CN114111995A - Wireless weighing device and method for weighing type unmanned vending machine - Google Patents
Wireless weighing device and method for weighing type unmanned vending machine Download PDFInfo
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- CN114111995A CN114111995A CN202111412755.9A CN202111412755A CN114111995A CN 114111995 A CN114111995 A CN 114111995A CN 202111412755 A CN202111412755 A CN 202111412755A CN 114111995 A CN114111995 A CN 114111995A
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01G—WEIGHING
- G01G19/00—Weighing apparatus or methods adapted for special purposes not provided for in the preceding groups
- G01G19/40—Weighing apparatus or methods adapted for special purposes not provided for in the preceding groups with provisions for indicating, recording, or computing price or other quantities dependent on the weight
- G01G19/413—Weighing apparatus or methods adapted for special purposes not provided for in the preceding groups with provisions for indicating, recording, or computing price or other quantities dependent on the weight using electromechanical or electronic computing means
- G01G19/414—Weighing apparatus or methods adapted for special purposes not provided for in the preceding groups with provisions for indicating, recording, or computing price or other quantities dependent on the weight using electromechanical or electronic computing means using electronic computing means only
- G01G19/4144—Weighing apparatus or methods adapted for special purposes not provided for in the preceding groups with provisions for indicating, recording, or computing price or other quantities dependent on the weight using electromechanical or electronic computing means using electronic computing means only for controlling weight of goods in commercial establishments, e.g. supermarket, P.O.S. systems
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- G—PHYSICS
- G07—CHECKING-DEVICES
- G07F—COIN-FREED OR LIKE APPARATUS
- G07F11/00—Coin-freed apparatus for dispensing, or the like, discrete articles
- G07F11/02—Coin-freed apparatus for dispensing, or the like, discrete articles from non-movable magazines
Abstract
The invention relates to a wireless weighing device for a weighing type unmanned vending machine, namely a method, wherein the device comprises a weighing part, a display part, an energy supply part and a communication part; the weighing part is arranged below a tray of the weighing type unmanned vending machine and used for sensing the weight of the commodities on the tray in real time; the energy supply part is arranged inside a cabinet body of the weighing type unmanned vending machine and is used for supplying energy to the weighing part by utilizing a wireless energy transmission technology; the communication part is arranged in the weighing type automatic vending machine and is used for realizing information transmission between the weighing part and the server by utilizing a wireless communication technology; the display part is arranged on the surface of the weighing type automatic vending machine and is used for displaying data. The invention utilizes the characteristics of wireless communication technology and wireless technology to enable the position and the quantity of the weighing parts to be freely arranged in the unmanned vending machine, thereby facilitating the planning of the internal space of the weighing type unmanned vending machine.
Description
Technical Field
The invention relates to the technical field of design of unmanned vending machines, in particular to a wireless weighing device and a wireless weighing method for a weighing type unmanned vending machine.
Background
With the popularity of mobile payments, vending machines incorporating new technologies are emerging again. Unlike the unmanned vending machine using visual recognition, the weighing type unmanned vending machine has an advantage of being able to vend bulk goods, but the current weighing type unmanned vending machine has problems of a complicated deployment process and low weighing precision. The complex deployment process is mainly because each commodity in the unmanned vending machine needs one weighing device, and a plurality of weighing devices can cause complex and cumbersome wiring, and bring difficulty to the deployment of the weighing type unmanned vending machine. Meanwhile, the weighing precision is not high mainly because the weighing module with a large range is difficult to identify the increase and decrease of the commodities with lower quality and the influence of aperiodic external force on the weighing device generated in the process of taking the commodities by a user.
Disclosure of Invention
The invention aims to provide a wireless weighing device and a wireless weighing method for a weighing type unmanned vending machine. The weighing type unmanned vending machine at least partially solves the problem that the existing weighing type unmanned vending machine is complex in deployment process or low in weighing precision.
In order to achieve the purpose, the invention provides the following scheme:
a wireless weighing apparatus for weighing a vending machine, comprising: a weighing component, a display component, an energy supply component and a communication component;
the weighing part is arranged below a tray of the weighing type unmanned vending machine and used for sensing the weight of the commodities on the tray in real time; the weighing device comprises a plurality of weighing parts, and each weighing part corresponds to one commodity;
the energy supply part is arranged inside a cabinet body of the weighing type unmanned vending machine and is used for supplying energy to the weighing part by utilizing a wireless energy transmission technology;
the communication part is arranged in the weighing type automatic vending machine and is used for realizing information transmission between the weighing part and the server by utilizing a wireless communication technology; the server is used for calculating the commodity price according to the commodity weight information and the commodity type information;
the display component is arranged on the surface of the weighing component and used for displaying data.
