An optimal control model for human postural regulation

This paper proposes a convex optimal control problem as a mathematical model of human postural control during quiet standing. The human body is modeled as a two-segment inverted pendulum controlled by a single ankle torque. Several performance criteria that are quartic in the state and quadratic in the control are utilized. The discrete-time approximation to each of these problems is a convex programming problem. These problems were solved by the Newton-KKT method. The solutions are shown to exhibit many of the experimentally observed postural control phenomena, especially greater sway than would occur with a linear feedback control without delay.