Rachana Ashok Gupta

Networked Control System: Overview and Research Trends

Networked control systems (NCSs) have been one of the main research focuses in academia as well as in industry for many decades and have become a multidisciplinary area. With these growing research trends, it is important to consolidate the latest knowledge and information to keep up with the research needs. In this paper, the NCS and its different forms are introduced and discussed. The beginning of this paper discusses the history and evolution of NCSs. The next part of this paper focuses on different fields and research arenas such as networking technology, network delay, network resource allocation, scheduling, network security in real-time NCSs, integration of components on a network, fault tolerance, etc. A brief literature survey and possible future direction concerning each topic is included.

A Delay-Tolerant Potential-Field-Based Network Implementation of an Integrated Navigation System

Network controllers (NCs) are devices that are capable of converting dynamic, spatially extended, and functionally specialized modules into a taskable goal-oriented group called networked control system. This paper examines the practical aspects of designing and building an NC that uses the Internet as a communication medium. It focuses on finding compatible controller components that can be integrated via a host structure in a manner that makes it possible to network, in real-time, a webcam, an unmanned ground vehicle (UGV), and a remote computer server along with the necessary operator software interface. The aim is to deskill the UGV navigation process and yet maintain a robust performance. The structure of the suggested controller, its components, and the manner in which they are interfaced are described. Thorough experimental results along with performance assessment and comparisons to a previously implemented NC are provided.

Performance assessment and compensation for secure networked control systems

Network-control-systems (NCS) have been gaining popularity due to their high potential in widespread applications and becoming realizable due to the rapid advancements in embedded systems, wireless communication technologies. This paper addresses the issue of NCS information security as well its time-sensitive performance and their trade-off. A PI controller implemented on a network to control the speed of the DC motor is used to illustrate the performance assessment for secure networked control systems. Network security algorithms DES, 3DES, and AES are integrated with the application to secure the sensor as well as control data flow on the network. Standard 2k factorial experiment design is used to study and estimate the effect of each security algorithm. A 1-D gain scheduler is then designed to compensate for the adverse effect due to security. Thorough experimental results, system factors including network security and system gain affecting the performance are evaluated, analyzed, and categorized.

Overview of Networked Control Systems

Networked control systems (NCS) have been one of the main research focuses in academia as well as in industrial applications for many decades. NCS has taken the form of a multidisciplinary area. In this chapter, we introduce NCS and the different forms of NCS. The history of NCS, different advantages of having such systems are the starting points of the chapter. Furthermore, the chapter gives an insight to different challenges which come with building efficient, stable and secure NCS. The chapter talks about different fields and research arenas, which are part of NCS and which work together to deal with different NCS issues. A brief literature survey concerning each topic is also included in the chapter. iSpace is the test-bed for NCS and it attends the practical issues and implementation of NCS. At the end, iSpace at ADAC is presnted as a case study for NCS with different experimental results.

Concurrent visual multiple lane detection for autonomous vehicles

This paper proposes a monocular vision solution to simultaneous detection of multiple lanes in navigable regions / urban roads using accumulator voting. Unlike other approaches in literature, this paper first examines the extent of lane parameters required for continuous control of any vehicle manually or autonomously. The accumulator-based algorithm is designed using this fundamental control knowledge to vote for the required lane parameters (position of lanes and steering angle required) in the image plane. The novel accumulator voting scheme is called “Parametric Transform for Multi-lane Detection.” This paper not only adapts predictive control in the image plane, but also detects multiple lanes in the scene concurrently in the form of multiple peaks in the accumulator. This method is robust to shadows and invariant to color, texture, and width of the road. Finally, the method is designed for dashed/continuous lines.

A Network based, Delay-tolerant, Integrated Navigation System for a differential drive UGV using Harmonic Potential Field

Network based integrated navigation systems are a multidisciplinary effort whose aim is to produce a network structure and components that are capable of integrating sensors, actuators, communication, and control algorithms in a manner to suit real-time navigation and/or obstacle avoidance. There are many challenges to be overcome in order to put such a distributed and heterogeneous system together. This paper deals with some of these issues, i.e. the adverse effect of processing delays on the system and efficient integration of different modules. This paper describes a delay-resistant sensory-motor module for navigating a differential drive unmanned ground vehicle (UGV) in an indoor cluttered environment. The module consists of an early vision edge detection stage, a harmonic potential field (HPF) planner; a network based quadratic curve fitting controller and gain schedule middleware, (GSM). Though the different techniques and algorithms used to implement the navigation system have been previously well-studied algorithms, the novel contribution in this paper is the way all these different modules are integrated together for the first time to create an efficient structure for a network based integrated navigation system making it easy to implement and realize for many different applications. The structure of this module and its components are described. Thorough experimental results along with performance assessment comparing to the previous implementation are also provided to illustrate the effectiveness of the new integrated navigation structure

