CN215728820U - Intelligent door adopting millimeter wave radar to realize non-contact control - Google Patents
Intelligent door adopting millimeter wave radar to realize non-contact control Download PDFInfo
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
- G01S13/00—Systems using the reflection or reradiation of radio waves, e.g. radar systems; Analogous systems using reflection or reradiation of waves whose nature or wavelength is irrelevant or unspecified
- G01S13/88—Radar or analogous systems specially adapted for specific applications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
- G01S13/00—Systems using the reflection or reradiation of radio waves, e.g. radar systems; Analogous systems using reflection or reradiation of waves whose nature or wavelength is irrelevant or unspecified
- G01S13/02—Systems using reflection of radio waves, e.g. primary radar systems; Analogous systems
- G01S13/06—Systems determining position data of a target
- G01S13/08—Systems for measuring distance only
- G01S13/32—Systems for measuring distance only using transmission of continuous waves, whether amplitude-, frequency-, or phase-modulated, or unmodulated
- G01S13/34—Systems for measuring distance only using transmission of continuous waves, whether amplitude-, frequency-, or phase-modulated, or unmodulated using transmission of continuous, frequency-modulated waves while heterodyning the received signal, or a signal derived therefrom, with a locally-generated signal related to the contemporaneously transmitted signal
- G01S13/343—Systems for measuring distance only using transmission of continuous waves, whether amplitude-, frequency-, or phase-modulated, or unmodulated using transmission of continuous, frequency-modulated waves while heterodyning the received signal, or a signal derived therefrom, with a locally-generated signal related to the contemporaneously transmitted signal using sawtooth modulation
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
- G01S13/00—Systems using the reflection or reradiation of radio waves, e.g. radar systems; Analogous systems using reflection or reradiation of waves whose nature or wavelength is irrelevant or unspecified
- G01S13/02—Systems using reflection of radio waves, e.g. primary radar systems; Analogous systems
- G01S13/50—Systems of measurement based on relative movement of target
- G01S13/58—Velocity or trajectory determination systems; Sense-of-movement determination systems
- G01S13/583—Velocity or trajectory determination systems; Sense-of-movement determination systems using transmission of continuous unmodulated waves, amplitude-, frequency-, or phase-modulated waves and based upon the Doppler effect resulting from movement of targets
- G01S13/584—Velocity or trajectory determination systems; Sense-of-movement determination systems using transmission of continuous unmodulated waves, amplitude-, frequency-, or phase-modulated waves and based upon the Doppler effect resulting from movement of targets adapted for simultaneous range and velocity measurements
Abstract
An intelligent door and a non-contact control system for realizing non-contact control by adopting a millimeter wave radar, wherein the control system (10) comprises: a millimeter wave radar sensor (101) that transmits a radar beam and receives a reflected radar beam to detect a user gesture command; the state feedback component (102) is used for feeding back state information to a user to realize state interaction; a processor (103) connected to the millimeter wave radar sensor (101), the state feedback section (102), and the motion drive section (104); the control system (10) replaces algorithm optimization with system design, and simplifies the design while considering both control reliability and convenience, so that the control system is applied to embedded terminals with limited resources, and the technical effects of non-contact conditional opening, and convenient and reliable control are achieved.
Description
Technical Field
The utility model relates to a non-contact control intelligent door and a non-contact control system.
Background
In daily life, the opening and closing control of the door can be realized through various ways, the most common door is controlled by a mechanical opening and closing through a handle, and the door is opened by rotating the handle, pulling the handle and the like; for the control of elevators and the like, the switches may be controlled by means of electronic buttons or the like. These contact control methods are easy to become shortcuts for the propagation of bacteria and viruses in public places, and have public health and potential safety hazards. For example, elevator panels need to be rigorously disinfected to avoid contagious infections during a pandemic.
In order to avoid the defect of contact control, the automatic door sensing the approach of an object is also widely applied to public places such as markets, hotels and the like, and can be automatically opened when the approach of the object is detected; however, such automatic doors are not suitable for occasions where automatic opening is prohibited in some situations, such as elevators, and when the elevator car is not at the current floor, automatic opening of the elevator door is dangerous and needs to be strictly avoided. Similar automatic door also has the application and covers on intelligent refrigerator, intelligent closestool, and the shortcoming is only to utilize the trigger condition that distance information detection object is close to, and is too simple, triggers by mistake easily.
In order to avoid false triggering, conditions for opening the automatic door need to be set more complicated, for example, a more complicated gesture is used for control, but for the recognition of the complicated gesture, the current system recognition method needs to pay a large calculation cost, has a low accuracy, and cannot ensure the reliability of the opening of the door.
Therefore, it is desirable to provide an intelligent door which is opened in a non-contact condition and is convenient and reliable to control.
Disclosure of Invention
The utility model provides a non-contact control intelligent door and a non-contact control module of the intelligent door; the millimeter wave sensor is applied to the intelligent door, and the opening/closing control of the door or other control functions such as upstairs going and downstairs going requests of the elevator are realized by detecting the gesture of a user; the device can be applied to occasions where public places and public transportation means need to be frequently contacted, such as an elevator of a market and an office building, an airport, a railway station, a toilet door on a train and an airplane and the like, so as to cut off the propagation path of bacteria and viruses, guarantee the public health and safety, ensure the reliability of opening and avoid misoperation. The method can also be applied to non-contact control of kitchen and bathroom electrical appliances such as intelligent refrigerator doors and the like so as to improve the control reliability.
