KINECT REHABILITATIONStroke 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

• Developed for the Xbox 360 gaming console• Tracks your movements: you are the controller• Sensors

1. Depth Camera and Sensors2. RGB Camera3. Microphone array4. Motorized base

MICROSOFT KINECT

• 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.

DEPTH IMAGING

• 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

OpenNI Microsoft

Raw depth and image data Yes Yes

Joint position tracking Yes Yes

Save raw data stream to disk Yes No

Joint tracking without calibration No Yes

Easy installation No Yes

Number of joints available 15 20

Quality of documentation Adequate 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

OpenNI MicrosoftAverage Frame Rate(fps) 25.0 19.6Std Deviation(between trials) 5.8 2.3Minimum (fps) 9.8 14.1Maximum (fps) 30.0 23.7

IDENTIFYING PHASES OF MOVEMENT

DATA STABILITY

Standard Deviation of Joint Positionswhile Subject is Motionless

Joint OpenNI (cm) Microsoft (cm)

Head 0.34 1.8Hip 0.42 1.2Knee 0.70 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?