CN108307767B - Detection of obstacles obstacle avoidance system and method suitable for full-automatic weeder - Google Patents
Detection of obstacles obstacle avoidance system and method suitable for full-automatic weeder Download PDFInfo
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- CN108307767B CN108307767B CN201810031611.0A CN201810031611A CN108307767B CN 108307767 B CN108307767 B CN 108307767B CN 201810031611 A CN201810031611 A CN 201810031611A CN 108307767 B CN108307767 B CN 108307767B
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- A—HUMAN NECESSITIES
- A01—AGRICULTURE; FORESTRY; ANIMAL HUSBANDRY; HUNTING; TRAPPING; FISHING
- A01D—HARVESTING; MOWING
- A01D34/00—Mowers; Mowing apparatus of harvesters
- A01D34/006—Control or measuring arrangements
- A01D34/008—Control or measuring arrangements for automated or remotely controlled operation
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- A—HUMAN NECESSITIES
- A01—AGRICULTURE; FORESTRY; ANIMAL HUSBANDRY; HUNTING; TRAPPING; FISHING
- A01D—HARVESTING; MOWING
- A01D75/00—Accessories for harvesters or mowers
- A01D75/18—Safety devices for parts of the machines
- A01D75/185—Avoiding collisions with obstacles
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- Environmental Sciences (AREA)
- Measurement Of Velocity Or Position Using Acoustic Or Ultrasonic Waves (AREA)
Abstract
The invention discloses the detection of obstacles obstacle avoidance systems and method that are suitable for full-automatic weeder, it include: MCU module, MCU module is connected by the ultrasonic transducer for transmitting of transmit circuit and ultrasonic phase array, and the top of weeder is located at for the ultrasonic transducer of transmitting；MCU module controls transmit circuit driving ultrasonic transducer and issues ultrasonic signal, ultrasonic signal is reflected by front obstacle, emit signal and received by several for received ultrasonic transducer, several form ultrasonic phase array receiving array for received ultrasonic transducer；The ultrasonic phase array receiving array passes sequentially through signal amplification conditioning module, detection low-pass filter, A/D conversion module and connect with MCU processing module；MCU processing module is connect with host computer.Application mode identification technology and ultrasonic phased array technology carry out identification judgement to front obstacle, realize the automatic intelligent work of robot and full-automatic weeder.
Description
Technical field
The present invention relates to the detection of obstacles obstacle avoidance systems and method that are suitable for full-automatic weeder.
Background technique
With the improvement of people's living conditions, full-automatic weeder has been obtained for increasingly extensive application.But in many
In garden or greenery patches usually in addition to the meadow of plantation, there are also trees, swing, unlike material the facilities such as man-made tourist site.To weeding
The requirement of machine is only to trim to lawn, avoids trees, artificial hillock etc., in addition should also pass through swing (if height allows) etc. and set
Apply, i.e., should as far as possible for all weeders can by the lawn in space trim.Existing full-automatic weeder
Due to can not the artificial facility such as grass, shrub, swing to front identify, thus will appear certain plot trimmings less than, cut
Drop to situations such as trees even hurt knife.
The invention of current various full-automatic weeders has very much:
A kind of intelligent weeder that CN204682323 patent is proposed, is imaged by weed identification video camera, self-navigation
Machine and controller realize the identification of front obstacle；One kind disclosed in CN206005198 patent is based on infrared ray sensing
The automation weeder of device；A kind of weeder for evading function automatically with barrier disclosed in CN106612973 patent
Deng.Using video technique, its cost is very high, while will receive the influence of the environmental factors such as illumination, sleet, dust, temperature, thus
It limits its scope of application.Influence using infrared sensor vulnerable to ambient environmental factors such as sunlights, in actual use
It will appear measured deviation.A kind of mobile robot all-directional ultrasonic obstacle avoidance apparatus disclosed in CN202939487 patent uses
Positioning and measurement device of the ultrasonic sensor as barrier, determines position and the distance of barrier, reaches avoidance
Purpose, but it can not provide barrier attribute information, cannot distinguish between different barriers, and be easy by environment such as sleet, dusts storm
Influence and judge by accident, cannot accomplish the intelligent recognition avoidance to front obstacle.
In conclusion the critical issue that the devices such as robot of intelligent weeder and similar applications are faced is exactly nothing
Method identifies the obstacle identity in front, so that it is the weeds that wipe out which, which distinguishes,；And such as illumination,
The property of barrier is steadily identified in the high-interference environments such as sleet, dust.
Summary of the invention
In order to solve the deficiencies in the prior art, the present invention provides the detection of obstacles avoidances for being suitable for full-automatic weeder
System and method has using ultrasonic sensor as detection sensor, integrated use mode identification technology and ultrasonic phase
Control battle array technology carries out identification judgement to front obstacle, the equipment that can be realized the similar applications such as robot and full-automatic weeder
Realize automatic intelligent work.Ultrasonic sensor have be not illuminated by the light, smog, sleet, temperature, the environmental factors such as inflammable and explosive
It influences, it is stable and reliable in work, it round-the-clock can use.