The utility model provides an intelligent door for realizing non-contact control by adopting a millimeter wave radar, which comprises: the door comprises a door frame (1), a door plate (2), a moving part (3) for driving the door plate (2) to open and close, and a control system (10); the control system (10) comprises: a millimeter wave radar sensor (101) that transmits a radar beam and receives a reflected radar beam to detect a user gesture command; the state feedback component (102) is used for feeding back state information to a user to realize state interaction; a processor (103) connected to the millimeter wave radar sensor (101), the state feedback section (102), and the motion drive section (104); according to the user gesture command received by the millimeter wave radar sensor (101), the control state feedback component (102) outputs state information and executes corresponding control operation. The control operation is to control the motion of the motion driving part (104) so as to drive the motion part (3) to drive the door panel (2) to move, and the intelligent door is opened and closed.
The millimeter wave radar sensor (101) includes a transmission circuit (1011) that transmits the radar beam, a reception circuit (1012) that receives the reflected radar beam, and a digital signal processing circuit (1013). The transmission circuit (1011) comprises: m transmitting antennas for emitting the radar beam, configured in a phased array mode or a MIMO mode; power amplification, linear power amplification, to drive the transmitting antenna; a digital control oscillation circuit and a digital phase-locked loop to realize frequency modulation. In order to improve the modulation bandwidth and the linearity, the numerical control oscillating circuit and the digital phase-locked loop adopt a 2-point injection structure. The receiving circuit (1012) comprises: n receiving antennas arranged in a ULA or URA manner; a low noise amplifier LNA for amplifying an amplitude of a received signal; mixing, namely mixing the received signal amplified by the low-noise amplification LNA and a local frequency modulation signal to obtain an intermediate frequency signal; low-pass filtering and variable gain amplification; and the analog-to-digital conversion circuit converts the analog signal into a digital intermediate frequency signal. The digital signal processing circuit (1013) includes: the slope generating circuit generates a sawtooth or triangular signal for adjusting the oscillation frequency of the numerical control oscillation circuit; fast Fourier Transform (FFT), namely obtaining a target distance, a radial speed and an incidence angle by searching a peak value of signal amplitude after FFT; a window function for reducing spectrum spreading due to FFT truncation; a first-in first-out buffer FIFO for buffering the FFT transformed data for further processing by the processor (103).
The control system (10) further comprises a communication interface (105) which is connected with the processor (103) and realizes interconnection and information interaction between the control system (10) and the external environment.
The control system (10) may have the following physical form combinations according to application requirements: PCB level integration based on surface mount technology, package level integration based on SIP technology, or silicon chip level integration based on SOC technology.
The millimeter wave radar sensors (101) and the state feedback component (102) in the control system (10) are respectively provided with two sets which are respectively used for processing user gesture commands and state interaction on the inner side and the outer side of a door, shielding processing is carried out between the two sets of millimeter wave radar sensors (101), and the priorities of the two sets of millimeter wave radar sensors (101) need to be set.
A non-contact gesture control system, comprising: a millimeter wave radar sensor (101) that transmits a radar beam and receives a reflected radar beam to detect a user gesture command; it is characterized by also comprising: the state feedback component (102) is used for feeding back state information to a user to realize state interaction; a processor (103) connected to the millimeter wave radar sensor (101) and the state feedback section (102); and the processor (103) detects the user gesture command in real time, feeds back an execution state in real time, decomposes the complex gesture into a plurality of simple gesture sequences, confirms the simple gesture sequences section by section, and executes corresponding control operation after receiving the complete user gesture command. The recognition of each user gesture command by the processor (103) comprises a plurality of interaction processes of mutual confirmation of the user and the control system, the interaction processes are started when the user approaches the millimeter wave radar sensor (101) and ended when the user leaves the millimeter wave radar sensor (101), and the processor (103) executes corresponding actions each time the interaction is confirmed, so that the recognition of the complex gesture command is decomposed into a plurality of progressive steps of basic gesture recognition and gradual confirmation.
The utility model integrates the millimeter wave radar sensor and the state feedback component in the system to realize bidirectional interaction, detect gesture commands in real time, feed back the execution state, decompose complex gestures into a plurality of simple gesture sequences and confirm the control protocol section by section, thereby avoiding the problems of insufficient recognition rate of the complex gestures by a simple recognition algorithm and occupation of a large amount of calculation and storage resources, namely, the algorithm optimization is replaced by system design, and the design is simplified while the control reliability and the convenience are considered, so that the system is applied to embedded terminals with limited resources. Each gesture control command can comprise a plurality of interactive processes which are mutually confirmed, wherein the interactive processes start when the command is close to the radar sensor and end when the command is far from the radar sensor, and each time the interaction is confirmed, corresponding execution actions exist, so that the complex control gesture is decomposed into a plurality of progressive steps, and the command execution can also be cancelled by early ending.
In addition, the utility model can also realize the following beneficial effects:
1. the millimeter wave sensor is applied to the intelligent door, and the opening and closing of the door are controlled by detecting the gesture of a user, so that the propagation path of bacteria and viruses can be cut off, and the public health and safety are guaranteed;
2. the state feedback component is arranged in the control system, so that the problem of identifying complex gestures of a user is effectively solved, the complex gestures of the user can be decomposed into a plurality of sections of basic gesture sequences, the system identifies and responds to each basic gesture, and confirms the basic gesture one by one in the using process, so that the reliability of gesture identification is ensured, the reliability of opening of the intelligent door can be ensured, and misoperation is avoided;
3. the millimeter wave radar sensor is arranged in the control system to serve as input, the state feedback component serves as output, the input state of a user is fed back in real time, a closed-loop control system is formed, and simple and convenient human-computer interaction is achieved.
