The Design And Research Of Measuring And Controlling System In The Thermal Balance Experiment

The issue is the design of a multi-route temperature sampling, measuring and controlling intelligent systems. It is researched and developed in order to be against the thermal balance experiment requirements in the aerospace field.In the past, the temperature control tests are carried out manually by the handlers. Th testing handlers commonly sample the temperature of different payloads and equipments under the testing needs. This method will require handlers to find the correct temperature data lines from all the data lines and power lines. This operating way is complex andtime-consuming.Compared to this condition, we design the temperature measurement and control as a separate system. Testing handlers can complete the uniform management of the payloads and equipments through the temperature management platform.We use thermal-control simulators available in the thermal balance experiment, which simulate the themperatrue conditions of the payloads and equipments. By collecting temperature data, the handlers can control the working temperature of the equipments involved in the tests.Temperature controlling system of the thermal balance experiment is divided into two main parts: Measuring and Controlling Unit and Ground Controlling Unit (PC). Measuring and controlling unit is the hardware circuit, and the ground controlling unit is the user terminal of the whole system. This paper deals with the process of the design and manufacture of the system and the system's performance has been analyzed.In this design, the power lines and thermal resistance wires (temperature datas lines)of the thermal-control simulators are concentrated in the modules. All temperature datas collection, processing, transmission and other operations will be completed in the systems.The hardware design of the circuit makes the ARM (AT91R40008) and CPLD (XC95144XL) as the core. ARM microprocessor is in charge of the state management of the whole system, and CPLD is the main logic design of address decoding and timing controlling. The system it in the function of 112 temperature data acquisition of seven payloads and equipments. Meanwhile controlling the temperature of seven payloads and equipments To be undertaken because of the acquisition temperature channel more, we used ADG506 Analog Switches for multi-channel choice, then the temperature analog signals were conversed into digital signals throughout AD1674. Finally, the temperature datas can be transimmted to the PC by RS232 bus.To ensure the reliability of the system, we have followed circuit design criteria of the aerospace field in the hardware circuit design process . For example, under the premise of achieving the required function, simplifying the circuit design, maximizing the use of standard circuit and mature technology,utilizing the watchdog circuit for the key chips to prevent running time, appropriate use of redundant design design, use cold standby switch methods and so on.The design of the software, including system software and PC management platform two parts. System software mainly achieves the temperature acquisition and controlling functions,in which ARM monitoring unit dominated the whole system will be completed and the state management function.For example, CPLD work state control, temperature acquisition state management, digital PID algorithm, as well as the PC serial port communications. CPLD logic of the system as a whole to achieve, including multi-channel decoding the address. AD conversion timing control, the PWM control of heating units on/off.PC developed a temperature management platform of the system, the handlers will grasp at any time throughout the system in operation. The system can take out the work orders issued and temperature datas transmission and other operations between measuring and controlling unit and the PC throughout the serial communication. PC can also be used for the real-time temperature curve shows and the temperature datas storage and other functions.In the design of this subject, for guaranteeing the entire system's performance and target, we have carried out a separate reliability modeling and expection in the light of the whole hardware circuit designed. The results prove that the system has fully met the scheduled task requirement.In a word, the temperature controlling system we have designed has the characteristics of simple structure, conveniention for operating, high measuring precision and so on. It has certain practicality and higher society popularized value.