CN109240150A - A kind of tractor pressure magnetic induction electric signal output control circuit - Google Patents
A kind of tractor pressure magnetic induction electric signal output control circuit Download PDFInfo
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- CN109240150A CN109240150A CN201810910608.6A CN201810910608A CN109240150A CN 109240150 A CN109240150 A CN 109240150A CN 201810910608 A CN201810910608 A CN 201810910608A CN 109240150 A CN109240150 A CN 109240150A
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- G—PHYSICS
- G05—CONTROLLING; REGULATING
- G05B—CONTROL OR REGULATING SYSTEMS IN GENERAL; FUNCTIONAL ELEMENTS OF SUCH SYSTEMS; MONITORING OR TESTING ARRANGEMENTS FOR SUCH SYSTEMS OR ELEMENTS
- G05B19/00—Programme-control systems
- G05B19/02—Programme-control systems electric
- G05B19/04—Programme control other than numerical control, i.e. in sequence controllers or logic controllers
- G05B19/042—Programme control other than numerical control, i.e. in sequence controllers or logic controllers using digital processors
- G05B19/0423—Input/output
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- G—PHYSICS
- G05—CONTROLLING; REGULATING
- G05B—CONTROL OR REGULATING SYSTEMS IN GENERAL; FUNCTIONAL ELEMENTS OF SUCH SYSTEMS; MONITORING OR TESTING ARRANGEMENTS FOR SUCH SYSTEMS OR ELEMENTS
- G05B2219/00—Program-control systems
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Abstract
The invention discloses a kind of tractors to press magnetic induction electric signal output control circuit, including master controller, power system circuit, communication system circuit, clock system circuit, reset circuit system, signal amplification and signal effective value transformation circuit system.Tractor provided by the invention presses magnetic induction electric signal output control circuit, it can be in sensor operational process, detecting element survey signal can real-time perfoming filtering, the pre-processings such as shaping and amplification, and it is converted into the signal that controller can identify, A/D conversion is carried out to signal by controller again, software filtering and sampling calculate, obtain the actual value of sensor institute dynamometry, and, the pressure magnetic induction electric signal that the present invention designs this answer circuit will digitally, simulation ground and signal ground separate respective cabling, it is effectively reduced high-frequency noise on digitally to simulation and the interference of signal ground.
Description
Technical field
The present invention relates to field of agricultural machinery, more particularly to a kind of tractor pressure magnetic induction electric signal output control electricity
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 logical for adjusting the tractive force of farm implements
It crosses resistance control system to realize, resistance control system is a very important subsystem of electrohydraulic hitch system.Tradition
Tractor use the power that is promoted as farm implements of simple hydraulic device, control section be it is mechanical, behaviour is passed through by driver
Vertical handle and a set of rod piece mechanism input signal in the form of displacement, output quantity are then by spring, cam and power, position tune
The displacement that section lever mechanism is converted into, to realize adjustment of the manipulation main control valve to farm implements position.Mechanical course it is hydraulic
Suspension uses rod piece and elastic element, and structure is more complicated, the sluggishness of elastic element, mechanical friction and rod piece breathing
It will affect regulation performance, and the shadow of the uncertain factors such as non-linear due to variation, hydraulic lift mechanism by edaphic condition
It rings, the work quality of conventional hydraulic suspension mechanism is not high, therefore the foundation for causing the precise control model of system is relatively more tired
Difficulty, and be unfavorable for realizing the automation and intelligence of tractor set operation.Currently, electrohydraulic hitch system has replaced tractor
Traditional hydraulic lift mechanism.
But the most important problem of setting of electrohydraulic hitch system is how to establish mechanical displacement and tractor at present
Resistance situation to electric signal conversion, due to the special power environment of tractor itself, in sensor operational process, detection member
The pre-processings such as the signal that part is surveyed needs to filter with real-time perfoming, shaping and amplification, and be converted into controller and can know
Other signal, then A/D conversion, software filtering and sampling are carried out to signal by controller and calculated, obtain the reality of sensor institute dynamometry
Actual value.Therefore those skilled in the art are dedicated to developing a kind of tractor pressure magnetic induction electric signal output control circuit, Neng Goujing
Really resistance suffered by induction tractor, realizes feedback, and then make electro-hydraulic hitch system in resistance control system more accurately
System is sensitiveer and accurately realizes control.
