A control system and method that keeps solar arrays on a satellite pointing
toward the sun. Exemplary control systems and methods are implemented as
follows. An orbit propagator computes satellite orbital location data and
computes a sun vector referenced to an inertial reference frame. A
coordinate transformation processor processes the sun vector in the
inertial reference frame and a sensed satellite attitude signal to
generate a sun vector referenced to a satellite body reference frame. A
solar array position processor processes a step count derived from a solar
array pointing control system and sensed solar array position to generate
an estimate of the position of the solar array. A summing device sums the
solar array position estimate output, the body frame gun vector, and a
bias signal derived from a ground command, to produce a solar array
position error signal. A filter filters the solar array position error
signal. A current regulator processor processes a measured solar array
current to produce another solar array position error signal based on
current output. An eclipse processor processes the satellite orbital
location data, the solar array position error output signal, and the low
pass filtered solar array position error signal to generate a step
command. The solar array pointing control system processes the step
command to generate control signals that point the solar array at the sun.