Optionally, the weighing unit includes: the device comprises a weighing sensing module, a signal conditioning module, an analog-to-digital conversion module, a control module and a network transmission module;
the weighing sensing module is connected with the signal conditioning module and is used for sensing the weight of the commodities on the tray of the weighing type unmanned vending machine in real time to obtain a commodity weight sensing signal;
the signal conditioning module is connected with the analog-to-digital conversion module and is used for carrying out signal amplification processing and signal filtering processing on the commodity weight sensing signal to obtain a commodity weight conditioning signal;
the analog-to-digital conversion module is connected with the control module and is used for performing analog-to-digital conversion on the commodity weight conditioning signal to obtain a commodity weight digital signal;
the control module is connected with the network transmission module and is used for processing the commodity weight digital signal to obtain a commodity weighing signal;
the commodity weighing signal is displayed through the display part; and the commodity weighing signal is uploaded to the server through the network transmission module.
Optionally, the energy supply component comprises: the wireless energy supply control module, the wireless energy transmitting module and the wireless energy receiving module;
the wireless energy supply control module is connected with the wireless energy transmitting module; the wireless energy supply control module is used for controlling the work of the wireless energy transmitting module;
the wireless energy transmitting module is arranged on a back plate in the weighing type unmanned vending machine and is used for transmitting electromagnetic energy;
the wireless energy receiving module is arranged on the weighing component and used for receiving the electromagnetic energy transmitted by the wireless energy transmitting module.
Optionally, the wireless energy transmitting module includes a magnetic coupling resonance transmitting coil and a magnetic conducting strip; the magnetic coupling resonance transmitting coil is used for transmitting electromagnetic energy; the magnetic conductive strip is used for controlling the emission direction of electromagnetic energy;
the wireless energy receiving module comprises a magnetic coupling resonance receiving coil, a rectifying unit, a filtering unit and a voltage stabilizing unit;
the magnetic coupling resonance receiving coil is connected with the rectifying unit and used for receiving electromagnetic energy to obtain alternating current;
the rectifying unit is connected with the filtering unit, the filtering unit is connected with the voltage stabilizing unit, and the alternating current is subjected to rectifying processing, filtering processing and voltage stabilizing processing in sequence to obtain voltage-stabilized direct current.
Optionally, the control module includes a task scheduling unit, an initialization setting unit, a weighing signal processing unit, a data display unit, and a data network transceiver unit;
the initialization setting unit, the weighing signal processing unit, the data display unit and the data network transceiving unit are respectively connected with the task scheduling unit; the task scheduling unit is used for scheduling the initialization setting unit, the weighing signal processing unit, the data display unit and the data network transceiving unit;
the initialization setting unit is used for performing initialization setting; the weighing signal processing unit is used for processing the digital signal transmitted by the analog-to-digital conversion module to obtain commodity weight information; the data display unit is used for controlling the display component to display data; the data network transceiver unit is used for transmitting data information to the network transmission module and receiving the data information sent by the network transmission module.
Optionally, the weighing sensing module senses the weight of the commodity on the tray of the weighing type unmanned vending machine in real time by using a resistance strain type pressure sensor.
Optionally, the communication component includes a wireless router and a hub.
Optionally, the signal conditioning module performs signal amplification processing on the commodity weight signal by using a differential amplifier.
A weighing method for a wireless weighing apparatus of a weigh-type vending machine, comprising:
sensing the weight of the commodities on a tray of the weighing type unmanned vending machine in real time to obtain a commodity weight sensing signal;
preprocessing the commodity weight sensing signal to obtain a commodity weight digital signal;
performing Hilbert transform processing on the commodity weight digital signal to obtain a signal envelope;
acquiring waveform data from the last maximum point in the signal envelope to the stationary part of the signal;
carrying out empirical mode decomposition on the wave line data, and extracting a residual signal representing a static load in a decomposition result;
calculating the mean value of the residual signal, and obtaining a commodity weighing signal according to the mean value of the residual signal and a fitting curve; and the fitting curve is obtained by performing overall least square processing on the mean value of the residual signal and the calibration data of the weighing sensor.
Optionally, before performing hilbert transform processing on the product weight digital signal, the method further includes performing digital filtering processing on the product weight digital signal.