Drawings
FIG. 1 is a schematic view of the overall structure of the present invention;
FIG. 2 is a block diagram of the control system of the present invention;
FIG. 3 is a time function of the frequency of a sawtooth FMCW radar transmitted and reflected signal;
FIG. 4 is a schematic diagram of angle of incidence (DOA) estimation based on multiple receive antennas;
FIG. 5 is a block diagram of a millimeter wave radar sensor RF front end and digital signal processing architecture;
FIG. 6 is an ADPLL frequency modulation schematic;
FIG. 7 is a diagram showing the relationship between the arrangement direction of the receiving antennas of the millimeter wave radar sensor and the sliding direction of the gesture;
FIG. 8 is a gesture simulating a key;
FIG. 9 is a schematic diagram of a gesture command sequence structure and an interactive control state transition;
fig. 10 is a schematic diagram of the arrangement direction of a non-contact elevator control panel and a corresponding millimeter wave radar receiving antenna designed by the utility model.
Detailed Description
The making and using of the presently preferred embodiments are discussed in detail below. It should be appreciated, however, that the present invention provides many applicable inventive concepts that can be embodied in a wide variety of specific contexts. The specific embodiments discussed are merely illustrative of specific ways to make and use the utility model, and do not delimit the scope of the present invention.
Provided are an intelligent door and a millimeter wave radar-based non-contact control method on the intelligent door. The overall structure of the intelligent door is shown in fig. 1, and comprises:
a doorframe 1;
the door plate 2 plays a role of space partition; the door panel 2 can be made of various materials, such as metal, glass, composite wood and the like, and can also be in various forms, such as single-leaf, double-leaf and the like, and various opening and closing movement modes, such as moving, rotating and the like;
the moving part 3 is a mechanical part for driving the door panel 2 to open and close, and is driven by a driving part such as a motor and the like to realize the translation or rotation of the door panel 2, for example, in a guide rail, rotating shaft and other modes;
in the control system 10, the control system 10 transmits a radar beam through the millimeter wave radar sensor 101, receives a reflected radar beam to detect a user gesture command, outputs a detection state in the form of light or sound through the state feedback unit 102, and the processor 103 controls the motion driving unit 104 to drive the motion unit 3 to open or close the door according to the recognized command, and the control system 10 may further transmit the command to an upper system or a cloud through the communication interface 105 to realize a more complex control function.
Fig. 2 is a block diagram of a control system 10 having an intelligent door control apparatus of the present invention, and the control system 10 will be described in detail below with reference to fig. 2.
A millimeter wave radar sensor 101 including a transmitting circuit 1011 that transmits a radar beam, a receiving circuit 1012 that receives a radar reflection signal, and a digital signal processing circuit 1013; the millimeter wave radar sensor 101 provides a quick and simple control input interface by transmitting radar beams, receiving radar transmission signals and performing digital signal processing on the reflection signals; however, since the input by the millimeter wave radar sensor 101 is a non-contact input, it is not possible to provide a state output in the form of force feedback or the like, and the user cannot know whether the input has succeeded or not and whether the input needs to be performed next.
The status feedback component 102, which generally includes a control panel forming a human-computer interaction interface, and an output interface, such as a Light Emitting Diode (LED), a Liquid Crystal Display (LCD) or a Speaker (Speaker), on which status information can be fed back by light or sound, provides visual or auditory status feedback, so that a user can sense the execution status of his gesture command, decide to continue or cancel the current command, and achieve more effective human-computer interaction.
And a processor 103 that connects motion driving section 104, millimeter wave radar sensor 101, state feedback section 102, communication interface 105, and storage medium 106.
Storage medium 106 comprises a static or dynamic random access medium 1061 for caching code and runtime dynamic data; and a non-transitory storage medium 1062 to store a program executed by the processor; the program includes instructions for: recognizing a door opening and closing gesture command according to a radar reflection signal received by the millimeter wave radar sensor 101, controlling the state feedback part 102 to output state information, and driving the motion driving part 104 to act so as to open or close the door; upper layer communication protocol processing based on the communication interface 105, such as TCP/IP, http, etc.; and to implement self-testing and calibration of the control system 10.
The motion driving part 104 is controlled by the processor 103, converts the electric energy into mechanical energy, and drives the motion part 3 to drive the door panel 2 to open and close; the motion driving means 104 may take the form of, for example, a motor.
The communication interface 105 implements interconnection and information interaction between the control system 10 and an external environment, and includes a wired communication interface, such as a control bus like I2C and SPI, or a communication link like ethernet, USB, pci express, and a wireless communication interface, such as WiFi, bluetooth, and the like. Therefore, the control system 10 can be integrated into a more complex system as a component, such as an elevator panel, and can be interconnected with an elevator dispatching system through control buses such as I2C and SPI to send upstairs and downstairs requests; the Internet of things (IoT) can be accessed through a wired wireless communication link, and remote control is realized through the cloud.
The components of the control system 10 may have the following physical form combinations according to application requirements:
a. surface Mount Technology (SMT) based PCB level integration;
b. package level integration based on SIP technology (System in Package);
c. silicon Chip level integration based on SOC technology (System on Chip).
