Reduced-order weight design for H∞ loop shaping method under open-loop magnitude constraints

H
∞
loop shaping method is known to be one of the effective control methods, however, there are two drawbacks of H
∞
loop shaping method: The first one is that the control performance of the designed controller depends on the weights, however, it is difficult to design the appropriate weights. The second one is that the designed controller tends to be higher order. For these two drawbacks, the objective of this paper is to design a reduced-order weight under the specified open-loop magnitude constraints.