Interaction Protocols for Multi-Robot Systems in Industry 4.0

In this chapter, the main methods of communication among multi-robot systems involved in Machine-to-Machine (M2M) applications, especially with regard the communication, reliability, stability and security among these robots, presenting various concepts through papers already published. A comparative study was carried out between two communication protocols applied in M2M technologies, the Queue Telemetry Transport (MQTT) developed by IBM along with Eurotech and the Constrained Application Protocol (CoAP). A study and survey of the characteristics of each of the protocols was carried out, as well as the method of operation of each of them and how both can be used in applications involving multiple robots. It was concluded that both protocols are considered ideal for use in in applications involving multi-robot systems. However, although the two protocols have been designed for application in environments with limited communication, the MQTT exchange protocol has advantages over CoAP, as a lower ovehead between message exchanges.

Reconfigurable Intelligent Surface in Wireless-Powered Interference-Limited Communication Networks

The commercialization of future wireless communication systems faces crucial problems in terms of reduced network cost of deployment and high power consumption. As a result, reconfigurable intelligent surfaces (RIS) have been suggested as a promising approach to overcome these existing challenges. In this paper, the performance of RIS in a wireless-powered interference-limited communication network is investigated. In this network, an energy-constrained access point (AP) is powered by a dedicated multiantenna power beacon (PB) and communicates to a destination limited-interference node via the RIS. It is assumed that the RIS experiences generalized-K fading distribution while the PB and interferers links are subjected to Nakagami-m fading distributions. To evaluate the system performance, the analytical closed-form expression of the probability distribution function (PDF) for the concerned system is derived. Through this, the exact closed-form expressions of the systems outage probability, average delay-tolerance throughput and average bit error rate are obtained. The analysis quantifies the effects of the number of reflecting elements in the RIS, number of interferer nodes, fading parameters on the AP and interferer links and number of antennas on the PB. It is deduced from the results that there is a kind of symmetry relationship between the analytical and simulation results. Additionally, the results illustrate that the proposed system with an RIS outperforms the conventional system without an RIS. Finally, the accuracy of the derived analytical expressions is validated through a Monte-Carlo simulation.

Networked Iterative Learning Fault Diagnosis Algorithm for Systems with Sensor Random Packet Losses, Time-varying Delays, Limited Communication and Actuator Failure : Application to the Hydroturbine Governor System

An iterative learning fault diagnosis (ILFD) algorithm for networked control systems (NCSs) subject to random packet losses, time-varying delays, limited communication and actuator failure is proposed in this paper. Firstly, in order to evaluate the effect of fault on system between every iteration, the information of state error and information of fault tracking estimator from the preceding iteration are used to improve the fault estimation achievement in the actual iteration. The state variable, the Bernoulli process of random packet losses, network communication delay, limited communication and actuator failure are introduced to establish an extended statespace model of the system. Secondly combining Lyapunov stability theory for linear repetitive processes and linear matrix inequality (LMI) technique, new sufficient condition for the existence of an iterative learning fault diagnosis is established. Finally, the feasibility and effectiveness of the proposed design method is illustrated on a dynamic hydroturbine governing system model based on Matlab/Simulink and TrueTime toolbox