Background
The aim of research of the servo control system of the electric steering engine is to complete the development of an intelligent digital electric steering engine with high precision and high frequency response output.
The static and dynamic characteristics of the steering engine directly influence the flying direction and accuracy of the missile, the development of the high-performance electric steering engine has important significance for improving the performance of the aircraft, the high-performance electric steering engine becomes an important subject of military scientific research of all countries, and full-electric, digital and intelligent steering engines are the development directions of the current steering engines. Compared with the traditional analog control steering engine, the digital electric steering engine is easier to realize an advanced control scheme, has the advantages of good performance, easy maintenance, high reliability and the like, and is one of the key factors for realizing the high precision, high sensitivity and high reliability of the modern advanced aircraft.
The research aims to establish a mathematical model of a precise digital electric steering engine system, design and realize an intelligent, high-stability and digital electric steering engine system, and strives to apply a new scheme of modern advanced control based on the application of a digital signal processor to improve the overall static and dynamic performance of the steering engine.
Compared with the traditional control steering engine realized by an analog circuit, the digital electric steering engine has the following advantages:
1) digital communication and system distribution control. The digital communication of the control system can fundamentally solve the problems of signal attenuation and crosstalk caused by analog signal transmission, and can realize distributed control on the basis so as to solve the defect of high concentration of danger caused by centralized control and greatly improve the safety and flexibility of the control system.
2) The system has high control precision and strong expandability. The control algorithm is realized by software, and the control algorithm (such as variable structure control, dual-mode control, fuzzy control and the like) can be continuously improved to improve the control precision of the system. Meanwhile, the improvement only relates to software, and hardware is not changed or is rarely changed, so that the realization is very easy, and the inheritance is good. The steering engines with different parameters and models can be controlled by modifying the parameters through a serial port (RS-422 or RS-485).
3) The parameters are easily adjusted and optimized. The digital steering engine uses programs to realize important parameters of frequency, dead zone, amplification factor, correction loop section and the like of a control part in the system, and is convenient to adjust and excellent in parameters.
4) The system is convenient to debug and the production consistency is good. The control system is connected with the intelligent automatic test equipment through the communication interface, debugging is carried out under the support of test software, and the best debugging parameters are solidified, and the solidified parameters do not change along with time, so that the performance of the control system is stable and consistent.
5) The reliability is high. The system is designed by adopting a high-integration device, wherein a system control chip DSP microprocessor replaces most of analog devices of the analog steering engine, the types and the number of components are reduced, a circuit is simplified, and the reliability is improved.
6) The intelligent degree is high. The microprocessor of the digital steering engine can realize the acquisition and processing of signals such as displacement, moment, speed, angle and the like, and has the advantages of powerful system function, small controller volume and high intelligent degree.
7) Meanwhile, the control mode of the analog steering engine is simple and direct, and the performance is reliable.
Therefore, digitalization of the electric steering engine has become the development direction of the missile steering engine. The steering engine system based on the digital signal processor is researched and designed to have great theoretical significance and engineering practical value.
Disclosure of Invention
In order to solve the problem of the steering engine in the prior art, the invention provides a steering engine control system. The invention adopts the following technical scheme:
a steering engine control system comprises
A digital control circuit for processing the current state and the target state of the steering engine to obtain a voltage signal uc;
A power drive circuit, a controlled end connected with the output end of the digital control circuit, and a digital control circuit outputting a voltage signal ucThe input is amplified in a power driving circuit, and the driving end of the power driving circuit is connected with a servo motor;
servo motor as a drive, and a signal theta of the servo motormConveying to a speed reducing transmission mechanism;
the speed reduction transmission mechanism amplifies the torque of the servo motor, and drives the control surface after amplification to deflect the control surface to a required angle;
the feedback potentiometer is used for receiving the rotation angle delta of the control surface;
the AD acquisition circuit is connected with the digital control circuit, and the signal of the feedback potentiometer passes through the AD acquisition circuit and then is input into the digital control circuit as a negative feedback control signal theta and a positive feedback control signal theta;
and the position sensor is used for detecting the current position of the control surface and sending the current state of the steering engine to the digital control circuit.
Specifically, an electro-optical electric isolation circuit for isolating the strength is further arranged between the power driving circuit and the digital control circuit.
In particular, the position sensor is a conductive plastic potentiometer of the WDD series.
