The first design only allows colocated feedback. The second design allows feedback from within a region of the structure. The third allows communication between adjacent local controllers so that information from neighboring regions can be used for the feedback. The last employs a distributed implementation of the full state feedback. The simulation results for the control of a long beam in bending show that employing the more complicated decentralized designs at the lower level of the hierarchic architecture will slightly improve the overall performance. However, the implementation costs for these more sophisticated designs are shown to increase dramatically. The most efficient hierarchic design for this beam example is one which combines a good global design with a simple colocated feedback. This conclusion may change for structures which require more performance at the local level.
Local Control Design Methodologies for a Hierarchic Control Architecture