CN108923648A - A kind of dedicated and tractor pressure magnetic induction sensor power circuit - Google Patents
A kind of dedicated and tractor pressure magnetic induction sensor power circuit Download PDFInfo
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- CN108923648A CN108923648A CN201810910607.1A CN201810910607A CN108923648A CN 108923648 A CN108923648 A CN 108923648A CN 201810910607 A CN201810910607 A CN 201810910607A CN 108923648 A CN108923648 A CN 108923648A
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
- H02M3/00—Conversion of dc power input into dc power output
- H02M3/02—Conversion of dc power input into dc power output without intermediate conversion into ac
- H02M3/04—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters
- H02M3/10—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
- H02M3/145—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal
- H02M3/155—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only
- H02M3/156—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only with automatic control of output voltage or current, e.g. switching regulators
- H02M3/157—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only with automatic control of output voltage or current, e.g. switching regulators with digital control
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- Combined Controls Of Internal Combustion Engines (AREA)
Abstract
The invention discloses a kind of tractors to press magnetic induction power circuit, it is characterized in that：Input power is connect with the battery on tractor, and the power circuit includes prime power circuit and final stage power circuit；The front stage circuits realize conversion of the 24V voltage to 5V voltage；The final circuit realizes conversion of the 5V voltage to 3.3V voltage；The front stage circuits, which are also realized, converts 15V for 24V voltage；The final circuit, which is also realized, is converted to -15V voltage for+15V voltage.Using power circuit provided by the invention, the power demands of shear stress sensor on tractor can be effectively realized, and then the shear stress induction of tractor sensor is better achieved.
Description
Technical field
The present invention relates to field of agricultural machinery, more particularly to a kind of dedicated electric with tractor pressure magnetic induction sensor power supply
Road.
Background technique
In order to adapt to various farm implements and its different operating conditions, three are generally used on current most of wheeled tractors
Kind regulative mode：Power is adjusted, position is adjusted, height adjustment, Tractor Abroad additionally used torque adjusting in recent years, pressure is adjusted,
Comprehensive adjustment.Power adjusting is for the purpose of maintaining tractor engine load steady, is to pass through for adjusting the tractive force of farm implements
For resistance control system come what is realized, resistance control system is a very important subsystem of electrohydraulic hitch system.Traditional
Tractor uses the power that is promoted as farm implements of simple hydraulic device, control section be it is mechanical, manipulation is passed through by driver
Handle and a set of rod piece mechanism input signal in the form of displacement, output quantity are then to adjust thick stick by spring, cam and power, position
The displacement that linkage is converted into, to realize adjustment of the manipulation main control valve to farm implements position.The hydraulic suspension of Mechanical course
System uses rod piece and elastic element, and structure is more complicated, and sluggishness, mechanical friction and the breathing of rod piece of elastic element will affect
Regulation performance, and since the uncertain factors such as non-linear of variation, hydraulic lift mechanism by edaphic condition are influenced, traditional liquid
Press the work quality of suspension mechanism not high, therefore the precise control model for causing system is established relatively difficult, and is unfavorable for
Realize the automation and intelligence of tractor set operation.Currently, the hydraulic suspension that electrohydraulic hitch system has replaced tractor traditional
Suspension mechanism.
But the most important problem of setting of electrohydraulic hitch system is how to establish mechanical displacement and tractor at present
How the conversion of resistance situation to electric signal is designed power circuit, is made sensor due to the special power environment of tractor itself
Operational process can suitably realize that magnetic circuit is converted and forms electric signal output.And establish this sensor-based system, it is necessary first to solve
The work for being the cooperation for realizing power-supply system, how the power environment on tractor being improved to as suitable sensor operation certainly
Environment is current technical staff's problem to be solved, therefore those skilled in the art are dedicated to developing one kind suitable for dilatory
The tractor of machine electrical voltage system presses magnetic induction power circuit.
Summary of the invention
In view of the above drawbacks of the prior art, it is suitable for drawing technical problem to be solved by the invention is to provide one kind
The tractor of machine electrical voltage system presses magnetic induction power circuit.
To achieve the above object, magnetic induction power circuit is pressed the present invention provides a kind of tractor, input power and dilatory
24V battery connection on machine, the power circuit includes prime power circuit and final stage power circuit；The front stage circuits are real
Existing conversion of the 24V voltage to 5V voltage；The final circuit realizes conversion of the 5V voltage to 3.3V voltage；
The front stage circuits, which are also realized, converts 15V for 24V voltage；The final circuit, which is also realized, converts+15V voltage
For -15V voltage.
Preferably, the diode for protecting the accumulator polarity is provided in the power circuit.
Preferably, the reference voltage is set as 3V.
Preferably, the front stage circuits include three proper voltage voltage stabilizing chips and output voltage chip；Described three rectify electricity
Voltage stabilizing chip is pressed to use L7815；The output voltage chip uses DCDC_S5；The final circuit includes that charge pump voltage is anti-
Turn device and low voltage difference analog power；The charge pump voltage inversion device is set as ICL7662CPA；The low voltage difference analog power
It is set as SPX1117；The power system circuit further includes AD conversion a reference source potential circuit, including a reference source voltage output core
Piece, a reference source voltage output chip are set as AD530ART.
Preferably, the power circuit to digitally, simulation and signal ground power respectively, then utilize Zero-ohm resistor
Series connection is for ground.
