Design and Research of Distributed Real Time Surveillance Control System

Transactions on Computer Science and Technology June 2015, Volume 4, Issue 2, PP.40-43

Design and Research of Distributed Real Time Surveillance Control System Wentao Sun Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences, Changchun 130033, China Email: swtxpscm@163.com

Abstract Distributed real time surveillance control system is used especially in distributed computer measure and control system, mostly in widely dispersed measure points without human surveillance. This paper describes theory、construction、control strategy, stability analysis of distributed real time supervisory control and data acquisition system, implements distributed measure signals collection and design of supervisory control system. The realization of virtual instrument based on VC++ can accomplish measurement signals acquisition, storage, display and analysis, also the result of surveillance control system is provided, and shows the functional powerful agility of virtual instrument based on VC++.

Keywords: Real Time; Distributed; Virtual Instrument

1 INTRODUCTION Distributed real time surveillance control system adopts technology of computer, measurement, communication and virtual instrument, achieves data acquisition from dispersed measure points in time, implements local and long-distance control automatically, supports malfunction diagnosis, safety management and production attemperation.

Distributed real time surveillance control system is made up of three parts: distributed data acquisition branch, surveillance and control branch and communication net, principle of “distributed measure, concentration control” insures the system running reliably.

The functions of distributed data acquisition branch includes gather, record and display of acquisition data, an alarm given and management, as well as failures memory and trend analysis is realized from man-machine interface by images, graphics and sounds, to show equipment work states and performance parameters.

Virtual instrument possesses obvious advantages to implement distributed real time surveillance and control branch by various soft equipment based on the same hardware. Modularization, opening and interchange characteristics guarantee to assemble various soft equipment in order to satisfy surveillance and control functions.

2 DESIGN OF DISTRIBUTED REAL TIME SURVEILLANCE AND CONTROL SYSTEM 2.1 Conformation of Distributed Real Time Surveillance and Control System Distributed real time surveillance and control system consociates distributed data acquisition branch, surveillance and control branch and communication net.

Surveillance and control branch includes controller and data server. Communication net is made up of Ethernet and data exchange interface, data exchange interface connects distributed measure points and Ethernet. Distributed data acquisition branch includes dispersed measure points such as video monitors、motor driver and coder equipment, these equipments transmit measure data, for example, outburst signals, period signals and video signals. Surveillance and control branch and Distributed data acquisition branch are synchronized by synchronization signal generator.

Figure1 shows the construction of distributed real time surveillance and control system.

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Data server

Controller

TCP/IP

Synchronize

Data Exchange Interface

Video monitor

Coder Equipment

Motor Driver

FIGURE 1 CONSTRUCTION OF DISTRIBUTED REAL TIME SURVEILLANCE AND CONTROL SYSTEM

Surveillance and control software running in controller manages the whole distributed real time surveillance and control system, it is a multithreading intelligent software with kindly man-machine interface to cope with data processing, such as malfunction orientation and deal with, working state surveillance to dispersed measure equipments.

2.2 Design of Data Exchange Interface Data exchange interface is main part of distributed real time surveillance and control system, it works for data collection, package, transmission from dispersed measure equipments, and transport control information from controller to dispersed measure equipments. Figure 2 shows the construction of data exchange interface. video1 Sec signal synchronization

sam ple inter face

IC CPLD

CPU

16C554

inter face

coder Focus judge

TM320 C5402

Servo driver1 IC 16C554

Surveillance

video2

display

inter face

Servo driver2 Servo driver3 controller

FIGURE 2 CONSTRUCTION OF DATA EXCHANGE INTERFACE

3 METHOD OF FEEDBACK CONTROL WITH FAULT TOLERANCE IN REAL TIME Real time method of feedback control with fault tolerance is put to use in surveillance and control system to track every distributed equipment. When data quantity produced by a long distance surveillance equipment in one sample period is more than communication transmission ability, a beforehand process according to data flow variation will run by judgement of priority level to send a minimum data package which is the key parameter to distributed surveillance equipment, so data loss in a sample period can be avoided and dispatching conditions of controller is met.