Detection of obstacles obstacle avoidance system suitable for full-automatic weeder, comprising: MCU module, the MCU module pass through hair
The ultrasonic transducer for transmitting of transmit-receive radio road and ultrasonic phase array connects, and the ultrasonic transducer for transmitting is located at weeding
The top of machine；MCU module controls transmit circuit driving ultrasonic transducer and issues ultrasonic signal, and ultrasonic signal passes through front
Barrier reflects, and transmitting signal is received by several for received ultrasonic transducer, several are for received super
Acoustic wave transducer forms ultrasonic phase array receiving array；The ultrasonic phase array receiving array passes sequentially through signal amplification conditioning mould
Block, detection low-pass filter, A/D conversion module are connect with MCU processing module；The MCU processing module is connect with host computer；
Each ultrasonic transducer of the receiving array of ultrasonic phase array both participates in reception and reflects ultrasonic signal, often
A received ultrasonic signal of ultrasonic transducer passes through signal amplification conditioning module and carries out preposition amplification, detection and low pass filtered
Then wave processing is converted into digital signal feeding MCU module by A/D conversion module and is stored, MCU module passes through to each
Railway digital signal is handled, so that it is determined that the attribute of front obstacle, position and shape information.
The MCU processing module is using ARM single-chip microcontroller as core processor.
The signal amplifies conditioning module, comprising: sequentially connected signal buffer, gain adjustable amplifier and signal solution
Adjust device；Wherein demodulator of PM signal PM is used to demodulate the obstacle information that ultrasonic wave carries from modulated signal to come, the signal
The ultrasonic transducer of the receiving array of buffer and ultrasonic phase array connects, and the demodulator of PM signal PM and low-pass filter connect
It connects.
The ultrasonic phase array works in such a way that single-shot is received more:
Firstly, the ultrasonic transducer for transmitting emits N number of short pulse, then by remaining super in ultrasonic phased array
Acoustic wave transducer is synchronous to receive signal, and after amplification, conditioning and detection, low-pass filtered device is stored in after sending A/D conversion module
It is stored in MCU module, receive signal using any road of storage and weeder is measured apart from obstacle using peak detection method
The distance D of object, and judge whether distance D is greater than preset distance；
If distance D is greater than preset distance, then it is assumed that front clear, before weeder is according to the route of planning
Row；
If distance D is not more than preset distance, then it is assumed that there is barrier in front；
By horizontal distance immediately ahead of the center O point of ultrasonic phase array for O ' of D centered on, to make perpendicular to the face of O O '
For virtual detection section, virtual detection interface and receiving array plane are parallel plane, according to default rule in detection section
Interior selection virtual focus point is detected；By calculating the distance between each virtual focus point and each reception energy converter, obtain each
Virtual focus point to respectively be used for received ultrasonic transducer range difference be di, by range difference diIt is obtained divided by the speed of ultrasonic wave
Corresponding time ti, to obtain virtual focus point and each phase difference θ for receiving signal between energy converteri, utilize θiTo each road signal
Carry out phase shift superposition, obtain the obstacle information near each virtual focus point, so that it is determined that out the attribute of front obstacle, position with
Shape.
To the analysis method of barrier attribute are as follows: wavelet decomposition is done to the superimposed signal of phase shift, by the high-frequency energy of signal
The ratio of component and low frequency energy component is measured as characteristic value, by using pre-stored data train come svm classifier
Device is classified, and distinguishing front obstacle is grass or other barriers；
The step of selecting virtual focus point are as follows: centered on O ' point, weeder local width is that radius does circle, circle it is inscribed just
Rectangular lower-left, upper left, bottom right, upper right, central point, central point top, central point lower section, central point left and central point right
Nine points be virtual focus point；
[t is only received after i.e. A/D conversion using time window technology for the influence for reducing interference signali-Δ,ti+Δ]
Signal in period, to further increase signal-to-noise ratio.
