Research on Belt Conveyor Monitoring and Control System

Transcription

1 Research on Belt Conveyor Monitoring and Control System Shasha Wang, Weina Guo, Wu Wen, Ruihan Chen, Ting Li, and Fang Fang Hebei Polyteehie University, Electronic Information Engineering, Hebei tangshan , China Abstract. The design and development objective of the entire belt conveyor control system is to minimize physical labor, which can make full use of other energy and variety of information other than manpower operation so as to increase efficiency and reduce accidents. This paper makes an in-depth analysis of implementation possibilities and requirements of the ARM-based monitoring of belt conveyor system by using LM3S8962 chip as a research object to design a set of belt conveyor monitoring system. The fault detection and control of belt conveyor can be done through the on-site sensors information signal collection by remote monitoring of belt conveyor and the motor protection. Keywords: μc/os-ii, LM3S8962, CAN bus, belt conveyor. 1 Introduction Conveyor used in production logistics has become major and common logistics equipments. Belt conveyor is an important type of conveyor. Belt conveyors is widely used in mines underground tunnel, mine ground transportation systems, open pit mining and ore dressing plant, it can be used to tilt transport or horizontal transport. Currentl intelligent management of belt conveyors has a certain study, but single function, and the results are not satisfactory [1]. Belt Conveyor Control System according to the various points of remote sensors send the signal came to realize on the belt conveyor start-stop and fault detection [2]. This system including control system hardware and software design and μc/os-ii migration; use RS485 and CAN bus protocol established CAN control network. The central control system uses 32-bit high-cost-effective LM3S8962 microcontroller [3], which provides high performance, a wide range of integration capabilities, as well as the choice of location in accordance with requirements applicable to a variety of cost-focused and clearly requires the ability to connect a process control applicable to a variety of cost-focused and clearly requires the ability to connect a process control application program. Makes the whole system is simple, small size and low power consumption. System also supports CAN-Bus, PWM with dead zone and other powerful functions, its characteristic is peripheral devices simple, yet very powerful, rich resources, stable operation and inexpensive, so it can be widely used in all kinds of large-scale industrial controls. In this system equipped with R. Zhu et al. (Eds.): ICICA 2010, Part I, CCIS 105, pp , Springer-Verlag Berlin Heidelberg 2010

2 Research on Belt Conveyor Monitoring and Control System 335 a Multi-tasking Real Time Operating Systemμ C/OS-II. Because of μc/os-ii transplant simple and fast real-time response characteristics, makes the system reliability, stability and real-time have been a better guarantee. Thus it is widely used 16-bit, 32-bit or 64-bit microcontroller, DSP or microprocessor. Shorter development cycle of systems, reduce development costs. 2 System Hardware Platform Design Conveyor control system design is intended to facilitate user operation of industrial control systems, as well as the safety operation of industrial control increase security coefficient, and reduce the staff time to the operating system. Therefore, the basic functions of conveyor control system are: belt conveyor start control; belt fault detection and control; belt fault protection control; manual emergency stop control, etc. [4] The main chip of the system is produced by Luminary Micro s Stellaris family of microcontrollers LM3S8962 processor, the chip has a 256KB FLASH and 64KB SRAM, storage capacity to meet the design requirements, without external expansion. LM3S8962 provide high performance, extensive integration capabilities, as well as the choice of location in accordance with requirements applicable to a variety of cost-focused and clearly requires a process of control and connectivity of applications. This micro-controller is designed for industrial application; these programs include remote monitoring, test and measurement equipment [5], factory automation and so on. LM3S8962 contains two RS485 modules, so using the RS485 interface chip 75LBC184 as a communications module. PCF8574 chip selected as the LM3S8962 microcontroller s external expansion of its current consumption is very low, and the output latch with a large current drive capability can directly drive LED. System overall block diagram as illustrated in Fig.1. Fig. 1. System overall block diagram and the system main modules include: key modules, motor drive module, CAN bus module, detection module, the alarm task module and emergency stop module 3 μc/os-ii Transplantation μc/os-ii is an exoteric sound code real time embed operating system. It can work independently of each task, it is easy to implement on time and correctly implemented, so that the design of real-time applications and extension easier, so that the application

