A system for operating a barrier system such as a garage door, gate or
fence. A DC motor is connected to and operates a barrier drive. A power
amplifier is configured to receive power signals from a power supply and
to output modulated DC signals to the DC motor. A controller implements
an intelligent closed-loop motion control algorithm to control the power
amplifier according to a non-linear motion profile. A feedback sensor
provides status signals to the controller to determine position or speed
of the barrier.