In distributed real time surveillance and control system, data exchange between controller and each distributed surveillance equipment is restricted by time synchronization. If a long distance surveillance equipment is broke down, some measurement will not fulfill in synchronization period, sometimes this may bring economy loss. To solve such a problem, a fault tolerance method must be provided to insure the surveillance and control system running normally with some long distance surveillance equipment in trouble.

Method of feedback control with fault tolerance in real time is effective for malfunction correction by software in distributed real time surveillance and control system. Currently main/assistant version technology is put to use, it is a powerful software based on algorithm RMFF, PB-Overloading, SS. Through this software, surveillance and control system separates period data from every long distance equipment into subsidiary group by data quantity, remain time quantum in advance, when abrupt data frequently deliver to cause responding troublesome, they can be dispatched to - 41 http://www.ivypub.org/cst

data packages with less data, so that exchanging of period data and abrupt data are all transported successfully, efficiency and reliability of distributed real time surveillance and control system are increased. Figure 3 is the flow-process diagram of method of feedback control with fault tolerance in real time.

Start

Data overflow

N

Y Add last overflowed data

Period data calculation

N

Abrust data calculation Y

RMFF Process

Period/abrust data Q calculation Q > limited quantity

N

Y Clip data according to priority

Controller

SS process

Data export

Data and overflowfeedback

FIGURE 3 FLOW-PROCESS DIAGRAM OF METHOD OF FEEDBACK CONTROL WITH FAULT TOLERANCE

4 RESULT OF SURVEILLANCE AND CONTROL IN REAL TIME

servo drive curve in tense power control without compensation descent edge - start time, ascending edge- stop time

(A)Servo drive curve in tense power control without compensation

servo drive curve in tense power control with compensation descent edge - start time ascending edge - stop time

(B) Servo drive curve in tense power control without compensation FIGURE 4 COMPENSATION IN TENSE POWER CONTROL BY SURVEILLANCE AND CONTROL SYSTEM

Figure 4 shows servo drive curve in tense power control course, in this course the distributed real time surveillance and control system decides compensating or not by surveillance data. Figure 4 A shows servo drive curve in tense power control without compensation, Figure4 B shows servo drive curve in tense power control with compensation.

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Pulses in Figure A and B identify time sequence, descent edge is the start time of tense power control, ascending edge is the stop time.

In Figure 4 A, precision accuracy of tense power control is not satisfied, compensation is needed.

In Figure 4 B, compensation is added in tense power control by surveillance and control system repeatedly till precision accuracy demand.

5 STABILITY ANALYSIS Distributed real time surveillance and control system works with multi in/out in fixed period, data flush and control information are transported in net with time delay, synchronization difference and clock drive divergence, even though, no data package lose in net transport.

In such application conditions, a net control model is established to analyze the stability of distributed real time surveillance and control system, with many experiences, a result is obtained: in sample frequency 50Hz and transport time delay less than 5ms condition, if data package is divided properly, the surveillance and control system works normally. If the function of the surveillance and control system is extended, the stability shall be analyzed again.

6 CONCLUSIONS Construction design, strategy of surveillance and control as well as stability analysis of distributed real time surveillance and control system is presented in this paper, also the key point solutions. A feasible instance is provided for distributed real time surveillance and control system.

ACKNOWLEDGEMENTS The research work was supported by my colleagues and family.

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AUTHORS Wentao Sun was born in Shengyang city, May 1967, earned his doctoral degree in automation in Changchun Institute of Optics, Fine Mechanics and Physics in 2008.

He is working for Changchun Institute of Optics, Fine Mechanics and Physics, as a Vice Researcher, his major field is about engineering applications of software in opto-electrical measurement.

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