According to the specific embodiment provided by the invention, the invention discloses the following technical effects:
the invention relates to a wireless weighing device for a weighing type unmanned vending machine, which comprises a weighing part, a display part, an energy supply part and a communication part, wherein the display part is used for displaying the weighing state of the weighing part; the weighing part is arranged below a tray of the weighing type unmanned vending machine and used for sensing the weight of the commodities on the tray in real time; the weighing device comprises a plurality of weighing parts, and each weighing part corresponds to one commodity; the energy supply part is arranged inside a cabinet body of the weighing type unmanned vending machine and is used for supplying energy to the weighing part by utilizing a wireless energy transmission technology; the communication part is arranged in the weighing type automatic vending machine and is used for realizing information transmission between the weighing part and the server by utilizing a wireless communication technology; the server is used for calculating the commodity price according to the commodity weight information and the commodity type information; the display component is arranged on the surface of the weighing component and used for displaying data. The invention utilizes the wireless communication technology and the full wireless characteristic of the wireless technology, so that the positions and the quantity of the weighing parts can be freely arranged in the unmanned vending machine, and the planning of the internal space of the weighing type unmanned vending machine is convenient; the all-wireless weighing device provided by the invention has the advantages that the positions and the number of weighing components can be freely arranged in the vending machine, and the loss caused by weighing errors can be reduced by using an accuracy improving algorithm.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings needed in the embodiments will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings without creative efforts.
FIG. 1 is a schematic view of a weighing apparatus for a weighing-type vending machine according to the present invention;
FIG. 2 is a schematic diagram of a weighing apparatus for a weighing-type vending machine according to the present invention;
fig. 3 is a schematic flow chart of a weighing method for the weighing-type automatic vending machine according to the invention.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be obtained by a person skilled in the art without any inventive step based on the embodiments of the present invention, are within the scope of the present invention.
The current weighing type unmanned vending machine has the problems of complex deployment process and low weighing precision. In order to solve the problems of complex deployment process and low weighing precision of the existing weighing type unmanned vending machine, the invention provides a wireless weighing device and a method for the weighing type unmanned vending machine, which enable the position and the number of weighing parts to be freely arranged in the unmanned vending machine through the characteristics of wireless communication and wireless communication, and facilitate the planning of the internal space of the weighing type unmanned vending machine; meanwhile, weighing signals are processed through a precision lifting algorithm, and the problem that the existing weighing type unmanned vending machine is low in weighing precision is solved.
In order to make the aforementioned objects, features and advantages of the present invention comprehensible, embodiments accompanied with figures are described in further detail below.
As shown in fig. 1, the present embodiment discloses a wireless weighing device for a weighing type automatic vending machine, which specifically includes: a weighing component, a display component, an energy supply component and a communication component;
the weighing part is arranged below a tray of the weighing type unmanned vending machine and used for sensing the weight of the commodities on the tray in real time; the weighing device comprises a plurality of weighing parts, and each weighing part corresponds to one commodity;
the energy supply part is arranged inside a cabinet body of the weighing type unmanned vending machine and is used for supplying energy to the weighing part by utilizing a wireless energy transmission technology;
the communication part is arranged in the weighing type automatic vending machine and is used for realizing information transmission between the weighing part and the server by utilizing a wireless communication technology; the server is used for calculating the commodity price according to the commodity weight information and the commodity type information;
the display component is arranged on the surface of the weighing component and used for displaying data.
The weighing device can be freely deployed in the unmanned vending machine by utilizing the wireless communication technology and the wireless energy transmission technology, and the problem that the conventional weighing type unmanned vending machine is complex in deployment is solved
In particular implementation, the weighing means comprises: the device comprises a weighing sensing module, a signal conditioning module, an analog-to-digital conversion module, a control module and a network transmission module;
the weighing sensing module is connected with the signal conditioning module and is used for sensing the weight of the commodities on the tray of the weighing type unmanned vending machine in real time to obtain a commodity weight sensing signal;
the signal conditioning module is connected with the analog-to-digital conversion module and is used for carrying out signal amplification processing and signal filtering processing on the commodity weight sensing signal to obtain a commodity weight conditioning signal;
the analog-to-digital conversion module is connected with the control module and is used for performing analog-to-digital conversion on the commodity weight conditioning signal to obtain a commodity weight digital signal;
the control module is connected with the network transmission module and is used for processing the commodity weight digital signal to obtain a commodity weighing signal;
the commodity weighing signal is displayed through the display part; and the commodity weighing signal is uploaded to the server through the network transmission module.
In specific implementation, the weighing component is arranged below a tray in the unmanned vending machine, and changes of the weight of the commodities on the tray are sensed in real time. The signal conditioning module and the analog-to-digital conversion module receive the electric signals from the weighing sensing module, and output the electric signals to the control module, namely the SOC embedded system after the electric signals are subjected to amplification modulation, analog filtering, analog-to-digital conversion and the like. The SOC embedded system displays the read weight information on a display part after digital filtering and error and temperature compensation, and transmits the weight information to a server end through a network transmission module and an antenna, so that the server can perform operations such as total price calculation according to corresponding commodity weight change. The control module receives the commodity weight information processed by the signal conditioning circuit and the analog-to-digital conversion unit, eliminates interference by digital filtering, displays the information on the display screen and uploads the information to the server through the network transmission unit. When the commodity information needs to be updated, the SOC embedded system downloads data from the server and updates the commodity information on the display. The embedded system can be formed by a 51-series 89C51 singlechip or an STM32 module taking an ARM chip as a core. The present invention is not particularly limited thereto.