3 336 S. Wang et al. considerably simplify the design process. It has been successfully transplanted in digital signal processor (DSP), 16/32-bit MCU. 3.1 μc/os-ii System Structure To conduct μc/os-ii migration, we must first understand the μc/os-ii architecture [6]. Fig. 2. is a μc/os-ii the relationship between the file structure and hardware. When using μc/os-ii in an application, the system needs is provided by the user application software and μc/os-ii configuration section [7]. Fig. 2. This is μc/os-ii system structure. μc/os-ii configuration file is associated with the application, its code including: OS_CFG, H, INCLUDES.H. The code has nothing to do with the processor type. 3.1 Based on LM3S8962 s μc/os-ii Transplantation This system chose LM3S8962 ARM and LMlink compiler accord with the operating system. The host through the JTAG interface target board to establish cross-development environment for debugging [8]. μc/os-ii migration hierarchical structure are shown in Fig. 3. In the process of transplantation, μc/os-ii of the core code without modification can be placed directly on μc/osiisource folder. Startup.S file in the catalogue of Target is the microcontroller startup code and interrupt vector table, Target.C and Target.H provide MCU initialization function TargetInit() and other simple peripheral control API. The μc/osii\ports directory is stored μc/os-ii transplant code, which includes OS_CPU_C.C, OS_CPU_A.ASM, OS_CPU.H three necessary files. The μc/os-ii when transplanted to the ARM processor need to modify these three files. 1. OS_CPU.H File OS_CPU.H file contains the μc/os-ii need constant, macros, and custom types. OS_CPU.H need to provide for growth in the direction of the stack. Stack growth direction different processors is not the same, CortexM3 the stack is high address to low address growth, so the definition of constant OS_STK_GROWTH 1 [9].

4 Research on Belt Conveyor Monitoring and Control System 337 OS_CPU.H also calls the macro definition OS_TASK_SW() to switch the task-level context. Because the context switch has a close relationship with the processor: #define OS_TASK_SW() OSCtxSw() Fig. 3. In the User layer, user directory store user code and settings. In part of the middle layer, middleware directory store intermediate files which provide by company or write by user themsleves. μc/os-ii Source directory in the source layer, is used to store μc/os-ii source code. Transplantation layer consists of two directories: μc/os-ii Ports directory and Target directory. In Driver Library layer, LM3S_DriverLib directory store lm3s MCU-driven function, it is directly facing the target board hardware layer; in general, in addition to μc/os-ii, the other code to be directly or indirectly, through its access to the hardware. 2. OS_CPU_C.C File In OS_CPU_C.C defined C function, OSTaskStkInit () function is associated with the CPU, so porting the code to modify the function. 3. OS_CPU_A.ASM File μc / OSII transplant need to write five simple assembly language functions. OS_ENTER_CRITICAL():close the interrupt source. OS_EXIT_CRITICAL():re-open interrupt source. OSStartHighRdy():run the current highest priority task. OSCtxSw():give up the CPU to use a task right call. OSIntCtxSw(): exiting interrupt service function OSIntExit () is called to realize the task switching interrupt. Because LM3S MCU only supports 8-bit interrupt priority in the high three, so here is the 1 left 5 is B, the macro is defined as OS_CRITICAL_INT_PRIOEQU (1 <<5) [10]. To recover from the new task stack R4 ~ R11;Restore interrupted;abnormal return; completion of the work, and then depending on the target board as long as the actual

