Design of calibrating controllers for heliostats

A heliostat (steerable mirror in solar/electric energy conversion) is oriented to reflect light beam to a central receiver. The heliostat periodically tracks the sun, which serves as a precise reference. A calibrating controller is developed for reducing the effect of the ground that a heliostat is installed on and regulating a heliostat which reflects light incorrectly to the central receiver because of an external disturbance such as wind. A steepest descent method with backtracking line search and a least-squares algorithm is used to estimate a slope of the ground. A full-state feedback with a nonlinear observer is used to correct the position of light on a central receiver to a reference position. Simulation results are given for typical heliostat configuration.