Spacecraft Vacuum Thermal Test Control System Based On Distributed Network

With the development of spacecraft technology, future spacecraftfunctionality and operating conditions will become more and more complex,spacecraft in-orbit power is also growing, and some high-precision equipmenthas stringent requirement to its operating environment. All these newchallenge will promote spacecraft thermal control system forward continually.At the same time, the development of spacecraft thermal control technologyalso put forward higher requirement to ground vacuum thermal test, this canverify the feasibility and function completeness of thermal control system.Vacuum thermal test includes thermal vacuum test and thermal balance test,during the test, need to simulate vacuum, cold black and solar radiationenvironment; especially for the solar radiation environment, high-powerexternal heat flow simulator will be needed to achieve that. These high-powerequipments will generate high heat in a short time. Therefore, how to controlthese external heat flow simulating equipments precisely according thespacecraft operating conditions, is a key point of vacuum thermal test controlsystem.This paper details the spacecraft vacuum thermal test and vacuumthermal test system, and analysis the weaknesses and inadequacies of thetraditional vacuum thermal test control system; then re-design and developthe traditional test control system combined with the new requirement andcharacters in the new situation. According to control theory, distributedcontrol network can concentrated display system status and concentrate all ofthe settings, and system control functions distributed to reduced the risk of single point failure, to avoid system failures, improve the control systemstability and reliability; for this reason, the author design vacuum thermaltesting control system based on distributed network control technology.This paper firstly introduces the general control structure and flow of thevacuum thermal test control system based on distributed network control; theentire control system terminals include server, monitor terminals, controllersand data collector, all these terminals have the ability to be connected withEthernet. Then paper details the control system hardware and software; thehardware including severs and monitors, power controller, programmable DCpower (including heating cage), data collector (including thermocouples), allof them have internet access capabilities, and constitute the distributednetwork using TCP/IP protocol. This design can decentralized the risk ofsystem failure, and improve the system reliability. System software mainlyincludes sever software and monitor terminal software.In addition, this paper also summarizes the key technology used in thecontrol system; the key technology includes distributed network, advancedPID control technology and high-speed signal processing technology.Distributed network can improve the stability and reliability of control system;the improved design of control system uses incremental digital PID controlalgorithm, the PID control parameters can adaptive tuning based on fuzzylogic, this algorithm can meet the requirement of control accuracy and controlautomatic adjustment. In addition, the power controller based onhigh-performance DSP technology is also the key technology of this controlsystem.Finally, the author test the control system performance and reliabilitypattern mode, to test the dynamic characteristics and anti-jamming capabilityof the temperature closed-loop control system, and verify the nodesautomatically switch and closed-loop automatically switch capability in the case of single node and dual node failure. The test results show that thedynamic characteristics of control process are good,the anti-interferenceability is strong, a variety of backup mode and reliability guarantee mode canoperate effectively, and the control system can meet the requirement ofvarious types of spacecraft vacuum thermal test.