Disturbance observer (DOB) is generally introduced into motion control systems to eliminate undesired disturbances and plant uncertainty. The DOB is also used for system identification. This work presents a novel experimental identification algorithm using disturbance observer to identify inertia, viscous coefficient, and friction of linear-motor-driven motion system. A conventionally adopted algorithm for determining the inertia of the motion system based on orthogonal relations among system responses is modified and extended to estimate the viscous coefficient and the magnitude of Coulomb friction of the underlying system. The advantages of the proposed method are high convergence rate and only one experiment needed to evaluate the system parameters. The proposed algorithm is demonstrated to be workable by both simulation and experiment.
SUMMARYThis paper investigates robust observer-controller compensator design using Vidyasagar's structure (VS). VS has a unit matrix parameter H similar to the Q parameter for the Youla-Kucera parameterization. VS can be designed based on the left coprimeness of the central controller in the H ∞ -loop shaping design procedure (H ∞ -LSDP) and therefore can preserve the intrinsic properties of the H ∞ -LSDP. This paper introduces algebraic methods to simplify the design of H in the VS controller by solving specific algebraic equations. In particular, the algebraic design of H can achieve two things. First, a dynamic H adjusts the tracking performance and yields the integral action. Second, a dynamic H rejects the input and output sinusoidal disturbances with known frequencies. These attributes are indications of the flexibility of the proposed method since the output-feedback controller design of the H ∞ -LSDP cannot easily deal with such conditions. This paper discusses the achieved loop and the closed-loop behavior of the system with VS, and also gives two numerical examples. The first example shows that the proposed method results in a better design in many aspects than the resulting from H ∞ -LSDP. The second example shows the application of the proposed method to rejecting input and output step disturbances, and input and output multiple sinusoidal disturbances, for which the H ∞ -LSDP can hardly be used.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.