Design And Realization Of Leafy Greenhouse Measurement And Control System Based On Fuzzy PID Controller

With the rapid development of computer technology,the control of agricultural greenhouse environment is also developing towards the intelligent direction,but the agricultural greenhouse environment is a multi-factor coupling and time-varying control object,it is difficult to accurately describe and model.And climate change is obvious in four seasons in Jiangsu and Zhejiang provinces,the summer is hot and humid,the winter is cold and dry,and the temperature difference and humidity difference between day and night are large,the existing control system's control mode is fixed,it can not change with the environment changes,so it is difficult to achieve a good control effect.PID controller is widely used in the control field of industry and agriculture,it has the characteristics of stable performance and easy realization.When the system structure is not clear and can not be accurately modeled,the use of PID technology is ideal.However,how to adjust the parameters of the PID controller is the key problem of the system.The control rules of the conventional PID controller are generally fixed after establishment,the adaptability to the system's running changes and the ability of anti-interference are insufficient,so it's easy to produce a large overshoot.Because fuzzy control is a kind of nonlinear control technology,it can use fuzzy logic reasoning to complete the decision according to the change of operation environment,the fuzzy algorithm and PID controller are combined to reduce the system overshoot and improve the response speed and anti-interference ability.In view of the characteristics of climate change in Jiangsu and Zhejiang provinces,through the study on the growth environment of leafy vegetables,this paper has designed a PID controller based on the fuzzy algorithm,which is used to control the greenhouse environment of leafy vegetables.In the design of the controller,the output value is determined by the temperature difference between the actual value and the set value and its rate of change,and the fuzzy reasoning is used to adjust the three parameters Kp,Ki and Kd of the PID controller,so the PID parameters can be self-adjusted online,and it improves the PID controller's adaptive performance.Finally,the actual operation results of the system were tested in Luhe Agricultural Demonstration Base of Jiangsu Academy of Agricultural Sciences.The results showed that the system could control the greenhouse environment according to the actual situation of the site,the overshoot was small,the response time was short,and the system had met the control demand of modern precision agriculture for greenhouse environment.