单通道电液伺服系统的设计

Design of Single Channel Electro-hydraulic ServoSystemWang XinNo. 586 mail box Northwestern Polytechnical University Xi’an 710072, Chinamatchboxchina@Yan Daiwei dwyan75@ Xi’an 710065, ChinaAbstract—In this paper an single channel electro-hydraulic servo system is designed to validateǃcompare and ex plore different control schemes on restraining Additional Torque inherent in force loading system. Also it is discussed how to improve loading performance by improving the electronic circuit. By the feedforward signals of velocity it is ex pected to ex pend the bandwidth or even higher and reduce the additional torque. The electronic design theory of loading system was mainly ex plored and was made experiments on subsystems and the whole system. The PID control technique was used to adjust the parameters.Keywords- Servo System; PID Control technique; Instrumentation AmplifierI.I NTRODUCTIONElectro-hydraulic servo loading system (referred to EHSLS) is in the design stage of vehicle loop simulation of test and is one of the main equipment used to simulate the role of manipulation. The dynamic loads on the controller for the new vehicle development and applications performance test data for the promotion of new technologies are to provide the reliable experimental data. It is a torque servo system, but the simulation process also needs to simulate the change of dynamic load, so EHSLS is a very complicated electric- hydraulic composite system. From the point of view of control, it is a strong coupling, time-varying controlled object. Study on the electro-hydraulic servo loading system involves the system dynamics, hydraulic transmission, and control theory and computer control technology with multidisciplinary content.II.D ESIGN OF E LECTRO-HYDRAULIC SERVO LOADINGSYSTEMSystem works as follows:(1) Electronic control system boot, the system closed-loop operation before the closed-loop system is the hardware work. Hardware closed loop is zero torque, and steering gear control system from one party to maintain the zero and an initial point of view, to ensure the safety of electro-hydraulic servo loading system.(2) Closed-loop simulation system operation, control computer system for real-time acquisition angle coded signal, and the AD signal acquisition, the amount of control by the control algorithm adopted after the formation of DA card output to the servo valve.(3) The object is loaded actuator position servo control system to simulate dynamic loads in a typical steering angle movement. Provided by the control computer commands the corner position, measured by the angle encoder as a feedback control of the actual amount of rotation to achieve closed-loop control of position servo system.(4) To load the device is loaded servo system, servo control computer corner and set according to the load factor to calculate the gradient of the command torque loading system; the size of load torque and the steering gear system by the loading system measured between the torque sensors. Electro-hydraulic servo loading bench in the work process tracking command torque signal, and torque sensors measure the signal used as feedback to achieve closed-loop control.(5) Control computer real-time monitoring system operation, to receive control commands through the man-machine interface, display system status and data. Finally, record the experimental data file for the operator to experiment result analysis and research.Active movement in the loading servo motor in the two chambers have forced flow, two-chamber pressure imbalances caused by changes in output torque, resulting in excess torque disturbance. The extra torque of the mixing, loading system will seriously affect the control performance [1]. As long as the steering system motion, the disturbance is inevitable, especially in the steering and reversing system startup when the extra torque will have a great impact, so that a serious deterioration in the performance of loading system. Thus removing the steering movement of the loading system to produce extra torque servo loading system problem is the key technical problems.III.E LECTRICAL S YSTEM C OMPONENTS Single-channel passive electro-hydraulic servo loading system consists of oil sources, the hydraulic system console, single load simulator test bed, and electrical control cabinet four major components [2].Hydraulic oil source and load test the system console in the main test bed for the load simulator to provide hydraulic power and its corresponding control.This work is supported by National Nature Science Foundation underGrant 61074194.532 978-1-4244-8756-1/11/$26.00c 2011IEEESingle load simulator test bed by the angle sensor (resolver), damping spring rod, torque sensors, load hydraulic motors, hydraulic motors and hydraulic servo steering gear off valve assembly formed. The side of the test rig, the installation of an amplifier junction box. Through the cable system will be test bed connecting electrical control cabinet.Electrical control cabinet system includes the following components:(1) power control box. (2) Power chassis. (3) control chassis. (4) computer system.