自動化專業(yè)本科生畢業(yè)設計 外文翻譯-數(shù)控鉆床控制系統(tǒng)設計

1、 密 級分類號編 號成 績本科生畢業(yè)設計 (論文)外 文 翻 譯原 文 標 題CNC DRILLING MACHINE CONTROL SYSTEM DESIGN譯 文 標 題數(shù)控鉆床控制系統(tǒng)設計作者所在系別電子工程系作者所在專業(yè)自動化作者所在班級作 者 姓 名作 者 學 號指導教師姓名指導教師職稱完 成 時 間2021年12月07日北華航天工業(yè)學院教務處制譯文標題伺服系統(tǒng)的設計3-Axis數(shù)控鉆床基于xPC目標原文標題Design of Servo System for 3-Axis CNC Drilling Machine Based on xPC Target作 者Butler Jero

2、me譯 名杰羅姆巴特勒等國 籍美國原文出處Atomation Professional English CauseAbstract As special equipments, the CNC drilling machines require servo systems specially designed. So there is a substantial waste of time and energy. In order to solve this problem, a design proposal for the servo system of 3-axis CNC drilli

3、ng machine based on xPC Target is presented in this paper. Taking a CNC drilling machine model as the experiment platform, the block diagram of the servo system was designed using SIMULNK tools, and compiled into a real time system by VC complier, which could run on X86 computer. Rapid developing of

4、 a servo system for 3-axis CNC drilling machine is easily implemented by this proposal. The experimental results demonstrate that the feed system of the drilling machine model could carry out a quick precisionpositioning. Key words-servo systems; drilling machines; xPC Target;I. INTRODUCTIONThe CNC

5、drilling machine is mainly for drilling holes with numerical control. The most products are special Figure 1. The control system structure of 3-axis CNC drilling machineequipments, which are widely used in hole processing technology for the PCB and large porous tube sheet parts.1 And, these products

6、 most are special equipments, can be classified as CNC vertical drill, drilling center, CNC PCB drill, CNC deep-hole drill and other large CNC drilling machine.2 It is applicable to machining the parts with lots of precise holes in procedures of drilling, spreading, weaning and threading. Especially

7、, its important to improve the machining accuracy and efficiency that choose a special CNC drilling machine to work the PCB and large porous tube sheet. While, the design of servo system is the most complex in the process of designing a special CNC drilling, and require plenty of time to program and

8、 debug. So, it not only consumes the valuable intellectual resources, but constrains to market the product timely. XPC Target is a tool set based on Matlab/SIMULINK that is provided by MathsWorks. It has a wealth of I/O device modules which support the majority of integrated circuit boards.3 And, xP

9、C Target introduced a host-target technical means, one PC as host computer, and another industrial computer as target computer, two computers connected with network cards and communicate through TCP/IP protocol. The systems by xPC Target can run onX86 computer real-time. It achieves simulation on bo

10、ard and rapid prototyping of control systems. The CNC technology lab for scientific research in Guangdong province developed a 3-axis CNC drilling machine model which is based on the product manufactured by Shenzhen Open Technology Corporation. Using the drilling machine model as test platform, desi

11、gned the special servo system based on XPC Target. II. SERVO CONTROL SYSTEM STRUCTURE OF THE 3-AXIS CNC DRILLING MACHINE The control system of the 3-axis CNC drilling machineis a two-level computer control structure: the host computeris a personal computer, and carries out drawings,commands, communi

12、cations etc. the lower computer is anembedded computer of PC/104, as the core unit of servocontrol system in the drilling machine.The host computer communicates the data of commands and motion states with the embedded computer of PC/104 by RS232, As shown in Fig.1. And, apply the Modbus communicatio

13、n protocol to keep the data mutually transmitted exactly. In this system, ADT652 expansion card according with PC/104 bus is used as the I/O interface of the system. Using the software of SIMULINK, designed servo control system of 3-axis CNC drilling machine based on XPC Target. And, the software of

