Applied Mechanics and Materials Online: 2013-09-27 ISSN: 1662-7482, Vols. 423-426, pp 2805-2808 doi:10.4028/www.scientific.net/amm.423-426.2805 2013 Trans Tech Publications, Switzerland Control System of Tension Test for Spring Fan Wheel Assembly Kunqi Wang a, Chencong Meng b, Ping Li c and Jingqi Fan d School of Mechatronic Engineering, Xi an Technological University, Xi an, 710021, China a Kunqwang2012@yeah.com, b 15276039@qq.com, c Pingli01@163.com, d 363741069@qq.com Keywords: PLC. Tension test. Software design. Fuzzy PID. Abstract. This design is a basic method for testing spring fan wheel assembly and steel cable tension control system. PLC is used as logic control core. Stepping motor and magnetic powder braker is used as an executive element. The constant tension control of the running process of the system is completed. The fuzzy control process of PID system includes two parts of tension loading and damping loading. The method of modular software is used to make the program structure clear. Introduction Tension test bench is a equipment about spring fan wheel assembly and steel cable tension test [1]. In transverse tension [2] provisions, completion of loading steel cable, shrinkage, steel cable tension test function. To ensure the test spring fan wheel assembly tension is maintained at a constant value range, so as to achieve the purpose of component testing. Because the tension test and control system is a testing system of dynamic, prone to overshoot in the measurement of control, overload and other problems, often cannot reach the ideal control effect. Fuzzy PID control system [3, 4] of this design can make the system has fast response speed, smaller steady-state error, high control accuracy. The overall structure design The following is a spring fan wheel assembly and steel cable tension test chart, as shown in figure 1. The movement principle is composed of test software feedback control of stepper motor and reducer ball screw assembly drives cable lateral movement, in order to achieve control of the steel cable tension transverse tensile. The lateral force is mainly composed of a wire rope, stepper motor, magnetic powder brake, ball screw, tension sensor. In the main motor operation, the tension signal can be detected by the tension sensor, and transmitted to control system. The control system sends out the control signal, step motor rotating is drived, the magnetic powder brake reducer, driven by tensile screw, lateral force and control components. The hardware design of control system In the system for tension control to meet the requirements of two aspects: (1) a predetermined value range of tension with components, to protect the components of the function (2) requires tension loading and damping load. Stepping motor, ball screw, rail and stent is composed to Tension loading. The software control stepping motor automatic loading; damping loading by the stepper motor. Stepper motor, torque sensor, magnetic powder brake and servo power is composed to damping loading, The tension sensor, torque sensor, angle sensor and A/D converter and high-speed data acquisition card is composed to Detection of tension and the corner part, To complete the conversion of cable tension and torque measurement. The following is Structure diagram of control system, as shown in figure 2. In the design of the tension control system, small PLC is used as logic control core, through which to control each link in the process of testing. By controlling the motor of the magnetic powder brake and step, realize the constant tension control of testing process. According to the test sequence, the tension control system can be divided into two parts tension loading and damping loading process. All rights reserved. No part of contents of this paper may be reproduced or transmitted in any form or by any means without the written permission of Trans Tech Publications, www.ttp.net. (ID: 130.203.136.75, Pennsylvania State University, University Park, USA-19/02/16,04:05:43)
2806 Applied Materials and Technologies for Modern Manufacturing Fig.1. The structure of spring fan wheel assembly Fig. 2. The assembly and cable tension test chart Tension loading In the tension control, tension given value and feedback of tension values are compared, and a deviation of e (t) is generated. The input deviation after tension control PID algorithm, an output u (t), is used to control the DC speed regulator, and DC speed regulator according to the output of the tension controller, control of stepper motor speed, in order to maintain the normal range within the testing process to achieve constant tension, tension test process. Because the DC speed - stepper motor system itself is already a double closed-loop system, then test the tension control process is at least a 3 closed loop control system. The following is structure diagram of Tension loading, as shown in figure 3. Damping loading Tension sensor mounted on the tension cable on the induction to convert pressure into voltage signal, a signal amplifier, a 0 V-10 V standard signal, input PLC analog input port, tension control. In the tension control, tension setting