Summary of the invention
In view of the above drawbacks of the prior art, technical problem to be solved by the invention is to provide a kind of tractors to press magnetic
Electrical signal of reaction output control circuit can accurately incude resistance suffered by tractor, more accurately in draught control system
Feedback is realized in system, and then is kept electrohydraulic hitch system sensitiveer and accurately realized control.
To achieve the above object, the present invention provides a kind of tractors to press magnetic induction electric signal output control circuit, including
Master controller, communication system circuit, clock system circuit, resets circuit system, signal amplification and signal at power system circuit
Effective value transformation circuit system.
Preferably, the power system 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
It also realizes and converts 15V for 24V voltage；The final circuit, which is also realized, is converted to -15V voltage for+15V voltage.
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
Chip, a reference source voltage output chip are set as AD530ART.
Preferably, the clock system circuit includes the external crystal-controlled oscillation that crystal oscillator frequency is 11.0592MHz；The reset system
Circuit of uniting includes reset chip, and the reset chip is set as CAT1021；The signal amplification and effective value transformation system electricity
Road includes instrumentation amplifier；The instrumentation amplifier is set as INA114；The signal amplification and effective value transformation circuit system
Including A/D converter；The A/D converter is set as AD736.
Preferably, the communication system circuit includes one or more below, serial communication circuit, CAN communication circuit；
The serial communication circuit includes level translator, signal transmitting and receiving chip；The level translator uses RS-232；The letter
Number transceiving chip uses SP3232；The CAN communication circuit includes CAN controller, and the CAN controller is integrated to follow CAN rule
The CAN protocol of model V2.0B；The CAN controller uses LPC2378.
The beneficial effects of the present invention are: tractor provided by the invention presses magnetic induction electric signal output control circuit, it can
In sensor operational process, signal that detecting element is surveyed can the pre-processings such as real-time perfoming filtering, shaping and amplification, and will
It is converted to the signal that controller can identify, then carries out A/D conversion, software filtering and sampling to signal by controller and calculate,
Obtain the actual value of sensor institute dynamometry, also, the pressure magnetic induction electric signal that designs of the present invention this answer circuit will digitally, mould
Quasi- ground and signal ground separate respective cabling, and the high-frequency noise being effectively reduced on digitally to simulation is done with signal ground
It disturbs.
Detailed description of the invention
Fig. 1 is electric signal output control circuit composition figure.
Fig. 2 is front stage circuits hardware elementary diagram in electric signal output control circuit.
Fig. 3 is final circuit hardware elementary diagram in electric signal output control circuit.
Fig. 4 is a reference source potential circuit hardware elementary diagram in electric signal output control circuit.
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, a kind of tractor presses magnetic induction electric signal output control circuit, including master controller, power-supply system
Circuit, clock system circuit, resets circuit system, signal amplification and signal effective value transformation system electricity at communication system circuit
Road.
Further, such as Fig. 2 to Fig. 3, power system circuit includes prime power circuit and final stage power circuit；Prime electricity
Realize conversion of the 24V voltage to 5V voltage in road；Final circuit realizes conversion of the 5V voltage to 3.3V voltage；Front stage circuits are also real
Now 15V is converted by 24V voltage；Final circuit, which is also realized, is converted to -15V voltage for+15V voltage.
Further, such as Fig. 2 to Fig. 4, front stage circuits include three proper voltage voltage stabilizing chips and output voltage chip；Three ends
Positive voltage voltage stabilizing chip uses L7815；Output voltage chip uses DCDC_S5；Final circuit includes charge pump voltage inversion device
With low voltage difference analog power；Charge pump voltage inversion device is set as ICL7662CPA；Low voltage difference analog power is set as
SPX1117；Power system circuit further includes AD conversion a reference source potential circuit, including a reference source voltage output chip, a reference source
Voltage output chip is set as AD530ART.