5 338 S. Wang et al. situation of Target directory 3 files, μc/os-ii can run on the LM3S8962 microcontroller. μc/os-ii don t use C language of int, short, long Etc. data type, because they are concerned with the compiler type, implied not portability. μc/os-ii redefined data types. typedef unsigned char BOOLEAN; typedef unsigned char INT8U; typedef unsigned int INT16U; typedef unsigned long INT32U; typedef double FP64; typedef unsigned int OS_STK; typedef unsigned int OS_CPU_SR; μc/os-ii needs to close all access to critical code which could undermine the critical code execution of interruptions; then open interruption before exit critical code. We can modify the macro OS_CRITICAL_INT_PRIO, before set to enter the critical code need to close equal and below a certain priority interrupt. In μc/os-ii, it defined two macros respectively close and open the interrupts: OS_ENTER_CRITICAL and OS_EXIT_CRITICAL. #define OS _CRITICAL_METHOD 3 #define OS_ENTER_CRITICAL() {cpu_sr=os_cpu_sr_save();} //Close interrupt #define OS_EXIT_CRITICAL() {OS_CPU_SR_Restore cpu_sr ;} //Open interrupt When using these macros function, need to define local variables cpu_sr. #if OS _CRITICAL_METHOD==3 OS_CPU_SR cpu_sr=0; #endif The main task of the whole control system include: literacy UART0 tasks, alarm task, show task, start and stop tasks. Literacy UART0 tasks: primarily responsible for interacting with the host computer, parsing the host computer sends control commands over and perform, and finally returns the results of the implementation of the PC. Alarm Task: loop detection remote sensor, if the system abnormal, sending signals to the control system. When there is a failure to send signals to the display task. Display task: After receive the signal which send from alarm task, judge fault type, and displayed the corresponding text on the LCD screen.

6 Research on Belt Conveyor Monitoring and Control System 339 Start-stop task: primarily responsible for controlling the start and stop the belt conveyor. Sensor send a signal over to meet the launch conditions, you can start the system, if failure to determine fault signal, in case of failure, judge fault signal, and decide whether to need to stop system. Finish the above task code; write related interrupt service routines and start operating systems, applications began to run. If you need to add other function, need to increase its mission and call the certainly system service. 5 Conclusion By LM3S8962 microcontroller design of belt conveyor control system with rich functionality and powerful real-time processing capabilities, features easy to extend. The operating system uses the μc/os-ii to simplify programming, enhance modularity. This high-performance microcontroller, combined with real-time operating system has already become a kind of control system development trend. On this basis, you can use the RS-485 communication mode from the CAN bus instead, to increase the communication range. References 1. Qiang, L., Wen, D., Wu, S.-t.: Study on Graft of ARM and μc/os-ii/os-based Embedded System. J. Journal of Shandong University of Science and Technology (Natural Science), Qingdao (2006) 2. Yanwei, Y.: Research on Belt Off-tracking Monitoring and Rectification Device for Belt Conveyer. J. Mining & Processing Equipment, Luoyang (2002) 3. Wang, J., Ji, Q.: The Real-time Embedded OSμC/OS- Porting on ARM7 Processor. J. Computer Knowledge and Technology, Hefei (2009) 4. Tian-jing, Z.: Causes and precaution against the belt off its caurse in belt conveyor. J. Coal Mine Machinery, Haerbin (2001) 5. Li-zhao, Z., Xiao-rong, C., Yan-fen, L.: The Research of Porting Embedded Operating System μc/os-ii on ARM. J. Instrumentation Technology, Shanghai (2009) 6. Yun, Y., Yong, Z.: Research and implementation of porting μc/os-ii based on ARM7. J. Computer Engineering and Design, Beijing (2009) 7. Zhang, X.: The Task Analysis of Interface in μc/os-ii Operating System. J. Software Guide, Wuhan (2009) 8. Jiang, F.: The Porting of Real-Time Operation System μc/os-ii on ARM. J. Microcomputer Information, Beijing (2008) 9. Labrosse, J.J.: Micro C/OS-II The Real-Time Kernel, Second Edition. CMP Media, LLC, New York (2002) 10. Ji-kui, F., Yan-jing, S.: Design of intelligent monitoring substation node based on μc/os-ii. Computer Engineering and Design, Beijing