value and the tension feedback value, get a deviation of e (t). When the tension feedback value is less than the tension of the given value, deviation of the input signal e (t) is a positive (+); when the tension feedback value is greater than the tension of the given value, deviation of the input signal e (t) is negative (-). The input deviation after tension PID algorithm procedure, obtains the output u (t). A control power amplifier is used to drive the output current amplification, magnetic powder brake. To control the braking current brake through the tension set value and feedback value, then control the brake output brake torque, so that the tension is maintained in a certain range, to achieve constant tension. The following is structure diagram of damping loading, as shown in figure 4. Fig.3. Schematic diagram of tension loading structure Fig.4. Schematic diagram of damping loading
Applied Mechanics and Materials Vols. 423-426 2807 The software design of control system The PLC program is the key to the realization of tension control, in the course of programming, the focus is through the feedback of sensor data to the stepper motor, reducer, ball screw assembly position control, ensure the tension within a predetermined range of values. Program software is used by Visual C++ 6, and object oriented method is used for block design. Design using multiple document template structure of Visual in C++, which is different from the common software structure, but a similar to the general commercial software -- Microsoft Word structure. The structure not only in data storage and processing of clear structure, but also can operate on multiple documents, and because it has inherited the traditional style of the Windows interface, therefore, the user can conveniently operation, without the need to spend a lot of time to get familiar with the operating interface. The system software is divided into four parts: user interface design, acquisition and preprocessing data, control calculation and data into the motor, test report output. System software flow diagram is shown in figure 5. The control system algorithm PID controller is a linear controller, according to the given values of r(t) and the actual value of output y(k) constituted the control deviation e (t), the ratio, the deviation of e integral and differential by linear combination of control volume, the object control. Conventional digital PID control law k e( j) U(k)=K p e(k)+k i j= 0 +K d [e(k)-e(k-1)] (1) Fuzzy PID algorithm Fuzzy PID variable K p, K i and K d auto-tuning algorithm overcomes the disadvantages of PID method, but the selection of its parameters has certain blindness, debugging time is relatively long. In this paper, a kind of change K p, K i,and K d fuzzy self-tuning PID algorithm, can achieve better control results. The control structure is shown in figure 6. Fig.5. System control flow chart Fig.6. Schematic diagram of fuzzy PID control structure
2808 Applied Materials and Technologies for Modern Manufacturing Control system simulation The control system is adjusted according to the fuzzy PID PLC, using MATLAB simulation [5, 6]. Unit step experiment is served on the closed-loop tension control system. While K P = 0.50, K i =0.01, K d =0.02, in order to ensure the system input steady-state error of e ss =0.1, the overshoot of M =15%, adjusting the time of t< 2.5S, from the response curve is shown in Figure 7. Fig.7. The system step response curve After the fuzzy PID PLC regulation, the actual order system step response curve and the theory of PID step response curve is identical, within allowable error. Conclusion PLC is used as logic control core in the system.to realize the real-time control of the tension test, in which case the constant tension test process. Tension control system software design uses the modular design to operate easily. The overshoot, settling time and other parameters of system are improved in the practical test by fuzzy PID control method. Acknowledgements This work was supported by Bureau of Science and Technology of Shaanxi Province for Supporting of Foundation (2010K09-08), and Foundation of Key Subject Construction of Shaanxi Province. References [1] Gongyuan Yang. Technology and application of mechanical and electrical control technology, edited by Publishing House of electronics industry,beijing,(2005). [2] Wenfeng Yu and Jingyi Du. Industry Control and Applications, Vol. 26, No. 4(2007),p.26-28. [3] Yonghua Tao. Control and application of the new PID, edited by Machinery Industry,Beijing,(2000). [4] Jinhuan Zhang. Journal of Wuhan University of Technology (Information & Management Engineering Edition), Vol.27, No. 5(2005),p.286-290. [5] Jingun Liu. Advanced PID control MATLAB simulation, edited by Publishing House of electronics industry, Beijing:(2006). [6] Kexin Wei and Yunliang Wang. MATLAB language and automatic control system design, edited by Mechanical Industry, Beijing (2004).
Applied Materials and Technologies for Modern Manufacturing 10.4028/www.scientific.net/AMM.423-426 Control System of Tension Test for Spring Fan Wheel Assembly 10.4028/www.scientific.net/AMM.423-426.2805