In some specific application scenarios, in order to support simultaneous control of the inside and outside of the door, two sets of millimeter wave radar sensors 101 and state feedback components 102 are required to realize simultaneous user control gesture input and state output inside and outside the door; shielding the middle of the two sets of millimeter wave radar sensors 101 to isolate radar signals on two sides; in addition, when the same component needs to be operated when control commands are received from multiple millimeter wave radar sensors 101, the processor 103 needs to determine gesture commands received from the inner side and the outer side according to a set priority to solve a conflict; for example, when the high priority side receives a door close command, the other side will be masked.
The millimeter wave radar sensor 101 can measure the distance, the radial velocity and the incident angle of a target at the same time, and the working principle of the millimeter wave radar sensor 101 is described below by taking a sawtooth-shaped Frequency Modulated Continuous Wave (FMCW) as an example; the millimeter-wave radar sensor 101 may also adopt millimeter-wave radar technology of other modulation modes, such as a three-level frequency modulation continuous wave radar or a pulse radar.
The FMCW millimeter wave radar sensor sends FMCW radar beams and receives signals reflected by targets on a radar beam propagation path, information about target distance, radial speed and angle is extracted from the signals, discrete measurement of gesture tracks is obtained, and smooth tracks are obtained based on Bayes filtering of the measurement. The basic principle is as follows:
fig. 3 is a waveform of a linear FMCW transmitted radar signal and a single target reflected received radar signal, with frequency varying with time. The frequency characteristic is that, assuming that the initial phase is 0, the amplitude normalized transmitting frequency modulation signal is:
s(t)＝cos(2πfct+πα(t-mT)2)
where α is the slope of the chirp, fcFor the carrier frequency, as shown in fig. 3, T is the frequency modulation signal period and m is the period number.
Assuming that the distance between the target and the sensor is R, the radial velocity is v, and the speed of light is c, the delay is passed
The later received signals are:
r(t)＝cos(2πfc(t-τ)+πα(t-τ-mT)2)
the intermediate frequency signal after mixing and low-pass filtering is:
where H (t) is the low pass filtered impulse response function.
Let ts＝t-mT,0≤tsT ≦ T, and assuming slow motion of the target (it is usually reasonable to apply this assumption for gestures), let TsSubstituting + mT into g (t) to obtain
Wherein the content of the first and second substances,
its fourier transform is:
taking the frequency as the positive part:
therefore, it is not only easy to use
Thus the target distance can be detected
Is estimated.
Is provided with
For phasors from the FFT peak sequence, the sequence is then Fourier transformed (Doppler FFT)
P(f)＝δ(f-Tfd)
Therefore, it is not only easy to use
Therefore, the radial velocity can be estimated by detecting the peak of | p (f) |.
Because the distance and the radial speed only reflect the information of one dimension of the target, only whether the target approaches or not can be detected; in order to obtain accurate target position information, 2D position measurement of the target by an array of multiple receive antennas is required. The N independent receiving antennas are arranged in an equidistant linear array ula (uniform linear array) form, or an MIMO radar technology may be adopted, and M transmitting antennas and N receiving antennas are arranged in a specific form to obtain an mxn virtual array, so as to improve the angular resolution.
Figure 4 shows a form of receive antenna array. For the receiving antenna array, if the distance between adjacent antennas is d, the phase difference between adjacent receiving channels is
Where θ is the incident angle and λ is the wavelength.
Similarly, the velocity is estimated according to the peak value of Doppler FFT, the Fourier transform (angle FFT) is carried out on the phasor formed sequence at the peak value of the FFT amplitude of the N channels, and the peak value is used as the estimation of omega, so that the velocity is estimated according to the Doppler FFT peak value
The angle of incidence is estimated. The angular resolution achieved by this method is limited by the number of arrays, e.g. pairs
An ULA array of (1), angular resolution of
For an array with N-8, the angular resolution is approximately 15 °.
For higher angular resolution, Capon or music (multiple Signal classifier) methods may be used. MUSIC is a vector space-based method, the number of targets to be detected needs to be known in advance, and Capon has the advantage that the estimation of the incident angles and the powers of a plurality of target reflected signals can be directly obtained without the need of knowing the number of targets, so that the method can be used for initializing the MUSIC.
With K targets at different angles of incidence thetakThe reflected signals are received by the N receiving antennas at the same time, and the vectors of the K reflected signals S (t) and the N received signals X (t) are expressed as
S(t)＝[s1(t),…sK(t)]T；X(t)＝[x1(t)…xN(t)]T
For each reflected signal, the vector of phase differences arriving at the N receive antennas can be expressed as a steering vector
The matrix of K steering vectors is represented as
A(θ)＝[a(θ1),…a(θK)]
Therefore, it is not only easy to use
X(t)＝A(θ)S(t)+Q(t),Q(t)＝[q1(t)…qN(t)]T
Where q (t) is a vector representation of the noise in the received signal. Is provided with
y(t)＝WHX(t),W＝[w1…wN]T
Then
P(W)＝E(|y(t)|2)＝WHE(X(t)X(t)H)W＝WHRW
The Capon method finds an optimization problem targeting maximum signal-to-interference ratio by suppressing all undesired angle signal energy while keeping the desired angle signal gain at 1:
min(P(W))subject to WHa(θ)＝1
with a Lagrangian objective function of
Therefore, it is not only easy to use
According to WHa (theta) is 1
Thereby to obtain
By searching for PcaponThe peak value of (theta) exceeding the threshold value can obtain the target number K and the corresponding incidence angle theta at the same timekAnd (6) estimating.