The beneficial effects of the invention are as follows：Since input power is directly from the 24V Vehicular accumulator cell on tractor, on circuit
Additional diode is to protect battery polar.By chip transformation, voltage 5V, 3.3V are provided, wherein 3.3V is LPC2378 chip
The operating voltage of CPU operation voltage and I/O operation voltage and level translator SP3232, the 5V of isolation are peripheral interface circuit
It uses.Signal amplification circuit and signal effective value transformation circuit require the reference voltage an of ± 15V, so also wanting in system
The power circuit an of ± 15V is designed, in addition A/D conversion circuit sets the reference voltage of a 3V.LPC2378 chip pin connects
The power supply of oral area point takes the scheme on total ground, and digitally, simulation and signal ground first separate respective cabling, then with 0 ohm
Resistance string alliance is effectively reduced high-frequency noise on digitally to simulation and the interference of signal ground.
Using power circuit provided by the invention, the power demands of shear stress sensor on tractor can be effectively realized,
And then the shear stress induction of tractor sensor is better achieved.
Detailed description of the invention
Fig. 1 is power circuit front stage circuits hardware elementary diagram provided by the invention.
Fig. 2 is power circuit final circuit hardware elementary diagram provided by the invention.
Fig. 3 is a reference source potential circuit hardware elementary diagram in electric signal output control circuit.
Fig. 4 is to realize sensor electric signal output control circuit composition figure using power-supply system of the invention.
Fig. 5 is reset and storage circuit hardware elementary diagram in electric signal output control circuit.
Fig. 6 is signal amplification and effective value transformation hardware circuit principle figure in electric signal output control circuit.
Fig. 7 is the structural schematic diagram of tractor resistance detection device.
Fig. 8 be in Fig. 7 B to cross-sectional view.
Fig. 9 is installation site figure of the resistance detection device in electrohydraulic hitch system of Fig. 7.
Figure 10 is the equivalent circuit diagram of tractor resistance detection device.
Figure 11 is CAN message transmission flow figure.
Figure 12 is that CAN message receives flow chart.
Figure 13 is the receive process figure of CAN data.
Figure 14 is the initialization flowchart of CAN communication link.
Figure 15 is the transmitting-receiving flow chart of serial communication.
Specific embodiment
Present invention will be further explained below with reference to the attached drawings and examples：
As shown in Figure 1 to Figure 3, a kind of tractor presses magnetic induction power circuit, the battery on input power and tractor
Connection, power circuit includes prime power circuit and final stage power circuit；Front stage circuits realize that 24V voltage turns to 5V voltage
It changes；Final circuit realizes conversion of the 5V voltage to 3.3V voltage；
Front stage circuits, which are also realized, converts 15V for 24V voltage；Final circuit, which is also realized, is converted to -15V electricity for+15V voltage
Pressure.
Further, the diode for protecting accumulator polarity is provided in power circuit.
Further, reference voltage is set as 3V.
Further, front stage circuits include three proper voltage voltage stabilizing chips and output voltage chip；Three proper voltage pressure stabilizings
Chip uses L7815；Output voltage chip uses DCDC_S5；Final circuit includes charge pump voltage inversion device and low pressure differential mode
Quasi- power supply；Charge pump voltage inversion device is set as ICL7662CPA；Low voltage difference analog power is set as SPX1117；Power-supply system
Circuit further includes AD conversion a reference source potential circuit, including a reference source voltage output chip, the setting of a reference source voltage output chip
For AD530ART.
Further, power circuit to digitally, simulation and signal ground power respectively, then utilize Zero-ohm resistor string
Alliance.
Since input power is directly from the 24V Vehicular accumulator cell on tractor, additional diode is on circuit to protect electricity
Pond polarity.By chip transformation, voltage 5V, 3.3V are provided, wherein 3.3V is CPU operation voltage and the I/O behaviour of LPC2378 chip
Make the operating voltage of voltage and level translator SP3232, the 5V of isolation is peripheral interface circuit use.Signal amplification circuit
The reference voltage an of ± 15V is required with signal effective value transformation circuit, so also to design the electricity an of ± 15V in system
Source circuit, in addition A/D conversion circuit sets the reference voltage of a 3V.The power supply of LPC2378 chip pin interface section is taken
The scheme on total ground, and digitally, simulation ground and signal ground first separate respective cabling, then with the series connection of 0 Ohmic resistance for ground, effectively
Ground reduce digitally on high-frequency noise to simulation and signal ground interference.
This system mainly uses two-stage power supply mode, i.e. prime power circuit and final stage power circuit, prime power circuit
Function be that the 24VDC supply voltage that battery is provided is converted to the voltage of 5VDC, be ready for the conversion of next step voltage,
The component also to need 5VDC in system provides power supply simultaneously, while 24VDC supply voltage is converted to+15VDC；Final stage power supply
The function of circuit is the supply voltage of 5VDC to be converted to 3.3VDC to be system power supply and+15VDC voltage is converted to -15VDC
The reference voltage of ± 15VDC is provided for signal amplification circuit.
The DCDC_ of the three proper voltage voltage stabilizing chip L7815 and output 5V of output+15VDC are selected in prime power circuit
S5.LM7805 is a kind of three terminal integrated voltage stabilizer, it improves the reliability of entire control system.So-called integrated regulator is general
Refer to the integrated circuit for the unstable constant voltage through over commutation being converted into stable output voltage.This kind of device has preferable
Voltage regulation characteristic, adjustment of load characteristic, inhibit input voltage alternating component characteristic, temperature stability and overheat, overcurrent and
Safety operation area automatic protection functions.The schematic diagram of prime power circuit is as shown in Figure 1.
