Weizhong Yang

Crop Model-Based Greenhouse Optimal Control System: Survey and Perspectives

A survey is presented of the developments in scientific literature on the greenhouse optimal control. The related problems to optimal control were discussed, and the schematic diagram of optimal control system, combined crop models and optimization algorithm were covered focusing on issues such as: model simplification and validation, definition of objective function, input or output constraints and dynamic optimization, and especially structure-function Greenlab model was made s a first exploration for the optimal control application. Not only the above research issues were listed in the paper, the perspectives and the solutions are presented as well. It is pointed out that only the crop growth model is integrated into the greenhouse climate optimal control, the best economical result and energy-saving can be warranted.

Soil Water Sensor Based on Standing Wave Ratio Method of Design and Development

Soil moisture is one of the most important parameters in the soil properties, the traditional methods of soil moisture measurement is time-consuming. And it can’t meet the soil moisture measurement’s real-time and fast requirements. This paper analyzes the relationship between soil moisture and its dielectric properties, research the standing wave ratio method for measuring soil water content. Firstly, design hardware circuit, plate making, and welding circuit board, then insert the probe into the soil, by measuring the reflection coefficient, we can know the probe impedance which depend on the soil dielectric constant. At last we can find the internal relation between output voltage and soil water content, by measuring the multiple sets of different water content of soil.

Light Simulation Inside Tomato Canopy Based on a Functional-structural Growth Model

This paper present how the light transfer and interception inside the canopy was computed by combining a tomato dynamic growth model. The tomato functional structural growth model was applied to produce the topology and geometry of individual plant, and through transformation, the canopy could be composed of multi-individual plants. In this simulation system, a radioactive transfer model named hierarchical instantiation for radiosity, was coupled effectively into this tomato growth model to compute the repartition of light energy throughout the canopy, so the key interface technology when integration were explained in the paper. Finally, the visualization results were presented for the light simulation inside canopy.

Study on Greenhouse Temperature Variable Universal Adaptive Fuzzy Control

Abstract: Basic fuzzy controller (BFC) has been successfully adopted to control greenhouse environment temperature. Variable universal adaptive fuzzy controller (VUAFC) which can contracts or expands the universal of the fuzzy variables of the BFC by the value of response error has been developed to get better control performance. By analyzing the result of experiments, VUAFC improved the performance of the fuzzy controller greatly.