14、 the system was downloaded to the PC/104 and real-time operated ascompiled and debugged successfully. After complicated computing, the PC/104 modulates the results into a corresponding PWM signal that is exported to the motor drive circuit through ADT652 board. Then, the motor driving the correspond

15、ing axis rotates at a definite speed under control. At the other side, a incremental rotational photoelectric encoder was fixed on the servo motor of the relevant feeding mechanism to obtain its position，which is fed back to the PC/104 by the I/O port of ADT652. While, the motional speed of the spin

16、dle servo motor is obtained by speed senor, and is fed back to the PC/104 by the ADC channel of ADT652.III. ESTABLISH THE SERVO CONTROL SYSTEMIn general, the servo control of CNC drilling machines feeding mechanism is point-to-point control. And, thefeeding rate of X, Y-axis could obviously affects

17、promoting the production efficiency, but the Z-axis feeding rate would not archive the effect for the factors of the drill and the processing materials. On this platform, a DC motor is used as the power set of the feeding mechanism. Compared with AC motor control, DC motors drive circuit is more sim

18、ple and reliable. Moreover, the speed adjusting accuracy and dynamic response characteristics of the DC motor are more ideal with a greater speed range and higher speed adjusting accuracy.4 So, it can be satisfied with the experiment requirement better. As the value of inductance (L) in the armature

19、 circuit of DC motor is very low, it can be ignored in the mathematical model of the servo systems. Then, taking the armature voltage (Ua(s) as the input value and the motor speed (s) as the output value, the mathematical model of armature-control DC motor is established, and the model can be regard

20、ed as a 1st-order system. The transfer functionof the model is: Taking the angle of the motor (s) as the input valueand the linear displacement of the workbench (Xo(s) as the output value, the mathematical model of the working platform can be also simplified as a 2nd-order system. Its transfer funct

21、ion is:With comprehensive consideration on the mathematical model of the DC motor and the working platform, the servo system can be simplified as a 2nd-order system model. Its transfer function is:The servo control system of the X-axis feeding system for the CNC Drilling Machine is presented in this

22、 paper.And the other feeding systems are not described in detail for being similar with the X-axis.A. Mathematics modelingOn the 3-axis CNC drilling machine model, a Maxon motor F2260 is fixed as the power set of the X-axis feedingmechanism. And the rotation of motor can be converted into the linear

23、 motion of the workbench through the mechanism of lead screw. We can create the transfer function with the characters about the motor and workbench which is shown in the table I. The transfer function of X-axis servo system is obtained by the above parameters of Motor and workbench: B. PID controlle

24、r designIn this paper, a PID compensator is designed to adjust the motion of the servo system according to themathematical model above. And its parameters are set withthe experiential formula of Ziegler-Nichols5 by MATLAB software. The formula is: In the formula, the Km is the value of proportional

25、gain as the time systems begin to shock, and the m is theoscillation frequency at this point. Firstly, the mathematical model of the controlled object is converted into a discrete model using zero-order holder. Then, use the commands of rlocus and rlocfind to obtain the oscillation gain Km and the o

26、scillation frequencym at the critical point . Finally, the parameters of the PIDcompensator can be obtained by the formula (5):The step responding curves about the pre-tuning and after-tuning are shown in Fig.2. We can find that theoscillation and overshoot of the systems step responding was elimina

27、ted for the adjustment of the PID compensator, and the system can get to a steady-state in 1.5 seconds. In addition, an integral weakening technique is introduced in the PID compensator to enhance the stability of the servo systems. the technique is that when thedeviation value (ei) between the feed

28、back value and the aim parameter of servo system is greater than a stipulated threshold, the section of integral doesnt work. So the integral value will not be too large. Only when the deviation value is small, It works to eliminate the static error of system. Its PID algorithm is presented as posit

