Research On Data Scheduling Policies For Networked Control Systems Under Transmission Constraints

Networked control systems(NCSs) are spatially distributed systems in which the communication between sensors,estimators,controllers,etc is sustained by a shared digital communication network.Compared with the conventional wired or special wire control,NCSs have lots of advantages such as smaller networking cost,flexible working and rapid reconstruction.However,the constraints in NCSs,such as limited sensor/controller energy and limited communication bandwidth,restrict the system performance extremely.Given the considerations mentioned above,the objective of this dissertation is to optimize system performance under resource constraints.In this dissertation,we investigate the optimal multiple-sensor data scheduling problems and the optimal linear quadratic regulation(LQR)control data scheduling problems.The main work is summarized as follows.1.For the optimal multiple-sensor data scheduling problems under the limited communication bandwidth and sensor energy,we design the optimal schedules to minimize the terminal estimation error.Aiming to first-order systems,we consider the optimal schedule for general systems,extending the previous work from two different scenarios where an explicit optimal schedule was provided for only a class of systems.For higher-order systems,under an assumption about the system state matrix,aiming to each of three different scenarios,we derive the optimal policy for the case of free process noise.2.Aiming to the LQR control data scheduling problems with limited controller-system communication,we construct an optimal scheduling policy for general first-order systems.First,we derive the necessary and sufficient condition for a comparison function to be positive.Based on this,we obtain the horizon of the optimality of this policy in general first-order systems,and indicate the optimal schedules for other systems depend on the terminal weight of a quadratic performance cost.3.Aiming to the LQR control data scheduling problems with multiple-system sharing a limited communication bandwidth,we give the corresponding optimal scheduling policy for several particular classes of problems.First,we build the analytical expression of the quadratic performance for multiple systems.Furthermore,the rigorous proof for each class of problems is provided.We present that in each instance the consequent optimal policy is a simple index policy.As a result,this implies that the optimal schedule is easy to compute according to the proposed scheduling rule.