Suitable for the detection of obstacles barrier-avoiding method of full-automatic weeder, step:
Step (1): ultrasonic transducer of the train of pulse control of the MCU module output setting length of weeder for transmitting
Ultrasonic signal is issued, wherein the energy converter for being located at array center is transmitting transducer, remaining is reception energy converter；
Step (2): pass through A/D after encountering the conditioned reflected ultrasonic signal of barrier, detection and low-pass filtering
Conversion module is sent into MCU module and is stored；
Step (3): by subject to the echo-signal all the way that is arbitrarily designated, utilize peak detection method carry out obstacle distance just
Step determines；According to the obstacle distance D measured；Judge whether distance D is greater than preset distance；If distance D is greater than
Preset distance, then it is assumed that front clear, weeder move ahead according to the route of planning；If distance D is no more than pre-
The distance first set, then it is assumed that there is barrier in front；
By horizontal distance immediately ahead of the center O point of ultrasonic phase array for the O ' point of D centered on, to make perpendicular to the face of O O '
To detect section, virtual focus point is chosen in detection section and is detected；The step of selecting virtual focus point are as follows: in being with O ' point
The heart, weeder local width are that radius does circle, lower-left, upper left, the bottom right, upper right, central point, central point of the inscribed square of circle
Top, below central point, nine vertex of central point left and central point right are virtual focus point, and calculate nine virtual focus points
Coordinate；
Step (4): emit a ultrasonic pulse string, each ultrasonic transducer of the receiving array of ultrasonic phase array again
It both participates in reception and reflects ultrasonic signal, each received ultrasonic signal of ultrasonic transducer passes through signal amplification and adjusts
It manages module and carries out preposition amplification, detection and low-pass filtering treatment, be then converted into digital signal feeding by A/D conversion module
MCU module is simultaneously stored, and needs to use time window will be other than virtual focus point set distance before being sent into MCU module storage
Back echo signal is shielded；
Step (5): using the reception signal for being stored in MCU module, according to the position of virtual focus point, with it is specified all the way
Reception signal is benchmark signal, and residue is used for the signal that received ultrasonic transducer receives and carries out phase shift superposition, thus
Several signals being concerned with reference signal are formed, and superimposed signal is stored in MCU module according to the serial number of virtual focus point；
Step (6): to each virtual focus point, the method that step (5) is respectively adopted carries out the pretreatment of signal, then utilizes
The road peak detection Fa Duige signal is detected, so that it is determined that whether each virtual focus point position is with the presence of barrier and obstacle out
The azimuth information of object；
Step (7): taking out the digital signal of the intermediate point stored in MCU module, carry out wavelet function feedback respectively, benefit
Reflected signal characteristic is extracted with the multiscale space energy-distributing feature of wavelet transformation, in conjunction with svm classifier, front is hindered
The attribute of object is hindered to be identified；
Step (8): MCU module each virtual focus point signal superimposed to phase shift scans and recognizes, and obtains virtual focus point
The 2D digital picture of barrier in neighbouring set distance；When weeder is mobile, MCU module successively obtains the virtual of each moment
The 2D digital picture of barrier, forms the 3D rendering of barrier near focal point set distance, obtains barrier according to 3D rendering
Spatial depth on shape and size；
Step (9): the attribute of the barrier after identification, shape and size are notified into host computer.
In the step (2), ultrasonic phase array is circumferentially to place four respectively on four vertex of inscribed square
For received ultrasonic transducer, centre bit puts a ultrasonic transducer for transmitting, five ultrasonic transducers
It is all made of the transceiver piezoelectric ceramic transducer of same centre frequency.The circumference is centered on O point, and weeder itself is wide
Degree is that radius does circle.
In the step (5), multiple Digital Signal Processing is carried out using the signal of a synchronous acquisition, respectively obtains obstacle
Multiple features of object；
In the step (7), the wavelet function feedback is to carry out wavelet decomposition to signal and reconstruct high fdrequency component
And low frequency component, using high fdrequency component and the energy ratio of low frequency component as signal characteristic, using trained SVM divides in advance
Class device classifies to signal characteristic, so that it is determined that the property of front obstacle and being identified out.
The step (8), steps are as follows:
Step (81): sliding-model control is carried out to the section of scanning, i.e., section is divided into several discrete points, respectively institute
Discrete point is stated as virtual focus point to be scanned judgement；
Step (82): it after scanning starts, from first specified discrete point as virtual focus point, is arrived according to the virtual focus point
It is each used for the differential time of flight of received ultrasonic transducer in ultrasonic phase array, calculates each channel signal phase to be moved
Position simultaneously successively carries out Signal averaging；
Step (83): barrier attribute is distinguished using classifier；
Step (84): the comprehensive information of each virtual focus point in a detection plane judges position and the 2D letter of barrier
Breath；
Step (85): with the movement of weeder, being constantly scanned newly-generated virtual focus point, to form front
The 3D location and shape of barrier in search coverage.
Compared with prior art, the beneficial effects of the present invention are:
1. introducing the signal processing method of wavelet pretreatment and Wavelet decomposing and recomposing.By external hardware to echo-signal
Filtering, improves and is converted into digital signal by A/D conversion module amplification, filters out most of noise of signal.In order to extract back
The feature of wave signal introduces wavelet transformation and handles signal, and to treated, signal carries out wavelet function feedback, obtains
The high fdrequency component and low frequency component of signal using the ratio of its high and low frequency component as signal characteristic, and are classified using SVM,
To identify meadow from front obstacle, to realize that intelligent barrier avoiding lays the foundation.
2. present invention employs the ultrasonic phased arrays that single-shot is received more.Relative to the ultrasound phase-control array 1 system of multiple illuminators and single receiver,
The present invention does not need to provide the driving pulse to timing requirements harshness, can reduce the error of hardware system from source, energy disappears
The complexity of consumption and circuit；
3. sufficiently having used the abundant hardware resource and operation energy of ARM Cortex-M4 kernel to simplify system design
Power, using a synchronous acquisition and the signal that stores, by different Digital Signal Processing distinguish acquired disturbance object away from
From, orientation and attribute information, the complexity and cost of system are reduced, system power dissipation is reduced.
4. not influenced using ultrasonic wave as detectable signal by environmental factors such as light, magnetic field, dust, environment is adapted to
Ability is strong, can work normally under with rugged environments such as corrosive gas, radiation, dust.
5. after tested, realizing and only needing 3 ultrasonic transducers to the positioning of front obstacle and intelligent recognition.The present invention
Using 4 reception energy converters, once there is the failure of some energy converter, system still can normally work, and improve and be
The robustness of system.
