CN104457781A - Self-adaption step number detection method based on single-axis accelerometer - Google Patents
Self-adaption step number detection method based on single-axis accelerometer Download PDFInfo
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- CN104457781A CN104457781A CN201410806143.1A CN201410806143A CN104457781A CN 104457781 A CN104457781 A CN 104457781A CN 201410806143 A CN201410806143 A CN 201410806143A CN 104457781 A CN104457781 A CN 104457781A
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- G01C22/00—Measuring distance traversed on the ground by vehicles, persons, animals or other moving solid bodies, e.g. using odometers, using pedometers
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Abstract
The invention provides a self-adaption step number detection method based on a single-axis accelerometer, wherein the single single-axis accelerometer is adopted and is fixed on the rear side of the waist of a pedestrian and is utilized for measuring the accelerated speed of the pedestrian in the vertical direction; and according to the periodical fluctuation change characteristics of the gravity center of a human body in the vertical direction, the detection of the number of walking steps of the human body can be realized by identifying the numbers of wave crests and wave troughs of output signals of the accelerometer. A dual-window step number detection method is provided for effectively solving the problem that the detection rate of the step number is reduced due to factors such as vibration, and a window length self-adaption regulation principle is provided according to the motion state of the human body, so that the accurate detection of the step number of the pedestrian at different walking speeds is realized. The self-adaption step number detection method based on the single-axis accelerometer is simple and effective, is easy to realize and has the definite robustness to resisting disturbances, such as vibration.
Description
Technical field
The present invention relates to a kind of self-adaptation step number detection method based on single-axis accelerometer, effectively can resist the interference that the factors such as vibration cause, realize advancing to human body the accurate counting of step number, belongs to pedestrian navigation field, can be used for improving pedestrian's positioning precision in pedestrian navigation.
Background technology
An emerging technology in field of inertia technology in recent years based on the pedestrian navigation of MEMS (micro electro mechanical system) (MEMS) inertial sensor, usually, under the gps signal invalid situation such as indoor, mountains and rivers, valley, tunnel, be applied to fire-fighting, the disaster relief, blind person guide, the occasion such as personal scheduling in building.In having radio field to close, employing wireless electricity locates comparative maturity to pedestrian, and is widely applied.And when radio signal cannot be obtained, usually rely on motion sensor and realize pedestrian independently locate in conjunction with inertial technology, kinesiology, and MEMS (micro electro mechanical system) inertial sensor is conventional motion sensor.Because MEMS (micro electro mechanical system) inertial sensor exists the complicacy of larger device error and pedestrian's walking motion, the pedestrian based on MEMS (micro electro mechanical system) inertial sensor is made independently to be positioned with certain difficulty.Due to MEMS (micro electro mechanical system) inertial sensor is placed on loins carry out pedestrian location have easy to use, make waist formula pedestrian locate become study hotspot.
How accurately to detect step number problem for waist formula pedestrian location, existing major part research is that when utilizing pedestrian to walk, center of gravity dipping and heaving variation characteristic, to detect step number, namely detects step number by sky to accelerometer output signal.But in walking process, pin lands and other disturbances can produce various vibration, thus causes sky to introduce various undesired signal to accelerometer, makes the accuracy rate detecting step number decline.For in waist formula pedestrian location, how to resist when pedestrian walks the interference of vibration to improve step number verification and measurement ratio, this is a difficult point in pedestrian navigation field and is also urgent problem.
Summary of the invention
Object of the present invention: cause step number verification and measurement ratio decline problem in pedestrian navigation for effectively solving the disturbing factors such as vibration, under study movement state, gravity center of human body's fluctuations regular basis proposes a kind of Dual-window step number detection method, and according to human motion state, length of window self-adaptative adjustment criterion is proposed, realize pedestrian's accurate detection to step number under the different speed of travel.
Technical solution of the present invention is: by gravity center of human body's fluctuations rule under analysis motion state, find out the characteristic quantity that can characterize walking step number.The disturbance factor be subject to during this characteristic quantity of further analysis moves in practice, a kind of self-adaptation step number detection method based on single-axis accelerometer is proposed, the method is characterised in that: introduce two for extracting the one-dimension array (abbreviation window) of pedestrian sky to acceleration peak value, length of window L is exactly array length, namely comprised sampling number, two window head and the tail only overlapping sampling number; To come when identifying rows people walks sky to the crest number of acceleration by Dual-window, and by human motion state self-adaptative adjustment length of window, the undesired signal that when effectively can resist walking, vibration produces, realizes the accurate detection of pedestrian's step number.
