The system consists of an electrical drive and a weakly damped mass-spring system. The position of the "bird" (mass) should follow a given reference signal. For this reason the controller is designed by loop shaping or as a continuous time state feedback controller.
Laboratory model double-mass oscillator
Two carts, mounted on rails, are connected by a spring. As input variable of the systems serves the voltage applied to the DC-motor of the right cart. The video clip above shows the so-called "chirp" experiment. A sinusoidal input signal with rising frequency is applied to the system. As expected, the position of the second cart is also a sinusoidal signal. By observing the amplitudes and the phase shift of the two sine waves the Bode diagram of the transfer function can be determined. Additionally the resonance frequency (about 3.4Hz) of the system can be observed. This leads to the conclusion that the system's transfer function possesses a conjugate complex pole pair.
Laboratory model lifting magnet
The aim of this experiment is to levitate a ferromagnetic object beneath a electromagnet. The vertical position of the object is measured and should follow a specified reference signal. The difficulty of stabilization lies in the nonlinearity of the system.
Laboratory model Reaction Wheel Pendulum
At first sight the Reaction Wheel Pundulum is a quite simple electromechanic device. A DC motor with a flywhell is mounted at the end of the pendulum. By applying a voltage to the motor the flywheel gets into rotation. The torque which accelerates the wheel also produces a counter torque according to the "Actio=Reactio" principle. This counter torque leads to a motion of the pendulum. It is the aim to implement a control algorithm which allows the pendulum to swing up and remain in the unstable equilibrium point.
The Quarter Vehicle serves for the testing of active-suspension control algorithms. The aim of the control loop is to compensate road undulations and other disturbances, so that the driver of the vehicle notices as little pitch and rolling motion as possible. The laboratory model consists of three masses, which are vertically displaceable. The top mass (blue) represents the quarter vehicle body, which is connected by two springs with the middle mass, the "wheel" of the car (red). The active suspension mechanism is placed between vehicle mass and wheel mass and consists of a DC-motor. The middle mass is again linked by two springs to the lowest mass (grey) which represents the street. It can be shifted by a DC motor to simulate different road profiles.
Laboratory model Two-Tank-System
The tank-system is equipped with a level control. The level control should demonstrate the priniciple of state feedback control by linearization. Starting with the experimental identification of the system's parameters for the nonlinear plant, a linear state feedback controller and extended state feedback controller (with reference signal input) are designed and verified. The main focus is on control quality with respect to parameter variation of the plant and additional disturbances.
Institute of Automation and Control Graz University of Technology Inffeldgasse 21/B 8010 Graz