Design Of Vehicle-mounted Medical Temperature Control System

In the medical filed, the temperature control system has wide applicatins,such as medication transportation, medical agent storage and in-vitro tissue andblood processing. Therefore, it is very important to design a vehile-mountedmedical medical temperature control system. The kernel parts of the systeminclude the stability and accuracy.By analyzing the existing thermostatic system, a system design solution wasproposed in this paper. The control system includes TEC modual used as a frontend to measure temperature, AD7705chip used as the ADC, and NTC componetused as the heating or cooling unit.Through the NTC, the controller converts the temperature into analogvoltage. After that,16-bit high precision A/D converter was applied to transferthe analog voltage into digital signal, which is convenient for STM8S105. Themeasured temperature is displayed on the LED in real time. Users can set theneeded temperature through the keystroke. When the temperature is set,STM8S105exports PWM signal to control DRV592circuist. The DRV592drivesTEC to achieve heating or cooling model to make sure the temperature is in thesetting value range.According to the water tank experiment, a combined control method isoffered to meet the temperature control and overcome the controller’snonlinearity and hysteresis. When temperature error between the set value andactual temperature value is large, the lookup table control method is used toreduce the heating or cooling time of temperature. When the error is within1℃,the incremental PID control method is applyed to decrease the overshoot. Thepurpose of the control system is within the range of37±0.1℃. Meanwhile, thefuzzy PID control and BP-NN PID control algorithms have been studied and analyzed by Matlab simulation, which offers further improvement for systemupdate.