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 packet
Include instrumentation amplifier；Instrumentation amplifier is set as INA114；Signal amplification and effective value transformation circuit system include A/D conversion
Device；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, no longer superfluous here
It states.
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 is as shown in Figure 1.
Power system circuit: since input power is directly from the 24V Vehicular accumulator cell on tractor, additional two on circuit
Pole pipe is to protect battery polar.By chip transformation, voltage 5V, 3.3V are provided, wherein 3.3V is that the CPU of LPC2378 chip is grasped
Make the operating voltage of voltage and I/O operation voltage and level translator SP3232, the 5V of isolation is peripheral interface circuit use.
Signal amplification circuit and signal effective value transformation circuit require the reference voltage an of ± 15V, so also to design in system
The power circuit of one ± 15V, in addition A/D conversion circuit sets the reference voltage of a 3V.LPC2378 chip pin interface
Partial power supply takes the scheme on total ground, and digitally, simulation ground and signal ground first separate respective cabling, then with 0 ohm of electricity
Resistance series connection is effectively reduced high-frequency noise on digitally to simulation and the interference of signal ground for ground.
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, carry out standard for the conversion of next step voltage
It is standby, while also the component to need 5VDC in system provides power supply, while 24VDC supply voltage is converted to+15VDC；Final stage
The function of power circuit be the supply voltage of 5VDC is converted to 3.3VDC be system power supply and+15VDC voltage is converted to-
15VDC provides the reference voltage of ± 15VDC 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 one
As refer to the integrated circuit for the unstable constant voltage through over commutation being converted into stable output voltage.This kind of device have compared with
Voltage regulation characteristic well, inhibits input voltage alternating component characteristic, temperature stability and overheat, is excessively electric adjustment of load characteristic
Stream and safety operation area automatic protection functions.The schematic diagram of prime power circuit is as shown in Figure 2.
Select charge pump voltage inversion device ICL7662CPA that+15VDC is converted into -15VDC, low pressure differential mode in final circuit
5VDC is converted into 3.3VDC by quasi- power supply SPX1117, as shown in Figure 7.Because requirement of the system to supply voltage is relatively high, and
And power consumption is not very big, this system power supply selection low voltage difference analog power SPX1117, feature are as follows: output electric current is big, output
Voltage accuracy is high, and stability is high, and has some substitute products that can directly replace with it, can reduce procurement risk.Although
The input voltage that 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.Select 5V
As prime voltage output, there are two reasons, first is that this voltage meets the requirement of SPX1117, second is that many devices need at present
5V is wanted to power, this 5V can also serve as prime and final stage.
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: 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.
If using standard operational amplifier can not only amplified signal both ends voltage, and any direct current signal can be amplified, made an uproar
Sound and other common-mode voltages, therefore useful measuring signal can be submerged in DC offset voltage and noise.And use instrument with putting
Big device can well solve this problem.The main function of instrumentation amplifier is exactly to inhibit amplification common-mode DC voltage or suppression
Any other voltage to two input terminal common modes is made, differential signal voltage, i.e. voltage difference between two input terminals are simultaneously amplified.
The accurate instrumentation amplifier INA114 that the design uses BURR-BROWN company in the U.S. to release, INA114 size is small, and precision is high,
Cheap, 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
Need a non-essential resistance RG that the arbitarygainvalue G between 1 to 10000, the relationship of yield value and non-essential resistance can be set
Formula is 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
It must consider the parameter of tested waveform.RMS conversion technology can be used, this method is the definition according to real available value
Formula does not pass through obtained from the operation for carrying out " square-average-extract square root " to input ac voltage as circuit
It is average to convert but the virtual value of AC signal is directly converted into direct current signal in proportion.The low price of AT company of the U.S. is true
Virtual value-DC converter AD736 is very typical one kind, and AD736 uses the averaging integrated after signal square can
Directly to 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 AC value conversion is carried out in AD736 chip, finally fed in LPC2378 chip with direct current output.R20,VD1,
VD2 composition 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
Necessary external capacitor when for AD736 for AC measurment.The value of average capacitance C25 directly affects the low frequency characteristic of AD736,
Here C25=33 μ F is selected.