In practical applications, various interferences and noises cause measurement errors of distance, radial velocity and angle, so that the direct measurement results need to be filtered to obtain a smooth estimation of the target track. This filtering process can be expressed as: given all past measurements, the posterior probability distribution of the current target state, i.e., p (x), is estimatedk|y1:k)：
Wherein y is1:kRepresents all measurements before time k, p (x)k|xk-1,y1:k-1)＝p(xk|xk-1) Is based on the Markov assumption, i.e. given xk-1，xkWith an earlier state x1:k-2And all measurements of y in the past1:k-1Is irrelevant.
Suppose that
The position and speed states of the target in the Cartesian coordinate system,
for measuring angle, distance and radial velocity in a polar coordinate system, a dynamic model of a target in a state space is assumed to be a constant velocity model, namely
Where T is the sampling rate, i.e., the time interval between two adjacent measurements, assuming that the distribution of velocity variations is zero mean Gaussian
Then
The observation model from the state space to the measurable feature space is a cartesian to polar mapping
Wherein
For measurement errors, because of h (x)k) Non-linear, so p (y)k|xk) Non-gaussian, so that an exact analytical solution for the integral operation in the bayesian recursion process is usually not available, but only an approximate solution. The following steps can be equally applied to other state or measurement space coordinate system selection, such as 3D measurement space
Or other dynamic models such as Singer acceleration models, etc.
The Extended Kalman Filter (EKF) is substituted into the observation model h (x)k) The first order linear approximation of the first order linear approximation, and the resulting bayesian recursive solution. According to h (x)k) First order Taylor's expansion, ykIn that
The vicinity can be approximated as
Wherein the content of the first and second substances,
so p (y)k|xk) In that
Approximately Gaussian distribution of the surroundings is
According to Gaussian approximation, an exact analysis solution of integral operation in a Bayesian recursion process can be obtained, so that the EKF recursion process is simplified as follows:
the initial conditions are
Wherein the content of the first and second substances,
for initial distance, radial velocity and angle of incidence measurements, initial state
Is y0Mapping in Cartesian coordinate System, an initial covariance matrix P0|0Is a diagonal matrix, parameter
For simulating random variations of the initial state.
Slave states according to a dynamic model
Is updated to
Is predicted by
Pk+1|k＝FPk|kFT+GQkGT
Kalman gain of
According to measurement yk+1From state estimation
Is updated to
Is prepared by
Recursively iterating the steps to obtain the track of the target in the state space
And its covariance P0|0,…,Pk|k) Is estimated. Kalman filtering is not optimal for the estimation of non-linear moving objects due to the first order linear approximation.
For optimal filtering performance, particle filtering can be used, which is to combine p (x)k|y1:k) The Monte-Carlo approximation of (A) is substituted into the Bayesian recursion process, so that a numerical solution of integral operation is obtained, the linear assumption is removed, the method is suitable for optimal estimation of the nonlinear change state, and the approximation error is reduced along with the increase of the number of particles. Particle filter with N particles xki,i∈ [1,N]And weight w thereofk|k i,
Approximation p (x)k|y1:k) The following were used:
then p (x)k+1|y1:k) Can be approximated as
Because p (x)k+1|y1:k+1) Difficult to sample directly, p (x)k+1|y1:k+1) The particle approximation of (a) needs to be obtained from Importance Sampling (Importance Sampling) according to a proposed Distribution (a), and the selection of the optimal proposed Distribution needs to contain both the current particle approximation and the current measurement information, so p (x) is usually selectedk+1|xk i,yk+1) To propose a distribution, let its particles be approximated by
Sampling according to importance
Wherein
Thus, importance samples, p (x)k+1|y1:k+1) Reduces the sampling problem to the proposed distribution p (x)k+1|xk i,yk+1) Due to the sampling problem of
Wherein the observation model p (y)k+1|xk+1) non-Gaussian linearity of (a) such that p (x)k+1|xk i,yk+1) Direct sampling is also difficult. However, as described below, with reference to the method of linear approximation in EKF, p (x) is utilizedk+1|xk i,yk+1) The complex sampling problem can be simplified to gaussian sampling by gaussian approximation:
observe model p (y)k+1|xk+1) At xk iLinear gaussian approximation of the surroundings
Substituting into the EKF recursive process to obtain p (x)k+1|xk i,yk+1) Is solved by approximation analysis
Wherein the Kalman gain is
Kk+1 i＝(GQk+1GT)H(xk i)T(H(xk i)(GQk+1GT)H(xk i)T+Rk+1)-1
So p (x) can be obtained by Gaussian samplingk+1|xk i,yk+1) The sample point of (1).
In summary, the particle filtering process is as follows:
from a Gaussian distribution
Obtaining N sample points, and the weight of each sample
As an initial particle approximation.
According to p (x)k+1|xk i,yk+1) Obtaining N sample points of the current state and the weight thereof by Gaussian sampling
Then p (x)k+1|y1:k) Is approximately as
From the current measurement yk+1Information of (2), update weight wk+1|k jIs wk+1|k+1 j
Thus, can obtain
So that an estimate of the current state can be obtained as
Recursion and iteration are carried out on the processes to obtain the track of the target in the state space
Is estimated.