Such as Fig. 2, select charge pump voltage inversion device ICL7662CPA that+15VDC is converted into -15VDC in final circuit, it is low
5VDC is converted into 3.3VDC by pressure difference analog power SPX1117, as shown in Fig. 4-3.Because of requirement ratio of the system to supply voltage
It is higher, and power consumption is not very big, this system power supply selection low voltage difference analog power SPX1117, and feature is：Export electric current
Greatly, output voltage precision is high, and stability is high, and has some substitute products that can directly replace with it, can reduce procurement risk.To the greatest extent
The input voltage that pipe SPX1117 allows is up to 20V, but excessively high voltage rises the calorific value of chip, and cooling system is bad to be set
Meter, while influencing the performance of chip.In this way, it is necessary to which front stage circuits adjust, and the output of prime is selected as 5V.5V is selected to make
For prime voltage output, there are two reasons, first is that this voltage meets the requirement of SPX1117, second is that many devices need 5V at present
Power supply, this 5V can also serve as prime and final stage.
Such as Fig. 3, due to needing to carry out A/D conversion in sensing system, the reference voltage of A/D conversion in the design
VREF=3V, a reference source select AD530ART, and basic circuit is as shown in Figure 3.
The power system circuit provided in the technical program can provide electricity for following tractor sensor technology schemes
Source：
A kind of tractor pressure magnetic induction electric signal output control circuit, including master controller, power system circuit, communication system
System circuit, clock system circuit reset circuit system, signal amplification and signal effective value transformation circuit system.
Further, such as Fig. 5 to Fig. 6, clock system circuit includes the external crystal-controlled oscillation that crystal oscillator frequency is 11.0592MHz；It is multiple
Position circuit system includes reset chip, and reset chip is set as CAT1021；Signal amplification and effective value transformation circuit system include
Instrumentation amplifier；Instrumentation amplifier is set as INA114；Signal amplification and effective value transformation circuit system include A/D converter；
A/D converter is set as AD736.
Further, communication system circuit includes one or more below, serial communication circuit, CAN communication circuit；String
Port communications circuit includes level translator, signal transmitting and receiving chip；Level translator uses RS-232；Signal transmitting and receiving chip uses
SP3232；CAN communication circuit includes CAN controller, the integrated CAN protocol for following CAN specification V2.0B of CAN controller；CAN control
Device processed uses LPC2378.Serial communication circuit and CAN communication circuit can use conventional circuit and realize which is not described herein again.
This system design uses the ARM7-LPC2378 microcontroller of Philips company as main control chip, the chip
It is not only able to satisfy the control and human-computer interaction demand of acquisition system, and there is powerful network function, the system of can be realized is wanted
The various communication protocols asked, while its good reliability, greatly ensure that the requirement of the application of industry spot.
The control system hardware circuit design of intelligent piezomagnetic resistive force sensor mainly include power-supply system, clock system,
The design of design, the signal amplification and signal effective value transformation system of reset system and debugging interface, the design of communication system, control
System hardware system composition processed is as shown in Figure 1.
Clock circuit：The clock circuit of system selects the frequency of external crystal-controlled oscillation for 11.0592MHz.Use 11.0592MHz
Crystal oscillator can make serial port baud rate more accurate, while can support the PLL function and ISP function inside ARM7 microcontroller chip
Energy.
Reset circuit system：Since the high speed of ARM chip, low-power consumption and low-work voltage cause its noise margin lower,
All various aspects such as the ripple of power supply, transient response performance, the stability of clock source and Power Supply Monitoring reliability also proposed more
High requirement.In order to guarantee that any situation generates reliable and stable reset signal, this system selects CAT1021 reset chip, such as
Shown in Fig. 5, it has the function of hand-reset, allows to read and write when wherein WP is low/empty.CAT1021 includes 1 accurate Vcc
Monitor slowdown monitoring circuit and 2 open-drain outputs：RESET andWhen Vcc is lower than threshold voltage is resetted, RESET pin will become
For high level,It will become low level.CAT1021 contains write-protect pin (WP), if WP connection high level, writes
Operation is prohibited.
JTAG debugging interface：It can be potentially encountered many problems in the system development stage, need to debug program, hardware
Test.In order to facilitate exploitation, system debug circuit is devised.Being connected by the interface circuit with ULINK can be carried out emulating
It debugs.The pull down resistor that a 10K is met on RTCK pin keeps the inside ULINK interface of LPC2378 after system reset enabled,
It can direct ULINK artificial debugging.
Signal amplification and effective value transformation circuit system：Since force snesor differential wave adjusts the simulation electricity of circuit output
Pressing signal is voltage difference, very small, and the measurement range of LPC2378A/D module is 0~3.3V, so defeated to sensor
Analog voltage signal out carries out signal enhanced processing and output signal range is amplified within controller measurement range.Such as
Fruit using standard operational amplifier can not only amplified signal both ends voltage, and any direct current signal, noise can be amplified
With other common-mode voltages, therefore useful measuring signal can be submerged in DC offset voltage and noise.And instrument is used to amplify
Device can well solve this problem.The main function of instrumentation amplifier is exactly to inhibit amplification common-mode DC voltage or inhibition pair
Any other voltage of two input terminal common modes simultaneously amplifies differential signal voltage, i.e. voltage difference between two input terminals.The design
The accurate instrumentation amplifier INA114 released using BURR-BROWN company of the U.S., INA114 size is small, and precision is high, and price is low
Honest and clean, offset voltage is low (50 μ V), drifts about small (0.25 μ V/ DEG C), and common-mode rejection ratio is high (being 50dB when G=1000), only needs one
Non-essential resistance RG can be arranged the arbitarygainvalue G between 1 to 10000, and the relational expression of yield value and non-essential resistance is public affairs
Formula 4-1.The output signal range of sensor is proportionally amplified to 0~3V by adjusting resistance RG.