6. structure is simple, it is at low cost, be easily achieved, be easy to adjust, stability with higher and all weather operations etc. it is excellent
The detection of obstacles obstacle avoidance algorithm and network system realization suitable for full-automatic weeder of point realize weeder or similar applications
Device to the intelligent recognition function of front obstacle.
7. being handled using echo-signal of the mode identification technology to barrier, to identify the property of barrier.
Wavelet analysis is a kind of emerging branch of mathematics, has multiscale space energy-distributing feature abstraction function, the energy for being included
It measures spectrum distribution and the size, shape and type of front reverberation is closely related, thus in signal processing, image procossing, voice
Processing and numerous nonlinear science fields are widely applied.The signal that receives ultrasonic receiver in this patent into
Row wavelet decomposition, and reconstruct the low frequency component and high fdrequency component of signal respectively, using low frequency and the ratio of high fdrequency component as
The identification feature of front obstacle, and utilize the intelligent recognition of svm classifier realization front obstacle.
8. carrying out pattern-recognition using echo-signal merely, it only can be realized the approximate distance measurement of barrier, can not obtain
Obtain the information such as orientation, the shape of barrier.For the determination for realizing barrier more information, this patent uses ultrasonic phase array skill
Art, Digital Signal Processing and mode identification technology realize the identification to the azimuth-range information of different barriers.For drop
Low cost, reduces the power consumption of whole system, and this patent uses the ultrasonic phase array that single-shot is received more, and Reusability one acquisition
To data by way of being verified one by one to virtual focus point, to it is N number of space different parts place receiver letter
Number phase shift processing is carried out, to realize to the detection of front specific location spatial obstacle object and obtain the azimuth-range of barrier
Information.
Signal processing technology and phased-array technique are used by comprehensive, the identification to front obstacle may be implemented and sweep
It retouches, by the fusion to multiple cross section informations, realizes the identification of barrier attribute, azimuth-range.
Detailed description of the invention
The accompanying drawings constituting a part of this application is used to provide further understanding of the present application, and the application's shows
Meaning property embodiment and its explanation are not constituted an undue limitation on the present application for explaining the application.
Fig. 1 is system block diagram of the invention；
Fig. 2 ultrasonic phase array receives schematic diagram；
Fig. 3 ultrasonic phase array plan view；
Fig. 4 is detecting visual floor map in front of the present invention；
Fig. 5 is the scanning surface schematic diagram of discretization；
Fig. 6 (a) is the original signal data after A/D conversion；
Fig. 6 (b) is signal data of the Fig. 6 (a) after wavelet pretreatment；
Fig. 6 (c) is the classification results figure to the different front reverberations of multiple groups.
Specific embodiment
It is noted that following detailed description is all illustrative, it is intended to provide further instruction to the application.Unless another
It indicates, all technical and scientific terms used herein has usual with the application person of an ordinary skill in the technical field
The identical meanings of understanding.
It should be noted that term used herein above is merely to describe specific embodiment, and be not intended to restricted root
According to the illustrative embodiments of the application.As used herein, unless the context clearly indicates otherwise, otherwise singular
Also it is intended to include plural form, additionally, it should be understood that, when in the present specification using term "comprising" and/or " packet
Include " when, indicate existing characteristics, step, operation, device, component and/or their combination.
As shown in Figure 1, being suitable for the detection of obstacles obstacle avoidance system of full-automatic weeder, which includes a MCU master control
Module, MCU module are using ARM Cortex-M3 as the 32-bit microprocessor of kernel, using the STM32F103 single-chip microcontroller of ST company
For core processor；Comprising a transmit circuit, signal driving ultrasonic transducer is issued by MCU and issues ultrasonic signal, to preceding
Square barrier is detected, and ultrasonic transducer uses centre frequency for 40KHz, the piezoelectric ceramic ultrasound transducing of transceiver
Device, radiation pattern are discontinuous transmission, issue the pulse signal in 10 periods every time, guarantee the accurate detection to front obstacle；
Ultrasonic transducer forms phased array according to specific spatial distribution, in the present embodiment, using simplified array arrangement,
Place four ultrasonic transducers respectively on four vertex of square, centre bit puts an energy converter, is detailed in Fig. 3 institute
Show；The operating mode more received in the present embodiment using single-shot, in detail as shown in Figure 2；The array is connect with signal amplifying and conditioning circuit,
After the original signal that signal amplifying and conditioning circuit receives reception supersonic array is filtered, amplifies, improves, A/D is sent to convert
Module；A/D conversion module is the analog-digital converter being internally integrated by kernel processor chip STM32F104, possesses very high resolution
Echo-signal accurately can be converted to digital signal and MCU module is sent to be stored by rate, the original signal number after A/D conversion
According to shown in such as Fig. 6 (a)；Signal processing module is by the software realization based on MCU, and specific completion is to digital signal time domain or change
Change the processing in domain.Wherein Time Domain Processing includes the phase shift overlap-add operation to each road signal, threshold test, verifying virtual focus point etc.
