Guchuan Zhu

Speed tracking control of a permanent-magnet synchronous motor with state and load torque observer

This paper is concerned with the speed tracking control problem for a permanent-magnet synchronous motor (PMSM) in the presence of an unknown load torque disturbance. After a brief review of the mathematical model of the PMSM, a speed tracking control law using the exact linearization methodology is introduced. The tracking control algorithm is completed by adding an extended observer which provides, on the one hand, the motor speed and acceleration and, on the other hand, estimates the unknown load torque. The stability of the closed-loop system composed of a nonlinear speed tracking controller and an observer is studied by the way of Lyapunov theory. Furthermore, the decoupling of the state observer and the load torque observer is discussed. Finally, a real-time implementation and the experimental results of the proposed control strategy are presented.

A System Architecture for Autonomous Demand Side Load Management in Smart Buildings

This paper presents a system architecture for load management in smart buildings which enables autonomous demand side load management in the smart grid. Being of a layered structure composed of three main modules for admission control, load balancing, and demand response management, this architecture can encapsulate the system functionality, assure the interoperability between various components, allow the integration of different energy sources, and ease maintenance and upgrading. Hence it is capable of handling autonomous energy consumption management for systems with heterogeneous dynamics in multiple time-scales and allows seamless integration of diverse techniques for online operation control, optimal scheduling, and dynamic pricing. The design of a home energy manager based on this architecture is illustrated and the simulation results with Matlab/Simulink confirm the viability and efficiency of the proposed framework.

Flatness-Based Control of Electrostatically Actuated MEMS With Application to Adaptive Optics: A Simulation Study

Typical adaptive optics (AO) applications require continual measurement and correction of aberrated light and form closed-loop control systems. One of the key components in microelectromechanical system (MEMS) based AO systems is the parallel-plate microactuator. Being electrostatically actuated, this type of devices is inherently instable beyond the pull-in position when they are controlled by a constant voltage. Therefore extending the stable travelling range of such devices forms one of the central topics in the control of MEMS. In addition, though certain control schemes, such as charge control and capacitive feedback, can extend the travelling range to the full gap, the transient behavior of actuators is dominated by their mechanical dynamics. Thus, the performance may be poor if the natural damping of the devices is too low or too high. This paper presents an alternative for the control of parallel-plate electrostatic actuators, which is based on an essential property of nonlinear systems, namely differential flatness, and combines the techniques of trajectory planning and robust nonlinear control. It is, therefore, capable of stabilizing the system at any point in the gap while ensuring desired performances. The proposed control scheme is applied to an AO system and simulation results demonstrate its advantage over constant voltage control

Peak-load shaving in smart homes via online scheduling

This paper addresses the problem of load-shaving in Smart Homes in view of improving energy efficiency in Smart Grids. An architecture of home power management systems, allowing the separation of domestic power load control from grid dynamics, is introduced. In this framework, the operation of appliances is modeled as a finite state machine which enables the implementation of online scheduling borrowed from the techniques developed in real-time computing systems. A scheduling algorithm is developed for peak-load shaving and the simulation results confirm the effectiveness and the efficiency of the proposed approach.

Nonlinear Control of an Electrostatic Micromirror Beyond Pull-In With Experimental Validation

This paper is aimed at demonstrating the potential benefits of applying nonlinear control techniques to a type of microelectromechanical system, namely, electrostatic micromirrors, in order to extend their stable operation range, enhance the systems performance, and allow controller tuning and system operation to be performed in a systematic manner. A nonlinear tracking control based on feedback linearization and trajectory planning has been developed. Aspects essential to the implementation, such as the prevention of devices from destruction due to contact, modeling and sensing schemes, the influence of the dynamics of the driving circuit on performance, and the device characterization, have been thoroughly addressed, and practical solutions have been proposed. The experimentation is performed on a setup built with low-cost commercial off-the-shelf instruments and components in a laboratory environment. The experimental results show that the developed control system can achieve stable operation beyond the pull-in position for both set-point and scanning controls.

Modeling and Control of Electrostatically Actuated MEMS in the Presence of Parasitics and Parametric Uncertainties

Due to the compact layout, manufacturing tolerance, modeling errors, and environmental changes, microelectromechanical systems (MEMSs) are subjected to parasitics and parameter variations. In order to better guarantee their stability and a certain level of performance, one must take into account these factors in the design of MEMS control systems. This work presents two robust control laws for a parallel-plate electrostatic microactuator in the presence of uncertainties. The dynamical model of the system, including parallel and serial parasitics, is firstly established and two control schemes, both based on input-to-state stabilization and robust backstepping, are proposed. The stability and the performance ofthe system using these control schemes are demonstrated through both stability analysis and numerical simulation.

Robust control of an electrostatically actuated MEMS in the presence of parasitics and parametric uncertainties

Due to the compact layout, manufacturing tolerance, modeling errors, and environmental changes, micro-electromechanical systems (MEMS) are subjected to parasitics and parameter variations. In order to better guarantee their stability and a certain level of performance, one must take into account these factors in the design of MEMS control systems. This work presents two robust control laws for a parallel-plate electrostatic micro-actuator in the presence of uncertainties. The dynamical model of the system is firstly established and two control schemes, both based on input-to-state stabilization (ISS) and robust backstepping, are proposed. The stability and performance of the system using these control schemes are demonstrated through both stability analysis and numerical simulation

NetSimplex: Controller Fault Tolerance Architecture in Networked Control Systems

The assurance of reliability becomes increasingly challenging as the complexity of networked control systems (NCS) rapidly increases. Simplex architecture was designed to tolerate control software design and implementation. This architecture consists of a high assurance controller (HAC) and a high performance controller (HPC). The HAC uses the linear state feedback control to create a large maximum stability region (MSR). The HPC aims at achieving a better control performance and may use any design. However, the plants states under HPC must stay within the MSR, or the control is switched to HAC.

Modelling and control of an electrostatically actuated torsional micromirror

This work aims at developing control algorithms for an electrostatically actuated torsional micromirror, extending the operational range of the device to a full 90° tilt angle. The analytical model of the micromirror equipped with an additional vertical electrode is established. Since the geometrical extent of the device is comparable to the air gap, the effect of the fringing field is also incorporated into the model. It is shown that the considered system is differentially flat and, based on this property, a closed-loop control scheme is constructed for both scanning control and set-point control. In addition, the desired performance can be specified through reference trajectories, allowing the control system tuning to be performed in a systematic way. The simulation results demonstrate the advantage of the developed control scheme over the constant voltage control.

Improving the Performance of an Electrostatically Actuated MEMS by Nonlinear Control: Some Advances and Comparisons

Though certain control schemes, such as charge control and capacitive feedback, can extend the stable travelling range of electrostatically actuated micro-devices to the full gap, the transient behavior of actuators is dominated by their mechanical dynamics. Thus, the performance may be poor if the natural damping of the devices is too low or too high. The presented work aims at improving the performance of a parallel-plate electrostatic micro-actuator by nonlinear control. Three control schemes, based on differential flatness, control Lyapunov functions, and backstepping, are considered, which are capable of stabilizing the system while ensuring desired performances. The simulation results demonstrate the efficiency of the considered control schemes and provide some comparisons on their performance.