A kind of fall detection method
Technical field
The present invention relates to field of sensing technologies, particularly relate to a kind of fall detection method.
Background technology
Falling down the part as physical activity, is the large factor affecting health, especially for patient and the elderly, fall down detect most important.Research shows, in the elderly of China's over-65s, have quite a few people once to fall down, and the incidence of falling down raises with advancing age, and thus succouring the elderly fallen down in time will reduce disability rate and mortality ratio greatly; What also cannot realize human body at present falls down detection.
Summary of the invention
The technical problem to be solved in the present invention is, provides a kind of fall detection method of activity personal security exception.
For solving the problem, the present invention adopts following technical scheme:
A kind of fall detection method, comprises the steps:
Step S1, by the real-time human body moving state information of 3-axis acceleration sensor, obtain 3-axis acceleration data;
Step S2, to obtain acceleration information based on 3-axis acceleration sensor and calculate amplitude vector value SVM;
Step S3, to compare with the threshold values pre-set according to described SVM value, judge that current active is in above-mentioned some states, detect whether there is the phenomenon of falling according to the change of state.
As preferably, according to each component value obtaining X, Y, Z tri-directions from 3-axis acceleration sensor; Then according to the employing exploitation difference of front and back twice; Again calculate the square value of each three component differences, i.e. SVM value, computing formula model is:
SVM=(X
n-X
n-1)
2+(Y
n-Y
n-1)
2+(Z
n-Z
n-1)
2
Wherein: X
nrepresent the X component value of the 3-axis acceleration of current acquisition, X
n-1represent the X component value of the last 3-axis acceleration obtained; Y
nrepresent the Y-component value of the 3-axis acceleration of current acquisition, Y
n-1represent the Y-component value of the last 3-axis acceleration obtained; Z
nrepresent the Z component value of the 3-axis acceleration of current acquisition, Z
n-1represent the Z component value of the last 3-axis acceleration obtained.
As preferably, in step S3, deterministic process is as follows:
Judge whether current SVM value exceedes first threshold, if so, then SVM value exceedes the number of times increase of described first threshold; If whether the number of times that SVM value exceedes described first threshold exceedes preset times, then current state is updated to falling state of falling;
Judge whether current SVM value exceedes described first threshold, if, then judge the number of sample points whether number of times that SVM value exceedes described first threshold is less than SVM value and exceedes described first threshold, if, then SVM value exceedes the number of times increase of described first threshold, judge whether the number of times that SVM value exceedes first threshold exceedes falling state threshold number of falling, and if so, then current state is updated to crash situation of falling;
Judge whether current SVM value exceedes Second Threshold, if, then judge the number of sample points whether number of times that SVM value exceedes Second Threshold is less than SVM value and exceedes described Second Threshold, if so, then the number of times that SVM value exceedes Second Threshold increases, and judges whether the number of times that SVM value exceedes Second Threshold exceedes shock threshold number of falling, if, judge whether current maximum sampling SVM value exceedes current SVM value, if so, then current state is updated to stationary state of falling;
Judge that whether current SVM value is lower than Second Threshold, if so, then the number of times that SVM value exceedes Second Threshold increases, and judges whether the number of times that SVM value exceedes Second Threshold exceedes the static threshold number of times that falls down to the ground, and if so, then current state is updated to preparation alarm condition.
Wherein, described first threshold is falling state SVM threshold values of falling, and Second Threshold is crash situation SVM threshold value of falling.
Based on the physical activity acceleration signal that 3-axis acceleration sensor gathers, propose a kind of signal amplitude based on fixed threshold vector moving average method.The method is according to acceleration signal feature during physical activity, the threshold value preset is utilized to adjudicate acceleration signal amplitude vector SVM value, use multiple sampling and state variation tendency to distinguish the strenuous exercises such as running fast, what accurately achieve human body falls down detection simultaneously.
Accompanying drawing explanation
Fig. 1 is the process flow diagram of fall detection method of the present invention;
Fig. 2 is the test result adopting detection method.
Embodiment
Below in conjunction with embodiment and accompanying drawing, technical scheme of the present invention is further elaborated.