The weighing sensor is used for converting a pressure signal into an analog electric signal, and is widely used in a resistance strain type pressure sensor, a piezoelectric type pressure sensor and a capacitance type pressure sensor. The resistance strain type pressure sensor is generally composed of a Wheatstone bridge consisting of resistance strain gauges, and has the advantages of good stability, higher sensitivity and high precision. The piezoelectric pressure sensor is a sensor based on piezoelectric effect, and has good stability, high precision and sensitivity, but a wide-range sensor is yet to be researched. The capacitive pressure sensor is a sensor for measuring pressure by using capacitance change, has high precision and sensitivity, but has short service life and severe environmental requirements. Preferably, the weighing sensing module can sense the weight of the goods on the tray of the weighing type unmanned vending machine in real time by using the resistance strain type pressure sensor. It should be noted that the real-time sensing of the weight of the product on the tray of the weighing-type unmanned vending machine by using the resistance strain type pressure sensor is only a preferred embodiment provided by the present embodiment, and those skilled in the art can select different types of pressure sensors according to actual requirements.
The signal conditioning module is used for amplifying millivolt level electric signals of the resistance strain type pressure sensor, and in practical application, the electric signals are generally amplified by using a non-inverting amplifier, an inverting amplifier or a differential amplifier, wherein the differential amplifier only amplifies differential mode signals, but inhibits common mode signals, and the characteristic is very beneficial to bridge output signals of the resistance strain type pressure sensor. Therefore, in the implementation, the signal conditioning module of the invention utilizes the differential amplifier to amplify the commodity weight signal. The band-pass filter in the conditioning circuit is used for inhibiting spike pulse and various interference signals, and commonly used RC active filter, LC filter, ceramic filter and mechanical filter. Wherein the RC active filter is composed of an RC element and an operational amplifier. It has small volume, light weight and high quality factor. Therefore, in the specific implementation, the signal conditioning module of the invention utilizes the RC active filter to perform signal filtering processing on the commodity weight signal.
The analog-to-digital converter is used for converting an analog electric signal into a digital signal which can be stably output, and mainly includes an integration type, a successive comparison type, a parallel comparison type/serial-parallel comparison type, a capacitor array successive comparison type, and a voltage-frequency variation type. In particular, the present invention employs a CS5532 chip that supports 24-bit analog-to-digital conversion.
When the application is actually deployed, the energy supply component comprises: the wireless energy supply control module, the wireless energy transmitting module and the wireless energy receiving module;
the wireless energy supply control module is connected with the wireless energy transmitting module; the wireless energy supply control module is used for controlling the work of the wireless energy transmitting module;
the wireless energy transmitting module is arranged on a back plate in the weighing type unmanned vending machine and is used for transmitting electromagnetic energy;
the wireless energy receiving module is arranged on the weighing component and used for receiving the electromagnetic energy transmitted by the wireless energy transmitting module.
The wireless devices are generally of an electromagnetic induction type, a magnetic resonance type, a radio wave type, an electric field coupling type, and the like. The magnetic coupling resonance receiving coil on the weighing device is in resonance coupling with the magnetic coupling resonance transmitting coil on the unmanned vending machine so as to achieve the highest energy transmission efficiency. And then alternating current obtained from the coupling coil is converted into direct current after rectification, filtering and voltage stabilization and is supplied to a weighing device for use. In addition, considering that a plurality of weighing devices are arranged in a vending machine, the wireless transmitting device on the vending machine and the wireless receiving device on the weighing devices are in a one-to-many mode. In addition, the wireless energy receiving module and the wireless transmission module on the vending machine are close to each other as much as possible so as to improve the energy transmission efficiency. When practical application, wireless energy supply control module can judge whether to control wireless energy emission module to carry out work according to whether there is the user to be close weighing type unmanned vending machine, controls wireless energy emission module to carry out work promptly when the user is close weighing type unmanned vending machine certain threshold value distance after, otherwise controls wireless energy emission module not to carry out work for energy saving.
As shown in fig. 2, the wireless energy transmitting module includes a magnetic coupling resonance transmitting coil and a magnetic conductive strip; the magnetic coupling resonance transmitting coil is used for transmitting electromagnetic energy; the magnetic conductive strip is used for controlling the emission direction of electromagnetic energy;
the wireless energy receiving module comprises a magnetic coupling resonance receiving coil, a rectifying unit, a filtering unit and a voltage stabilizing unit;
the magnetic coupling resonance receiving coil is connected with the rectifying unit and used for receiving electromagnetic energy to obtain alternating current;
the rectifying unit is connected with the filtering unit, the filtering unit is connected with the voltage stabilizing unit, and the alternating current is subjected to rectifying processing, filtering processing and voltage stabilizing processing in sequence to obtain voltage-stabilized direct current.