29、ion type: The outcome of simulation indicates vividly that the PID compensator fulfills the requirements very much of quick precision positioning in the point-to-point control of CNC drilling machine.C. Design servo system base on xPC targetThere are a set of xPC target tools in the SIMULINK softwar

30、e, such as RS232 communication tool, timing tool,I/O interface tool etc. these can be used in to establish control block diagram of the servo system.6According to the servo system models which be described as the formula (4), using MATLAB/SIMULINKwe can easily establish the simulation models for the

31、 3-axis CNC drilling machine. The control block diagram of the X-axis servo system is shown in fig.3. This is only a non-real-time, off-line simulation studies.7 But, when the system is running on the actual hardware in which integration of in-the-loop testing and debugging can beachieved.On the har

32、dware, an ADT652 based on the PC/104 bus is used as the data acquisition card. And, the PORTA ofADT652 reads pulses of the incremental rotational photoelectric encoder in real-time, and sends it to PC/104which would converts it into a angle value as feedback of the system.8 Here, the PORTAs address

33、is 0 x308, andthe base address of ADT652 is set as 0 x300 through jumper. Then, the deviation value (ei) between the feedback value and the aim parameter of servo system is involved in the operation of the PID compensator designed well. The skill of limiting integration is use in the PID compensator

34、. At last, a regulating variable comes to output. the regulating variable is converted to a PWM signal which is sent to the motor drive circuit through the PORTB of ADT652, which address is 0 x309. So, the speed control loop for the servo motor of X-axis is created. With MATLAB/ SIMULINK running on

35、the host computer, and the development environment9 of Real-TimeWorkshop, xPC Target and VC6.0 compiler set well, the block diagram of the servo system designed well could be converted into an application which would be download to the target computer (PC/104) through TCP/IP protocol. Then, the CNC

36、system is created and could run on the 3-axis CNC drilling machine model in real-time.The servo control block diagrams of the other feeding systems for the three-axis CNC drilling machine modelare similar with the X axis, so they are no longer detaileddescribed hereThe three-axis CNC drilling machin

37、e model was used as the experimental platform which dimension is 200mm150mm50mm corresponding to its XYZ axis. And the servo system is established and regulated according to the Fig.1. Then, the servo control system block diagram was complied into an application by the VC compiler in a MatlabRTW env

38、ironment properly set up. At last, an experiment was carried out to detect the performance of the system designed here on the drilling machine model, taking a personal computer as the host computer and the PC/104 as the target computer in which the application generated is running in real-time.the c

39、oordinate point of the target is situated at 100000 m,70000m,30000m. And the host computer sent the coordinates and control commands to the lower computer. The workbench ran to the target point with the control of the CNC system. The actual position of the workbench was measured exactly by the grati

40、ng rules which were installed on the lathe guide rails. The measurement accuracy of the grating rule is 1(m).10 In each experiment, the workbench ran from the zero position to the same target described above. And, the experimental data on position by grating rules is shown in the table below. The ov

41、erall precision parameters of the drilling machine system can be drawn after analysis of the data in the table II: the positioning accuracy : 0.02(mm) the reorientation accuracy: 0.01(mm).Theoretically, the control accuracy could be achieved to 3(m), because an optical encoder with 500 lines isused

42、on the servo motor.But the actual error is greater than that. There are some reasons.1) The elastic deformation of workbench impacts.2) There is a measurement error on the grating rule.3) The error of screw assembly impacts4) The error of zero point impacts.V. CONCLUSIONThis paper presents a design

43、proposal for the servo control system of three-axis CNC drilling machine based onXPC Target. The development of the whole control system could be completed in a short time by this method. And, the experimental results demonstrate that the feeding system can run to the target position quickly and pre

44、cisely. This design scheme could be widely applied to develop the intelligent control systems for various special CNC drilling machines, and also be used to develop the control system for the equipment of automatic production line.REFERENCES1 YUEKANG Shan, CHANG Xu, QING Jiang, “Based-on computer vi