Amplified signal is sent into LPC2378 after effective value transformation circuit and is handled in the design.Measurement exchange
A kind of common method of signal virtual value is using the AC/DC conversion circuit of average value response, and this circuit uses integrated transporting discharging
The conversion of AC/DC is realized with diode composition precision linear rectification circuit, circuit is simple, at low cost.In scientific experiment and engineering
In practice, a large amount of non-sinusoidal waveform can be encountered.In order to realize the accurate measurement to any AC signal voltage effective value, without
Consider the parameter of tested waveform.RMS conversion technology can be used, this method is the definition according to real available value, is led to
Obtained from oversampling circuit carries out the operation of " square-average-extract square root " to input ac voltage, i.e., not by averagely rolling over
It calculates but the virtual value of AC signal is directly converted into direct current signal in proportion.The low price real available value-of AT company of the U.S.
DC converter AD736 is very typical one kind, and AD736 uses the averaging integrated after signal square that can directly measure
The authentic and valid value of waveform, and measurement sensitivity, accuracy also substantially improve.AD736 conversion accuracy is 0.3%
(AD736K is through external circuit adjustment up to 0.1%), full range voltage 200mV, supply voltage be+2.8V (- 3.2V)~±
16.5V, 200 μ A of quiescent power supply current in semiconductor integrated circuit.
As shown in fig. 6, when working sensor, core is can be set in the resistance value for adjusting sliding variable resistance R9 for the connection circuit of AD736
Arbitarygainvalue between piece INA114 from 1 to 10000, differential wave is after INA114 amplifies, through capacitor C23 blocking, into
Enter progress AC value conversion in AD736 chip, is finally fed in LPC2378 chip with direct current output.R20, VD1, VD2 group
At protection circuit.R20 value is bigger, and protective value is better, but frequency characteristic will be made to degenerate, and taking R20 is 33K Ω.C24 is
AD736 is used for necessary external capacitor when AC measurment.The value of average capacitance C25 directly affects the low frequency characteristic of AD736, here
Select C25=33 μ F.
ARM-LPC2378 is internally integrated the successive approximation type a/d converter of 10bit, needs external offer reference voltage
VREF.Channel 7 is selected in A/D conversion, and analog signal is accessed from LPC2378 pin AD0.7.The output of piezomagnetic intelligent force sensor
Analog signal be directly accessed microprocessor after amplification, rectification, filtering and carry out digital-to-analogue conversion, do not need to increase new A/D and turn
Change chip.
Communication system circuit：Communication system shares two schemes, is serial communication mode and CAN communication mode respectively.With
Family selects corresponding communication mode according to host computer signal communication type.Scheme is first is that intelligent piezomagnetic resistive force sensor passes through string
Port communications mode is communicated with other host computers.When intelligence sensor is communicated with other controllers, it is also possible to which UART is direct
Data exchange.When intelligence sensor needs are communicated with PC machine, since PC machine serial ports is RS-232 level, then need RS-232 electric
Flat turn parallel operation SP3232 meets communicating requirement, it has an efficient charge pump, and operating voltage only needs 0.1 μ F capacitor when being 3.3V
It can be operated, charge pump allows to send the signal for meeting RS-232 under some voltage of SP3232 in+3.3V to+5V.
SP3232 chip has 2 drivers and 2 receivers, need to only use 1 driver and 1 receiver in the design.SP3232 core
The ESD of piece is protected so that the pin of driver and receiver can bear ± 15KV human-body model and IEC1000-4-2 air gap
Discharge mode.Meanwhile it includes a kind of low-power consumption shutdown mode, the driving output of device and charge pump are prohibited under the mode,
Under off state, source current is lower than 1 μ A.Scheme is second is that the communication of intelligence sensor and other controllers passes through CAN interface reality
It is existing.Bus is the channel of CPU connection external equipment, generally includes data/address bus (DataBus), address bus (AddressBus)
With control bus (ControlBus).Address bus is responsible for sending address information to external equipment；Control bus is responsible for sending letter
Number control external equipment read or write-in information；Control bus is responsible for sending signal control external equipment.Bus is advised
Communication standard of the model between CPU and peripheral hardware, simplifies the design of external devices.It is can be effectively reduced out using general bus
Send out cost.The CAN controller of LPC2378 is integrated with a complete CAN protocol (following CAN specification V2.0B), can complete object
The institute for managing layer and data link layer is functional.The pin CAN1RXD and CAN1TXD of CAN controller 1, pass through as built in LPC2378
Isolation bus transceiver CTM1050T is connected with CAN physical bus, it is integrated with all necessary electrical components in inside, including
Isolation circuit, CAN transceiver, power circuit and esd bus protect device, can more avoid drawing due to surge, interference
The bus error or element fault risen.The logic level transition of CAN controller is the differential level of CAN bus by CTM1050T,
And there is (DC2500V) isolation features, ESD defencive function and the anti-bus over-voltage of TVS pipe.