The control module comprises a task scheduling unit, an initialization setting unit, a weighing signal processing unit, a data display unit and a data network transceiving unit;
the initialization setting unit, the weighing signal processing unit, the data display unit and the data network transceiving unit are respectively connected with the task scheduling unit; the task scheduling unit is used for scheduling the initialization setting unit, the weighing signal processing unit, the data display unit and the data network transceiving unit;
the initialization setting unit is used for performing initialization setting; the weighing signal processing unit is used for processing the digital signal transmitted by the analog-to-digital conversion module to obtain commodity weight information; the data display unit is used for controlling the display component to display data; the data network transceiver unit is used for transmitting data information to the network transmission module and receiving the data information sent by the network transmission module.
The main program of the software of the invention is mainly responsible for task scheduling, namely the task scheduling unit schedules other modules to run in order. When the main program starts to run, initialization setting is firstly carried out, including initialization of modules such as a clock, a GPIO port and an analog-to-digital converter. The analog-to-digital converter converts an analog voltage signal output by the weighing sensor into a numerical value form. And then the task scheduling unit schedules the weighing signal processing unit to perform data calculation to obtain a weighing result, and finally the data display unit is called to perform result display and the data network transceiving unit uploads weight data.
In practical applications, the communication component includes a wireless router and a hub. In some specific scenes, wireless communication modes such as ZigBee or Bluetooth can also be adopted.
When shopping by using the vending machine, a user firstly scans the two-dimensional code or carries out biological characteristic collection to provide identity information. And after the server passes the verification, opening the door of the vending machine cabinet, and informing the weighing device to start weighing through a network. And then after the user finishes taking the commodity once and closes the cabinet door, each weighing unit detects the weight change of the corresponding commodity, sends the weight change data to a wireless route on the unmanned vending machine through a network transmission unit, and then uploads the weight change data to the server through the Internet. The server identifies the type and weight of the goods taken away by the user, then automatically calculates the price and deducts money from the corresponding account according to the identity information of the user. When the vending machine is replenished with replaced goods, the server sends data to each weighing unit through the internet and a wireless route. After the control unit of each weighing unit acquires the data, the data is delivered to the display part to update the displayed commodity type and price information. Since there are multiple weighing devices in each vending machine, each message sent by the communication component has a unique identifier for identifying the source and destination of the data in order to achieve many-to-one communication between the weighing devices and the server. For the information sent by the server to the weighing device, in order to save system resources, the weighing device receives the information in an external triggering mode. And after the weighing device terminal receives the message, the program enters an interrupt service program and carries out corresponding response.
In the specific implementation, the control module in the weighing component is utilized to realize high-precision calculation of the commodity weighing signal, and in order to improve the calculation speed, a person skilled in the art can also use the server to perform high-precision calculation of the commodity weighing signal. As shown in fig. 3, the specific method for acquiring the commodity weighing signal includes:
s1: and sensing the weight of the commodities on the tray of the weighing type unmanned vending machine in real time to obtain a commodity weight sensing signal.
S2: and preprocessing the commodity weight sensing signal to obtain a commodity weight digital signal.
The preprocessing comprises signal amplification, signal filtering and analog-to-digital conversion, wherein the commodity weight sensing signal is an electric signal, and the commodity weight sensing signal is subjected to signal amplification, signal filtering and analog-to-digital conversion to obtain a commodity weight digital signal. In addition, digital filtering is carried out on the commodity weight digital signal, the digital filtering can carry out filtering on various interference signals, and several commonly used technologies suitable for being used by a weighing system are as follows: limiting filtering, speed limiting filtering, median filtering, arithmetic mean filtering, depolarized mean filtering, and moving mean filtering. Preferably, the invention may use a moving average filtering. It should be noted that the use of moving average filtering is only a preferred implementation provided by the present embodiment, and those skilled in the art can modify the implementation according to actual needs.
S3: and performing Hilbert transform processing on the commodity weight digital signal to obtain a signal envelope.
The weight of the commodity may be increased or decreased for many times during the process of taking the commodity in shopping by a user, so that the vibration of the weighing device is inevitably caused, and the vibration is forced vibration with continuous non-periodic excitation. Therefore, the data waveform of the weighing sensor can be used for calculation only after the last time of taking by the user, so that the last maximum value point of the signal envelope needs to be found out to identify the pulse waveform caused by the last time of taking by the user, and the waveform data after the last maximum value point until the waveform is basically stable is used for subsequent calculation.