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50、g with amagnetic levitation device for neural network control law implementation and verification, American Society of Mechanical Engineers, Dynamic Systems and Control Division (Publication) DSC, vol. 72, no. 2, 2003, pp. 1293-1301.10 J. Liu, K. Butler Jerome, A. Evans Gary, K. DeFreez Richard, “Gr

51、ating theory for feedback and outcoupling of quantum well laser structures, Proceedings of SPIE - The International Society for Optical Engineering, vol. 2399, 1995, pp. 84-94. 介紹數(shù)控鉆床主要為通過數(shù)字控制進行鉆孔。很多產(chǎn)品都是特殊的工件,它們被廣泛應用于PCB孔加工和大型多孔不見的加工。1這些產(chǎn)品大局部是特殊的設備,它們可分為數(shù)控立式鉆、鉆孔中心、數(shù)控PCB鉆、數(shù)控深孔鉆和其他大型數(shù)控鉆床。2它適用于加工鉆井、傳播、

52、脫機和穿線等有很多精密孔的工件。特別是,要提高加工精度和效率,選擇一個特別的數(shù)控鉆床加工PCB及大型多孔管很重要。同時, 設計一個特殊的數(shù)控鉆是設計的伺服系統(tǒng)中最復雜的設計過程,它需要足夠的時間來方案和調(diào)試。因此,它不僅需要有豐富的知識資源,而且制約了市場的產(chǎn)品及時性。XPC目標是以Matlab / SIMULINK根底的一個工具, Matlab / SIMULINK是由MathsWorks提供的。它具有豐富的I / O設備模塊支持大多數(shù)集成電路板。3一臺計算機作為上位機(主機),另一種工業(yè)計算機作為目標電腦,兩臺計算機通過網(wǎng)卡連接，通過TCP / IP協(xié)議交流。這個系統(tǒng)能在X86 計算機的實

53、時系統(tǒng)中運行。它能對成型的控制系統(tǒng)進行快速仿真。數(shù)控技術實驗室進行科學研究，開發(fā)了一種3-axis數(shù)控鉆床模型,該模型是基于開放的高新技術公司制造的產(chǎn)品。利用鉆孔機的測試平臺模型,設計了基于XPC目標的特殊伺服系統(tǒng)。II。3-AXIS數(shù)控鉆床的伺服控制系統(tǒng)結構3-axis數(shù)控鉆床的圖1?？刂葡到y(tǒng)的體系結構3-axis數(shù)控鉆床 人伺服系統(tǒng)設計方案的根底le control system控制系統(tǒng)包括兩級計算機控制結構:主機一臺，并落實圖紙、指揮、通訊等，一個以PC / 104做為為核心的嵌入式計算機的鉆孔機伺服控制系統(tǒng)。通過RS232,主機的命令與機器運動狀態(tài)數(shù)據(jù)與PC / 104嵌入式進行溝通。

54、如圖1。運用網(wǎng)絡通信協(xié)議確保數(shù)據(jù)相互傳播的正確性。在這個系統(tǒng)中, 根據(jù)PC / 104總線的ADT652擴充卡用來作為系統(tǒng)的I / O接口。利用SIMULINK仿真軟件,設計以XPC目標為根底的3-axis數(shù)控鉆床伺服控制系統(tǒng)。系統(tǒng)的軟件被成功下載到PC / 104和實時操作編譯和調(diào)試。在復雜的計算后,PC / 104調(diào)整輸出為一個相應的PWM脈寬調(diào)制信號, 通過ADT652板被輸出到電機驅動電路。然后, 控制電機驅動相應的軸在一定的旋轉速度之下。在另一邊,一個增量旋轉光電編碼器固定在伺服馬達相關的進料機構以獲得其位置,反應到PC / 104的ADT652 I / O端口。同時,通過測速器得到

