The Measurement And Control System Research Temperature, Humidity And Carbon Dioxide Of Greenhouse

Greenhouse is an important component of protected agriculture. Measuring and controlling system is the basis of the management automation in the greenhouse. With the growth rules analyzing measurement data and controlling circumstance condition, it makes greenhouse better condition than outdoor in the unfit season, and more productive and high quality.This thesis presents the measuring and controlling system about temperature, humidity and carbon dioxide's density in the greenhouse, composed of host PC and secondary MCU. Considering the accuracy and economical, this thesis design AT89S52 as the core control apparatus, and choose the sensors with high ration between performance and cost. After the nonlinear is compensated with least square method to measuring result, it has reduced the nonlinear error of sensor and achieved accurate measurement and accuracy control. When the parameter has exceeded the limit, including temperature, humidity and carbon dioxide's density, the single-chip microcomputers activate the audible and visual alarm. At the same time, the single-chip microcomputers control the solid state relay to actuate mechanism for compensation. For different parameters, we can use keyboard to set the anticipant range of the crop. The secondary computer communicate with the host computer through RS232. In order that it's convenient to debug, transplant, amend, this thesis design the software using C language. The model block is composed of data acquisition, keyboard and display, serial communication, data processing and so on. At the last, this thesis present the reliability and the measures to against interference, and make the system work more reliable and stable.This thesis choose the devices as full consideration of the ration between performance and cost as possible. After debugging, measuring result is in good agreement with anticipate. This measuring and controlling system is simple, reliable, stable and low cost. It can be applied notonly in greenhouse, but also in environment monitoring and constant hygrothermal factory. And it has much of value to apply and popularize in other fields.