Reason, and then determine the azimuth information of front obstacle；Transform-domain processing using wavelet pretreatment and signal wavelet decomposition with
Reconstruct, obtains the attribute information of front obstacle, final to realize the functions such as barrier feature information extraction and intelligent recognition；Pass through
Successively all virtual focus points on the section of front are scanned, to verify depositing for virtual focus point on the specific range section of front
In situation, and according to the 2D digital information of echo-signal Formation cross-section barrier；When carrying invention system platform movement,
MCU can be scanned with the continuous pair cross-section of Fixed Time Interval, can be by the virtual focus point on verifying different cross section, before formation
The 3D digital information of side space barrier, so that the identification and Path selection for barrier form provide foundation；System is to front
Corresponding prompt information is returned to according to scanning result after the completion of spacescan, output equipment is sent to, is done with controlling transmission device
It acts out and informs user.
In conjunction with Fig. 1, for the present invention using embedded system as core, one constructed using ultrasonic phase array as sensor can be to preceding
Side space implements the intelligent barrier avoiding system of scanning.Scanning probe, orientation recognition, the attribute that the system can be realized barrier obtain
It the functions such as takes, be imaged, and can realize that relevant information exports.
In conjunction with Fig. 1, when the resolution requirement to spatial obstacle object is not high, indexed by the discretization of reduction pair cross-section,
The structure for simplifying phased array, can be such that whole system is simplified, and the major function realized has:
1. the transmitting of ultrasonic wave, data receiver, data processing, storage and prompt information output function；
2. the orientation characteristics of barrier identify, scan image is formed, signal amplification, graphical information exports and data store function
Energy；
3. the emission control of ultrasonic wave, signal acquisition, the coordinate setting to the transform-domain processing, picture signal that receive signal
And real time information output function；
4. can be estimated to the substantially shape and its essential attribute for detecting object by remembering acquired obstacle information
Meter；
In conjunction with Fig. 3, the phased array uses 5 centre frequencies to press for the EU10AIF40H07A of 40KHz, transceiver
Electroceramics ultrasonic transducer forms simplified two-dimensional rectangle array, and that MCU module controls a ultrasonic transducer transmitting is super
Sound wave, the receives echo-signal of remaining energy converter independently, and it is converted into digital signal, it is folded by the phase shift to digital signal
Add, threshold test processing, and then verify virtual focus point and whether there is, forms the scanning function to different virtual focus points and different section
Energy.
In conjunction with Fig. 4,5, the area of space that the present invention is scanned is that one with a certain distance from receiving array has certain indulge
Deep, width and height space, the present embodiment receive phase using a rectangular space, nearest scanning surface centre distance
0.6 meter of battle array center is controlled, farthest scanning surface centre distance receives 1.0 meters of phased array center, following ground proximity 50mm, top margin
Ground level is higher than weeder machine clear height, and left and right width is greater than machine clear span (being dynamically adapted)；It is detailed in Fig. 4, Fig. 5.
In conjunction with Fig. 3,4,5, the present invention carries out sliding-model control to scanning surface first, i.e., scanning surface be divided into M × N number of from
Then scatterplot is scanned verifying using various discrete point as virtual focus point respectively.The virtual coke verified needed for each scanning surface
Points can select that (virtual focus point number is more, and data processing complexity and required precision are also higher, thus cost as needed
Also higher), height × width is used in the present embodiment, and totally 36 virtual focus points, are detailed in Fig. 5 for 6 × 6.By calculating transmitting transducer
To virtual focus point and virtual focus point to each flight time for receiving energy converter, reasonably plans scanning mode, realize section
Scanning.
It, can be by the ginseng to each spacescan point to accelerate scanning speed under the premise of scanning virtual focus point position is constant
Number calculates complete and be made into table in advance, realizes that the verifying of virtual focus point scans using lookup table mode.
In conjunction with Fig. 6 (a), Fig. 6 (b), wherein Fig. 6 (a) is the original signal data after A/D conversion, and Fig. 6 (b) is Fig. 6 (a)
Signal data after wavelet pretreatment, from being can be seen that in the signal that A/D is converted in Fig. 6 (a), there are more high frequencies to do
Signal is disturbed, these interference signals can impact subsequent signal processing, influence the accuracy of system, and the present invention uses small echo
The digital signal processing method of analysis pre-processes signal, obtains the signal waveform in Fig. 6 (b), it can be seen that high
Frequency interference component is obviously removed, and convenient for later signal processing, improves the accuracy of system.
In conjunction with the classification results figure that Fig. 6 (c), Fig. 6 (c) are to the different front reverberations of multiple groups.The present invention uses DB6 small echo
1 layer of wavelet decomposition is carried out to signal and reconstructs the low frequency component and high fdrequency component of signal, compares the pass of low frequency and high fdrequency component
System obtains the attribute of front obstacle, is extracted using the multiscale space energy-distributing feature of wavelet transformation, the energy for being included
It measures spectrum distribution and the size, shape and type of front reverberation is closely related, to provide foundation for intelligent barrier avoiding.
Received digital echo signal is converted by A/D to be stored in array x [n], then can be obtained after 1 layer of wavelet decomposition
Its approximation coefficient and detail coefficients:
Wherein cA1 is 1 layer of wavelet decomposition approximation coefficient, cD1For 1 layer of wavelet decomposition detail coefficient, g0[n] is low-pass filtering
Device, h0[n] is high-pass filter.