The self-adaptation step number detection method based on single-axis accelerometer described in utilization, comprises the following steps:
(1) single-axis accelerometer to be fixed on rear side of human lumbar and to be used for the measurement row man day to acceleration;
(2) set gait cycle (time that row makes a move) T (1)=0.2 second, accelerometer signal maximum crest number N1=0, accelerometer signal minimum trough number N2=0 during initialization, advance step number N=0;
(3) the length L (N) of gait cycle T (N) and system sampling frequency fs self-adaptative adjustment two window is utilized;
The peak-peak of contained accelerometer output signal in each window asked for respectively by (4) two windows, judge whether two window peak-peaks are same numbers corresponding under same sequential, be, then N1=N1+1, otherwise N1 is constant, and the sequential j of peak-peak appears in record, and be stored in maxpeak_time (N1);
The minimum peak of contained accelerometer output signal in each window asked for respectively by (5) two windows, judge whether two window minimum peak are same numbers corresponding under same sequential, be, then N2=N2+1, otherwise N2 is constant, and the sequential j of minimum peak appears in record, and be stored in minpeak_time (N2);
(6) as N1=N2 and N1>0 time, step number N=N+1, and calculate gait cycle T (N), otherwise N and T (N) is constant, thus realize self-adaptation step number and detect.
Principle of the present invention: Wen Zhonghang makes a move and refers to that single pin steps a step forward, and sky when az represents that pedestrian walks is to acceleration.Do not considering under the disturbed conditions such as vibration, accompanying drawing 1 is shown in acceleration az corresponding relation in pedestrian's walking step state and corresponding sky.
When human body two foot is across time maximum, now gravity center of human body is in extreme lower position, and az reaches minimum trough value; When people continues forward stride again, position of human center starts up to move, az monotone increasing in this time; When human body is at erectility, now both legs are almost in vertical state, and center of gravity reaches extreme higher position, and az reaches maximum crest value; Then gravity center of human body arrives extreme lower position along with paces from extreme higher position, completes the action that row forward makes a move, and forms a period of change.
Known in vertical direction fluctuations rule by center of gravity, row makes a move one skilled in the art's center of gravity when extreme higher position, and az signal is corresponding appearance crest always, sees red circular mark in accompanying drawing 2.When not considering that vibration etc. is disturbed, pedestrian's row makes a move, the corresponding appearance of az once maximum crest.Therefore az occurs that crest times N um_crest and step number Num_step meets following relational expression:
Num_crest＝Num_step (1)
If not vibrate etc. when affecting, just can calculate by detecting az crest occurrence number Num_crest the step number that pedestrian walks.It can also be seen that from accompanying drawing 1, az trough number also equals step number, and during pedestrian's row makes a move, an az crest and az trough is always had to occur, apply this feature can think, just think that when az crest and trough occur in succession row makes a move, step number verification and measurement ratio can be improved like this.But always there is various undesired signal in actual walking process, vibration when wherein landing exports accelerometer signal and has the greatest impact, and during these undesired signals make often to walk, ghost peak appears in az, see accompanying drawing 2 Green sphere shaped markup.These ghost peak make to utilize az input step number accuracy rate to decline, and how effectively to resist vibration interference and to improve step number verification and measurement ratio, for this vibrational perturbation problem, to propose a kind of self-adaptation Dual-window step number detection method.
Quote two self-adaptation overlaid windowss to detect the peak value that in each step, sky occurs to acceleration az, comprise maximum crest value and minimum trough value.Detect ultimate principle: window refers to the one-dimension array for extracting az peak value; Length of window L is exactly array length, namely comprised sampling number; Two windows head and the tail are overlapping sampling numbers only, if the maximum crest value of two windows is the same numbers under same sequential, then thinks that the unique maximal value of two windows is the maximum crest value of az in this step, in like manner can obtain the minimum trough value of az.Accompanying drawing 2 is Dual-window sense acceleration meter output signal az peak value principle schematic.
But the long meeting of length of window L makes detected step number on the low side, the in like manner too short meeting of window makes step number bigger than normal, does not reach the effect accurately calculating step number.In order to can the peak-peak of the self-adapting detecting different people step number of walking with friction speed and az and minimum peak.Further analysis design mothod data, find that length of window is relevant with pedestrian walking speed, can according to pedestrian walking speed different and self-adaptative adjustment length of window.For ease of simplifying, gait cycle T (time that row makes a move) is used to characterize walking speed herein.Can show that the relational expression of length of window L and gait cycle T is as follows by analysis:
L＝T*fs (2)
Wherein fs is system sampling frequency, all more applicable when formula (2) is walked with friction speed to different people, is carried out the length L of self-adaptative adjustment two overlaid windows by the difference of the speed of travel.Through great many of experiments, gather the true number that different pedestrian walks with friction speed, find that pedestrian is generally no more than 5 steps in the cadence (step number in the unit interval) just starting the starting stage per second, following rule-of-thumb relation summed up further to the test result of different pedestrian under different starting speed:
L＝0.2*fs (3)
Because pedestrian's walking speed when ground zero is little, cadence is within 5 steps are per second, change further on this basis afterwards, so available formula (3) is to setting home window length, in walking process, use formula (1) to carry out self-adaptative adjustment length of window again.
