Control of biological clock in crassulacean acid metabolism using nullcline design

The nonlinear dynamical behavior of the crassulacean acid metabolism is discussed from the control theoretical viewpoint. The state-variables of the nonlinear dynamic equations are an internal CO₂ concentration, a malate concentration in the cytoplasm, a malate concentration in the vacuole, and an order of the tonoplast membrane. The input variables are an external CO₂ concentration, a light intensity and a temperature. We have recently presented a dynamic estimator of the tonoplast order and a fuzzy identifier of the nonlinear function in the dynamics of the tonoplast order. In this paper, we propose two types of the feedback controllers of the CAM model using the external CO₂ concentration and the light intensity as an input.