By approximation coefficient cA1 and detail coefficients cD1Approximate signal and detail signal can be reconstructed:
Wherein A1For the approximate signal of 1 layer of Wavelet decomposing and recomposing, D1For the detail signal of 1 layer of Wavelet decomposing and recomposing, g1[n]
=g0[- n], h1[n]=h0[-n]。
Feature is extracted to echo-signal after wavelet function feedback:
Wherein s is signal characteristic information, PLFor low frequency component, PHFor high fdrequency component.
The present invention identifies signal using the machine learning algorithm of Linear SVM.Linear SVM is one linear
The classifier that can divide, some training samples marked can be defined for the classification line that inhomogeneity sample space separates by being one
This, LinearSVM algorithm exports the classification line of an optimization, and formula (3) below defines the expression formula of classification line:
F (x)=β0+βTx (3)
β is called weight vectors, β in formula0It is called biasing.
Classification line can have countless expression formula, i.e., by arbitrarily scaling β and β0.It is realized by algorithm, we can be with
The optimal classification line classified, the classification of complete pair signals.
In embodiment, the present invention has carried out comparative test to different front obstacles, chooses weeds respectively, trees make
For experimental subjects, by carrying out data acquisition respectively to experimental subjects, obtaining their echo-signal and carrying out wavelet pretreatment,
Compare the relationship of its high frequency and low frequency component, chooses trained and test data, classify with Linear SVM algorithm, to survey
Test system judges whether correctly to front obstacle.The detection range range that the present invention is set is institute between 0.6m~1.0m
Only to choose echo-signal, at this, the corresponding point in section is analyzed.15 groups of weed datas and 15 groups of trees have been taken respectively
The wooden data are analyzed, and the low frequency component and high fdrequency component of each signal are isolated, and construct a two-dimensional coordinate point P as the letter
Number characteristic information s, with low frequency component PLFor abscissa x, with high fdrequency component PHIt is clear in order to show for ordinate y, to original
Data have done logarithm process.
The logarithmic coordinates point of signal depicts two-dimensional coordinate figure according to embodiments of the present invention, the data of weeds and trees
Point is placed in a coordinate diagram.System uses Linear SVM algorithm and classifies to data, is taken in 15 groups of data respectively
First 10 groups be used as training, latter 5 groups be used as test, be detailed in Fig. 6 (c), by figure it can be concluded that, can be right using Linear SVM algorithm
Signal is classified, and is traversed respectively to the data point of two classifications and is sought Euclidean distance, the mathematic(al) representation of two-dimensional space are as follows:
Wherein (x1,y1), (x2,y2) it is respectively two-dimensional coordinate point coordinate, OρFor the Euclidean distance of two coordinate points.
Show that two groups most short Euclidean distance is respectively a1--b1 and a2--b2.The midpoint c1 of a1b1, a2b2 line is taken respectively,
C2 makes straight line L as two coordinates, this straight line is our the optimal classification lines to be looked for, it can be deduced that in formula (3)
ParameterThen obtain the equation of optimal classification line L are as follows:
X-2y+3=0 (5)
For the classification results for determining data, we can find out data point and the relative positional relationship for line of classifying is sentenced
It is disconnected.
Such as to signal characteristic P0(x0,y0) classification judgement is carried out, f (x, y)=x-2y+3 is enabled, there is following estimate of situation:
f(x0,y0)=x0-2y0+ 3 > 0 (6)
f(x0,y0)=x0-2y0+ 3 < 0 (7)
If inequality (6) is set up, signal characteristic P is obtained0(x0,y0) in the top of classification line L, it is possible to determine that classification is
Weeds.
If inequality (7) is set up, signal characteristic P is obtained0(x0,y0) in the lower section of classification line L, it is possible to determine that classification is
Trees.
By experimental verification, signal is handled with Linear SVM algorithm, can achieve the purpose of identification classification,
And then weeds and trees can be distinguished, the attribute information of front obstacle is obtained, realizes the function of intelligent barrier avoiding.
It will be understood by those skilled in the art that each module or each step of aforementioned present invention can be filled with general computer
It sets to realize, optionally, they can be realized with the program code that computing device can perform, it is thus possible to which they are stored
Be performed by computing device in the storage device, perhaps they are fabricated to each integrated circuit modules or by they
In multiple modules or step be fabricated to single integrated circuit module to realize.The present invention is not limited to any specific hardware and
The combination of software.
The foregoing is merely preferred embodiment of the present application, are not intended to limit this application, for the skill of this field
For art personnel, various changes and changes are possible in this application.Within the spirit and principles of this application, made any to repair
Change, equivalent replacement, improvement etc., should be included within the scope of protection of this application.