In the implementation, the commodity weight digital signal is expressed as a real-valued function x (t), and the Hilbert transform is recorded as
Wherein t represents time, x (t) represents a real-valued function of the digital signal of the weight of the commodity,
a hilbert transform of the digital signal representing the weight of the article.
Based on the real-valued function x (t) of the product weight digital signal and the Hilbert transform of the product weight digital signal
An analytic signal can be obtained:
wherein A isi(t) is a function of the magnitude,
in order to be a function of the phase,
wherein the amplitude function Ai(t) is the envelope of the signal that needs to be solved.
S4: and acquiring waveform data from the last maximum point in the signal envelope to the stationary part of the signal.
The purpose of the last extremum of the envelope of the signal is to avoid the effects of local fluctuations on the signal. In the implementation, an extreme value window delta based on experience is set. A value on a signal is considered to be an extreme value when it is greater or less than all values in the window. Then only a comparison from the end of the signal envelope onwards is required,the first extreme x (t) foundn) I.e. as the last extreme value of the envelope, tnThe position of the last extreme.
And extracting the target signal sequence after the position of the last extreme value of the signal envelope is obtained. In order to avoid the impact influence brought by the user when taking the commodity, the invention extracts the last extreme value t of the envelopenThe portion by the time the signal is substantially stable is taken as the target signal sequence y (t). The signal substantially stabilizes at a time T after the user closes the cabinet door of the vending machine, T being an empirically based constant. The acquired target signal sequence y (t) is waveform data from the last maximum point in the signal envelope to the signal plateau.
S5: and carrying out empirical mode decomposition on the wave line data, and extracting a residual signal representing the static load in a decomposition result.
Empirical Mode Decomposition (EMD) is a Decomposition method based on local characteristics of a signal, which decomposes a complex signal into a series of Intrinsic Mode Functions (IMFs) and a residual. Wherein the Intrinsic Mode Function (IMF) reflects the dynamics of the signal and the residual reflects the trend or mean of the signal. The Intrinsic Mode Function (IMF) needs to satisfy two conditions: the number of the extreme points is the same as or different from the number of the zero crossing points by one at most; at any point, the mean of the upper envelope determined by all local maxima points and the lower envelope determined by all local minima points is zero. The condition that the Intrinsic Mode Function (IMF) needs to satisfy is also the termination condition of the Empirical Mode Decomposition (EMD) decomposition. Based on this condition, the waveform data y (t) can be decomposed by using an Empirical Mode Decomposition (EMD) method through the following steps:
s51: obtaining an average value m (t) of waveform data y (t), wherein the specific obtaining method comprises the following steps:
finding out all maximum value points in waveform data Y (t) and solving upper envelope line Y by cubic spline interpolationmax(t); finding out all minimum value points of waveform data Y (t) and calculating lower envelope Y by cubic spline interpolationmin(t) of (d). Then, the upper envelope Y is determinedmax(t) and lower envelopeYminAverage value m (t) of (t):
wherein m (t) is the average value of the waveform data Y (t), Ymax(t) is the upper envelope of the waveform data Y (t), Ymin(t) is the lower envelope of the waveform data y (t).
S52: obtaining an intermediate function h (t) according to the waveform data y (t) and the average value m (t), wherein the method comprises the following specific steps:
h(t)＝y(t)-m(t)
wherein h (t) is a median function, y (t) is waveform data, and m (t) is an average value.
S53: judging whether the intermediate function h (t) is an Intrinsic Mode Function (IMF) function, if the condition of the Intrinsic Mode Function (IMF) is not met, regarding h (t) as new y (t), and repeating the steps S51 and S52 until h (t) meets the condition of the Intrinsic Mode Function (IMF). When the inter-function h (t) satisfies the condition of the eigenmode function (IMF), it is expressed as an eigenmode function (IMF) component c (t):
c(t)＝h(t)
where h (t) is an intermediate function, and c (t) is an Intrinsic Mode Function (IMF) component.
S54: decomposing the waveform data y (t) according to the Intrinsic Mode Function (IMF) component c (t), wherein the specific decomposition method is as follows:
r(t)＝y(t)-c(t)
where r (t) is the decomposition function, y (t) is the waveform data, and c (t) is the Intrinsic Mode Function (IMF) component.
S55: recording the decomposition function r (t) as waveform data y (t), and repeating the steps S51-S54 until the decomposition function r (t) is smaller than a preset threshold value.
In practical implementation, whether to stop the repetition of the steps S51 to S54 may be determined according to whether the decomposition function r (t) is a monotonic function, that is, the repetition of the steps S51 to S54 may be stopped when the decomposition function r (t) is a monotonic function.