Performance Assessment of Data and Time-Sensitive Wireless Distributed Networked-Control-Systems in Presence of Information Security

Distributed network-control-systems (D-NCS) are a network structure and components that are capable of integrating sensors, actuators, communication, and control algorithms to suit real-time applications. They have been gaining popularity due to their high potential in widespread applications and becoming realizable due to the rapid advancements in embedded systems, wireless communication and data transfer technologies. This paper addresses the issue of D-NCS information security as well its time-sensitive performance with respect to network security schemes. We use a wireless network based, robot navigation path tracking system called Intelligent Space (iSpace) as a D-NCS test bed in this paper. The paper classifies the delay data from every NCS module (sensors, actuators and controllers). We define performance parameters for this NCS test bed. Various system factors including network delay, system gain, affecting these performance parameters are recognized. Network security algorithms DES and 3DES are integrated with the application to secure the sensitive information flow. Standard statistical approach such as 2k factorial experiment design, analysis of variance, hypothesis testing is used to study and estimate the effect of each factor on the system performance especially security features. Thorough experimental results, tables of detailed characterization and effect estimate analysis is presented followed by the discussion on the performance comparison of NCS with and without wireless security.

Characterization of data-sensitive wireless distributed networked-control-systems

Distributed networked-controlled-systems (NCS) are a multidisciplinary effort whose aim is to produce a network structure and components that are capable of integrating sensors, actuators, communication, and control algorithms in a manner to suit real-time applications. They have been very popular and widely applied for many years now due to the rapid advancements in data and communication wireless technologies. There are many challenges to be overcome in order to put such a heterogeneous system together. Key issues to be considered are network delay, data sensitivity and information security. This paper characterizes a wireless distributed NCS, a testbed called iSpace based on these key factors. We integrated static network security algorithms DES and 3DES with the NCS testbed iSpace - a multidisciplinary network based robot navigation system - and characterized it on the basis of bandwidth requirement, data classification and data sensitivity, network delay effect on the system performance. The paper demonstrates through results that a dynamic optimization is required between network security for reliability and time-sensitivity of the NCS. Future work in dynamic optimization in security is suggested.

Information security with real-time operation: performance assessment for next generation wireless distributed networked-control-systems

Distributed network-control-systems (D-NCS) are a multidisciplinary effort whose aim is to produce a network structure and components that are capable of integrating sensors, actuators, communication, and control algorithms in a manner to suit real-time applications. They have been gaining popularity due to their high potential in widespread applications and becoming more realizable due to the rapid advancements in wireless communication and data transfer technologies. This paper addresses the issue of D-NCS information security as well its real-time performance with respect to network security protocols and encryption schemes. We use a wireless network based, robot navigation path tracking system called intelligent space (iSpace) as a D-NCS test bed in this paper. The paper classifies the data from every NCS module (sensors, actuators and controllers) according to bandwidth requirement, time and information sensitivity. We define performance parameters for this NCS test bed. Various system factors affecting these performance parameters are recognized. Network security algorithms DES and 3DES are integrated with the application to encrypt the sensitive information flow. These wireless security features are considered as an added factor to the NCS. Standard statistical approach (2k factorial experiment design) is used to study and estimate the effect of each factor on the system performance especially security additions. Thorough experimental results, tables of detailed characterization and effect estimate analysis is presented followed by the discussion on the performance comparison of NCS with and without wireless security.

LAP: Link-Aware Protection for Improving Performance of Loss and Delay Sensitive Applications in Wireless LANs

Radio links exhibit highly unpredictable properties such as variable bandwidth and bit error rates that affect the performance of applications in wireless networks. Besides, another critical concern is the protection of applications due to shared and open wireless medium. However, protection services add additional performance overhead to carry out their operations, and incur varying effects on the network performance, depending on link characteristics. Thus, how to provide protected and high performance service is a challenging issue in wireless networks. The problem is even more challenging for real-time applications such as voice over IP (VoIP) with stringent delay and packet loss requirements. In this paper, we present a novel approach to improve application performance by implementing Link Aware Protection (LAP) in wireless local area networks (LANs). LAP exploits dynamic security policy management (DSPM) scheme for adapting protection with varying link quality. We present a real-time implementation of LAP in our wireless LAN testbed. As a case study, we demonstrate VoIP performance on our LAP enabled wireless clients. The results show the possibility of maintaining an adequate protection and achieving improved performance for VoIP streams under link variations.