Claims (10)
1. being suitable for the detection of obstacles barrier-avoiding method of full-automatic weeder, characterized in that
Step (1): ultrasonic transducer of the train of pulse control of the MCU module output setting length of weeder for transmitting issues
Ultrasonic signal, wherein the energy converter for being located at ultrasonic phase array center is transmitting transducer, remaining is reception energy converter；
Step (2): it is converted after encountering the conditioned reflected ultrasonic signal of barrier, detection and low-pass filtering by A/D
Module is sent into MCU module and is stored；
Step (3): by subject to the echo-signal all the way that is arbitrarily designated, utilizing peak detection method to carry out tentatively sentencing for obstacle distance
It is fixed；According to the obstacle distance D measured；Judge whether distance D is greater than preset distance；If distance D is greater than preparatory
The distance of setting, then it is assumed that front clear, weeder move ahead according to the route of planning；It is set in advance if distance D is not more than
Fixed distance, then it is assumed that there is barrier in front；
By horizontal distance immediately ahead of the center O point of ultrasonic phase array for O ' of D centered on, using the face perpendicular to O O ' as spy
Section is surveyed, virtual focus point is chosen in detection section and is detected；The step of selecting virtual focus point are as follows: centered on O ', remove
Careless machine local width is that radius does circle, the lower-left of the inscribed square of circle, upper left, bottom right, upper right, central point, central point top,
Nine vertex of central point lower section, central point left and central point right are virtual focus point, and calculate the seat of nine virtual focus points
Mark；
Step (4): emitting a ultrasonic pulse string again, and each ultrasonic transducer of the receiving array of ultrasonic phase array is joined
Ultrasonic signal is reflected with reception, each received ultrasonic signal of ultrasonic transducer passes through signal amplification conditioning mould
Block carries out preposition amplification, detection and low-pass filtering treatment, is then converted into digital signal by A/D conversion module and is sent into MCU mould
Block is simultaneously stored, and needs to use time window by the obstacle other than virtual focus point set distance before being sent into MCU module storage
Object echo-signal is shielded；
Step (5): using the reception signal for being stored in MCU module, according to the position of virtual focus point, with specified reception all the way
Signal is benchmark signal, and residue is used for the signal that received ultrasonic transducer receives and carries out phase shift superposition, to be formed
Several signals being concerned with reference signal, and superimposed signal is stored in MCU module according to the serial number of virtual focus point；
Step (6): to each virtual focus point, the method that step (5) is respectively adopted carries out the pretreatment of signal, then utilizes peak value
The road detection Fa Duige signal is detected, so that it is determined that whether each virtual focus point position is with the presence of barrier and barrier out
Azimuth information；
Step (7): the digital signal of the intermediate point stored in MCU module is taken out, carries out wavelet function feedback respectively, utilization is small
The multiscale space energy-distributing feature of wave conversion extracts reflected signal characteristic, in conjunction with svm classifier, to front obstacle
Attribute identified；
Step (8): MCU module each virtual focus point signal superimposed to phase shift scans and recognizes, and obtains near virtual focus point
The 2D digital picture of barrier in set distance；When weeder is mobile, MCU module successively obtains the virtual focus point at each moment
The 2D digital picture of barrier, forms the 3D rendering of barrier, obtains the sky of barrier according to 3D rendering in neighbouring set distance
Between shape and size in depth；
Step (9): the attribute of the barrier after identification, shape and size are notified into host computer.
2. being suitable for the detection of obstacles barrier-avoiding method of full-automatic weeder as described in claim 1, characterized in that the step
Suddenly in (1), ultrasonic phase array is circumferentially to place four on four vertex of inscribed square respectively for received ultrasound
Wave transducer, centre bit put a ultrasonic transducer for transmitting, and five ultrasonic transducers are all made of identical central
The transceiver piezoelectric ceramic transducer of frequency, the circumference are centered on O point, and weeder local width is that radius does circle.
3. being suitable for the detection of obstacles barrier-avoiding method of full-automatic weeder as described in claim 1, characterized in that
In the step (7), the wavelet function feedback is to carry out wavelet decomposition to signal and reconstruct high fdrequency component and low
Frequency component utilizes trained SVM classifier in advance using high fdrequency component and the energy ratio of low frequency component as signal characteristic
Classify to signal characteristic, so that it is determined that the property of front obstacle and being identified out.
4. being suitable for the detection of obstacles barrier-avoiding method of full-automatic weeder as described in claim 1, characterized in that
The step (8), steps are as follows:
Step (81): carrying out sliding-model control to the section of scanning, i.e., section be divided into several discrete points, respectively it is described from
Scatterplot is scanned judgement as virtual focus point；
Step (82): after scanning starts, from first specified discrete point as virtual focus point, according to the virtual focus point to ultrasound
It is each used for the differential time of flight of received ultrasonic transducer in phased array, calculates each channel signal phase to be moved simultaneously
Successively carry out Signal averaging；
Step (83): barrier attribute is distinguished using classifier；
Step (84): the comprehensive information of each virtual focus point in a detection plane judges position and the 2D information of barrier；
Step (85): with the movement of weeder, being constantly scanned newly-generated virtual focus point, to form front detection
The 3D location and shape of barrier in region.
5. what it is using the detection of obstacles barrier-avoiding method suitable for full-automatic weeder as described in claim 1-4 is any is
System, characterized in that it include: MCU module, the ultrasound for transmitting that the MCU module passes through transmit circuit and ultrasonic phase array
Wave transducer connection, the top of weeder is located at for the ultrasonic transducer of transmitting；It is super that MCU module controls transmit circuit driving
Acoustic wave transducer issues ultrasonic signal, and ultrasonic signal is reflected by front obstacle, and transmitting signal is used by several
It is received in received ultrasonic transducer, several form ultrasonic phase array receiving array for received ultrasonic transducer；
The ultrasonic phase array receiving array pass sequentially through signal amplification conditioning module, detection low-pass filter, A/D conversion module with
The connection of MCU processing module；The MCU processing module is connect with host computer；
Each ultrasonic transducer of the receiving array of ultrasonic phase array both participates in reception and reflects ultrasonic signal, Mei Gechao
The received ultrasonic signal of acoustic wave transducer, which passes through signal amplification conditioning module, to carry out at preposition amplification, detection and low-pass filtering
Then reason is converted into digital signal feeding MCU module by A/D conversion module and is stored, MCU module passes through to each number
Word signal is handled, so that it is determined that the attribute of front obstacle, position and shape information.
