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Publication Date: 2015-Mar-31
Document File: 5 page(s) / 50K

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Methods of measuring gait characteristics such as stride length, width, shuffling, asymmetry, speed, etc. of a person using the 3D Range camera are disclosed. The 3D range camera uses pulsed IR radiation to generate a 3D surface instead of a visual image. The output produced by the 3D range camera is of 2D arrays of a person’s body surface as they walk and are processed to 3D surface images. This method can be used to the measure gait characteristics of senior populations, with greater accuracy and at a much lower cost over conventional image analysis approaches.

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Changes in gait can be used to trigger fall prevention interventions, and diagnosis or trending of other conditions that affect gait. Assessing gait in a natural environment is required for various purposes. Gait measurement is required to monitor elderly patients and to provide telecare to seniors in the home environment who are at risk of falling and developing health issues. There is therefore a need, in these situations, for monitoring changes in gait characteristics accurately, unobtrusively, frequently and inexpensively.

Various techniques have been proposed for automatically analyzing a person's gait in different applications. Gait can be assessed by a physical therapist. This is expensive, infrequently done and arguably slightly more subjective than other techniques that are based on instrumented measurement. It is done in an unnatural environment such as a therapist's office.

Gait can be assessed with video. This requires sophisticated image analyses that are likely to be less accurate due to the limitations of video processing, or to require multiple cameras for better accuracy, thereby becoming more expensive. Another technique is to assess gait using sensors embedded in the floor. However, pressure sensors embedded in the floor can add to the cost of gait measurement.

Several references in the prior art discuss gait measurement. U.S. Patent No. 7,330,566 and U.S. Patent Application ser. No. 09/819,149 disclose methods of measuring gait parameters such as cadence, stride length, and height of a person by means of conventional video camera. U.S. Patent Application ser.No.  12/651,022, 12/435,985 and U.S. Patent No. 6,519,359 describe methods of acquiring 3D images of the object and to measure the distances to a scene. The light source to illuminate the object is vertical cavity surface emitting light emitting laser (VCSEL) and infrared light in the ‘022 application. The limitations of the methods disclosed in the above references have already been discussed.



A 3D range camera for measuring the gait characteristics such as stride length, width, shuffling, asymmetry, speed, etc. is disclosed, as briefly described with reference to the drawings, in which:

FIG.1 shows a schematic of the steps of scanning the person’s surface by pulsed IR radiation emitted from the 3D Range camera.

FIG.2 shows a schematic of the steps of reflecting back of pulsed IR radiation and measuring the gait characteristics of a walking person.


The novel methods disclosed are described more completely with reference to the drawings in Figure 1 and Figure 2. Figure 1 shows a schematic of the scanning operation by 3D range camera using pulsed IR radiation. The 3D range camera produces a 3D topographical image rather than a 3D visual image. The output produced by the camera is thus a 2D array of a person’s body surface as they walk.




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