Performance Analysis Of Networked Control Systems With Communication Constraints

Networked control system emerges with the rapid development of network communication, electronics and computer technology. Networked control system is widely used in aerospace, telemedicine, traffic control, industrial automation and other fields, which has attracted widespread attention of scholars. Previous research are most focused on the stability and structure of networked control system, but the relative research on system performance under network Communication constraints, especially performance limitation, is still at a preliminary stage. As an important aspect in the development of control theory, the study of system performance can effectively instruct the design network controller, being the foundation of maintaining system stability.Traditional research of system performance limitation thinks that the performance of system is only connected with the inherent characteristics of the controlled object and the input signal. However, with the introduction of network, the system will be influenced inevitably by the factors including quantization noise, channel noise, bandwidth constraints, and network channel energy, which would deteriorate the performance of the system. Then, the key point to the research of networked control system performance is how to establish the relationship between system performance and system internal the characteristics as well as communication parameters. This paper mainly studies the performance limitation of networked control system under communication constraint. Major research of this paper is summarized as follows:For the two basic network parameters, that are network noise and bandwidth limitation, the tracking performance limitation of multi-input multi-output continuous-time networked control system has been studied. With a Brownian motion stochastic process taken into involved, the precise expression of the best reachable performance is derived. Colored Gaussian noise is taken into consideration, which makes it more general and representative than the previous studies. Tracking performance index is measured by the energy of tracking residual and control input. The result illustrates the quantitative relation between the optimal tracking performance of the system and the parameters containing non-minimum phase zeros, unstable poles and the reference signal, network noise and network bandwidth.Most network transmissions are bi-directional, which have been weakened badly by the effects from network channel energy. Based on this, it raised the issues of best system tracking performance on bandwidth and energy constraints under colored white Gaussian noise backed in networked control systems. The study also includes instability, non-minimum-phase and zero-pole. Based on Euler parametric methods with the designing two-parameter controller, it obtains the infimum of the optimal tracking performance’s index. The results illustrate the quantitative relationship among the system’s best performance, internal network of the controlled object, network noise, network bandwidth, and energy constraints.For the quantization error, additive white Gaussian noise and bandwidth limitations, and the output feedback path evolves considering encoding and decoding for the unstable, non-minimum phase system, the continuous linear time-invariant, multi-input multi-output networked control systems optimal tracking performance are taken into consideration. The reference input is a random signal. With performance measured by tracking error energy, and the two parameters of the controller considered, explicit expression is obtained. Quantitative results reveal the relationship among the channel noise, network bandwidth, codec quantization error and the optimal tracking performance.It studies limits of networked control systems tracking performance confined to the color white Gaussian noise and bandwidth constraints using a new indicator. Performance indicators weighs not only the system network and system output and input energy difference between the reference signal of the trade-offs, and controlled object but also the energy of the control system, wrapping in delivery function. Based on the idea of frequency-domain and the performance indicators in the new form, using the Euler parametric tool, it solves the tracking performance limitations of networked control systems with the colored Gaussian band-limited channel. The results reflect the quantitative relationship between network characteristics (such as channel bandwidth, colored noise) and performance limitations.Based on the state-space approach, from the perspective of the time domain, the optimal adjustment problem of MIMO linear time-invariant networked control system with additional weak Gaussian white noise channel is studied. And it also introduced the average performance. We consider the regulation performance of the state feedback and output feedback separately and also make research on the fundamental performance limitations under single-parameter control and two-parameter control separately. Through the minimum achievement on controlled object, based on different scenarios to construct the corresponding Lagrange and Hamiltonian function, we aim at solving the system’s performance limitations. Best reachable regulate performance limitations of the system is given by the corresponding Riccati equation.Finally, a simple summary is given in the dissertation, as well as some future prospect of the study of optimal performance of networked control system.