On– Off Error Control Coding Scheme for Minimizing Tracking Error in Wireless Feedback Control Systems

Wireless control has advantages in the case of synchronous cooperative motion control. We consider a wireless feedback control system with multiple plants. In such situation, not only the control performance of individual plants but also the synchronization among the plants is important. However, synchronization errors occur because of packet losses in the wireless channel. In this paper, we propose a relay transmission scheme with predictive control information to reduce the influence of packet losses in the synchronization performance. Numerical examples clarify the reduction of synchronization errors by the proposed scheme.

Wireless sensor-actuator networks (WSANs) are being adopted in process industries because of their advantages in lowering deployment and maintenance costs. While there has been significant theoretical advancement in networked control design, only limited empirical results that combine control design with realistic WSAN standards exist. This paper presents a cyber-physical case study on a wireless process control system that integrates state-of-the-art network control design and a WSAN based on the WirelessHART standard. The case study systematically explores the interactions between wireless routing and control design in the process control plant. The network supports alternative routing strategies, including single-path source routing and multi-path graph routing. To mitigate the effect of data loss in the WSAN, the control design integrates an observer based on an Extended Kalman Filter with a model predictive controller and an actuator buffer of recent control inputs. We observe that sensing and actuation can have different levels of resilience to packet loss under this network control design. We then propose a flexible routing approach where the routing strategy for sensing and actuation can be configured separately. Finally, we show that an asymmetric routing configuration with different routing strategies for sensing and actuation can effectively improve control performance under significant packet loss. Our results highlight the importance of co- joining the design of wireless network protocols and control in wireless control systems.

Packet priority assignment for wireless control systems of multiple physical systems

There is a strong trend towards wireless networked Real-Time Control Systems. However, a variety of factors such as the variability of wireless channel capacities, multi-path fading, and ambient interference make it extraordinarily difficult to design and implement Wireless Control Systems (WCSs). To attack the uncertainty in available communication resource in WCSs, this chapter presents an Adaptive Feedback Scheduling scheme that takes advantage of the methodology of cross-layer design. The proposed approach exchanges information across the physical layer and the application layer in the presence of noise interference and link transmission rate variations. The overall QoC is guaranteed through controlling the deadline miss ratio of control loops. Design parameters of the feedback scheduler are adapted to dynamic changes in wireless channel capacity. To further improve the feedback scheduling performance, an event-driven invocation mechanism for feedback schedulers is suggested. Simulation results demonstrate that this approach is efficient to deal with channel capacity variations and noise interference, thus providing an enabling technology for wireless control in dynamic environments. It is also argued that in this context event-driven invocation mechanism improves the performance of the feedback scheduling system.KeywordsSampling PeriodTransmission RateMedium Access ControlControl PerformanceMedium Access Control ProtocolThese keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

The PIDPLUS algorithm is one of the candidates to be used in wireless automation systems. The control performance of this algorithm under packet losses is investigated in the paper. First, the performance of PIDPLUS is evaluated with respect to packet loss rates for a general first-order plus time-delay process, a model widely used for controller tuning. This simulation study reveals how the performance is affected by packet losses in a wireless control system. Secondly, we will elaborate on the implementation of PIDPLUS and discuss its design, tuning and performance in wireless control systems in light of an unstable case process. The results suggest that PIDPLUS can well be used for wireless control, but better performance could be attained by further development of the controller tuning methodology.

