Optimal control mechanism involving the human kidney

In this paper we study the control mechanism that regulates water and the concentration of sodium in human body. For this reverse engineering problem, a control system model is developed using a modification of the standard LQR theory. The control law derived in this paper reflects the realistic situation in which the body is in a supine position or a standing position, and also takes into account feedback time lag. The theoretical model is validated by experimental data fitting. Both computer simulations and experimental data fitting show that the proposed model can capture the main trends of water and salt outputs, and achieve tight control of the plasma concentration of salt as recorded in the experiment[7].