Because of DSP embedded technical intellectual brake control system research
Summary: A chief of raceabout brake circuit, among them brake the control device is a core of the system. Adopting DSP chip and peripheral circuit forms trapping circuit of speed in the circuit design of the hardware in this text, the electrical machinery driving controller adopts little control chip and peripheral circuit to form circuit such as electric current sampling, overcurrent protection, pressure governing, make use of CPLD to realize logic phase inversion of the trochanter position signal of the Brusless DC motor. On software design, the control of the method implementation system that the software combined with assembler language with language C. Proposed the control strategy of the fuzzy control adjustment PID parameter finally.
A foreword
The raceabout brake circuit has subsystem of the relatively independent function on the raceabout system, its function is static weight, dynamic shock load of bearing the raceabout and absorb the kinetic energy when the racing-cycle brake, realize braking and control of the raceabout. The quality of its characteristic influences quick reaction, safety brake and viability of the raceabout directly, and then influence the overall performance of the raceabout. This text has designed hardware and software of the raceabout all electric antiskid brakes control device, studied the control law that the suitable raceabout brakes finally.
2 system hardware circuit design
This raceabout brakes the control device is made up of antiskid control device and electrical machinery driving controller. Two control devices regard DSP chip as the core. Antiskid control device mainly regards slipping rate as the control objective, outputs the given brake pressure, regard DSP chip as CPU, a rate signal recuperate the circuit etc. in extra racing-cycles and machines. The pressure magnitude, and the magnitude of electric current of control motor that the driving controller of the electrical machinery mainly regulates braking, also regard DSP chip as CPU, the electric motor current feedback of the in addition peripheral circuit recuperates the circuit, over current protection circuit, brake pressure, look after circuit, four the intersection of three-phase and the intersection of full-bridge and inverter circuit,etc., form the driving controller of the electrical machinery.
2.1 Minimum system of DSP
The minimum system of DSP mainly involves memory expansion, JTAG interface disposing, the arrangement of reset circuit, ADC module and design of clock circuit,etc..
1,Memory expansion outside slice. Slices of external memory for remedy deficiency of RAM inside the DSP, consider in the debugging process can help, download the procedure to block in the at a high speed Static RAMing at the same time. The external SRAM adopts CY7C1041CV33. DSP can use the programm store on-chip, can use the programm store outside slice too, this is determined by pin XMP knife MC. JTAG interface. When the procedure needs debugging, procedure download, finish through the intersection of JTAG and interface, the interface walk abreast with PC through simulator mouth link.
2,Reset circuit and clock source module. Produce Power On Reset and hand-restoring low level reset circuit with the circuit of capacitance-resistance, produce the reset signal. And a hardware watchdog, its Ausgang produced the reset signal WDRST. Two of the chip of the power are input as +5V, it is that DSP supply power to export as +1.9V and +3.3V power, the output power supply has two reset signals respectively, when the power is unstable or overlow, will produce the reset signal.
3,Hardware disposition of analog to digital converter ADC module. The analog to digital converter ADC output voltage 2V, demand to output a low ESR ceramic electric capacity with capacity of 10 F of head joint and reach the ground of simulation. If the software is set up under the external reference pattern, ADCREFP can connect external input as the reference voltage of 2V, and connect a low ESR electric capacity with capacity of 1 F to 10 F. Otherwise, the precision of the internal reference source of AD will be influenced.