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.Piezomagnetic intelligent force sensor is defeated
Analog signal out is directly accessed microprocessor after amplification, rectification, filtering and carries out digital-to-analogue conversion, does not need to increase new A/D
Conversion 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
Serial communication mode is communicated with other host computers.When intelligence sensor is communicated with other controllers, it is also possible to which UART is straight
Connect data exchange.When intelligence sensor needs are communicated with PC machine, since PC machine serial ports is RS-232 level, then RS- is needed
232 level translator SP3232 meet communicating requirement, it has an efficient charge pump, and operating voltage only needs 0.1 when being 3.3V
μ F capacitor can be operated, and charge pump, which allows to send under some voltage of SP3232 in+3.3V to+5V, meets RS-232
Signal.SP3232 chip has 2 drivers and 2 receivers, need to only use 1 driver and 1 receiver in the design.
The ESD of SP3232 chip protect so that the pin of driver and receiver can bear ± 15KV human-body model and
IEC1000-4-2 bubble-discharge mode.Meanwhile it includes a kind of low-power consumption shutdown mode, the driving output of device under the mode
It is prohibited with charge pump, under off state, source current is lower than 1 μ A.Scheme second is that intelligence sensor and other controllers it is logical
Letter is realized by CAN interface.Bus is the channel of CPU connection external equipment, generally includes data/address bus (DataBus), address
Bus (AddressBus) and control bus (ControlBus).Address bus is responsible for sending address information to external equipment；Control
Bus processed is responsible for sending signal control external equipment reading or write-in information；Control bus is responsible for sending signal control outside
Equipment.The appearance of bus has standardized the communication standard between CPU and peripheral hardware, simplifies the design of external devices.Using general
Development cost can be effectively reduced in bus.The CAN controller of LPC2378 is integrated with a complete CAN protocol and (follows CAN rule
Model V2.0B), the institute that can complete physical layer and data link layer is functional.The pin of CAN controller 1 as built in LPC2378
CAN1RXD and CAN1TXD is connected by isolation bus transceiver CTM1050T with CAN physical bus, it is integrated in inside
All necessary electrical components, including isolation circuit, CAN transceiver, power circuit and esd bus protect device, can be compared with
Mostly avoid the bus error due to caused by surge, interference or element fault.CTM1050T is by the logic level of CAN controller
The differential level of CAN bus is converted to, and there is (DC2500V) isolation features, ESD defencive function and the anti-bus mistake of TVS pipe
Pressure.
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.LPC2378
CAN controller is one with sending and receiving the serial line interface of buffer, but it and without containing checking and accepting filter.Check and accept filtering
Device is an independent module, can carry out the filtering of CAN identifier to all channels CAN.CAN controller initializes
The messaging parameter of CAN is set.The CAN control register for needing to initialize has: mode register, receives code at time-division register
Register, mask register, bus timing register, output control register etc..It is worth noting that: this register can only
It just can write access in the case where CAN controller is in reset state.Initialization subroutine, which is substantially carried out, controls CAN built in LPC2378
The setting of device and the initialization for receiving buffer area.According to the communication protocol of regulation, bus baud rate is arranged in program first, configuration
Extend 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 and is stored in reception to delay using bit stream manager
It rushes in device, data receiver interruption is then generated by reception buffer after frame data reception has been expired and (notifies CPU received
To a 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.It must be eliminated interruptedly when exiting interruption
Location removes and receives interrupt flag bit, and software reset receives interrupt flag bit.When reading the data, reception buffering is emptied
Otherwise area can continuously generate interruption.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
The transmission for starting CAN controller is enabled, the data of transmission pass through respectively bit stream manager (become sent in bus two into
Code processed), mistake manages logic (be responsible for detection bus state and send whether there is mistake) and bit timing logic (management data
Transmission timing in bus), CAN transceiver (is responsible for bit stream data to be converted into the differential electrical that CAN bus can be transmitted
It is flat), this completes the transmissions of a frame CAN data.It is automatic by CAN controller that information, which is sent to bus from CAN controller,
It completes.
