Tracking and optimal control problems in human head/eye coordination

Human head and eye rotate in coordination to rapidly project images of targets from the visual space. Once a target is fixated, the head/eye complex maintains the stability of the image, even while the head continues to move. The dynamics of the head is constrained by Donders´ Law whereas the final position of the eye satisfies Listing´s constraint with respect to the final position of the head. The vestibuloocular reflex rotates the eye opposite to the forward movement of the head in order to compensate and maintain image stability. Using a dynamic model of the head and eye, the eye movement is modeled as a tracking control problem, where the tracking signal depends on the head movement trajectory. The torques required for the head and eye movements are computed by minimizing a suitable cost function. The paper computes the optimal torque and compares simulation results with experimentally measured data on human head/eye movement.