Rajiv Kumar

An Implementation of Time-Delay Compensation Scheme for Networked Control Systems Using MATLAB/Simulink

Networked Control Systems are feedback control systems wherein the control loops are closed through a real time network. The information from sensors and controllers in NCS is sent over a real-time communication network. Depending upon the topology and the routing algorithms used, the network can introduce non-deterministic and undesired delays, jitter and losses. In NCS, if the time-delay exceeds a specified tolerable limit, it leads to the degraded and deteriorated performance of the system. Communication networks inevitably introduce delays in NCSs. Therefore, it is necessary to compensate time-delay. However, this paper adopts the prediction based delay compensation technique by the use of Smith Predictor. The stability analysis has been done for different plant transfer functions. Transport layer protocol User Data gram Protocol (UDP) has been used for communication. Simulations have been done with help of MATLAB/Simulink. It has been illustrated that delay compensation depends upon the order and time constant of the system.

Performance comparison and detailed study of AODV, DSDV, DSR, TORA and OLSR routing protocols in ad hoc networks

Communication among the wireless links between mobile nodes is become popular research area because of its simplicity of deployment and mobility. Collection of all mobile nodes through which all wireless links are connected called as Mobile Ad hoc Network (MANET). MANET network gets too much attraction of researchers due to its mobility, reliability, self-repairing, dynamic infrastructure and independent with the help of center administration. Despite of numerous advantages it has many problems like synchronization, routing protocol, delay and shortest path. Many routing protocols have been proposed like OLSR, DSDV, DSR, AODV and TORA so far to improve the routing performance therefore these routing protocols are studied in depth and simulated using NS-2. The simulation and comparison results will briefly present the impact of network size, packet delivery ratio, average delay and average throughput.

A framework for continuity of mission-critical network services

A framework for the continuous delivery of mission-critical network services is proposed. The risk involved is assessed in a binary way, i.e., there is no risk until the network system supports the services up to the intended duration; otherwise, the mission fails and this gives rise to failure impact. The proposed framework is used to allocate network resources.

A dependable routing framework for seamless traffic flow over the computer network

This paper proposes a QoS routing framework for real-time mission-critical and life critical communication such as tele-engineering and telesurgery. Such communications are real-time and seamless, and demand the hard timeliness guarantees on message delivery lag-time and recovery delays encountered due to the network component failure. Success of the fulfillment of these two requirements depends upon the performance of routing. Routing framework proposed here can be divided into two parts:1) active channel routing; through which seamless traffic flows normally and, 2) backup channel routing; traffic flows after the failure of one or more component of the active path. Active channel routing scheme proposed here is able to select QoS path with minimum network elements. Backup routing is an active paths segment based local-recovery scheme. A network resource reservation based proactive routing / rerouting has been adopted so as to achieve a better service continuity. Backup routing scheme, identifies the weakest link or set of links of primary path. Routing method proposed in this paper is able to optimize resource utilization and ensures the continuity of seamless flow with optimum performance over the computer network.

Effect of Network-Induced Delay on Stability in Networked Control System.

In this paper, effect of network-induced delay on stability in networked control systems has been discussed. Four conditions of network-induced delay have been considered. In first condition, delay is less than the sam- pling period. Second, delay is equal to the sampling period. Third, delay is longer than the sampling period and fourth, delay is integer multiple of sampling period. A full state feedback controller has been included in closed-loop system. The problem of stability has been described in two ways, first, in finding the roots of the characteristics equation and second, as a response to the initial conditions of the networked closed-loop system. This work has been illustrated with the help of a numerical example.