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.There are LPC2378 series A RM 4 to meet 16C550 industry
Asynchronous serial port UART0~3 of standard.UART Universal Asynchronous Receiver Transmitter (UART) is exactly the pass that equipment room carries out asynchronous serial communication
Key module.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, and rs 232 serial interface signal sends and receivees.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 turned in a manner of inquiry
Data are changed to send 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, lead to
Often without changing hardware design and control program, and only the system configuration setting of sensor and certain running parameters are made corresponding
Modification, sensor can be made to meet the requirements well].The scope of application and versatility that such characteristic makes sensor are greatly
It improves, 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 protected
There are the system configurations in nonvolatile memory, and area is arranged.It such as also needs to demarcate, then ECU compounding practice person command sensor is gradually
Calibration is completed, and nominal data is stored in nonvolatile memory.Then sensor will by the new system configuration mode with
And current 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 in inner hole
Portion's face shears the position of concentration zones 3, and induction magnetic core 7 is provided at left and right sides of excitation magnetic core 6, is indulged where induction 7 magnetic pole of magnetic core
It is in 90 ° to section and longitudinal profile where the magnetic pole of induction magnetic core；The magnetic pole for incuding magnetic core 7 is located at shearing concentration zones；Excitation magnetic
Core 6 and induction magnetic core 7 form cylindrical entirety, are fitted close with inner hole 4；Fluted 8 are arranged in the middle part of shearing force shell 1；Excitation
Fixed device 9 is provided between 6 outside of magnetic core and induction magnetic core 7, fixed device 9 includes excitation magnetic core enclosure 91 and fixes
Portion 92, fixed part 92 are matched with the fixed groove 10 of 1 starting point of shearing force shell；1 end of shearing force shell is provided with down
Angle.
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 magnetic field locating for magnetic material
Uniformity 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 to sensing
In the device 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 again
Region, and according to the magnetization characteristic of ferromagnetic material, the saturated magnetization that the additional excitation intensity of magnetization had better not be greater than material is strong
Degree, otherwise, material embodies the telescopic deformation of volume.So the selection of magnetic field strength should be in minimum magnetic conductivity and maximum magnetic conductance
Between and be located at the big ascent stage of permeability curcve variation tendency in figure.Increasing coil line footpath may be allowed bigger exciting current
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, this
When permeability magnetic material have reached magnetic saturation.So being considered as, loss high with magnetic permeability when selecting the core material of sensor
Material of small, magnetization curve the line segment compared with performances such as wide, the big, magnetic stabilities of resistivity.Magnetic core use stacked magnetic core, two layers
Between appropriate gap can reduce the inductance value of coil, avoid direct current cable order core saturation, while stacked high resistivity magnetic
Core can 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 has very high initial permeability, high resistivity, extremely low coercivity
It with very high maximum permeability, is quick on the draw to small-signal, saturation induction density is low.According to the comparison of two kinds of materials, originally
Embodiment 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
The influence of edge effect should increase magnetic pole face size as far as possible, reduce magnetic pole pitch.So the inside of piezomagnetic force snesor
It should cooperate between structure and 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 whole
It is made into 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 and concentrates
Area, induction magnetic pole are located at shearing concentration zones both sides.Fixation device in figure encapsulates the hard plastic body head of internal element
It stretches out in a 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 strings again
It connects, forms differential connection, so magnetic flux is cancelled out each other, sensor output is zero；When axis is by shearing force, inherently respectively to
The magnetism of same sex magnetic material will change, and then magnetic field reforms into asymmetry, produce in 45 ° and 135 ° of its surface direction
Raw tensile stress and compression.According to ferromagnetics, as the saturation magnetostriction constant λ of steel materialS> 0, then in tensile stress direction