The maximum crest value of az and minimum trough value and the two corresponding sequential j (time point of appearance) in utilizing the method detection often to walk.The sequential occurred by maximum crest value and minimum trough value can obtain pedestrian's gait cycle T, and then adjusts length of window L with gait cycle T, realizes detecting based on single-axis accelerometer self-adaptation step number.
The present invention's advantage is compared with prior art:
(1) quote Dual-window and carry out recognition feature signal, effectively opposing vibration waits interference, accurately detects step number to reach.
(2) according to the difference of pedestrian's speed of travel and adaptively changing length of window, and then self-adapting detecting step number.
Accompanying drawing explanation
Fig. 1 is that gait and accelerometer output signal az relation schematic diagram;
Fig. 2 is Dual-window sense acceleration meter output signal az peak value principle schematic;
Fig. 3 is of the present invention based on single-axis accelerometer self-adaptation step number overhaul flow chart.
Embodiment:
Fig. 3 is self-adaptation step number overhaul flow chart of the present invention, is mainly divided into following step:
(1) single-axis accelerometer is fixed on rear side of human lumbar, ensures that accelerometer and human body are fixed as one, do not have relative motion, and for placing towards the measurement row man day to acceleration direction;
(2) set gait cycle (time that row makes a move) T (1)=0.2 second, accelerometer signal maximum crest number N1=0, accelerometer signal minimum trough number N2=0 during system initialization, advance step number N=0; And ask for the Dual-window length L (1) when pedestrian starts to walk with formula (1);
(3), in walking process, utilize gait cycle T (N) and system sampling frequency fs according to the length L (N) of formula L=T*fs self-adaptative adjustment two window;
The peak-peak of contained accelerometer output signal in each window asked for respectively by (4) two windows, judge whether two window peak-peaks are same numbers corresponding under same sequential, be, then N1=N1+1, otherwise N1 is constant, and the sequential j of peak-peak appears in record, and be stored in maxpeak_time (N1);
The minimum peak of contained accelerometer output signal in each window asked for respectively by (5) two windows, judge whether two window minimum peak are same numbers corresponding under same sequential, be, then N2=N2+1, otherwise N2 is constant, and the sequential j of minimum peak appears in record, and be stored in minpeak_time (N2);
(6) as N1=N2 and N1>0 time, step number N=N+1, and using gait cycle computing formula: T (N+1)=0.5* (maxpeak_time (N1)-maxpeak_time (N1-1)+minpeak_time (N2)-minpeak_time (N2-1)) * (1/fs) asks for gait cycle T (N+1), otherwise N and T (N) is constant, thus realize the detection of self-adaptation step number.
The content be not described in detail in this instructions belongs to the known prior art of professional and technical personnel in the field.
Claims (4)
1., based on a self-adaptation step number detection method for single-axis accelerometer, it is characterized in that comprising the following steps:
(1) single-axis accelerometer to be fixed on rear side of human lumbar and to be used for the measurement row man day to acceleration;
(2) set gait cycle (time that row makes a move) T (1)=0.2 second, accelerometer signal maximum crest number N1=0, accelerometer signal minimum trough number N2=0 during initialization, advance step number N=0;
(3) the length L (N) of gait cycle T (N) and system sampling frequency fs self-adaptative adjustment two window is utilized;
The peak-peak of contained accelerometer output signal in each window asked for respectively by (4) two windows, judge whether two window peak-peaks are same numbers corresponding under same sequential, be, then N1=N1+1, no, then N1 is constant, and the sequential j of peak-peak appears in record, and is stored in maxpeak_time (N1);
The minimum peak of contained accelerometer output signal in each window asked for respectively by (5) two windows, judge whether two window minimum peak are same numbers corresponding under same sequential, be, then N2=N2+1, otherwise N2 is constant, and the sequential j of minimum peak appears in record, and be stored in minpeak_time (N2);
(6) as N1=N2 and N1>0 time, step number N=N+1, and calculate gait cycle T (N), otherwise N and T (N) is constant, thus realize self-adaptation step number and detect.
2. the self-adaptation step number detection method based on single-axis accelerometer according to claim 1, is characterized in that: described step requires that accelerometer is placed on rear side of human lumbar in (1), and with accelerometer measures pedestrian sky to acceleration.
3. the self-adaptation step number detection method based on single-axis accelerometer according to claim 1, is characterized in that: time initial, get gait cycle T (1)=0.2 second; In step number testing process, pedestrian's gait cycle T (N) gets both acceleration crest and trough signal period average; And adjust length of window L (N) with gait cycle T (N), the difference according to pedestrian's speed of travel can be realized and adaptively changing length of window, thus carry out the detection of self-adaptation step number.
4. the self-adaptation step number detection method based on single-axis accelerometer according to claim 1, it is characterized in that: characterize walking step number with the periodicity Wave crest and wave trough number of single-axis accelerometer output signal, crest, trough signal is identified by Dual-window, the interference such as effective opposing vibration, accurately detect step number to reach.
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