The original data sequence may be represented by the calculated IMF component and the final residual:
for the purposes of the present invention, the EMD decomposes out the final residual signal r (t)e) Can represent the static load of the commodity, so that the average value of the residual amount
May be used to represent the weight of the article.
S6: calculating the mean value of the residual signal, and obtaining a commodity weighing signal according to the mean value of the residual signal and a fitting curve; and the fitting curve is obtained by performing overall least square processing on the mean value of the residual signal and the calibration data of the weighing sensor.
Averaging the residual amounts
Inputting the weight m into a curve obtained by using the total least square fitting, and obtaining the weight m of the commodity. The method for calculating the fitted curve by using the total least square method is as follows:
and taking the residual average value obtained by multiple experiments as a data matrix A, and taking the corresponding commodity true weight as a data vector b, and aiming at solving a parameter matrix x. The basic idea of total least squares is: not only is there interference E in the data vector b, but also in the data matrix a. The overall least squares method aims to correct for the interference of both. In other words, the overall least squares consideration is the matrix equation:
(A+E)x＝b+e
and (4) solving. Obviously, the above formula can also be rewritten:
or equivalently:
(B+D)z＝0
in the formula, addWide matrix B [ -B, a [ ]]And a disturbance matrix D [ -E, E [ ]]Are all m × (n +1) -dimensional matrices, and
is an (n +1) × 1 vector.
Decompose the singular values of the mx (n +1) augmented matrix B into
B＝UΣVH
And singular values are in order σ1≥σ2≥…≥σn+1Permutation, the right singular vectors corresponding to these singular values being denoted v1,v2,…,vn+1。
In the overall least squares solution of the over-determined equation, there are two possible cases.
The first case is σnIs significantly greater than sigman+1I.e. the smallest singular value is only one.
Through analytical calculation, the least square solution of the original matrix equation Ax ═ b is given by:
where V (i, n +1) is the i-th element of the n + 1-th column of the right singular vector V.
In the second case, the minimum singular value is multiple.
A total least squares solution can be found that is unique in some sense. The only possible solutions are two:
one is the minimum norm solution, the solution vector is composed of n parameters.
Determining the number of dominant singular values of the singular value decomposition of the augmentation matrix B as p, i.e. using sigmap>σn+1+∈≥σp+1≥…≥σn+1Determining p, wherein e is a positive number.
Let V1＝[vp+k,vp+2,…,vn+1]Is the column block form of the right singular vector V, for V1Partitioning is performed as follows:
then the TLS solution is eventually written as:
the other is an optimal least squares approximation solution, the solution vector contains only p parameters.
Obtaining a windowed segment of the kth column vector of the unitary matrix V
In the formula, V (i, k) is an element on the ith row and the kth column of the unitary matrix V, V (i +1, k) is an element on the kth column of the i +1 th row of the unitary matrix V, V (i + p, k) is an element on the kth column of the i + p th row of the unitary matrix V, and T represents transposition.
Calculating the effective rank p of the augmentation matrix B, and then solving:
calculating S(p)Inverse matrix S of-(p)Then the desired TLS solution x(p)＝[xTLS(1),xTLS(2),…xTLS(p)]TComprises the following steps:
xTLS(i)＝S-(p)(i+1,1)/S-(p)(1,1),i＝1,2,…,p
x in the above two casesTLSAfter the calculation is finished, the fitting curve of the total least square is AxTLS. Wherein A is a constant. Averaging the residual values obtained previously
Inputting the curve to obtain the commodityAnd (3) the weight m.
The weight m of the commodity before the weighing0And subtracting the obtained commodity weight m to obtain the commodity weight taken away by the user.
The embodiments in the present description are described in a progressive manner, each embodiment focuses on differences from other embodiments, and the same and similar parts among the embodiments are referred to each other.
The principles and embodiments of the present invention have been described herein using specific examples, which are provided only to help understand the method and the core concept of the present invention; meanwhile, for a person skilled in the art, according to the idea of the present invention, the specific embodiments and the application range may be changed. In view of the above, the present disclosure should not be construed as limiting the invention.
Claims (10)
1. A wireless weighing device for a weigh-able vending machine, comprising: a weighing component, a display component, an energy supply component and a communication component;
the weighing part is arranged below a tray of the weighing type unmanned vending machine and used for sensing the weight of the commodities on the tray in real time; the weighing device comprises a plurality of weighing parts, and each weighing part corresponds to one commodity;
the energy supply part is arranged inside a cabinet body of the weighing type unmanned vending machine and is used for supplying energy to the weighing part by utilizing a wireless energy transmission technology;
the communication part is arranged in the weighing type automatic vending machine and is used for realizing information transmission between the weighing part and the server by utilizing a wireless communication technology; the server is used for calculating the commodity price according to the commodity weight information and the commodity type information;
the display component is arranged on the surface of the weighing component and used for displaying data.