This control system is selected using two sets of communication modes for user：Serial ports direct communication and CAN communication, application range is more
Extensively.CAN communication program includes：Initialization (as shown in figure 14), the reception of CAN, the transmission of CAN of CAN controller.
LPC2378CAN controller is one with sending and receiving the serial line interface of buffer, but it and without containing checking and accepting filter.
Checking and accepting filter is an independent module, can carry out the filtering of CAN identifier to all channels CAN.CAN controller initialization
The messaging parameter of CAN is mainly set.The CAN control register for needing to initialize has：Mode register, connects time-division register
Receive code register, mask register, bus timing register, output control register etc..It is worth noting that：This register
It can only just can write access in the case where CAN controller is in reset state.Initialization subroutine is substantially carried out to CAN built in LPC2378
The setting of controller and the initialization for receiving buffer area.According to the communication protocol of regulation, bus baud rate is arranged first, matches for program
Set extension frame mode.
CAN DRP data reception process is as shown in figure 13, when CAN transceiver, which detects, has data in CAN bus, CAN transmitting-receiving
Differential level signal in CAN bus is converted into bit stream data by device, is aligned by error manager and bit timing logic unit
Data flow and timing are checked, bit stream data is converted into byte data using bit stream manager and is stored in reception buffering
In device, data receiver interruption is then generated by reception buffer after frame data reception has been expired and (CPU is notified to have been received one
Frame new data), and the various states of generation are indicated by changing the value of status register.
It is as shown that CAN message receives process Figure 12.The reception of message uses interrupt mode, complete in CAN initialization program
It is received at CAN after interrupting initialization, so that it may which message is received by interrupt service routine.When receiving a frame, buffer
When area is filled, interrupt；Or it when having sent a frame, interrupts.Interrupt address must be eliminated when exiting interruption,
It removes and receives interrupt flag bit, and software reset receives interrupt flag bit.When reading the data, it to empty and receive buffer area,
Otherwise interruption can be continuously generated.Interrupt service routine flow chart please refers to hereafter task design part.
CAN transmission flow is as shown in figure 11, sends data program and data to be sent in data storage area are taken out, composition
Information frame, and by the address ID of host, frame head is inserted, then send information frame to the transmission buffer area of CAN controller.Then it opens
The transmission of dynamic CAN controller is enabled, and the data of transmission pass through bit stream manager respectively and (become the binary system sent in bus
Code), mistake manages logic (be responsible for detection bus state and send whether there is mistake) and bit timing logic (management data total
Transmission timing on line), CAN transceiver (be responsible for bit stream data be converted into the differential level that CAN bus can be transmitted), in this way
Just complete the transmission of a frame CAN data.Information, which is sent to bus from CAN controller, to be automatically performed by CAN controller.
Serial communication refers to that one ground sequence of data transmits, its main feature is that communication line is simple, as long as a pair of of transmission
Line can realize two-way communication, thus greatly reduce cost.LPC2378 series A RM has 4 and meets 16C550 industry mark
Quasi- asynchronous serial port UART0~3.UART Universal Asynchronous Receiver Transmitter (UART) is exactly the crucial mould that equipment room carries out asynchronous serial communication
Block.Its important function is as follows：
1. handling serial/parallel, the parallel/serial conversion between data/address bus and serial port；
As long as 2. communicating pair using identical frame format and baud rate, can in the case where not shared clock signal,
Communication process only can be completed with two signal wires (RX and TX).
The program of serial ports Direct Communication includes：Initialization of (a) serial ports, rs 232 serial interface signal send and receive.Serial ports receives and dispatches process as schemed
Shown in 15, in the design, setting baud rate function enables slave computer synchronous with host computer, then, judges whether serial ports receives
The data that host computer is sent, how serial ports receives new data, then generates reception and interrupt, and receives data and carries out respective handling,
If not receiving the data of host computer transmission, using FIFO is sent, the A/D of signal processing is converted in a manner of inquiry
Data are sent in the form of character string.
Intelligent Sensorsystem is controlled using microcontroller, is greatly improved performance, has especially been also equipped with flexible adaptation
The ability of various different applications.When application environment or requirement change, such as set according to live feature different
Datum mark or change output signal type, the different signal processing algorithm of selection etc., due to micro-processor controlled flexibility, usually
Without changing hardware design and control program, and only the system configuration setting of sensor and certain running parameters work are repaired accordingly
Change, sensor can be made to meet the requirements well].Such characteristic greatly improves the scope of application of sensor and versatility,
Micro-processor controlled flexible characteristic is further embodied.
This project realizes the reconfiguration of intelligent displacement sensing system using external hanging type man-machine conversation mode.Made using ECU
For external hanging type people-machine Interface of intelligence sensor, number can be exchanged by CAN communication between the two or serial communication
According to realization sensor carries out system configuration with man-machine conversation mode.In addition, it is also expansible auxiliary with ECU is carried out to sensor
Digitalized calibration function is helped, more greatly improves system configuration ability.
When needing the system configuration (baud rate, the range ability of such as serial communication) to sensor to modify, it
It is established and is communicated by the communication mode and ECU of selection, the original system configuration setting of sensor is then sent to ECU and is shown, is grasped
Author can modify repeatedly these settings on ECU.Configuration modification finishes, then new configuration setting is passed back sensor and is saved
Area is arranged in system configuration in nonvolatile memory.It such as also needs to demarcate, then ECU compounding practice person command sensor is gradually completing
Calibration, and nominal data is stored in nonvolatile memory.Then sensor by the new system configuration mode and will work as
Preceding calibration setting work is until modifying system configuration or calibration next time.
