H ∞ Controller
Part of the Mechanical Engineering Series book series (MES)
This chapter presents the tuning process of the H∞ controller. It describes the H∞ controller modified for tracking purposes, gives the closed loop equations, and presents the 34-m antenna example, with the limits of the performance.
Definition and Gains
Application of the H ∞ controllers to antennas and telescopes is discussed in [ 1, 2, 3, 4, 5, 6, 7, 8]. The structure of an H ∞ controller is similar to that of the LQG controller, although its parameters are obtained from a different algorithm. The algorithm minimizes the system H ∞ norm, which is, in the case of a SISO system, the maximal magnitude of its transfer function. Also, in the algorithm the control ( u) and the disturbance ( w) inputs of a system are separated (see Fig. 9.1). The control ( y) and performance ( z) outputs are also parted. In our case the plant-controlled input ( u) is the velocity input to the drives, the disturbance input ( w) is the wind pressure at the antenna structure, the controlled output ( y) is the encoder...
KeywordsWind Gust Algebraic Riccati Equation Wind Disturbance Close Loop Transfer Function Acceleration Limit
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