Based on the above-described operation principle and signal processing steps, a block diagram of the millimeter wave radar sensor 101 is shown in fig. 5. The transmitting circuit 1011 includes, but is not limited to:
a.M transmitting antennas (e.g., M-2) for radar signal output. In fig. 5, all the transmitting antenna outputs are from the same signal source, so that the output gain can be improved; the signal path at the transmitting end in fig. 5 may also be slightly modified, different signals are transmitted through each or some of the antennas, and the distance between the transmitting and receiving antenna arrays is adjusted accordingly, so as to obtain an M × N virtual SIMO array by using MIMO radar technology, thereby improving spatial resolution. In order to avoid mutual interference of different transmitted signals, a Code division multiplexing technology such as Binary Phase Modulation or Hadamard Code can be adopted, so that the transmitted signals of all antennas are orthogonal to each other;
b. the Power Amplifier (PA) is used for amplifying linear power so as to drive the antenna to transmit a frequency modulation signal;
c. the linear frequency modulation continuous waveform generating circuit includes a digital controlled oscillator circuit (DCO) and A Digital Phase Locked Loop (ADPLL), and a structural block diagram is shown in fig. 6. The time-to-digital conversion circuit (TDC) is used for measuring a DCO output phase, the accumulator sigma is used for calculating a reference phase, a phase difference e is obtained by comparing the DCO output phase with the reference phase, the phase difference e is used as a DCO input after loop filtering, the oscillation frequency of the DCO input is controlled, and the e is driven to be 0, so that a negative feedback control loop is formed.
As shown in fig. 6, the modulation signal is connected to the control loop through 2 points, where h path directly adjusts the DCO output frequency, l path is used to counteract the change of the phase difference e generated by direct modulation, and as can be known from the PLL loop transfer characteristic analysis, l and h paths respectively have low-pass and high-pass characteristics, so that the all-pass characteristic can be obtained by properly combining the two paths of modulation signals. It can be seen that the 2-point injection architecture improves the bandwidth of frequency modulation, reduces linear distortion, and thus improves output signal linearity. Another advantage is that the frequency modulation bandwidth is no longer limited by the loop bandwidth, so that the TDC quantization noise can be suppressed by reducing the loop bandwidth, optimizing the system performance, and improving the measurement accuracy.
As shown in fig. 5, the receiving circuit 1012 of the millimeter wave radar sensor 101 includes N (e.g., N ═ 4) receiving antennas arranged in an ula (uniform linear array) or ura (uniform Rectangular array) manner, and N receiving channels, where the rf front end of each receiving channel includes, but is not limited to:
a. a Low Noise Amplifier (LNA) for amplifying the amplitude of the received reflected radar signal;
b. a Mixer (Mixer) for mixing the LNA amplified received signal with the transmit frequency modulated signal to obtain an intermediate frequency signal;
c. low-pass filtering, namely setting a filtering bandwidth according to the maximum effective distance or the ADC sampling rate, suppressing noise and interference, and avoiding aliasing caused by discretization sampling in the subsequent ADC process;
d. a Variable Gain Amplifier (VGA) for adjusting signal amplitude to fully utilize ADC dynamic range;
e. and the analog-to-digital conversion circuit (ADC) is used for converting the input time-amplitude continuous analog signal into a time-amplitude discrete digital signal for further processing by using a digital signal processing technology (DSP) so as to extract the gesture control command.
As shown in fig. 5, digital signal processing circuit 1013 of millimeter wave radar sensor 101 includes, but is not limited to:
a. a Ramp generating circuit (Ramp Gen) for generating a sawtooth or triangular modulation waveform to control the DCO oscillation frequency;
b. window function (Window) for reducing spectrum expansion caused by FFT truncation, thereby improving frequency resolution, wherein discrete sampling values of Window functions such as Hamming, Hanning or Blackman can be stored in Static Random Access Memory (SRAM) in advance, read out during operation, and multiplied with input digital signals;
c. fast Fourier Transform (FFT), as previously described, estimates of target distance, radial velocity, and angle of incidence may be obtained by searching for amplitude peaks after FFT;
d. a first-in first-out buffer (FIFO) for buffering the Fourier transformed data for further processing by the processor.
Based on the working principle and the system architecture of the millimeter wave radar sensor 101, the non-contact control method comprises the following specific steps:
a. a ramp generating circuit of a digital signal processing circuit 1013 in the millimeter wave radar sensor 101 generates a saw tooth or triangular signal, controls the DCO oscillation frequency in the transmitting circuit 1011, generates a frequency modulation signal, and transmits a radar beam through M transmitting antennas;
b. the receiving circuit 1012 of the millimeter wave radar sensor 101 detects a radar signal reflected by the user gesture movement through the N receiving antennas, and performs low-noise amplification, frequency mixing and analog-to-digital conversion on the received signal by the radio frequency front end to obtain a digital intermediate frequency signal;
c. millimeter wave radar sensor 101 digital signal processing circuit 1013 windows and Fast Fourier Transforms (FFT) the digital intermediate frequency signal and writes the result into a first-in-first-out buffer (FIFO) for processor 103 to read and process;
d. the processor 103 reads out the data after fourier transform from a first-in first-out buffer (FIFO) of the digital processing circuit 1013, searches for the peak value thereof, obtains the estimation of the distance and the radial velocity, estimates the incident angle by using a Capon or MUSIC method, and inputs the measurements as the observation of the target state space into a kalman filter or a particle filter to filter out the interference and noise in the measurement process, and obtains the smooth estimation of the user gesture motion trajectory;
e. based on tracking the gesture motion trajectory of the user, the state feedback component 102 is controlled to output the current state to the user and prompt the next action;
f. after receiving the complete control command, the processor 103 executes a corresponding command, such as controlling the motion driving part 104 to open and close the door; or the processor 103 ends the current command when it receives the cancel command.