2.2 raceabouts of front wheels and braking machine and signal processing circuit of a speed
The raceabout antiskid control device mainly regards slipping rate as the control objective, prevents the slippage of raceabout, the reference value of the output pressure after regulating from the deflection magnitude of the slipping rate, with the given slippage rate magnitude of tracing. There must be a rate signal of raceabout front wheel and braking machine on the antiskid control device and recuperate the circuit, it is mainly for getting the slippage rate feedbacked. The raceabout rate signal is substituted by raceabout front wheel rate signal that freedom rolls. Front wheel in raceabout and brake machine contain, test the speed sensor at the wheel, when the wheel rotate, the sensor will produce the alternate current signal of the sine wave form to test the speed, the machine wheel rotates the fake each time, the sensor sends out 50 periodic sine alternate current signals to test the speed. The amplitude of the alternate current signal of the sine varies with wheel speed, its signal, in order to bias 2.5V, the crest value is 0.3V, the amplitude of the permitted maximum signal is less than the sine wave signal of 5V. Convert signal of this sine wave to the square wave rear with the frequency to send into the capture unit of DSP, catch the intervals ncapture of counter value of the adjacent rising edge of rectangular wave, can calculate and receive the rotational speed value V of the wheel. Because CPUCLK is 150MHz, it is a timer among them to catch the time base, n is a frequency demultiplication coefficient of CPUCLK, it is the rolling radius of the wheel to be all, then the calculation type of the wheel speed is:
Recuperate the circuit:
2.3 Logic signal circuit
Electrical machinery driver choose ALTERA MAX7000A series the intersection of device and trochanter in electrical machinery of Company position equisignal to carry on logic punish, choose up to EPM7128AE with No. programmable I/0 mouth 76 and 100 pins, this CPLD can meet the systematic designing requirement. The device EPM7128AE has realized functions such as three-phase full-bridge inverter circuit triggering signal, overcurrent protection, positive and negative transferring to, openning and shutoff of the three-phase full-bridge of the electrical machinery,etc.. There are the logic signals of two electrical machineries on a slice of CPLD device EPM7128AE. Because the output of the position transducer CS3020 of Hall of the brushless direct current motor is the structure of opening a way of the collecting electrode, so pull upward 2K resistance, Hall’s signal SA, SB, SC sends to the input port of CPLD. TMS of interface of its JTAG, TCK, TDI, TDO four terminals must be connected and pulled upward the resistance, and then connect +5V power.
2.4 Driving circuit of power of the brushless direct current motor
The driving circuit of power of the brushless direct current motor adopts the constituent three-phase full-bridge of MOSFET tube in 6 nchannels taking specialized drive chip IR2130 of IR Company as the centre to go against Turn into the circuit. Its input is as PWM wave in the ground Power Groud, sends to the input port of IR2130, the power of the output control nchannel drives the tube MOSFET, therefore drive the brushless direct current motor. It is right to adopt this kind of driving means to mainly power drive the chip IR2130 ” Boot ” Technology forms the ingenious application of the power on high-tension side suspended, has simplified the design of the whole driving circuit, have improved the reliability of the system. And IR2130 drive the chip built-in circuit of inert zone, and functions such as overcurrent protection and low-voltage protection,etc., have reduced the complexity of circuit design greatly, has further improved the reliability of the system.
2.5 The electric current samples and over current protection circuit
The electric current of the brushless direct current motor was measured through mother’s resistance on the line of driving circuit of the power. The resistance on the bus wire is connected in parallel by the power resistor of two 0.01 s, the sampling circuit sampled the electric current through these two pieces of parallel sample resistance, sample the resistance and change the electric current signal into the voltage signal, the voltage signal sends to the electric current and controls the chip to amplify, then through being formed second order active smoothing circuit and filtered by OPA2344, win the feedback signal of the electric current finally, send to the analog to digital converter directly.
The over current protection circuit of the hardware, the normal operation of the system plays a very important role, it is mainly to the power device MOSFET and protection of electric motor. The system also has a software protection function, the signal OVCURX of the excessive load is sent to the input pin of DSP, when OVCUR is the high level, DSP will produce electric machine control and rotate the signal ENABLE and shut off the logic signal, make the electrical machinery stall. Have a overcurrent protection function chip IR2130 oneself.
2.6 Signal amplifying circuit of pressure and recuperating the circuit
The pressure signal amplifier adopts the amplifying circuit of subtraction that the difference fraction realizes, regard ultralow drift voltage operation amplifier as the core, magnification is 40 times, function that the amplifier is still furnished with adjusting zero bit and the degree of sensitivity regulates. Among them the chip 7809 offers +9V voltage for power chip 7660, the chip 7660 turns the voltage of +9V into – 9V, these two pieces of voltage +9V and – 9V are that OP07 supply power at the same time.