Magnetoelastic energy it is minimum, be direction of easy axis, i.e., magnetic conductivity increase, magnetic resistance reduce；And in compression direction, magnetic conductivity reduces,
Magnetic resistance increases.Therefore, the Φ value variation at E1, E2, E3, E4, then sensor has induction voltage output, by sensor
Calibration, can obtain the relationship of induced voltage and stress, so as to be promoted or reduced according to the size of tractive resistance and variation
Lifter, 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 are as follows:
Similarly
Because induction coil is differential connection, so the output voltage of sensor are as follows:
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 are as follows:
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 having inputted exciting current generates magnetic field, according between the variation of the relative permeability of magnetic material and mechanical stress
Relationship, magnetic conductivity changes when centrepin stress, and magnetic flux also changes, and the variation of induction coil induced flux produces
Raw induced 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 inducting flux
Amount variation generates induced electromotive force, to generate electric signal, the electric signal of generation is transmitted and located by control signal circuit
Reason, and then realize the detection of tractor resistance, it can accurately incude resistance suffered by tractor, and more accurate
Feedback is realized in resistance 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 electric signal output control circuit, it is characterized in that: including master controller, power-supply system electricity
Road, clock system circuit, resets circuit system, signal amplification and signal effective value transformation circuit system at communication system circuit.
2. tractor as described in claim 1 presses magnetic induction electric signal output control circuit, it is characterized in that: the power-supply system is electric
Road includes prime power circuit and final stage power circuit；The front stage circuits realize conversion of the 24V voltage to 5V voltage；The end
Grade 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.
3. tractor as described in claim 1 presses magnetic induction electric signal output control circuit, it is characterized in that: the front stage circuits packet
Include three proper voltage voltage stabilizing chips 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.
4. tractor as described in claim 1 presses magnetic induction electric signal output control circuit, it is characterized in that: the clock system is electric
Road includes the external crystal-controlled oscillation that crystal oscillator frequency is 11.0592MHz；
The reset circuit system includes reset chip, and the reset chip is set as CAT1021；
The signal amplification and effective value transformation circuit system include instrumentation amplifier；
The instrumentation amplifier is set as INA114；
The signal amplification and effective value transformation circuit system include A/D converter；The A/D converter is set as AD736.
5. tractor as described in claim 1 presses magnetic induction electric signal output control circuit, it is characterized in that: the communication system is electric
Road includes one or more below, serial communication circuit, CAN communication circuit；
The serial communication circuit includes level translator, signal transmitting and receiving chip；
The level translator uses RS-232；The signal transmitting and receiving chip uses SP3232；
The CAN communication circuit includes CAN controller, the integrated CAN protocol for following CAN specification V2.0B of the CAN controller；
The CAN controller uses LPC2378.
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| CN201810910608.6A CN109240150A (en) | 2018-08-12 | 2018-08-12 | A kind of tractor pressure magnetic induction electric signal output control circuit |
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| CN201810910608.6A CN109240150A (en) | 2018-08-12 | 2018-08-12 | A kind of tractor pressure magnetic induction electric signal output control circuit |
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|---|---|---|---|---|
| US5697339A (en) * | 1996-06-17 | 1997-12-16 | Same Deutz-Fahr S.P.A. | Electronic governor device for agricultural tractor engine |
| 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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| CN104696316A (en) * | 2013-12-06 | 2015-06-10 | 刘扬 | Electrical-hydraulic suspension control system of tractor |
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| US5697339A (en) * | 1996-06-17 | 1997-12-16 | Same Deutz-Fahr S.P.A. | Electronic governor device for agricultural tractor engine |
| 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 |
| CN104696316A (en) * | 2013-12-06 | 2015-06-10 | 刘扬 | Electrical-hydraulic suspension control system of tractor |
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Application publication date: 20190118 |