Gesture recovery and recognition method based on time domain Doppler effect

A recognition method and gesture technology, applied in the reflection/re-radiation of radio waves, measuring devices, instruments, etc., can solve the problems of simple application of limited gesture games and huge hardware cost, and achieve high sensitivity, low hardware complexity, The effect of strong robustness

Inactive Publication Date: 2014-05-14

ZHEJIANG UNIV

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Problems solved by technology

[0004] Traditional gesture recovery recognition uses computer image processing technology, which consumes huge hardware costs and require...

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Abstract

The invention discloses a gesture recovery and recognition method based on the time domain Doppler effect. A one-way transmitter is adopted for transmitting a single-frequency signal through an antenna; because of the Doppler effect, gesture motion information is modulated into the phase position of a reflected signal; receiving antennae of a plurality of receivers are placed in the best signal receiving positions, the multiple receivers and the transmitter share a same reference clock, phase synchronization is guaranteed, a radio frequency reflection signal is down-converted into medium frequency by a medium frequency receiver module, the medium frequency signal is down-converted into a digital baseband signal in an orthogonal mode by a digital down-conversion module, the digital baseband signal is collected by a signal collection module of a computer, the signal is processed through a comprehensive algorithm of time domain demodulation, and then gesture recovery and recognition based on the time domain Doppler effect is carried out. The method is high in sensitivity and robustness and low in hardware complexity; the accurate two-dimensional and three-dimensional motion information of gestures can be accurately recovered; any motion of a hand can be detected with the method, and the method will be widely applied to the field of gesture recognition based on the Doppler effect.

Application Domain

Input/output for user-computer interactionGraph reading +2

Technology Topic

Radio frequencyThree dimensional motion +12

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Examples

Experimental program(1)

Example Embodiment

[0023] Below in conjunction with accompanying drawing, specifically set forth the working principle and the implementation mode of the present invention:

[0024] like figure 1 As shown, the present invention uses a single-channel transmitter to transmit a single-frequency signal through an antenna. Due to the Doppler effect, the gesture motion information is modulated into the phase of the reflected signal; the receiving antennas of multiple receivers are placed in the best signal receiving position , Multiple receivers and transmitters share the same reference clock to ensure phase synchronization. The IF receiver module down-converts the RF reflection signal to IF, and the digital down-conversion module quadrature down-converts the IF signal to a digital baseband signal. Computer signal acquisition The module collects digital baseband signals, uses time-domain demodulation comprehensive algorithm signal processing, and performs time-domain Doppler gesture recovery recognition.

[0025] like figure 2 As shown, for the two-dimensional case, two receivers are needed, which is equivalent to taking the receiving antennas A and B of the two receivers as the centers at each moment, and using the arctangent or enhanced differential cross multiplication algorithm to convert the digital baseband signal Demodulate the distance to the receiving antenna of the receiver, draw a circle with this distance as the radius, and the intersection point of the circle constructed by the two signals at the same time is the position of the gesture at this moment, and the track of the intersection point changing with time is Accurate trajectory of gesture movements.

[0026] For the two-dimensional case, at least two receivers are required, and the distances between the initial position of the gesture movement and the receiving antennas A and B of the receiver are known, respectively d A0 、d B0 , the distance change value of the gesture movement relative to the receiving antenna A and B of the receiver at time t is d A (t), d B (t), using the arctangent or enhanced differential cross multiplication algorithm to demodulate the digital baseband signal to obtain the distance d relative to the receiving antenna of the receiver A0 +d A (t), d B0 +d B (t), at time t, take the receiving antennas A and B of the two receivers as the center of the circle respectively, and take the receiving antenna distance d of the corresponding receiver A0 +d A (t), d B0 +d B (t) Draw a circle for the radius, and the intersection point of the circle constructed by the two signals at the same time is the position of the gesture at this time. The trajectory of the intersection point changing with time is the accurate trajectory of the gesture movement.

[0027] For the three-dimensional case, three-way receivers are required, and the receiving antennas of the three-way receivers are not on the same plane. The trajectory of the ball intersection constructed after signal demodulation is the precise trajectory of gesture movement.

[0028] For the three-dimensional situation, at least three receivers C, D, and E are required, and the receiving antennas of the three receivers are not in the same plane, and the distance between the initial position of the gesture movement and the receiving antenna of the receiver is known, respectively d C0 、d D0 , d E0 , the distance change value of the gesture movement relative to the receiving antenna C, D, E of the receiver at time t is d C (t), d D (t), d E (t), using arctangent or enhanced differential cross multiplication algorithm to demodulate the digital baseband signal to obtain the distance d of the receiving antenna relative to the receiver C0 +d C (t), d D0 +d D (t), d E0 +d E (t), at time t, take the receiving antennas C, D, and E of the three receivers as the center of the circle respectively, and take the receiving antenna distance d of the corresponding receiver as C0 +d C (t), d D0 +d D (t), d E0 +d E (t) draws a ball with a radius, the intersection point of the ball constructed by the two signals at the same time is the position of the gesture at this moment, and the trajectory of the constructed ball intersection is the precise trajectory of the gesture movement.

[0029] like image 3 , Figure 4 Shown is the locus diagram of the construction circle intersection of the motion information of the two-dimensional object.

[0030] Assume that the single-frequency transmit signal expression is:

[0031]

[0032] S(t) is the transmitting signal, t is the time, f is the transmitting frequency, is the transmitter phase noise.

[0033] then pass figure 1 The signals received by the receiving antennas A and B of the receiver are respectively

[0034] R A = cos ( 2 πft - 4 π d A 0 λ - 4 πd A ( t ) λ ) ,

[0035] R B = cos ( 2 πft - 2 πd A 0 λ - 2 π d B 0 λ - 2 πd A ( t ) λ - 2 πd B ( t ) λ )

[0036] Among them, R A , R B are the signals received by the receiving antennas A and B of the receiver respectively, f is the transmitting frequency, d A0 and d B0 is the initial position of receiving antennas A and B from the human hand to the receiver, d A (t) and d B (t) are respectively the change value of the distance between the gesture movement and the receiving antenna A and B of the receiver at time t.

[0037] use figure 1 As shown, the motion distance change information d relative to the receiving antenna direction of the receiver is extracted A (t) and d B (t), taking the receiving antennas A and B of the receiver as the center respectively, d A +d A (t) and d B +d B (t) Draw a circle with radius. like image 3 , Figure 4 , it can be seen that the trajectory of the intersection of the two circles over time at the same moment is the exact trajectory of the gesture movement.

[0038] like Figure 5 , Image 6 As shown, the change of the moving distance of the two-dimensional uniform gesture movement relative to the receiving antennas of the two receivers is the distance change of the receiving antennas along the wave vector direction of the received electromagnetic wave. Therefore, the distance variation diagram of the receiving antennas relative to the two receivers is d A +d A (t) and d B +d B(t) Plot over time. The simulation increases the impact of white noise on the gesture recovery results to test the robustness of the present invention, as Figure 5 is the distance change diagram for the receiving antenna A, such as Image 6 It is the distance change diagram for the receiving antenna B.

[0039] like Figure 7 (normalized coordinates), Figure 7 for Figure 5 , Image 6 For the two-dimensional uniform-velocity gesture movement, the gesture recovery trajectory obtained by using the time-domain demodulation synthesis algorithm can be seen that the gesture movement can be accurately recovered. Figure 8 Gesture recovery trajectories obtained for sinusoidal motion recovery.

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Gesture recovery and recognition method based on time domain Doppler effect

AI-Extracted Technical Summary

Problems solved by technology

Abstract

Image

Examples

Example Embodiment

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