Why networked control system

Network caused delay directly contributes to the delay in the control loop and contributes towards instability of the system.

Data loss is similar in this respect. Therefore research must be done to enable common use of this type of control implementation. The remedy to the network delay is to use a dedicated real-time network in the implementation. This network is specially designed to have a guaranteed upper bound on transmission delay, so that stability is not jeopardized. However this is not a simple solution. Such networks must have carefully tuned parameters for each application, and cannot be readily expanded.

Similarly, they are not flexible in the amount of data they can transfer. Timed token protocol, master slave type protocols, TDMA type protocols are some examples. We propose to use normal data communication networks which cause losses and delay, but we cover for these problems by using a model of the controlled plant for making predictions of future control outputs. These decisions are refreshed at each sample and send to the actuator node. In the actuator node, if the control commands do not arrive for delay or loss, the previously sent prediction is used instead.

Please look here for a more detalied explanation of our method. This type of control system can be used in many real-time applications such as automation, automotive and process control. Especially in noisy environments such as automobiles and most types of factories; where large plants must be dealt with such as steel mills, printing and production lines, building automation; and cost is a significant factor. The idea is to use common technologies in control and communication in a place they were not initially intended.

Most of communication theory and computer theory is based on open-loop systems in which we must send data through as fast as possible or crunch numbers as fast as possible. In control, we are looking at closed-loop systems in which a given snippet of data should be sampled, processed, and output within a given time. This is latency. It is very possible that systems with high throughput can also have high latency and be useless for closed-loop applications.

It is possible to use a high speed communication network to reduce the amount of delay. Modern communication networks really have very high throughputs. For a control applications of kHz sampling frequency, they seem to be sufficient. Networked control systems: a survey of trends and techniques Abstract: Networked control systems are spatially distributed systems in which the communication between sensors, actuators, and controllers occurs through a shared band-limited digital communication network.

Several advantages of the network architectures include reduced system wiring, plug and play devices, increased system agility, and ease of system diagnosis and maintenance. Consequently, networked control is the current trend for industrial automation and has ever-increasing applications in a wide range of areas, such as smart grids, manufacturing systems, process control, automobiles, automated highway systems, and unmanned aerial vehicles. The modelling, analysis, and control of networked control systems have received considerable attention in the last two decades.

The exchange of information over imperfect channels raises the problem of studying how networks impact on the real-time behaviour of systems. The first part of this course will focus on methods for analysing stability and performance of networked control systems. In the second part, instead, we will study how to exploit networked architectures for realising coordinated behaviours among subsystems. We will introduce consensus algorithms and illustrate various applications to sensor networks, cooperative robotics, analysis of opinion dynamics and electric systems.

Communication networks, sampled-data systems, feedback control, graph theory, consensus algorithms. State-space models Linear systems in continuous and discrete time Basic concepts of stability Feedback control. Use a work methodology appropriate to the task. Demonstrate the capacity for critical thinking. Course slides on Moodle For the second part of the course: F.