6. the system as claimed in claim 5 using the detection of obstacles barrier-avoiding method for being suitable for full-automatic weeder, special
Sign is,
The signal amplifies conditioning module, comprising: sequentially connected signal buffer, gain adjustable amplifier and signal demodulation
Device；Wherein demodulator of PM signal PM is used to demodulate the obstacle information that ultrasonic wave carries from modulated signal to come, and the signal is slow
The ultrasonic transducer connection of the receiving array of device and ultrasonic phase array is rushed, the demodulator of PM signal PM is connect with low-pass filter.
7. the system as claimed in claim 5 using the detection of obstacles barrier-avoiding method for being suitable for full-automatic weeder, special
Sign is,
The ultrasonic phase array works in such a way that single-shot is received more:
Firstly, the ultrasonic transducer for transmitting emits N number of short pulse, then by ultrasonic wave remaining in ultrasonic phased array
Energy converter is synchronous to receive signal, and after amplification, conditioning and detection, deposit is in MCU after low-pass filtered device send A/D conversion module
Stored in module, using any road of storage receive signal and using peak detection method measure weeder apart from barrier away from
From D, and judge whether distance D is greater than preset distance；
If distance D is greater than preset distance, then it is assumed that front clear, weeder move ahead according to the route of planning；
If distance D is not more than preset distance, then it is assumed that there is barrier in front；
By horizontal distance immediately ahead of the center O point of ultrasonic phase array for O ' of D centered on, using the face perpendicular to O O ' as empty
Quasi- detection section, virtual detection interface and receiving array plane are parallel plane, are selected in detection section according to default rule
Virtual focus point is taken to be detected；By calculating the distance between each virtual focus point and each reception energy converter, obtain each virtual
Focus to respectively be used for received ultrasonic transducer range difference be di, by range difference diIt is obtained accordingly divided by the speed of ultrasonic wave
Time ti, to obtain virtual focus point and each phase difference θ for receiving signal between energy converteri, utilize θiEach road signal is carried out
Phase shift superposition, obtains the obstacle information near each virtual focus point, so that it is determined that the attribute of front obstacle, position and shape out
Shape.
8. the system as claimed in claim 7 using the detection of obstacles barrier-avoiding method for being suitable for full-automatic weeder, special
Sign is,
To the analysis method of barrier attribute are as follows: wavelet decomposition is done to the superimposed signal of phase shift, by the high-frequency energy of signal point
The ratio of amount and low frequency energy component as characteristic value, by using pre-stored data train come SVM classifier into
Row classification, distinguishing front obstacle is grass or other barriers.
9. the system as claimed in claim 7 using the detection of obstacles barrier-avoiding method for being suitable for full-automatic weeder, special
Sign is,
The step of selecting virtual focus point are as follows: centered on O ', weeder local width is that radius does circle, the inscribed square of circle
Lower-left, upper left, bottom right, upper right, central point, above central point, below central point, central point left and central point right nine
A point is virtual focus point.
10. the system as claimed in claim 7 using the detection of obstacles barrier-avoiding method for being suitable for full-automatic weeder, special
Sign is,
[t is only received after A/D conversioni-Δ,ti+ Δ] signal in the period, to further increase signal-to-noise ratio.
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| KR102292263B1 (en) * | 2018-08-03 | 2021-08-24 | 엘지전자 주식회사 | Moving robot, system of moving robot and method for moving to charging station of moving robot |
| KR102242713B1 (en) | 2018-08-03 | 2021-04-22 | 엘지전자 주식회사 | Moving robot and contorlling method and a terminal |
| KR102266713B1 (en) | 2018-08-03 | 2021-06-21 | 엘지전자 주식회사 | Lawn mover robot, system of lawn mover robot and controlling method for system of lawn mover robot |
| CN109250808A (en) * | 2018-10-25 | 2019-01-22 | 罗德斌 | A kind of sewage treatment machine people of environmental protection |
| CN111179568B (en) * | 2019-12-25 | 2021-08-10 | 中电海康集团有限公司 | Mowing robot communication method and system based on boundary electromagnetic signals |
| CN110974091B (en) * | 2020-02-27 | 2020-07-17 | 深圳飞科机器人有限公司 | Cleaning robot, control method thereof, and storage medium |
| CN111466165A (en) * | 2020-04-01 | 2020-07-31 | 信阳农林学院 | Multi-terrain weeding machine, control system and control method |
| CN113778084A (en) * | 2021-08-30 | 2021-12-10 | 普达迪泰（天津）智能装备科技有限公司 | Complex grassland environment intelligent obstacle avoidance system based on multispectral detection |
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