55、伺服電機主軸的運動速度, 通過ADT652 的ADC通道反應到PC / 104。三。建立了伺服控制系統(tǒng)一般來說,伺服控制數(shù)控鉆床的進料機構是點對點控制。而且X、Y軸進給率能明顯影響生產(chǎn)效率,但z軸進給率不會因為鉆頭和加工材料因素而受影響。在該平臺上,一個直流電機作為進料機構的動力裝置。和交流電機控制相比，直流電機的驅動電路簡單、可靠。此外,調(diào)速精度和動態(tài)響應特性的較為理想的直流電機速度調(diào)整的調(diào)速范圍大,精度更高。4因此,它可以更能滿足實驗要求。電感(L)的值在直流電機電樞電路很低,它在伺服系統(tǒng)的數(shù)學模型可以被忽略。然后,以電樞電壓(Ua(s)為輸入值和電機轉速(s)作為輸出值的電樞控制直流電機

56、的數(shù)學模型就建立了,該模型可以被看作是一種1階系統(tǒng)。所建立模型的傳遞函數(shù)是:以電機的角度(s)作為輸入值，工作臺線性位移 (Xo(s)作為輸出值,工作平臺的數(shù)學模型,也可以簡化為2階系統(tǒng)。其傳遞函數(shù)是：綜合考慮直流電機的數(shù)學模型和工作平臺、伺服系統(tǒng)可以簡化為2階系統(tǒng)模型。其傳遞函數(shù)是:x軸進料系統(tǒng)的數(shù)控鉆床伺服控制系統(tǒng)已在本文提出。其他軸的給料系統(tǒng)類似于x軸這里就不再不詳細描述。數(shù)學建模在3-axis數(shù)控鉆床模型中,F2260電機是固定作為x軸動力的裝置。旋轉電機可以將工作臺通過導螺桿轉換成的直線運動。我們能通過顯示在表中電機和工作臺的參數(shù)寫出傳遞函數(shù)。通過上述對運動的描述及工作臺的參數(shù)得到伺

57、服系統(tǒng)x軸的傳遞函數(shù):PID控制器設計b .本文設計了PID補償調(diào)節(jié)伺服系統(tǒng)的運動,根據(jù)上述數(shù)學模型和它與公式的參數(shù)設定用MATLAB軟件畫出Ziegler-Nichols5。采用該公式:該公式中的Km值是系統(tǒng)伴隨時間的比例增益,m是在這一點的振蕩頻率。首先,被控對象的數(shù)學模型轉化為離散模型，然后,用rlocus 和 rlocfind命令在臨界點獲得震蕩增益Km和震蕩頻率Wm。最后,PID補償器參數(shù)通過求解公式(5)得到:這一步的校正后和校正前的響應曲線顯示在圖2。我們可以發(fā)現(xiàn): 調(diào)整的PID補償器可以消除系統(tǒng)階躍響應的振動和超調(diào),該系統(tǒng)可以到達一個穩(wěn)態(tài)。此外,還介紹了整體弱化技術PID補償器

58、來提高伺服系統(tǒng)的穩(wěn)定性。這個技術是當偏差值(ei)之間的反應值和伺服系統(tǒng)的目的參數(shù)比規(guī)定閾值大、積分局部不起作用了。所以積分值不應太大。只有當偏差值小,它的作用是消除系統(tǒng)的穩(wěn)態(tài)誤差。它的PID算法如下:仿真結果明確說明,PID補償器非常滿足在點對點控制的數(shù)控鉆床需求的快速精確定位。C設計基于c xPC目標的伺服系統(tǒng)的在SIMULINK仿真軟件有一組xPC目標的工具 ,如RS232通訊工具,計時工具,I / O接口工具等等,這些可以用于建立伺服系統(tǒng)的控制框圖。6根據(jù)公式(4)描述伺服系統(tǒng)模型,利用MATLAB / SIMULINK仿真我們可以很容易的建立3-axis數(shù)控鉆床仿真模型。X軸伺服系統(tǒng)的控制框圖顯示在圖3。這只是一