Introduction. In order to ensure the sustainable functioning of critical infrastructures (CI), in conditions of the growth of various types of threats, security systems (SB) for various purposes, for example, technical SB, should be created on them. As such systems, first of all, there are security alarm systems, access control and some others. These systems are usually integral parts of the overall physical protection of CI, so they play an important role in ensuring the security of CI. One of the most important SB on the CI is the identification and access control system. In recent years, specialists in these systems have paid closer attention to the issues of ensuring the security of checkpoints for vehicles. It is known that they can be one of the most vulnerable places in the system of physical protection of the CI. Based on this, the task of improving identification and access control systems, including the vehicle, is currently an urgent scientific and practical task, and therefore require further study. Aims and Purposes. The purpose of this study is to develop a simplified conceptual design of the wireless identification and access control system of the vehicle on the CI. Methods. To achieve this goal, the methods of system analysis, elements of the theory of radio engineering, as well as methods of analysis, description, generalization, results of research works on the subject of research were used. Results and discussion. The existing systems of wireless identification and access control on CI are considered on the example of wireless identification and access control systems of the vehicle. Some ways of improving the safety and reliability of the operation of these systems are outlined. The analysis of ways to improve the systems of wireless identification and access control on CI is carried out on the example of wireless identification and access control systems of the vehicle. A simplified conceptual design of the wireless identification and access control system of the vehicle on CI has been developed. The main primary provisions of the system under development related to the circuit engineering stage of conceptual design are formulated. Conclusions. As a result of the conducted research, a simplified conceptual design of the wireless identification and access control system of the vehicle on CI has been developed. According to the authors, the developed simplified conceptual project, with appropriate adaptation, can be applied in practice for the purposes of ensuring the physical protection of CI. Keywords: critical infrastructure; identification systems; access control; wireless data transmission systems; conceptual project.

In this paper, we present an unequal error protection method for packet-loss resilient transmission of progressively compressed 3D meshes. The proposed method is based on a source and channel coding approach where we set up a theoretical framework for the overall system by which the channel packet loss behavior and the channel bandwidth can be directly related to the decoded mesh quality at the receiver. In particular, we develop a statistical distortion measure and optimize it to compute the best combination of (i) the number of triangles to transmit, (ii) the total number of channel coding bits, and (iii) the distribution of these error-protection bits among the transmitted layers in order to maximize the expected decoded mesh quality at the receiver. The proposed method differs from the earlier approaches in two major aspects: (i) determination of the number of channel coding bits (C) and (ii) the approach of reducing the source rate in order to accommodate for channel coding bits. When the proposed method is used to transmit a typical 3D mesh over a channel with a 10% packet loss rate, the distortion (measured using the Hausdorff distance between the original and the decoded overly sampled meshes) is reduced by 50% compared to the case when no error protection is applied.

The design of a wireless water level control system is introduced and discussed in detail. In this system, the wireless Proportional Integral (PI) controller is developed using the LabVIEW graphical user programming language. Zigbee wireless technology is chosen for the wireless data transfer system. The experimental testbed was built and the system software and hardware were implemented. In order to compare the performance of the wired and wireless system, a corresponding wired water level control system was built. Experimental results show that under the same PI parameters, the settling time of the wired system is 3.3 times faster than the wireless system. However, the percent overshoot using the wireless controller is 4% smaller.

Multi-node communication is an important aspect in wireless system development, especially in the context of non-line of sight communications. In this study, we explore the implementation of multi-node communication with bridge nodes to increase distance and reduce packet loss in the NRF24L01 transceiver module. The aim of writing this manuscript is to evaluate the effectiveness of using bridge nodes in improving the quality of multi-node communications on the NRF24L01 module in non-line of sight conditions. This study was carried out through a series of multi-node communication tests with certain configurations, including maximum power usage, 250kbps bit rate, and 5dBi antenna. Tests were carried out at different distances with and without the use of bridge nodes to compare communication performance. Our findings show that a configuration with three client nodes and an NRF24L01 module equipped with a 5dBi antenna is capable of achieving the longest distance of up to 125 m. In non-line of sight conditions, the packet loss rate at a distance of 25-75 m has very good communication quality, with packet loss values ranging from 0-6%. However, at a distance of 100 m, the packet loss percentage exceeds the threshold (15%). The use of bridge nodes succeeded in significantly reducing the packet loss rate, reducing the percentage of packet loss at client nodes C1, C2, and C3 to 6.00%, 6.67%, and 6.33% respectively. Thus, implementing the bridge node has proven effective in improving the quality of communication on the NRF24L01 module in non-line of sight conditions.