2. The wireless weighing apparatus for a weigh-type vending machine as recited in claim 1, wherein the weighing component comprises: the device comprises a weighing sensing module, a signal conditioning module, an analog-to-digital conversion module, a control module and a network transmission module;
the weighing sensing module is connected with the signal conditioning module and is used for sensing the weight of the commodities on the tray of the weighing type unmanned vending machine in real time to obtain a commodity weight sensing signal;
the signal conditioning module is connected with the analog-to-digital conversion module and is used for carrying out signal amplification processing and signal filtering processing on the commodity weight sensing signal to obtain a commodity weight conditioning signal;
the analog-to-digital conversion module is connected with the control module and is used for performing analog-to-digital conversion on the commodity weight conditioning signal to obtain a commodity weight digital signal;
the control module is connected with the network transmission module and is used for processing the commodity weight digital signal to obtain a commodity weighing signal;
the commodity weighing signal is displayed through the display part; and the commodity weighing signal is uploaded to the server through the network transmission module.
3. The wireless weighing apparatus for a weigh-type vending machine of claim 1, wherein: the energy supply component includes: the wireless energy supply control module, the wireless energy transmitting module and the wireless energy receiving module;
the wireless energy supply control module is connected with the wireless energy transmitting module; the wireless energy supply control module is used for controlling the work of the wireless energy transmitting module;
the wireless energy transmitting module is arranged on a back plate in the weighing type unmanned vending machine and is used for transmitting electromagnetic energy;
the wireless energy receiving module is arranged on the weighing component and used for receiving the electromagnetic energy transmitted by the wireless energy transmitting module.
4. The wireless weighing apparatus for a weigh-type vending machine of claim 3, wherein:
the wireless energy transmitting module comprises a magnetic coupling resonance transmitting coil and a magnetic conducting strip; the magnetic coupling resonance transmitting coil is used for transmitting electromagnetic energy; the magnetic conductive strip is used for controlling the emission direction of electromagnetic energy;
the wireless energy receiving module comprises a magnetic coupling resonance receiving coil, a rectifying unit, a filtering unit and a voltage stabilizing unit;
the magnetic coupling resonance receiving coil is connected with the rectifying unit and used for receiving electromagnetic energy to obtain alternating current;
the rectifying unit is connected with the filtering unit, the filtering unit is connected with the voltage stabilizing unit, and the alternating current is subjected to rectifying processing, filtering processing and voltage stabilizing processing in sequence to obtain voltage-stabilized direct current.
5. The wireless weighing device for the weighing-type unmanned vending machine as claimed in claim 2, wherein the control module comprises a task scheduling unit, an initialization setting unit, a weighing signal processing unit, a data display unit and a data network transceiving unit;
the initialization setting unit, the weighing signal processing unit, the data display unit and the data network transceiving unit are respectively connected with the task scheduling unit; the task scheduling unit is used for scheduling the initialization setting unit, the weighing signal processing unit, the data display unit and the data network transceiving unit;
the initialization setting unit is used for performing initialization setting; the weighing signal processing unit is used for processing the digital signal transmitted by the analog-to-digital conversion module to obtain commodity weight information; the data display unit is used for controlling the display component to display data; the data network transceiver unit is used for transmitting data information to the network transmission module and receiving the data information sent by the network transmission module.
6. The wireless weighing apparatus for a weigh-type vending machine of claim 2, wherein: the weighing sensing module senses the weight of the commodities on the tray of the weighing type unmanned vending machine in real time by using the resistance strain type pressure sensor.
7. The wireless weighing apparatus for a weigh-type vending machine of claim 1, wherein: the communication component includes a wireless router and a hub.
8. The wireless weighing apparatus for a weigh-type vending machine of claim 2, wherein:
and the signal conditioning module utilizes a differential amplifier to amplify the commodity weight signal.
9. A weighing method of a wireless weighing device for a weighing type vending machine is characterized in that:
sensing the weight of the commodities on a tray of the weighing type unmanned vending machine in real time to obtain a commodity weight sensing signal;
preprocessing the commodity weight sensing signal to obtain a commodity weight digital signal;
performing Hilbert transform processing on the commodity weight digital signal to obtain a signal envelope;
acquiring waveform data from the last maximum point in the signal envelope to the stationary part of the signal;
carrying out empirical mode decomposition on the wave line data, and extracting a residual signal representing a static load in a decomposition result;
calculating the mean value of the residual signal, and obtaining a commodity weighing signal according to the mean value of the residual signal and a fitting curve; and the fitting curve is obtained by performing overall least square processing on the mean value of the residual signal and the calibration data of the weighing sensor.
10. The method of claim 9, further comprising digitally filtering the product weight digital signal prior to the hilbert transform processing the product weight digital signal.
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