As shown in Figure 1, the embodiment of the present invention provides a kind of fall detection method, comprises the following steps:
Step S1, by the real-time human body moving state information of 3-axis acceleration sensor, obtain 3-axis acceleration data.
Step S2, to obtain acceleration information based on 3-axis acceleration sensor and calculate amplitude vector value SVM.
The component value in X, Y, Z tri-directions is obtained from 3-axis acceleration sensor, then according to the employing exploitation difference of front and back twice according to each; Again calculate the square value of each three component differences, i.e. SVM value, computing formula model is:
SVM=(X
n-X
n-1)
2+(Y
n-Y
n-1)
2+(Z
n-Z
n-1)
2
Wherein: X
nrepresent the X component value of the 3-axis acceleration of current acquisition, X
n-1represent the X component value of the last 3-axis acceleration obtained; Y
nrepresent the Y-component value of the 3-axis acceleration of current acquisition, Y
n-1represent the Y-component value of the last 3-axis acceleration obtained; Z
nrepresent the Z component value of the 3-axis acceleration of current acquisition, Z
n-1represent the Z component value of the last 3-axis acceleration obtained.
Step S3, to compare with the threshold values pre-set according to described SVM value, judge that current active is in above-mentioned some states, detect whether there is the phenomenon of falling according to the change of state.
Deterministic process is as follows:
Judge whether current SVM value exceedes first threshold, if so, then SVM value exceedes the number of times increase of described first threshold; If whether the number of times that SVM value exceedes described first threshold exceedes preset times, then current state is updated to falling state of falling, wherein, preset times is three times;
Judge whether current SVM value exceedes described first threshold, if, then judge the number of sample points whether number of times that SVM value exceedes described first threshold is less than SVM value and exceedes described first threshold, if, then SVM value exceedes the number of times increase of described first threshold, judge whether the number of times that SVM value exceedes first threshold exceedes falling state threshold number of falling, and if so, then current state is updated to crash situation of falling;
Judge whether current SVM value exceedes Second Threshold, if, then judge the number of sample points whether number of times that SVM value exceedes Second Threshold is less than SVM value and exceedes described Second Threshold, if so, then the number of times that SVM value exceedes Second Threshold increases, and judges whether the number of times that SVM value exceedes Second Threshold exceedes shock threshold number of falling, if, judge whether current maximum sampling SVM value exceedes current SVM value, if so, then current state is updated to stationary state of falling; Wherein, maximal value in current maximum sampling SVM value and the SVM value that calculates of each sampled value.
Judge that whether current SVM value is lower than Second Threshold, if so, then the number of times that SVM value exceedes Second Threshold increases, and judges whether the number of times that SVM value exceedes Second Threshold exceedes the static threshold number of times that falls down to the ground, and if so, then current state is updated to preparation alarm condition.
Wherein, described first threshold is falling state SVM threshold values of falling, and Second Threshold is crash situation SVM threshold value of falling.
In sum, the 3-axis acceleration data that method of the present invention gathers based on 3-axis acceleration sensor, calculate the variation characteristic of data by mathematical analysis, thus judge falling or other motion states of the elderly.
Adopt detection method of the present invention, the loins that a danger button wearable device is worn on old man can be made based on 3-axis acceleration sensor, test result as shown in Figure 2, can find out, all running activities are not all divided into falls down, namely, when distinguishing running and running especially fast and fall down, 100% accuracy is achieved.Falling down in detection, achieving the accuracy of 94.4%.
The present invention is based on 3-axis acceleration sensor write and optimize, main employing CC2541 single-chip microcomputer and ADXL362 3-axis acceleration sensor module and relevant button and switch, the loins that the wearable device making a miniature danger button is worn on old man detects in real time and reports to the police.
Last it is noted that above embodiment is only in order to illustrate technical scheme of the present invention, be not intended to limit; Although with reference to previous embodiment to invention has been detailed description, those of ordinary skill in the art is to be understood that: it still can be modified to the technical scheme described in foregoing embodiments, or carries out equivalent replacement to wherein portion of techniques feature; And these amendments or replacement, do not make the essence of appropriate technical solution depart from the spirit and scope of various embodiments of the present invention technical scheme.