Standard State-feedback Controller Research Articles

Reliable Centralized Control of PMSM

In this paper, we introduce the development methodology of a reliable centralized control applied to a synchronous permanent magnet machine. The proposed system is nonlinear, we linearize around a point of application. The resulting model will then be used to reproduce the dynamic behavior of the machine for a reliable control. The controller is based on the standard h infinite to increase performance, reduce measurement noise, and to tolerate the outage of certain sensors. To illustrate the results, we made a comparison between a standard state feedback control and reliable h infinite robust control. The simulation results shows, that the system in case of technical placements poles loses classic performance in the presence of an outage, that the reliable centralized robust control remain satisfactory performance even in the presence of outage.

Performance analysis for time-delay systems: application to the control of an active mass damper

This paper proposes a method to analyze, beyond stability, the performances of linear time-delay systems. Using robust analysis techniques, a sufficient condition that analyzes the location of eigenvalues in the complex plane is presented. More precisely, a set of quadratic inequality constraints are designed to define an admissible region for the infinitely many eigenvalues of a time-delay system and the quadratic separation theorem is applied to assess that the eigenvalues are effectively belonging to that stability region. This method is then used for the control of an active mass damper. A standard state feedback control is replaced with a static output feedback plus a static delayed output feedback. This strategy avoids the full measurement of the state and shows that delays in the dynamic may be helpful for stabilization. The closed-loop system is then expressed as a time-delay system and the performance criterion is exploited to analyze the stability and the damping properties. Simulations and experimental tests support the approach.

Experimental Comparison of Velocity Observers: A Scissored Pair Control Moment Gyroscope Case Study

We consider scissored pair gyroscopes as an auxiliary stabilization system for legged robots. A standard state-feedback control can stabilize the system if all states are available; thus, the velocity estimation becomes the key element for the stabilization. To this end, we implement and experimentally compare a model-free linear differentiator, a model-based full-state linear observer with time-varying gains, and a model-based homogeneous nonlinear differentiator. Moreover, we also show that the considered system cannot be partially linearized via a change of coordinates, and thus is not suitable for a recently reported class of nonlinear observers. The proposed designs are tested on an experimental scissored pair control moment gyroscope setup constructed for a walking robot stabilization.

Optimal Design of Complex Passive-Damping Systems for Vibration Control of Large Structures: An Energy-to-Peak Approach

We present a new design strategy that makes it possible to synthesize decentralized output-feedback controllers by solving two successive optimization problems with linear matrix inequality (LMI) constraints. In the initial LMI optimization problem, two auxiliary elements are computed: a standard state-feedback controller, which can be taken as a reference in the performance assessment, and a matrix that facilitates a proper definition of the main LMI optimization problem. Next, by solving the second optimization problem, the output-feedback controller is obtained. The proposed strategy extends recent results in static output-feedback control and can be applied to design complex passive-damping systems for vibrational control of large structures. More precisely, by taking advantages of the existing link between fully decentralized velocity-feedback controllers and passive linear dampers, advanced active feedback control strategies can be used to design complex passive-damping systems, which combine the simplicity and robustness of passive control systems with the efficiency of active feedback control. To demonstrate the effectiveness of the proposed approach, a passive-damping system for the seismic protection of a five-story building is designed with excellent results.

Closed-Loop Time-Optimal Attitude Maneuvering of Magnetically Actuated Spacecraft

This paper examines the performance of the pseudospectral optimal control scheme for closed-loop time-optimal attitude maneuvering of the NPSAT1 spacecraft, a magnetically actuated spacecraft designed and built at the Naval Postgraduate School. The closed-loop control is devised and implemented using the notion of Caratheodory-π solutions: repeated computation and update of the complete open-loop control solution in real-time. The performance of the pseudospectral feedback-control scheme is compared to a standard state feedback-control technique. It is shown that the use of standard state feedback control leads to significantly slower convergence time and may lead to substantially lower performance metrics. The substantial performance gains when using closed-loop optimal control are attributed to the optimal scheme’s ability to exploit the full maneuverability envelope of the spacecraft by applying bang-bang controls in all three directions. In contrast, traditional gain-based feedback control laws substantially limit the performance of the vehicle to well below its physical capabilities. The feasibility of each open-loop optimal control solution is verified by numerical propagation while Pontryagin’s necessary conditions for optimality are used to verify the solution’s optimality.