The reset circuit of this project minimum system, the chip of selection are CAT1021, and CAT1021 is embedded with one 2K
Serial EEPROM, the various system configuration definition of sensor are just stored in here, and the relation curve that rating test obtains is with grid
Form be stored in the inside, in later measurement process data fusion extend calculate.
The present invention is exclusively used in a kind of tractor resistance detection device, as shown in Figure 7 to 10, a kind of tractor resistance detection
Device, including shearing force incude shell 1, and shearing force induction shell 1 is internally provided with electrical signal conversion device 2, electric signal conversion
Device 2 is set as piezomagnetic force snesor, and piezomagnetic force snesor is connected with electric signal output control circuit.
Further, shearing force induction shell 1 is set as round pin shape；Being internally provided with for shearing force induction shell 1 is interior
Hole 4；Pressure sensor 5 is provided in inner hole 4；Pressure sensor 5 includes excitation magnetic core 6, and excitation magnetic core 6 is arranged inside inner hole
Face shears the position of concentration zones 3, and induction magnetic core 7, longitudinal direction where induction 7 magnetic pole of magnetic core are provided at left and right sides of excitation magnetic core 6
Section and longitudinal profile where the magnetic pole of induction magnetic core are in 90 °；The magnetic pole for incuding magnetic core 7 is located at shearing concentration zones；Excitation magnetic core 6
Cylindrical entirety is formed with induction magnetic core 7, is fitted close with inner hole 4；Fluted 8 are arranged in the middle part of shearing force shell 1；Excitation magnetic core
Fixed device 9 is provided between 6 outsides and induction magnetic core 7, fixed device 9 includes excitation magnetic core enclosure 91 and fixed part 92,
Fixed part 92 is matched with the fixed groove 10 of 1 starting point of shearing force shell；1 end of shearing force shell is provided with chamfering.
Since the output signal of sensor is related with the variation of magnetic flux in magnetic circuit, so the direct shadow of the rational design of magnetic circuit
Ring the size of sensor output signal.Magnetic Circuit Design seeks to reduce magnetic dispersion to the greatest extent, improves electricity-magnetic transfer efficiency, keeps away as far as possible
Exempt to generate the eddy current magnetism etc. that stray magnetic fields such as current vortex generates in device operation, improves the equal of magnetic field locating for magnetic material
Even property etc..So the mechanism of piezomagnetic force snesor should be close, material magnetic characteristic variation should be obvious.
The selection of the intensity of magnetization will affect the sensitivity of sensor, so according to the typical magnetization characteristic of ferromagnetic material
With the relationship of magnetic conductivity and magnetic field strength, the region for selecting magnetization characteristic more sensitive is more conducive to sensor.Due in sensor
In the course of work, for sensor by shearing force, the existing increase under tension and compression state of the magnetic conductivity of measured material has reduction area again
Domain, and according to the magnetization characteristic of ferromagnetic material, the additional excitation intensity of magnetization had better not be greater than the saturation magnetization of material,
Otherwise, material embodies the telescopic deformation of volume.So the selection of magnetic field strength should be between minimum magnetic conductivity and maximum magnetic conductance
And it is located at the ascent stage that permeability curcve variation tendency is big in figure.Increase the tolerable bigger exciting current of coil line footpath to pass through,
The intensity of magnetization can then be increased by increasing coil turn.
But due to the limitation of permeability magnetic material physical structure, by magnetic flux can not infinitely increase, pass through certain body
The magnetic flux of product permeability magnetic material is greatly to after certain amount, no matter being further added by electric current or the number of turns, magnetic flux is not further added by, at this moment
Permeability magnetic material has reached magnetic saturation.So when selecting the core material of sensor, be considered as high with magnetic permeability, loss is small,
Material of the line segment of magnetization curve compared with performances such as wide, the big, magnetic stabilities of resistivity.Magnetic core uses stacked magnetic core, between two layers
Appropriate gap can reduce the inductance value of coil, avoid direct current cable order core saturation, while stacked high resistivity magnetic core can
To prevent the generation of vortex or reduce energy loss caused by vortex.
Core material can influence the magnetic induction intensity in magnetic field, so selecting suitable core material for output signal
Power has a certain impact.After preliminary screening, the stable common magnetic core high resistivity material iron of the domestic performance of core material selection
Nickel alloy and silicon steel sheet, by the further comparison of two kinds of materials, the advantages of iron-nickel alloy is that have high magnetic under downfield
Conductance and very low coercivity.The processability of iron-nickel alloy is good, various shape complexity can be made, size requires accurate member
Part.Compared to silicon steel sheet B30P110, iron-nickel alloy 1J85 have very high initial permeability, high resistivity, extremely low coercivity and
Very high maximum permeability, is quick on the draw to small-signal, and saturation induction density is low.According to the comparison of two kinds of materials, this reality
Applying example can choose permalloy 1J85 as core material.
Since the coil wound on sensor magnetic pole can generate magnetic flux edge effect during the work time, i.e., closer to coil
The region at both ends, magnetic induction line more dissipate.Magnetic induction line diverging is unfavorable for the variation of induction coil induced flux, in order to reduce magnetic flux side
The influence of edge effect should increase magnetic pole face size as far as possible, reduce magnetic pole pitch.So the internal structure of piezomagnetic force snesor
It should cooperate between external structure closely, distance is unsuitable too far between excitation pole and induction magnetic pole.