Because the signal range of the voltage coming out from the signal amplifier of the voltage is +1V +5V, and the reference voltage of A/D module of DSP is +3.3V, the maximum value of the voltage signal sampled can’t exceed +3.3V. So the voltage signal should reduce the voltage signal to +3.3v through recuperating the circuit. Recuperate the circuit and adopt the delicate operation amplifier OPA2344, recuperate the voltage signal under +3V from +1V to +5V, need to presume magnification is 0.6, so that DSP samples.
3 control device software design
This raceabout brakes the software of the control device relies mainly on language C, the appropriate adoption assembler language, such software has been written for the whole system software to bring convenience. Language C makes the development of DSP procedure accelerate, and readability and portability increase greatly, C2000 Code Composer Studio (CCS) in TI Company Debug under the integrated development environment. Because of the limitations of space, only introduce the initialisation of system program and main flow of program here.
1,Initialisation of system program. The systematic procedure must set up initialisation to mouth of clock source, timer, watchdog, AD module, I/O, catching the unit, cutting off of DSP,etc. before operation, make systematic internal resource, peripheral device and hardware circuit assorted. The system, before operation, must turn off all break, in order to prevent the procedure runtime from producing the needless break or procedure to run and fly etc.. So after initialisation, system start, break down, enable the normal operation of procedure.
2,Main flow of program of the system. The main programs of the all electric brake circuits of raceabout include the initialized module of procedure, interrupt servicing of the timer, module, capture module, control module, regulation model of pressure, electric current regulation model of slipping rate of the rate signal of time sampling of analog quantity,etc.. Among them, the timer interrupt service routine provides the stationary clock for electric current, pressure, module of slipping rate to touch off, regard this time as the regulation basic reference of each module. In the procedure runtime, shut off systematic always cutting off at first, finishes initialisation, after receiving and braking the order, open and always cut off, enter dead loop that the procedure regulates, until the end of run of the procedure. The time that the electric current loop regulates is shortest, reflect fastest, size and electric current signal have a relation to sample speed, CPU clock cycle, filtering procedure of software etc. to strain wave parameter, DSP its control period, general time is a fraction of a. And pressure governing cyclic(al) time set as the intersection of current control and cyclic(al) the intersection of N and time, electric current regulating ring and pressure governing cyclic(al) the intersection of regulation and number of times can in situ measurement regulate time and fix, the slipping rate is longer. Main program flowchart of the system.
Fuzzy control strategy of 4 systems
The fuzzy controller is a applied key part in the control system of fuzzy control, its main course is in order to be accused of the course the precise amount that is outputted carrying on fuzzification in the systematic control loop that will fetched, and is regarded as the input of the fuzzy controller. Import and exports of the fuzzy controller are all actual precise amount. Then carry on fuzzy reasoning and set up the fuzzy control rule of the language type in inside, it is judged fuzzily and exported that input the condition. Turn fuzzy quantity into the actual precise amount finally, namely go for fuzzification. Picture 4 of concrete course the following that the fuzzy controller is designed is shown.
Fuzzy controller schematic diagram of Fig. 4
The author of this text innovates some
This text finish raceabout brake design of control system mainly, it is hardware design, software design, control strategy that study mainly. Hardware design adopts high-speed DSP chip and CPLD and design its peripheral circuit. The system has also designed the driving circuit taking IR2130 as the core, the signal hardware amplifying circuit of electric current, smoothing circuit and protective circuit, amplifying circuit and smoothing circuit of the pressure signal, raceabout speed and machine processing circuitry of a speed,etc.. The control strategy adopts the fuzzy control adjustment PID parameter. (Author: Liao YongHong Microcomputer information )
Tags: Because of DSP embedded technical intellectual brake control system research