In order to meet the requirements of improving the anti-interference capability of a system and avoiding false triggering caused by interference, a relatively complex gesture needs to be defined as a control command, and the processing of the complex gesture can increase the cost and the power consumption of the system.
In order to improve the convenience of use and not reduce the anti-interference capability, a complex gesture can be decomposed into a multi-segment basic gesture sequence, and the multi-segment basic gesture sequence is confirmed section by section in the use process, so that the function of receiving a gesture command of a user by combining the millimeter wave radar sensor 101 to realize input and the function of outputting a state by the state feedback component 102 are needed, and simple and convenient human-computer interaction is achieved.
Therefore, based on the above non-contact control steps, the control gesture definition and interaction method is as follows:
a. proximity sensor
Due to the limitation of the transmitting power of the millimeter wave radar sensor 101 and the change of the reflection characteristic of the surrounding environment, the gesture is required to be within an effective range, so that a sufficient signal-to-noise ratio is ensured, and false triggering caused by interference is avoided. Therefore, when the system tracks the target trajectory and detects that the target has approached within the set threshold range, the system is confirmed to be activated in the form of light or sound by the state feedback component 102, ready to receive a next command, and a next valid command, such as a next gesture trajectory movement direction, may be prompted. Such a prompt may improve interaction efficiency, similar to the auto-complete function of some text editors.
b. Control command
When the user determines that the gesture is close enough according to the light or sound fed back by the state feedback component 102 and prompts according to the next valid command, the next gesture action can be continued, which includes: sliding from left to right, sliding from right to left, sliding from top to bottom, sliding from bottom to top, pressing, lifting, circling, hooking, forking, etc., or ending the current command by moving away from the sensor.
The system tracks the target trajectory and updates the current state in real time through the state feedback component 102 until a complete control command is detected, if the up-down or left-right sliding angle exceeds a set threshold, the current command is confirmed and executed, if the motion driving component 104 is driven to switch the opening and closing state of the door.
In some application scenarios, when only a horizontal or vertical sliding gesture command needs to be detected, in order to improve the sensitivity and accuracy of measurement, the arrangement direction of the receiving antennas ULA should be consistent with the sliding direction of the gesture command, as shown in fig. 7, if it is necessary to support sliding left and right and up and down simultaneously, a plurality of millimeter wave sensors may be used to detect sliding in the horizontal and vertical directions, respectively, or to arrange the receiving antennas in a URA manner while detecting sliding in the horizontal and vertical directions.
c. Remote sensor
And when the target track is detected to be beyond the set threshold value range, ending the current command.
Pressing and lifting can simulate key actions as shown in fig. 8, and a specific electronic control panel, such as up and down keys of an elevator panel, can be operated in a non-contact mode by matching with a sliding gesture.
d. According to a specific application scene, combining the steps a, b and c to obtain a multi-segment control gesture definition
Being close to the sensor + push down lift up + keep away from the sensor, being close to the sensor + slide from a left side to a right side + keep away from the sensor, being close to the sensor + slide from a right side to a left side + keep away from the sensor, being close to the sensor + slide from last down + keep away from the sensor, being close to the sensor + slide from the bottom up + keep away from the sensor, being close to the sensor + slide from a right side to a left side + push up + keep away from the sensor etc..
FIG. 9 is a multi-segment control command sequence and an illustration of state transitions of the control system during an interaction. The sequence of control commands and the interaction process defined in fig. 9 will be described with reference to the application in the design of a non-contact control system for an elevator panel.
The state feedback component 102, as shown in fig. 10, includes 3 LEDs: going upstairs, going downstairs and activating, which are respectively represented as an up arrow, a down arrow and a frame of a solid line, so as to output the current state; according to the arrangement direction of the state feedback section 102, the control command sequence is defined as: proximity sensor + control command + distance sensor, wherein the control command comprises: slide from top to bottom and from bottom to top, and press down and lift up. Since only the vertical direction slide gesture command needs to be detected here, the receiving antennas of the millimeter wave radar are arranged in the vertical direction as shown by the hatched blocks in fig. 10, note that the actual millimeter wave receiving antenna size is not represented here, but only the arrangement direction is illustrated.
The control interaction process for going upstairs is as follows:
a. the idle state indicates that none of the 3 LEDs are on;
b. when a user stretches his hand to approach the elevator panel to a set threshold range, the elevator enters an activation state, and the LED is activated to be on; the hand slides upwards to exceed a set threshold value, the execution state is entered, the LED for going upstairs feeds back that the LED for going upstairs has received the request for going upstairs with the brightness of 1 or the color of 1, and the activation state is returned; pressing down and lifting the hand, entering an execution state again, sending a request for going upstairs to the elevator dispatching system, indicating that the elevator dispatching system is notified of the request for going upstairs by an LED for going upstairs with brightness of 2 or color of 2, and returning to an activation state;
c. when the hands leave the elevator panel, the elevator returns to an idle state, the LED is activated to be not bright, but the LED on the upstairs keeps the brightness 2 or the color 2;
d. if the elevator is far away from the elevator panel before the control system confirms that the elevator is pressed and lifted, the elevator dispatching system is not informed of the request of going upstairs or downstairs, and all the LEDs are not lightened when the elevator dispatching system returns to the idle state.