According to the above analysis, the basic structure size and pictorial diagram of excitation magnetic core are as shown in Fig. 3-3.It is wound on excitation magnetic core
Diameter is the enameled wire of 0.21mm, totally 240 circle.When exciting current passes through magnet exciting coil, a size will be generated with excitation electricity
Changing magnetic field is flowed, the magnetomotive force in this magnetic field is
e0=N0I0 (3-1)
N in formula0For magnet exciting coil the number of turns；I0For exciting current.
Basic structure size and the pictorial diagram for incuding magnetic core are as shown in Figure 3-4.Incude and is twined on each induction magnetic pole of magnetic core
The enamel wire coil for being 0.11mm around 90 circle line footpaths.When magnetic field changes, the variation of induction coil induced flux generates sense
Answer electromotive force.
Sensor internal mechanism is packaged into an entirety with duroplasts, such as both fixed relative position, such as Fig. 1 to Fig. 2
Shown, longitudinal profile where excitation magnetic core magnetic pole and longitudinal profile where the magnetic pole of induction magnetic core are in 90 °, and internal structure is integrally done
It at cylinder, is fitted close with centrepin inner hole, installation diagram is as schemed；The magnetic pole of internal excitation magnetic core is located at shearing concentration zones,
Induction magnetic pole is located at shearing concentration zones both sides.Fixation device in figure, the hard plastic body head for encapsulating internal element are stretched out
In one positioning protrusion insertion centrepin head edge positioning groove.
Such as Fig. 8, when non-stress, a symmetric magnetic field, each section of magnetic resistance phase of pin surfaces are formed between primary coil the two poles of the earth
Deng, equal by the magnetic flux of induction coil, since coil E1, E2 are reversely concatenated, E3, E4 are reversely concatenated, two groups of positive concatenations again,
Differential connection is formed, so magnetic flux is cancelled out each other, sensor output is zero；When axis is by shearing force, intrinsic isotropism
The magnetism of magnetic material will change, and then magnetic field reforms into asymmetry, generate to draw in 45 ° and 135 ° of its surface direction and answer
Power and compression.According to ferromagnetics, as the saturation magnetostriction constant λ of steel materialS> 0, then in the magnetic bullet in tensile stress direction
Performance is minimum, is direction of easy axis, i.e., magnetic conductivity increases, and magnetic resistance reduces；And in compression direction, magnetic conductivity reduces, and magnetic resistance increases
Greatly.Therefore, the Φ value variation at E1, E2, E3, E4, then sensor has induction voltage output, can by the calibration to sensor
Obtain the relationship of induced voltage and stress, so as to which lifter is promoted or reduced according to the size of tractive resistance and variation,
To keep the stabilization of engine load.
According to true form, when tension, magnetic conductivity increases, and magnetic resistance reduces, and magnetic flux increases；When compression, magnetic conductivity reduces, magnetic
Resistance increases, and magnetic flux reduces.
As the magnetic circuit of sensor can be equivalent to shown in Fig. 10 etc. by Figure 10 according to the principle Analysis of force snesor
Imitate magnetic circuit.R1, R2, R3, R4 be respectively magnetic flux flow through four induction magnetic pole magnetic resistance (including induction core reluctance, induction magnetic pole
To measured surface air-gap reluctance and corresponding measured surface section magnetic resistance), R5 be measured material surface without induction magnetic pole that
The magnetic resistance of part magnetic flux, R0 are the resistance that magnetic flux flows through excitation pole.In calculating process, because flowing through the magnetic flux Φ 5 of R5 relatively very
It is small, so ignoring.
Not to centrepin applied force or it is static when, by magnetic circuit symmetrically known to Φ 1=Φ 2=Φ 3=Φ 4, connected according to magnetic flux
Continuous property principle has Φ 0=Φ 1+ Φ 2+ Φ 3+ Φ 4, for taking a closed magnetic circuit.According to Ampère circuital theorem and magnetic circuit ohm
Law has
e0=N0I0=R0φ0+R1φ1=(4R0+R1)φ1 (3-19)
In formula
E0-magnetomotive force；
R0, r1-are respectively excitation pole and the air-gap reluctance for incuding magnetic pole E1；
The magnetic resistance of excitation pole in R0-loop；
The equivalent magnetic resistance of magnetic core is incuded in RE1-loop；
Measured surface E1-O2 sections of magnetic resistance in RC1O-loop；
Measured surface O1-E2 sections of magnetic resistance in RCO1-loop.
The magnetic conductivity relationship of magnetic resistance and material is
In formula
L-is the length of magnetic path of magnetic core and measured material；
μ-is the magnetic conductivity of magnetic core or measured material；
S-is the magnetic circuit sectional area of magnetic core or measured material.
