Non-fragile Dissipative Control For Networked Control Systems

It is usually difficult to analyze the stability of complex networked control systems(NCSs)by utilizing traditional stability criteria or directly constructing Lyapunov functions.While with the help of the dissipative control theory proposed in 1970 s,the dissipativity of each subsystem belonging to the complex NCSs can be analyzed from an energy perspective.As long as a nonnegative energy function exists,whose value variations in a certain time period are always less than the energy provision,the stability of the system can be assured.Therefore,it's very significant to study the dissipativity of NCSs.Due to the limit of network bandwidth,transmission collision or conflict may occur in data transmission,which definitely gives rise to some problems,such as packet dropouts,transmission time-delay,signal quantization errors and et al.Additionally,element parameters of the control systems will change due to the influence of their physical characteristics and environmental factors.All the above can be potential causes in deteriorating the performance of NCSs,even rendering the systems unstable.Under non-ideal conditions mentioned above,this dissertation mainly focuses on H? control problem and dissipative control problem of NCSs.This thesis contributes to the research area mainly in the following aspects:On one hand,the problem of non-fragile H? control for NCSs is studied.Most existing literatures only take network-induced delay as the negative factor into consideration.However,packet dropouts and quantization errors can also lead to system instability.Due to above reasons,two Bernoulli distributed sequences are utilized to describe the issue of random packet dropouts in the sensor-to-controller channel and the controller-to-actuator channel,respectively.Based on Lyapunov stability theories and the approach of Linear Matrix Inequalities(LMIs),the design of the controller with uncertain gains is converted into a convex optimization problem with LMIs as constraints,and linear functions as objectives.Adopting the similar analysis and design method,with two logarithmic quantizers being introduced to quantize the measured output and controlled input signals simultaneously.By utilizing the sector bound approach,uncertainties of the sector boundary can help convert the design problem of quantized feedback control into the robust control problem.By theoretical proof and numeric simulation,the presented non-fragile H? controller in this thesis can assure the stability of the closed system,and the predetermined H? performance index satisfied.On the other hand,the problem of non-fragile dissipative control for the nonlinear NCSs with parameter uncertainties is investigated.In the research,it is assumed that the nonlinear part of the system is sector bounded and the parameters' value range is norm-bounded.First of all,the full supply rate is provided from expectation's perspective to address the case with random packet dropouts,and the observer-based dissipative controller is designed.Furthermore,a new measurement model that can include the description of packet dropouts,time-delay,quantization errors and other incomplete measurement factors has been proposed.By using free-weight matrix techniques,the solution expressions of non-fragile dissipative controller gains can be obtained by solving LMIs with convex constraints.Theoretical proof and numeric simulation have illustrated the performance of the above control strategies.