(5) measured outside the terminal box.A.Torque motors and servo valvesAccording to technical requirements, select the Order PQ valve motor components of the main technical indicators are as follows: z Rated control pressure: 8 MPa z Rated current: 15 mA z Maximum torque: 200 Nm z maximum angular velocity: s deg/230zmaximum rotation angle: f deg40B.Torque SensorAccording to the technical requirements: The maximum load moment of 160N • m, load accuracy: 0.5%. Select torque sensor, model is AKC-17T. z Measuring range: 0 ~ 200 N • m z For the bridge voltage: 12V z Repeatability: 0.1% FS z Non-linear: 0.1% FS zSensitivity: 1.045mv / VC.Angle sensorSteering angle sensor is used to measure changes in angle sensor, especially during the off steering gear test, the steering angle sensor is a false measurement of closed-loop control component, so its accuracy is very important. Need to select a high precision multi-angle resolver as a position measuring device. The Model: 72XFS12A-1/32, accuracy were better than 40"D.Amplifier junction boxTorque amplifier to control cabinets and junction box connected to the bridge test bed. It is installed in the test stand on the side. In addition to connecting the cable box, there is a preamplifier board; this board has two channels to enlarge the torque amplifier and the speed of a channel amplifier. Channel torque amplifiers are from three amplifiers and precision voltage source corresponding composition. Threefirst stage amplifier is an instrumentation Burr Brown company amplifier INA121 composed of the data amplifier[3][4]. Its technical parameters: z offset drift ˖C V r P 2z bias current ˖pA 4r z quiescent current ˖A P 450r z offset voltage ˖V P 200r z nonlinearity ˖%001.0z voltage input protection ˖V 40r zhigh CMR ˖106dBFig.1 Diagram of INA121 AmplifierVoltage gain can be selected by an external resistor, where selected 1001 K , then the amplifier 's bandwidth is 50KHz. The second level is composed with OP07 op amp inverting summation, the voltage gain is 52 K , the third level is composed of second-order low-pass OP07 active filter, the voltage gain is 23 K , filter parameters are as follows: z bandwidth ˖2357154109C C R R n Z z Bandwidth frequency ˖Hz f n 375 z gain ˖23 K zloading system damping ratio ˖21)1(5104934105949510C R C R K C R C R C R C R [zThe total gain of the amplifier ˖1000321 K K K K The speed of a channel amplifier is reserved for the system.In this design, the system does not install speed motor, steering20116th IEEE Conference on Industrial Electronics and Applications 533angular velocity signal is a signal by the resolver angle encoder by calculating derived. Added to the system when the motor speed, can be machine guns gave the signal through the amplifier conditioning system. Amplifier circuit speed and torque signal amplifier circuit of the structure of the same, but the choice of circuit parameters and the actual work status. Torque sensor bridge power supply of high precision, good stability, power quality directly affects the accuracy of the sensor output, it must be high-precision voltage source. The design selected as the Burr Brown's REF02 precision reference[5], the output is +5 V, stability characteristics is C ppm $/5.8.Precision reference voltage source output of +5 V through two external high-precision resistors OP07 and the same reverse-phase amplifier, converted to ± 5V precision voltage source output as a sensor bridge supply voltage. The sensitivity is V mV /045.1, and the sensor for the bridge voltage is 10V . The sensor output voltage is 10V when the loading torque ismN 200Channel plate is the most important functions of the system board, which is the name of the schematic: TDB. Channel plate channel were controlled loading system and hydraulic steering gear off channels.Channel board has integrated amplifiers on each channel, closed-loop converters, preamplifier and power amplifier, and zero potentiometers used in the precision reference power supply and digital logic circuits. Look below to load the channel as an example the work of channel plate. N1 (OP07) is