Wireless is now a pervasive aspect of everyday life; from the Bluetooth module in a mobile handset to broadband wireless networks covering scores of square kilometres. No longer is wireless networking an experimental technology, it has become ubiquitous, and wireless closed-loop control is now being seriously considered for industrial applications. Wireless networking enables the vision of a security enterprise - ease of expansion with minimal implementation and maintenance costs. The bottom line is that wireless networking is cheaper. Computer-based simulation can help develop a thorough understanding of wireless control systems; the network and control system can be configured quickly and the results from modifications to either the protocol or the control strategy can be implemented and tested scientifically, without time-consuming and difficult hardware implementation.

There is an increasing interest in the use of wireless communication for aerospace applications especially for closed-loop control applications. This paper presents the challenges associated with wireless closed-loop control in safety-critical aerospace applications. It also highlights the potential advantages of a fly-by-wireless system. A case study of the design and implementation of a wireless feedback control system for an aircraft electric braking system is presented. A sensorless supervisory control approach is proposed for a wireless aircraft braking system. The developed sensorless supervisory control method addresses the issue of lost data packets in feedback loops, a key challenge in wireless implementations. Finally, the implemented algorithm is tested in real-time using a wireless hardware demonstrator. The effectiveness of the algorithm in real-time is assessed by deliberately introducing packet loss and radio interference.

The advance in wireless sensor networking technology is increasing the number of control systems that use these networks to transmit the relevant variable to be measured and controlled, despite of the more intense distortions caused by wireless channels. The performance of wireless communications systems is mainly limited by fading produced by multipath propagation. In order to minimize the fading effects, channel coding and diversity techniques are often used in wireless systems. Among the known coding techniques in the literature, the wavelet coding presents an interesting alternative to overcome the multipath fading, since it gets performance gain by transmitting in time diversity without compromising spectral efficiency. This paper investigates the use of wavelet coding in a system that operates over a wireless channel to control the rotation frequency of the direct current motor. Aspects such as packet error probability performance, hardware complexity and processing delays due to wavelet coding are analyzed, as well as its beneficial effects on the control system. In the proposed system, the wavelet coding was embedded in PIC microcontroller and a radio transceiver XBee is used to establish a wireless link. The obtained results demonstrate a reduction of fading effects on the control signal, as well as, a low cost for hardware implementation and a small impact on system processing time.

Wireless Model Based Predictive Networked Control System

A kind of new home nursing robot system (HNR) with the function of health diagnosing expert system and human physiological parameters monitor is designed for satisfying older, weak or sick persons at home. This paper discusses HNR’s mechanical structure, control system and communication. Its main subsystems are presented in detail, including product appearance design, mobile mechanism, arm mechanism, human physiological parameters monitor system, expert database in human health diagnosis for six basic life parameters, human-machine interface, entertainment system, LED lighting system and changing colors control, sensing and detection system, control system, robot’s positioning and vision correct motion deviation system, communication system, long-distance alarm system based on GSM short message. The result indicates that HNR has a humanized cartoon appearance by means of ergonomics and industrial design. A patient or an elder can expediently operate it by its wireless voice control system or touch-screen. A global localization with monocular vision suspended from the ceiling in unknown indoor environment ensures HNR’s motion precision and repeatability accuracy. Health diagnosing expert system gives states or an alarm on the condition of an over-standard physiological parameter value.

Monitoring and control of critical parameters is of paramount importance for most of the industrial processes. But laying cables from various sensors and actuators to monitoring stations increases cost and complexity. This problem calls for wireless implementations for monitoring and control applications. This paper presents a low cost wireless temperature monitoring and control system based on ZigBee wireless communication protocol. The system uses Microchip's PIC18F458 microcontroller as the field unit and NI LabVIEW interface as the monitoring unit. It utilizes a precision temperature sensor IC, which being a low cost sensor provides a reliable output within its operating range. The system follows a request-response methodology, where the field unit responds to the requests made by the monitoring unit.