The mathematical models of the greenhouse environment are MIMO systems, characterized by a high coupling, nonlinearity, parameter variation and they are highly influenced by disturbances. This paper uses a well-known greenhouse climate model with measurable external disturbances and a feedback-feedforward linearization, decoupling and disturbance compensations technique. Greenhouse climate model parameters/disturbances, which are susceptible to wrong estimation, are identified, i.e., heat transfer coefficient (UA), shading and leaf area index coefficient (α), and intercepted solar radiant energy (Si). The system response, in the case of nominal model and considering different levels of model uncertainty, are compared. Significant quality indicator degradations for setpoint step responses leads to reconsider the control structure using two degree of freedom (2DoF) PID controllers. Four 2DoF PI/PID tuning technique are compared at nominal condition and under parameter variations showing good performance.
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机译:温室环境的数学模型是MIMO系统,具有高耦合,非线性,参数变化等特点,并且受到干扰的影响很大。本文使用了一个众所周知的温室气候模型,该模型具有可测量的外部干扰以及反馈前馈线性化,去耦和干扰补偿技术。确定容易受到错误估计的温室气候模型参数/扰动,即传热系数(UA),阴影和叶面积指数系数(α)以及截获的太阳辐射能(Si)。在标称模型的情况下并考虑了模型不确定性的不同水平,比较了系统响应。设定值阶跃响应的质量指示器明显下降,导致使用两个自由度(2DoF)PID控制器重新考虑控制结构。比较了四种2DoF PI / PID调谐技术,它们在标称条件下和参数变化下均显示出良好的性能。
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