the virtual environment.
Plasma Pong
Finger extension.
Closing and opening of hand resets fluid shooting Hummingbird hunt
Integration of hand reach, hand-shaping and grasp using a pincer grip The Virtual Piano
Individual movement of each finger (fractionation).
It consists of a complete virtual piano that plays the appropriate notes as they are press NJIT RAVR system

Unilateral and bilateral training
HAS vs HAT training paradigm
Variation in dosage
Hand training Time to completion
Accuracy of finger motion TILT Simulation Why is there a need for a new simulation ?

Research suggests that competition among neural representations during training promotes better outcomes and Improved transfer of training to real world movements.

Neural control mechanisms of arm transport and hand object interaction are interdependent.

Training hand and arm together shows greater advantage for improving functional activities. Design Goals Magill RA, 2001 Harris, 2007 Adamovich, 2009 Training the upper extremity as single unit.

Virtual environment similar to real world. Design Objective 1 Movement of elbow and shoulder including abduction, extension and pronation of the arm.

Finger motion necessary for grasping objects of different sizes and shapes.

Virtual world designed to enhance the active and passive range of motion and hand eye coordination.

The design can also utilize bilateral movements guided by the less impaired upper extremity. Training the upper extremity as single unit. Design Objective 2 Virtual environment similar to real world. Four tables on a floor forms the main virtual world.

Various objects present within the virtual world similar to real life objects - soda cans, radio, teapot, clock, pen stand, etc.

Shapes used for objects similar to those found on a table.

Objects are present at varying heights and distance from the user. Fig: Tilt Simulation Setup Objects of various shapes and sizes Playing the Tilt simulation Desiging the virtual world :Using Virtools Virtools is a collection of technologies for 3D visualization and interactivity. The Virtools technologies can be broadly grouped as:

An Authoring application

A Behavioral engine

A Render engine

A Scripting language (VSL) Game design in detail Algorithms
concept of building blocks
Physicallize BB
ball physics Fixed objects and Movable Objects

Fixed objects: Four tables and the Floor
Varying heights and distances away from the user.
All the tables have elasticity and friction.

Table A Reaching, extension of arm and shoulder flexion.

Table B
Table D Transverse extension and abduction of the shoulders.

Table C Close range movement of the arm and manipulation of objects using fingers Movable objects:

Objects used to play the game
Objects vary in dimension.
Different physics properties Game Algorithms Different algorithms are required to control the course of the game

In Virtools logic is built in Virtools schematic editor using Building Blocks(BB).

Each building block requires certain amount of inputs and has a fixed class of objects, characters or 3D entity which they can be used on.

They can be used to trigger other BBs, assign properties or compute values.

Physicallize BB
Makes an object part of the physics world Physics of the ball

Physics of the ball
Friction coefficient: 1.5 units
Elasticity: 2 units
Mass : 10 units
Algorithms Proximity Algorithm:
Calculates the distance between two volumetric centers.
Used to calculate distance between the center of the ball and the goal.
When the ball is outside the set range the proximity BB runs in a loop.
When the ball enters the range the goal is achieved.
The proximity BB triggers reset algorithm.

Reset Algorithm:
Returns the ball to the starting position of the game.
Triggers the Scorecard and time algorithm.

Scorecard and Time algorithm:
Increments the value of score by one when triggered
by reset algorithm.
Records the total time taken by the user to complete the trial.

Proximity ,Reset and Scores Goal of the game is to pick and place objects.

Finger movements in real world is recorded using the Cyberglove system.

Position of the hand is tracked using Flock of Birds attached to the wrist.

Manipulation of objects in the virtual world is possible only with application of forces.

Cyberglove does not transfer forces to the virtual world.

Grasping and picking algorithm uses a VSL script as set of BBs.
Grasping and Picking Controlling game speed

Changing the physical properties – friction and elasticity.
Changing the force available for the ball in the motion controller BB.

Controlling game difficulty

Changing the proximity range- increasing or decreasing accuracy required by user.
Changing the time recorded to time available.

Adaptability of Tilt simulation Tilt simulation is designed to be included as an additional training method of NJIT RAVR system.

Stroke subjects recruited are trained on various systems over the 2 week training period.

Changes measured cannot be associated with a single system.

Two step validation

Qualitative - Use by stroke subjects to test design efficiency.
Quantitative – Use by healthy volunteers to test usability of design.

Validating and Testing Subjects:
3 subjects with a mean age of 53 years (2 Male, 1 Female)
6 months post stroke
Some active shoulder and elbow movement
Hemiparetic (2 subjects on left 1 on right)

Subjects were verbally explained about the system
Instructions were given to test design for – Size of the virtual world, ability to reach objects , visual appeal, ability to interpret movement of virtual hand.
Each subject tested the system for 15 minutes
Qualitative results: My game experience was positive.
Strongly DisagreeDisagreeNeutralAgreeStrongly Agree
The game exercised my fingers
Strongly DisagreeDisagreeNeutralAgreeStrongly Agree
The game exercised my elbow
Strongly DisagreeDisagreeNeutralAgreeStrongly Agree
The game exercised my shoulder
Strongly DisagreeDisagreeNeutralAgreeStrongly Agree
I could tell how big or small the objects were when I tried to grasp them.
Strongly DisagreeDisagreeNeutralAgreeStrongly Agree
Was the game: Easy OK Difficult :
If easy: What changes would you suggest?
If difficult, which task did you find difficult? / Why do you find the game difficult?
What changes would you like to see to make the game more interactive/ interesting?
Game Experience Questionnaire Subjects reported the VR world was “reachable”- eliminating need for resizing the environment.
Suggested addition of visual cues or sound effects to show interaction of objects with objects and hand with objects.
Questionnaire results Goal: To show the movements made in the real world are significantly similar to those made in the virtual world during the course of training.

Experimental Set Up:
Three objects are placed at fixed distance in both real and virtual world.
User starts moving from the starting position –picks object and places at end position.
Each user does the task with three objects 5 times with each object.

Quantitative measures Measurments The user performs the experiment with Cyberglove and the Flock of Birds attached to the wrist.

The 3d trajectory and velocity profile of the arm movement is calculated using the Flock of Birds

The joint angles are measured using the Cyberglove to show similarity in grasping action.
Make a GUI based game interface with menus.

Include sound and visual effects.

Adding a forearm to the hand model in the virtual world.

Test on stroke subjects.
Future Work Dr. Sergei Adamovich

Committee members
Dr. Alma Merians
Mr. Michael Bergen
Dr. Richard Foulds

Lab members
Cho, Soha, Gerry
Family and Friends

NIH Grant:
Acknowledgements R01 HD58301 NIDRR RERC GRANT H133 E05001
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