Design Of A Temperature And Humidity Controller Based On ARM

There are some points about high-class temperature and humidity controllers for damp heat test chambers, which are:①use color LCD and touch screen as Human-Machine Interface;②have large memory, which could shortage a lot of programs for temperature and humidity;③high precision of temperature and humidity measuring;④high precision and low fluctuate of temperature and humidity control, and have the ability of self-tuning which could adjust control parameter by itself when the test condition changes;⑤have much supplementary function, such as RS232, USB, Ethernet and so on. Temperature and humidity controllers in the similar grade or above are seldom produced all in our country.This study designs an ARM9 based high performance temperature and humidity controller, due to the normally low performance produced in our country. This study primarily appoints to several aspects below. First it studies the control methods for damp heat test chambers, and then analyzes thermodynamical processes of the air in the chamber and its mathematical model. Second, it analyzes the error of temperature and humidity detecting and the method to reduce error, and then gives a plan of high precision temperature and humidity measuring. Afterwards, analyzes the needs of the controller, and complete the hardware design. Last, chooses the suitable control algorithm, and implement it on the hardware platformThe main content of each chapter is given below.Chapter 1 introduces some back acknowledge of ARM, equipments for environmental test and something else like that. And it gives the primary of this study, includes mainly point, difficult points and the new.Chapter 2 studies the control methods for damp heat test chambers, and then analyzes thermodynamical processes of the air in the chamber and its mathematical model.Chapter 3 analyzes the error of temperature and humidity detecting and the method to reduce error, and then gives a plan of AD7711 based high precision temperature and humidity measuring.Chapter 4 analyzes the needs of the controller, and completes the hardware design.Chapter 5 chooses the suitable control algorithm, and implements it on the hardware platform.Chapter 6 analyzes the performance of the controller through experiment.Chapter 7 summarizes briefly.