KINECT REHABILITATION

Stroke Therapy Research Kathryn LaBelle

RESEARCH TOPIC

Can the Kinect’s joint-tracking capability be used in clinical and in-home stroke rehabilitation tools?

OUTLINE

• • • • • • • Background – – Stroke Therapy Kinect Potential of Kinect in Rehabilitation Research Questions Software Data Gathering Data Analysis Conclusions

STROKE THERAPY

• • Stroke survivors can experience: – restricted movement – loss of sense of balance – decreased strength Regained through physical therapy – balance exercises – range of motion activities – coordination practice

MICROSOFT KINECT

• • • Developed for the Xbox 360 gaming console Tracks your movements: you are the controller Sensors 1. Depth Camera and Sensors 2. RGB Camera 3. Microphone array 4. Motorized base

DEPTH IMAGING

• • • • Infra-red projector shines grid of light on the scene, encoded with data.

Light bounces off objects in the scene.

Kinect light sensors receive reflected light.

By analyzing time of flight and distoritions in the encoded data, the Kinect makes a depth map of the scene.

JOINT TRACKING ALGORITHM

• • • Input: depth map Machine learning algorithm – Collected recordings of people using the Kinect – Joint positions marked by hand – Algorithm was fed this “training” data and learned how to correctly identify joints from a depth image Output: x, y, z joint positions

JOINT TRACKING AND STROKE REHABILITATION

• • Clinical applications: – assess patients’ performance – track patients’ progress – pinpoint areas for improvement At-home exercise aids: – provides constructive feedback to patients – give encourgement and motivation – generate summary reports for doctors

RESEARCH QUESTIONS

• • • • • What SDKs and drivers are available for use with a PC?

What type of information can be obtained? What is the quality of the joint data obtained from the Kinect? – Sampling rates – Consistency How resilient is the Kinect’s joint data and performance to variation in testing conditions?

What functionality could be provided in a stroke therapy application that uses the Kinect?

SDK COMPARISON

Raw depth and image data Joint position tracking Save raw data stream to disk Joint tracking without calibration Easy installation Number of joints available Quality of documentation

OpenNI

Yes Yes Yes No No 15 Adequate

Microsoft

Yes Yes No Yes Yes 20 Excellent

SOFTWARE DEVELOPED

• • • • • Display depth video and skeleton Joint positions and instantaneous frames per second written to file Balance board integration Record depth stream to file Obtain joint positions from recording

DATA GATHERING

DATA ANALYSIS

• • • Sampling rates of joint position data Identifying phases of movement from joint positions Consistency and stability of joint positions

SAMPLING RATE

Average Frame Rate (fps) Std Deviation (between trials) Minimum (fps) Maximum (fps)

OpenNI Microsoft

25.0

19.6

5.8

9.8

30.0

2.3

14.1

23.7

IDENTIFYING PHASES OF MOVEMENT

DATA STABILITY

Head Hip

Standard Deviation of Joint Positions while Subject is Motionless Joint

Knee

OpenNI (cm)

0.34

0.42

0.70

Microsoft (cm)

1.8

1.2

1.5

DATA STABILITY: Assisted Tests

• • Clinical therapy often involves an assistant supporting a patient while he performs exercises Test procedure: – subject begins by sitting alone – assistant joins, putting hands on subject’s shoulders – subject stands up

DATA STABILITY: Assisted Tests

DATA STABILITY: Assisted Tests

DATA STABILITY: Assisted Tests

CONCLUSIONS

• • • • • • OpenNI Framework and Microsoft SDK for Windows are best tools to use Can provide significant functionality in a joint-tracking application – track and record joint positions in three dimensions – display image of tracked joints in real time – integrate Kinect with the Wii balance board Sampling rate exceeds acceptable level Phases of movement are easily identifiable from graphs of joint positions Joint position stability is more than adequate with one subject in view Skeleton merging could pose a problem for clinical use of Kinect

FUTURE WORK

• • • Deeper investigation into assisted exercises – Different types of exercises – Position the assistant differently – Determine conditions causing skeleton merging Further development of software Investigate applications in other fields of physical therapy

QUESTIONS?