loaded channel integrated amplifier, which received from the torque signal on the bus, and receives the angular velocity signal, and integrated amplified output. K1 is a closed-loop load-channel conversion converter relay, its contacts K1-1 position depends entirely on the system working state. When the system hardware when the K1-1 in a closed-loop long closed position, N2 preamplifier integrated amplifier input signal from the N1 in the output. When the system when the software control loop, K1-1 in a long open position, N2 pre-amplifier DA1 to receive control signals to the computer to form a closed loop control software. Output signal from the N2 and added to an inverting amplifier input (N3), N3 as the adder, the main control signal not only receives, but also provide input resistor R11 receives zero signal input resistance to provide an incentive to receive 800Hz signal and these signals are integrated, the given amplifier OPA551 [6]. Power amplifier receiving the output voltage signal before the class, and enlarge, convert the current signal, to drive the solenoid valve. N4 is current depth of peripheral device form a negative feedback voltage amplifier, the circuit diagram shown in Figure 2.The gain of the circuit is:3.010314164R RK Fig. 2 valve driving circuitWhen the input of N4 plus 10V input signal, the output drive current is 30mA. Power amplifier output current through the normally closed contact relay K3 is applied to the solenoid valve coil, then through the sampling resistor R18 back to land. Sampling resistor R18 at the sampled voltage on the feedback, the formation of the power circuit loop. In order to ensure the accuracy of current control, the sampling resistor , the size of theR18 selected precision resistors, resistance to 100:.Sampling resistor voltage just reflects the current flowing through the resistor. When the 30mA current flows through the sampling resistor, will produce 3V voltage drop, which is consistent with the gain 3.04 K of the circuit. Therefore, the voltage magnitude of this point can be shot through the N6 to the bus with the device plug, used for system testing. Debug state in the system, the relay's normally open contacts K3 connected, power amplifier current through the "dummy load" resistor R17 to resistor R18 constitute a sampling circuit, to avoid large currents in the debugging process the impact on the valve coil. OPA551 amplifier used in the system for the Burr Brown products, their characteristics and performance parameters associated with the following: z Wide supply voltage: V 4r to V30r z Output drive capability: the ability to 200mA continuous output current; z Low noise: Hz nV /14;z full protection: thermal shutdown and output current limiting;z thermal shutdown instructions; z High slew rate: s VP /15;z unity gain bandwidth: 3MHz;zWide Temperature Working: -40 ° C to 125 ° C.REF02 chip provide precision reference source and the N14, N15 chips (OP07) together constitute the baseline power output to zero potentiometer for zero adjustment of the system. D1 (74LS04), D2 (74LS32), D3 (74LS11) is part of digital logic circuits. It is based on the commands on the bus to transform the state, the control circuit to work. When you load the software, such as closed-loop channel command is active (low voltage), D1: A high output, then load the channel if there is no alarm and emergency signal, D3: A will output high level, so that the work of three tubes V7 and drive the relay K1, to make contact K1-1 closes, the software will load the channel53420116th IEEE Conference on Industrial Electronics and Applicationsswitching to the closed state. If the event of an alarm or emergency, the circuit will immediately release the relay K1, the system switches to the hardware loop state.IV.E XPERIMENT AND PID PARAMETERS ADJUSTMENTServo loading station computer system is another core system; the task is monitoring the conduct of tests, including binding experiments, control, and monitoring, experimental data processing. Loading system used in the computer system is essentially a real-time monitoring and control system. Therefore, in the design of the system, not only to consider the control issues, but also on information display, data storage and processing, and many other tasks, the most important thing is to meet the requirements of real-time systems. And the need to take into account the real-time acquisition and processing of data, this design uses a dual CPU of the IPC to complete.The hardware of the computer system is a dual-CPU IPC and its accompanying multi AD, DA, and DIO cards. The key technology of