Specifically, the chip in the digital control circuit is a TMS320F2812 DSP.
Specifically, the digital control circuit further comprises an interface circuit for communicating with the outside, a DA output module and an instruction monitoring module, wherein the interface circuit is a 422 interface, and the communication mode is full-duplex asynchronous communication.
Specifically, the servo motor of the steering engine is a MAX direct current motor RE 25302001.
Specifically, a control chip of the power driving circuit is driven by a kokai KK202D isolated digital brush motor.
Specifically, the power driving circuit is an H-bridge power tube circuit.
Specifically, the driving chip of the power driving circuit adopts a high-energy driving chip IR2130 of the American IR company.
Specifically, a MOS transistor irfu3607 of the IR company in the united states is adopted as a power transistor of the power driving circuit.
The invention has the advantages that: the digital control of the steering engine is realized, and the target direction of the steering engine can be realized more accurately and quickly.
Detailed Description
As shown in fig. 1 and 2, a steering engine control system includes a power supply, a digital control circuit 1, a power driving circuit 3, a servo motor 4, a reduction transmission mechanism 5, a feedback potentiometer 6, an AD acquisition circuit 7, and a position sensor. The servo motor 4 is a rare earth permanent magnet direct current servo motor 4.
The position sensor sends the current state of the steering engine to the digital control circuit 1, the controlled end of the power driving circuit 3 is connected with the output end of the digital control circuit 1, and the digital control circuit 1 processes the current state and the target state of the steering engine to obtain a voltage signal ucThe digital control circuit 1 outputs a voltage signal ucThe signal is inputted to the power driving circuit 3 and amplified. The driving end of the power driving circuit 3 is connected with the servo motor 4, and the servo motor 4 transmits a signal theta of the servo motor 4mThe torque of the servo motor 4 is amplified through the speed reducing transmission mechanism 5 to drive the control surface to deflect towards the required angle. The servo motor 4 is provided with a control surface rotating angle delta under the action of a speed reduction transmission mechanism 5, the rotating angle delta of the control surface is fed back to a feedback potentiometer 6, and signals of the feedback potentiometer 6 pass through an AD acquisition circuit 7 and then are input into the digital control circuit 1 as negative feedback and rudder control signals theta serving as positive feedback. Current voltage signal ucIn order to be the right time,the average direct current voltage applied to the servo motor 4 is positive, and the control surface rotates in the positive direction; u. ofcWhen the voltage is negative, the average DC voltage applied to the servo motor 4 is negative, and the control surface rotates in the negative direction. When the control surface deflects to the required angle, the error signal ucWhen the average direct current voltage applied to the servo motor 4 is zero, the control surface loses the driving torque and stops rotating. The rotation angle delta of the control surface forms a rudder feedback signal through the feedback potentiometer 6 and provides the rudder feedback signal to the digital control circuit 1 to form closed-loop control of the system.
Error signal ucWhen the absolute value of the dead zone is smaller than a set value D, determining that the dead zone falls into a dead zone range, and outputting the system control quantity to be 0; when the absolute value of the error of the system is greater than the set value D and less than the set value G, a PID control algorithm is adopted, and optimization is performed, and in order to adjust the smooth control of the control quantity in the process, the error can be subdivided into 2 segments, specifically: the method is characterized in that a first-stage integral control is introduced into a digital control module, and a second-stage differential control is added, wherein the integral term of the first-stage integral control integrates the error depending on time, and the integral term is increased along with the increase of time. Thus, even if the error is small, the integral term increases with time, which drives the output of the controller to increase, further reducing the steady state error until it equals zero. The two-stage differential control leads the change of the action of the suppression error to be advanced, namely when the error is close to zero, the action of the suppression error is zero, and the effectiveness of the whole control is ensured; when the error of the system is larger than the set value G, the output of the control quantity is full scale, and the system outputs 100% PWM so as to improve the adjustment speed of the system. The G is>D>0.
The error segmentation control method integrates the advantages of various algorithms, improves the control efficiency, and well solves the influence of nonlinear factors such as dead zones, gaps, friction and the like on the system precision, so that the control effect is more reasonable and effective.