The downstairs control interaction process is similar, except that the sliding direction is from top to bottom.
According to the design method of fig. 9, the above-mentioned interaction process can also be simply designed as follows: only upstairs and downstairs LEDs are used, and the activation LEDs are omitted:
a. in an idle state, the LED lights on the upstairs and downstairs are not on;
b. when a user stretches his hand to approach the elevator panel to a set threshold range, the elevator enters an activated state, and according to the detected region pointed by the gesture track extension, the gesture track is supposed to point to the LED on the upstairs, the LED on the upstairs is lightened by the brightness of 1 or the color of 1, and the reception of the request on the upstairs is confirmed;
c. if the elevator does go upstairs, the elevator enters an execution state by pressing along the current track, sends a request for going upstairs to the elevator dispatching system, lights an LED for going upstairs with brightness 2 or color 2 to indicate that the elevator dispatching system is informed of the request for going upstairs, and returns to an activation state;
d. if the elevator needs to go downstairs, the elevator slides from top to bottom, enters an execution state, turns off the upstairs LED, lights the downstairs LED with the brightness of 1 or the color of 1, confirms that the downstairs request is received, returns to an activation state, presses down, enters the execution state again, lights the upstairs LED with the brightness of 2 or the color of 2, indicates that the elevator dispatching system is informed of the downstairs request, and returns to the activation state
e. If the control system is far away from the elevator panel before confirming the pressing gesture, the elevator dispatching system is not informed of the upstairs/downstairs request, the idle state is returned, and all the LEDs are not lightened.
Claims (10)
1. An intelligent door adopting a millimeter wave radar to realize non-contact control comprises: the door comprises a door frame (1), a door plate (2), a moving part (3) for driving the door plate (2) to open and close, and a control system (10); characterized in that the control system (10) comprises:
a millimeter wave radar sensor (101) that transmits a radar beam and receives a reflected radar beam to detect a user gesture command;
the state feedback component (102) comprises a control panel forming a man-machine interaction interface, and an output interface which can feed back state information by light or sound and is used for feeding back the state information to a user to realize state interaction;
a processor (103) connected to the millimeter wave radar sensor (101), the state feedback section (102), and the motion drive section (104); according to the user gesture command received by the millimeter wave radar sensor (101), the control state feedback component (102) outputs state information and executes corresponding control operation.
2. The intelligent door of claim 1, wherein: the control operation is to control the motion of the motion driving part (104) so as to drive the motion part (3) to drive the door panel (2) to move, and the intelligent door is opened and closed.
3. The intelligent door of claim 1, wherein: the millimeter wave radar sensor (101) includes a transmission circuit (1011) that transmits the radar beam, a reception circuit (1012) that receives the reflected radar beam, and a digital signal processing circuit (1013).
4. The intelligent door of claim 3, wherein: the transmission circuit (1011) comprises:
m transmitting antennas for emitting the radar beam, configured in a phased array mode or a MIMO mode;
power amplification, linear power amplification, to drive the transmitting antenna;
a digital control oscillation circuit and a digital phase-locked loop to realize frequency modulation.
5. The intelligent door of claim 4, wherein: in order to improve the modulation bandwidth and the linearity, the numerical control oscillating circuit and the digital phase-locked loop adopt a 2-point injection structure.
6. The intelligent door of claim 3, wherein: the receiving circuit (1012) comprises:
n receiving antennas arranged in a ULA or URA manner;
a low noise amplifier LNA for amplifying an amplitude of a received signal;
mixing, namely mixing the received signal amplified by the low-noise amplification LNA and a local frequency modulation signal to obtain an intermediate frequency signal;
low-pass filtering and variable gain amplification;
and the analog-to-digital conversion circuit converts the analog signal into a digital intermediate frequency signal.
7. The intelligent door of claim 3, wherein: the digital signal processing circuit (1013) includes:
the slope generating circuit generates a sawtooth or triangular signal for adjusting the oscillation frequency of the numerical control oscillation circuit;
fast Fourier Transform (FFT), namely obtaining a target distance, a radial speed and an incidence angle by searching a peak value of signal amplitude after FFT;
a window function for reducing spectrum spreading due to FFT truncation;
a first-in first-out buffer FIFO for buffering the FFT transformed data for further processing by the processor (103).
8. The intelligent door of any one of claims 1-7, wherein: the control system (10) further comprises a communication interface (105) which is connected with the processor (103) and realizes interconnection and information interaction between the control system (10) and the external environment.
9. The intelligent door of any one of claims 1-7, wherein: the control system (10) may have the following physical form combinations according to application requirements: PCB level integration based on surface mount technology, package level integration based on SIP technology, or silicon chip level integration based on SOC technology.
10. The intelligent door of any one of claims 1-7, wherein: the millimeter wave radar sensors (101) and the state feedback component (102) in the control system (10) are respectively provided with two sets which are respectively used for processing user gesture commands and state interaction on the inner side and the outer side of a door, shielding processing is carried out between the two sets of millimeter wave radar sensors (101), and the priorities of the two sets of millimeter wave radar sensors (101) need to be set.
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