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METHOD FOR MOTION TRAJECTORY COMPENSATION

IP.com Disclosure Number: IPCOM000246261D
Publication Date: 2016-May-20
Document File: 3 page(s) / 87K

Publishing Venue

The IP.com Prior Art Database

Abstract

This invention proposes a mechanism to correct trajectory for table-top exercises for stroke rehab system with input of hand marker's vertical positon (Y) and arm length during exercise starting calibration and horizontal position (X) during exercise movement and according mapping tables. With this correction, the real-trajectory made by user can be mapped to straight line trajectory as user's expectation shown on display. Hence not only the target can be reached but also the user interaction interface is easy to be understood by user as well.

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Method for motion trajectory compensation

Stroke rehab system is used to guide, monitor post-stroke patients to do rehab movement exercises and assess the performance and quality of training by tracking patient's movement. A camera based movement tracking system can track patient's exercise status and give feedback using image processing and object recognition technologies.

For camera based rehab system, due to the characteristics of camera lens, perspective change, and movement on different plane of tracking object, the trajectory of the tracking object in real situation could be quite different from the ideal case. Especially, for table-top exercises (patients need to put forearm on a supporting table to perform exercises), since the table restricts the movement of forearm in vertical plane, the user will expect the guide trajectory shown on display is a straight horizontal direction line, when the real trajectory is actually is a curve. Figure.1 shows the table-top exercise "shoulder internal rotation".

Figure.1 Table-top exercise: shoulder internal rotation (left: starting position; right: moving to the target point)

The user is facing the camera and the shoulder is at same height as camera. During this exercise, the movement of hand marker is a curve actually captured by the camera since the hand is gradually moving far away from the camera from starting position to the target point. With different forearm length, the moving distance is also different between hand marker and camera. Then, without any further method, the user will find it is impossible to touch the target point, as shown in figure.2.


Page 02 of 3

Figure.2 Hand marker guiding and real situation trajectory and positions

To solve this problem a method is proposed in this invention.

The invention proposes a compensation method that the real motion trajectory of the subject is compensated according to a mapping table when it is presented on the display to be compared with the target motion curve, where the mapping table comprises the association of real motion trajectory and compensated based on the coordinate of reference point of the object(e.g. joint ) captured in the picture captured and the length of the subject.

This invention proposes a mechanism to correct trajectory for table-top exercises for stroke rehab system with input of hand marker's vertical positon (Y) and arm length during exercise starting calibration and horizontal position (X) during exercise movement and according mapping tables. With this correction, the real-trajectory made by user can be mapped to straight line trajectory as user's expectation shown on display. Hence not only the ta...