船舶减摇鳍系统H^(∞)控制器设计

利用Ｈ∞控制理论对船舶减摇鳍横摇姿态控制系统进行了混合灵敏度设计，并针对船舶减摇鳍系统的特殊性，解决了Ｈ∞控制器设计中与该系统不匹配的有关问题。另外，还提出了一种新的权函数的选择方法用以解决Ｈ∞控制器设计中存在的和对象的频带几乎一致的随机海浪干扰抑制问题。

H_∞ control of an overactuated tilt rotors quadcopter

In recent years,unmanned aerial vehicles(UAVs)have acquired an increasing interest due to their wide range of applications in military,scientific,and civilian fields.One of the quadcopter limitations is its lack of full actuation property which limits its mobility and trajectory tracking capabilities.In this work,an overactuated quadcopter design and control,which allows independent tilting of the rotors around their arm axis,is presented.Quadcopter with this added tilting mechanism makes it possible to overcome the aforementioned mobility limitation by achieving full authority on torque and force vectoring.The tilting property increases the control inputs to 8(the 4 propeller rotation speed plus the 4 rotor tilting angles)which gives a full control on the quadcopter states.Extensive mathematical model for the tilt rotor quadcopter is derived based on the Newton-Euler method.Furthermore,the feedback linearization method is used to linearize the model and a mixed sensitivity H∞optimal controller is then designed and synthesized to achieve the required performance and stability.The controlled system is simulated to assure the validity of the proposed controller and the quadcopter design.The controller is tested for its effectiveness in rejecting disturbances,attenuating sensor noise,and coping with the model uncertainties.Moreover,a complicated trajectory is examined in which the tilt rotor quadcopter has been successfully followed.The test results show the supremacy of the overactuated quadcopter over the traditional one.

H_∞ Robust Fault-Tolerant Controller Design for an Autonomous Underwater Vehicle’s Navigation Control System

In order to improve the security and reliability for autonomous underwater vehicle （AUV） navigation, an H∞ robust fault-tolerant controller was designed after analyzing variations in state-feedback gain Operating conditions and the design method were then analyzed so that the control problem could be expressed as a mathematical optimization problem. This permitted the use of linear matrix inequalities （LMI） to solve for the Hv controller for the system. When considering different actuator failures, these conditions were then also mathematically expressed, allowing the H∞ robust controller to solve for these events and thus be fault-tolerant. Finally, simulation results showed that the H∞ robust fault-tolerant controller could provide precise AUV navigation control with strong robustness.

Robust H∞ output feedback control for a class of uncertain Lur＇e systems with time-delays

In this work, the analysis of robust stability and design of robust H∞ output feedback controllers for a class of Lur'e systems with both time-delays and parameter uncertainties were studied. A robust H∞ output feedback controller based on Linear Matrix Inequalities (LMIs) was developed to guarantee the robust stability and H∞ performance of the resultant closed-loop system. The presented design approach is based on the application of descriptor model transformation and Park's inequality for the bounding of cross terms and is expected to be less conservative compared to reported design methods. Finally, illustrative examples are advanced to demonstrate the superiority of the obtained method.

A new extended H_∞ filter for discrete nonlinear systems

Nonlinear estimation problem is investigated in this paper. By extension of a linear H_∞estimation with corrector-predictor form to nonlinear cases, a new extended H_∞filter is proposed for time-varying discrete-time nonlinear systems. The new filter has a simple observer structure based on a local linearization model, and can be viewed as a general case of the extended Kalman filter (EKF). An example demonstrates that the new filter with a suitable-chosen prescribed H_∞bound performs better than the EKF.

Robust control of exciting force for vibration control system with multi-exciters

Due to the dynamical character of electromagnetic exciter and the coupling between structure and exciter(s),the actual output force acting on the structure is usually not equal to the exact value that is supposed to be,especially when multi-exciters are used as actuators to precisely actuate large flexible structure.It is necessary to consider these effects to ensure the force generated by each exciter is the same as required.In this paper,a robust control method is proposed for the multi-input and multi-output(MIMO)structural vibration control system to trace the target actuating force of each exciter.A special signal is designed and put into the coupled mul-ti-exciter-structure system,and the input and output signals of the system are used to build a dynamic model involving both the dynamical characters of the exciters and the structure using the subspace identification method.Considering the uncertainty factors of the multi-exciter/structure system,an H-infinity robust controller is designed to decouple the coupling between structure and exciters based on the identified system model.A MIMO vibration control system combined with a flexible plate and three electromagnetic exciters is adopted to demonstrate the proposed method,both numerical simulation and model experiments showing that the output force of each exciter can trace its target force accurately within the requested frequency band.

Robust control for active suspension system under steering condition

To minimize the auto body's posture change caused by steering and uneven road, and improve the vehicle's riding comfort and handling stability, this paper presents an H∞ robust controller of the active suspension system, which considers the effects of different steering conditions on its dynamic performance. The vehicle's vibration in the yaw, roll, pitch and vertical direction and the suspension's dynamic deflection in the steering process are taken into account for the designed H∞ robust controller, and it introduces the frequency weight function to improve the riding comfort in the specific sensitive frequency bands to human body. The proposed robust controller is testified through simulation and steering wheel angle step test. The results show that the active suspension with the designed robust controller can enhance the anti-roll capability of the vehicle, inhibit the changes of the body, and improve the riding comfort of the vehicle under steering condition. The results of this study can provide certain theoretical basis for the research and application of active suspension system.