Formula 3-21 is substituted into formula 3-20 and is obtained
In formula
Air gap under 0-excitation pole of δ；
δ 1-incudes the air gap under magnetic pole E1；
μ 0, μM, μ C-be respectively air, magnetic core, measured material absolute permeability；
S0-excitation pole end on projection and magnetic flux are in each area of section of excitation pole；
S1-induction magnetic pole end on projection and magnetic flux are in induction each area of section of magnetic pole；
The area of section that SC1O-magnetic flux is flowed through to the end excitation pole O2 in measured surface from induction magnetic pole；
The area of section that SCO1-magnetic flux is flowed through from the end excitation pole O1 to induction magnetic pole in measured surface；
N0-magnet exciting coil the number of turns；
L0, l1-are respectively excitation magnetic core in closed magnetic path, the length of magnetic path for incuding magnetic core；
The length of magnetic path that lC1O-magnetic flux is flowed through to the end excitation pole O2 in measured surface from induction magnetic pole；
The length of magnetic path that lCO1-magnetic flux is flowed through from the end excitation pole O1 to induction magnetic pole in measured surface；
According to the symmetry of magnetic circuit, lCO1 ≈ lC1O, SCO1 ≈ SC1O, δ0≈δ1, enable Then
Then
φ1=KMe0=KMN0I0 (3-24)
When centrepin bears shearing force, 45 ° and 135 ° of surface direction generates tension and compression stress, the magnetic conductivity on corresponding surface
It increases separately Δ μ C or reduces Δ μ C, then four induction coils output induced voltage is respectively+Δ U and-Δ U.
According to the symmetry of induction magnetic core, Φ 1 and Φ 2 are flowed through at E1 coil, Φ 1, Φ 2 are contrary, and active force is such as
When figure, μ C1=μ C- Δ μ C, μ C2=μ C+ Δ μ C, Φ 1 is reduced, Φ 2 increases, then
Since tension and compression stress absolute value is equal,And magnetic core and axis are transition fit relationship, magnetic gap variation
Influence it is comparatively small, can be by δ0Regard constant as, then the induced electromotive force that E1 coil generates is：
Similarly
Because induction coil is differential connection, so the output voltage of sensor is：
When loading static force
At this point,It is related with the variation of the magnetic conductivity of measured material and derivative of current.When sensor exciting current is sine
Signal I0=i0When sin ω t, sensor output voltage is：
As shown in figure 9, lower pull rod 13 exerts a force to centrepin, and centrepin is in lower pull rod and fulcrum bearing when tractor work
Maximum shear stress effect is born in 11 parting surface region, groove 8 is used to amplify the deformation that shear stress bears shell 1.Meanwhile
The magnet exciting coil for inputting exciting current generates magnetic field, according to the pass between the variation of the relative permeability of magnetic material and mechanical stress
System, magnetic conductivity changes when centrepin stress, and magnetic flux also changes, and the variation of induction coil induced flux generates induction
Electromotive force.
When work, pin-shaped sensor is assembled under farm implements between pull rod and tractor-drawn shell, when tractor operation,
Soil forms shearing force to sensor concentration zones by pull rod under tractor to the resistances of farm implements, it is made to generate shearing force and curved
Square, shearing force and moment of flexure here make its magnetic conductivity change, and magnetic flux also changes, induction coil and induced flux
Variation generates induced electromotive force, to generate electric signal, the electric signal of generation is transmitted and handled by control signal circuit,
And then realize the detection of tractor resistance, it can accurately incude resistance suffered by tractor, and more accurate hindering
Feedback is realized in Force control system.
The preferred embodiment of the present invention has been described in detail above.It should be appreciated that those skilled in the art without
It needs creative work according to the present invention can conceive and makes many modifications and variations.Therefore, all technologies in the art
Personnel are available by logical analysis, reasoning, or a limited experiment on the basis of existing technology under this invention's idea
Technical solution, all should be within the scope of protection determined by the claims.
Claims (5)
1. a kind of tractor presses magnetic induction power circuit, it is characterized in that：Input power is connect with the battery on tractor, described
Power circuit includes prime power circuit and final stage power circuit；The front stage circuits realize conversion of the 24V voltage to 5V voltage；
The final circuit realizes conversion of the 5V voltage to 3.3V voltage；
The front stage circuits, which are also realized, converts 15V for 24V voltage；The final circuit also realize+15V voltage is converted to-
15V voltage.
2. tractor as described in claim 1 presses magnetic induction power circuit, it is characterized in that：It is arranged in the power circuit useful
In the diode for protecting the accumulator polarity.
3. tractor as described in claim 1 presses magnetic induction power circuit, it is characterized in that：The reference voltage is set as
3V。
4. tractor as described in claim 1 presses magnetic induction power circuit, it is characterized in that：The front stage circuits include three proper
Voltage voltage stabilizing chip and output voltage chip；
The three proper voltage voltage stabilizing chip uses L7815；
The output voltage chip uses DCDC_S5；
The final circuit includes charge pump voltage inversion device and low voltage difference analog power；
The charge pump voltage inversion device is set as ICL7662CPA；
The low voltage difference analog power is set as SPX1117；
The power system circuit further includes AD conversion a reference source potential circuit, including a reference source voltage output chip, the base
Quasi- source voltage output chip is set as AD530ART.
5. tractor as described in claim 1 presses magnetic induction power circuit, it is characterized in that：The power circuit to digitally,
Simulation ground and signal ground are powered respectively, are then connected using Zero-ohm resistor for ground.
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| CN201810910607.1A CN108923648A (en) | 2018-08-12 | 2018-08-12 | A kind of dedicated and tractor pressure magnetic induction sensor power circuit |
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| CN2574062Y (en) * | 2002-10-17 | 2003-09-17 | 北京安控科技发展有限公司 | Current signal conditioning circuit |
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| CN2574062Y (en) * | 2002-10-17 | 2003-09-17 | 北京安控科技发展有限公司 | Current signal conditioning circuit |
| CN103158713A (en) * | 2013-03-11 | 2013-06-19 | 河南科技大学 | Tractor intelligent control method and intelligent control system |
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