Optimally, a photoelectric isolation circuit 2 is further arranged between the power driving circuit 3 and the digital control circuit 1 and used for isolating strong current and weak current. The digital control circuit 1 is connected with a power driving circuit 3 through a photoelectric isolation circuit 2, and the power driving circuit 3 drives a servo motor 4 to work. The feedback potentiometer 6 is connected with the servo motor 4 and returns information to the AD acquisition circuit 7, the AD acquisition circuit 7 also acquires signals at the output end of the power driving circuit 3, and the acquired signals are all transmitted to a control chip of the digital control circuit 1. The power supply supplies power to the isolation circuit, the feedback potentiometer 6 and the digital control circuit 1 respectively.
Specifically, the position sensor for detecting the current position of the control surface is a precision conductive plastic potentiometer of WDD series. The system obtains a feedback current signal by a method of connecting a sampling resistor in series in a main loop of a rudder machine, and the feedback current signal enters a chip of a digital control circuit 1 after being amplified and filtered by a front stage and a rear stage.
As shown in fig. 3 to fig. 5, the chip in the digital control circuit 1 is a TMS320F2812 DSP, the digital control circuit 1 further includes an interface circuit 8 for communicating with the outside, a DA output module 9, and an instruction monitoring module, the interface circuit 8 is a 422 interface, and the communication mode is full-duplex asynchronous communication. The scheme comprises a 422 interface A and a 422 interface B, each data packet consists of 9 words, the 1 st word is a data packet head word, the 9 th word is a checksum word, and the 2 nd to 8 th words are data words. Each word comprises 1 start bit, 8 data bits, 1 odd check bit and 1 stop bit, and the low bit and the high bit are sent firstly during communication. The checksum algorithm is the sum of the modulo-2 addition of the 2 nd word to the 8 th word in the packet. The other end of the interface circuit 8 is connected to the flight control component, and the flight control component repeatedly transmits 3 times in a 10ms cycle when transmitting the ZB-RI, ZB-R2, and ZB-R3 packets to the chip DSP of the digital control circuit 1, and transmits 10ms when transmitting the ZB-R4 packets. The DSP, upon receipt of the ZB-R4 data packets, should send response data packets ZB-T4, ZB-T1, ZB-T2 and ZB-T3 within 1ms, which are repeated 3 times in a 10ms cycle to the flight control components at the time of a state change, as shown in FIG. 5, where DJ is abbreviated steering engine. The flight control assembly is a missile-borne computer of a missile and is equivalent to an upper computer.
The software part in the DSP comprises
The initialization module is used for completing initialization of a system clock, a timer, a register, an interrupt, an A/D port and a PWM port of the chip DSP;
the signal acquisition and digital filtering module is used for acquiring the command signal and the feedback signal input by the upper computer 10 and filtering out the acquired coarse values;
the error calculation and control algorithm module calculates the errors of the command signal and the feedback signal and calculates the output value of the controlled variable according to the types and parameters of all components in the control system;
a PWM duty ratio calculation and distribution module; calculating the duty ratio of the pulse width modulation signal PWM corresponding to each power driving circuit 3, loading the comparison register parameters, and outputting the PWM signal;
and the communication control module is used for finishing the communication of the guidance computer of the upper computer 10 and issuing control instructions to all the steering engines.
The type of the servo motor 4 of the steering engine is MAX direct current motor RE 25302001. The rotation angle range of the potentiometer adopted by the position sensor is +/-15. The digital control circuit 1 can be correspondingly connected with different power driving circuits 3 through different pins. The speed reduction transmission mechanism 5 is a harmonic speed reducer. The system adopts the speed reduction ratio as follows: the reduction ratio of 128:1, the efficiency of the harmonic gear is about 80%, and the flexible teeth are adopted for transmission inside the reduction gear, so that the influence of transmission gaps on system characteristics can be effectively reduced.
The power driving circuit 3 includes a plurality of technical solutions, and two solutions are taken as examples in this embodiment.
The first scheme is as follows:
the control chip of the power driving circuit 3 is driven by a KeKa KK202D isolated digital brush motor. KK202D is a digital isolation type brush direct current motor driver module designed for a steering engine, and the input control ground of the module is isolated from the power output ground; the PWM signal at the control end of the module controls the positive and negative rotation of the motor, and the module can be directly accessed into a TTL digital control signal or a DSP control signal to directly control the motor. The circuit is powered by a single power supply, and has the characteristics of small volume, large output current, high conversion efficiency, simple external lead and the like. The driver module can greatly simplify a steering engine control method and greatly improve the reliability of the system. The method can be widely applied to a brush motor control system powered by a single power supply.
