A conservativeness-reduced design of a gain scheduled output feedback H/sub /spl infin// controller for an n-joint rigid robotic manipulator, which integrates the varying-parameter rate without their feedback, is proposed. The robotic system is reduced to be a linear parameter varying (LPV) form, which depends affinely on the varying-parameter. The design of a controller, which satisfies the closed-loop H/sub /spl infin// performance, is reduced to be a solution of the parameterized linear matrix inequalities (LMIs) of parameter matrices. With a use of the concept of "multi-convexity", the solution of the infinite LMIs in the varying-parameter and its rate space is reduced to be a solution of the finite LMIs for the vertex set. The proposed controller eliminates the feedback of the varying-parameter rate and prescribes its upper boundary so that the conservativeness of the controller design is reduced. The experiment results verify the effectiveness of the proposed design.