computer control system parameters are: CPU speed, word length; memory capacity; A/D, D/A converter bits long, the system sampling frequency.System work is divided into two ways. A closed-loop hardware torque, the other one is computer-controlled closed-loop torque by way of instruction.Closed-loop mode in the hardware, the system does not accept command torque, is based on zero moment way. Integrated amplifier from the amplifier output to receive the torque from the torque feedback signal. Through the closed-loop converter, preamplifier, power amplifier control valves and motor components of PQ valve to follow the steering movement of loading system, constitute the system's zero-torque loop. Closed-loop mode in the hardware, the system is based on a simple way to control the ratio. Control accuracy is not high, but because of its simple structure, high reliability, so it usually runs on two conditions: First, the system boot and this time before a simulation run, the system has been in the hardware loop work; Second, When unexpected situations arise at work into the emergency in order to protect the security of steering the system from the closed-loop control into the hardware, computer software, closed-loop zero-torque work, the loader not to steering force, freedom of movement in the steering gear is equivalent to state.Closed-loop control software in the computer mode, on the one hand to receive the computer by DIO given steering angle encoder position signal, with instructions to calculate the load torque gradient signal; the other hand, computer acquisition given by the torque sensor torque feedback angle encoder signals and the angular velocity signal is given, together with them and the command torque signal through the control signal calculated by the D/A output, after a closed-loop converters, preamplifier, power amplifier control valves and motor components of movement PQ valve, and through the torque sensor, torque by torque feedback signal amplifier to form a closed loop torque, so that the loader according to instructions to apply torque to the steering gear, to achieve torque servo load.Post-processing of data using sophisticated and powerful processing software GV32, it calls the data generated by each module files (extension. Fig files), and the curve displayed in the work area. The default setting in the horizontal axis is time, vertical axis means different things depending on the signal distinction. With the data in the G V32 transferred, display, zoom, and data processing and printing. G V32 softwareinterface is shown in Figure 3.Fig. 3 GV32 software GUIUsing PQ valve, Model HY141-0205, the standard sine signal amplitude 20deg, 1Hz. PID control parameters are different the actual angle tracking standard sine curve results as shown in Figure 4. Not specified, 1 is the standard sine curve; Curve 2 in the control of PID parameters Kp = 1.0 Ti = 5 cases by the actual angle of the curve; Curve 3 in the control PID parameters Kp = 1.0 Ti = 10 in obtained under the curve of the actual angle; curve 4 in the control of PID parameters Kp = 0.8 Ti = 10 received the case of the curve of the actual angle; curve 5 in the control of PID parameters Kp = 0.6 Ti = 10 in obtainedunder the curve of the actual angle.Fig. 4 PID controlled loading torqueV.CONLUSIONAt last a summary of my paper is made to the readers as follows:(1) Design the Electro-Hydraulic Servo Loading System (EHSLS) and the electric subsystem. Use the PQ servo valve in the system.20116th IEEE Conference on Industrial Electronics and Applications535(2) Write the code for computer control system. Debugthe hardware and software.(3) Adjust the parameters by PID control theory.(4) Do experiments on EHSLS and analyze the data andresults.R EFERENCES[1]Shang Yaoxing, Jiao Zongxia, Wang Shaoping, et al. Dynamic robustcompensation control to inherent high-frequency motion disturbance onthe electro-hydraulic load simulator. International Journal of ComputerApplications in Technology, August 2009,Volume 36, p117-124.[2]Li Jian-Ying, Shao Jun-Peng, Han Gui-Hua, et al. Study of the electro-hydraulic load simulator based on flow-press servo valve and flow servovalve parallel control. 2009 International Conference on IntelligentHuman-Machine Systems and Cybernetics, Volume 2, p70-74.[3]Lloyd, Alastai. Exploiting the instrumentation amplifier, ElectronicProduct Design. December 1993, Volume 14, p43-44.[4][EB/OL]/docs/prod/folders/print/ina121.html.[5][EB/OL]/docs/prod/folders/print/ref02.html.[6][EB/OL]/lit/ds/symlink/opa552.pdf53620116th IEEE Conference on Industrial Electronics and Applications。