Scheme II:
the power driving circuit 3 is an H-bridge power tube circuit, so that the servo motor 4 can easily realize reversible forward/reverse rotation, and the speed regulation adopts a PWM (pulse width modulation) technology, so that the control is simple and the reliability is high. The driving chip of the power driving circuit 3 adopts a high-energy driving chip IR2130 of the American IR company, and the power tube adopts a MOS tube irfu3607 of the American IR company.
In the scheme, the servo control system adopts a digital position-speed-current three-loop series control scheme, and the speed is obtained from the back electromotive force of the servo motor 4. Compared with analog control, digital control has flexible control, can realize advanced control algorithm and strategy, and can correct control parameters according to the change of feedback information, thereby improving the dynamic and static performance of the servo system.
As shown in fig. 4 and 5, the control system receives a command corresponding to a target state sent by the upper computer 10, detects an actual position of the control surface, a motor running speed and a motor working current in real time, realizes cascade control through a position-speed-current three-loop, and outputs a PWM control signal to the power driving circuit 3 after the digital control circuit 1 is integrated.
The position loop of the system can realize no-static-error control by adopting PI regulation, the position control precision is ensured, and the speed loop is used as an intermediate link to realize the requirement of rapidity of the system by adopting proportion (P) control. The current loop adopts a current cut-off negative feedback control method.
In detail, when the current of the motor is within a set amplitude, a steering engine control method is a position-speed double closed-loop control system; when the current is larger than the set amplitude, the current is controlled by adopting current cut-off negative feedback, and at the moment, the steering engine control method is a position-speed-current three-closed-loop control system, and the current of the system can always work in a safe range under the action of the current cut-off negative feedback.
A steering engine control method comprises the following steps;
s1, the initialization module in the digital control circuit 1 starts to work to complete the initialization work;
s2, the signal acquisition and digital filtering module receives the instruction signal and the feedback signal of the upper computer 10 for acquisition and filters out the acquired coarse values;
s3, calculating errors of the instruction signal and the feedback signal by an error calculation and control algorithm module, and calculating a controlled variable output value according to the types and parameters of all components in the control system;
s4, calculating the duty ratio of the PWM signal corresponding to each power driving circuit 3 by the PWM duty ratio calculating and distributing module according to the output value of the control quantity, loading the comparison register parameter and outputting the PWM signal;
s5, the communication control module completes communication of the upper computer 10 guidance computer and gives control instructions to all steering engines;
s6, sending the control command to the power driving circuit 3 through the photoelectric isolation circuit 2, and amplifying the control command;
s7, an AD acquisition circuit 7 acquires the amplified signals, the amplified signals drive a servo motor 4 to work, the torque of the servo motor 4 is amplified through a speed reduction transmission mechanism 5, and a control surface is driven to deflect towards a required angle;
and S8, the AD acquisition circuit acquires the deflection angle of the control surface obtained by the feedback potentiometer and the signal acquired in the step S7 as a feedback signal, and the feedback signal returns to the step S2 until the error of the feedback signal is less than the set value D.
As shown in fig. 4, the steps of the program in the digital control circuit are:
in step S1, system initialization is performed, and a self-check of the system is also completed, where the self-check is used to detect whether system initialization is successful, whether voltage and current are normal, and whether a communication link is normal; judging whether an interrupt instruction is received or not when the system normally enters, and entering an exception handling instruction when the system is abnormal, wherein the exception handling instruction comprises report error positions and information;
and the interruption instruction comprises a timing interruption instruction and a control interruption instruction, when the timing interruption instruction is received, an AD sampling subprogram in the digital control circuit works to acquire data acquired by the AD sampling circuit, the data enters a PWM duty ratio calculation and distribution module according to the feedback data, PWM is calculated according to the algorithm subprogram, and the PWM is output in the step S4. And returning to continue waiting instructions when the timed interrupt instructions are not accepted.
And when a control interrupt instruction is received, communicating an interrupt processing subprogram, and updating each parameter variable.
The invention is not to be considered as limited to the specific embodiments shown and described, but is to be understood to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the invention as defined by the appended claims.