The subject of this investigation is the rotary inverted pendulum system. It con-
sists of two links: a motor-driven horizontal link and an un-actuated vertical pen-
dulum link. The horizontal link is driven by a permanent-magnet, brushed DC
motor. A DC power supply together with a pulse-width-modulated (PWM) servo-
ampli®er, operating in the current mode, supplies power to the motor. Angular
position and velocity of the two links are measured with two rotary incremental
optical encoders having a resolution with quadrature decoding of 2048 pulses per
revolution. A slip-ring assembly, mounted between the housing and the motor shaft,
is used to connect power to the pendulum optical encoder and read the signal from
the three channels of the encoder. The horizontal link is counter-weighted and there
are leveling screws on the housing base.
System testing for parameter identi®cation and control system design is per-
formed in a MatLab/Simulink/dSpace real-time control environment. This allows for
rapid control system development and testing.