Hassanein H. Amer

Ethernet-Based Car Control Network

The use of networks for communication between electronic control units has increased in car industry over the last two decades. Several types of networks were developed for this purpose. In this study, Ethernet at gigabit speed is tested as a network for such system. The use of Ethernet helps integrating real-time control functions and non-real-time entertainment functions. Two main scenarios were simulated using OPNET. The fist one simulates pure control networks on board of a moving vehicle. The second scenario is the same as the first one with an added video load to simulate on-board entertainment. Both simulations were successful, as the end-to-end delays were below the maximum round-trip delays required by the system

Gigabit Ethernet for redundant networked control systems

In this paper, the use of fast and Gigabit Ethernet in advanced networked control systems is studied. Redundant control node scenario is the key factor for minimum down-time. Ethernet 802.3 protocol is tested without modification in frame format. Gigabit Ethernet succeeded to absorb the control traffic of several working machines while fast Ethernet could not.

WiFi implementation of Wireless Networked Control Systems

This paper studies a Wireless Networked Control System which utilizes the IEEE 802.11b protocol without modifications to communicate between sensors and actuators in a production line environment. OPNET simulations are used to measure the end-to-end delay from sensor to controller and then from controller to actuator. It is observed that the measured delays, including all types of data processing, encapsulation, decapsulation and propagation, meet real-time control network requirements while guaranteeing correct packet reception. The system is then subjected to noise and several worst-case scenarios are analyzed. Simulations indicate that the system is still able to meet the required end-to-end delays. All results are based on a 95% confidence analysis.

Effect of node distributions on lifetime of Wireless Sensor Networks

Wireless Sensor Networks has recently become an attractive research topic due to the rapidly growing field of applications. This paper focuses on prolonging network lifetime by investigating different node deployments including both geometric and uniform. Geometric distributions resulted in a 35.6% increase in lifetime as opposed to random distributions. Furthermore, different sink locations were examined. The optimum sink location introduced a considerable lifetime elongation compared to the previously used location.

Catastrophic short and open fault detection in MOS current mode circuits: A case study

In this paper, the issue of testing analog MOS current mode circuits for catastrophic open and short faults has been addressed. A case study based on the 6-transistor transconductor circuit is discussed. The five-fault model is assumed per transistor, namely a short circuit between any two terminals as well as an open-circuited drain or source. DC testing is performed in order to reduce test cost instead of AC testing which requires expensive equipments. Only one fault is assumed to exist in the circuit under test. PSpice simulations have been carried out using the 0.18µm MOS model provided from MOSIS. The circuit has been simulated for fault-free condition and after injecting a single fault at a time into the circuit. The simulation results have been analyzed and compared. It is found that the total fault coverage is 93%.

Fault-tolerant networked control systems under varying load

In this paper, a simulation study is made to test the fault tolerant ability of networked machines. This ability is introduced by reallocating loads in case of controller failure. Also, the increase in machine speed for higher production, is considered. The maximum speed of operation of individual machines and fault tolerant production-lines, is studied. All machine networks of this study are built on-top-of switched Gigabit Ethernet in star topology.

Fault tolerant two-level pyramid networked control systems

In this paper, a pyramid control hierarchy is proposed. It is based on the presence of a supervisor controller on top of separate controller nodes. A simulation study is conducted to test the functionality of the system. The proposed model is an enhancement of machine modeled in form of networked control systems (NCS). Two models are tested: one supervisor/two sub-controllers, one supervisor/three sub-controllers. All possible combinations of supervisor-controller intercommunication are tested. Also, all supervisor/controller inter-changeability possibilities are taken into consideration. Results are illustrated and discussed. Recommendations are drawn out. All machine models of this study are built using switched gigabit Ethernet in star topology

Lifetime optimization in hierarchical wireless sensor networks

Wireless sensor networks is a voracious field for research, especially after the great advances in MEMS based sensors. In this paper, environmental monitoring applications are considered where data may be continuously reported with the possibility of urgent alarming if necessary. Hierarchical architecture of the network is assumed in order to overcome the problem of energy constrained sensors. Two algorithms are proposed with the purpose of network lifetime elongation and the maximization of the use of the available energy. The first algorithm is a modification for LEACH-C to enhance its performance. It results in a 25% longer lifetime. The second algorithm is an energy efficient method to ensure full coverage of the network as long as sensors are still working. This achieves 32% longer lifetime than LEACH-C.

Fault tolerant Ethernet network model for control and entertainment in railway transportation systems

In this paper, simulations are run to study the performance of a fault tolerant control system over a single gigabit Ethernet network used in train wagons. The network is assumed to carry control data as well as additional entertainment traffic. The network consists of a Controller handling the sensor-to-actuator data and another Entertainment Server carrying video and Internet application packets. Fault-tolerance is introduced by reallocating loads in case of controller failure. Additionally, various qualities for the entertainment traffic carried by the network are used. OPNET was used to estimate the maximum allowable entertainment traffic that can be added to satisfy real-time sensor-to-actuator packet end-to-end delay constraints.

On the effect of interference on Wi-Fi-based Wireless Networked Control Systems

This study investigates a Wi-Fi-based Wireless Networked Control System. This system is first modified in order to enhance resistance to interference. Then, it is subjected to different types of interference. The system consists of a workcell containing 30 sensors, 30 actuators and 1 controller. All forms of interference modeled focus on the operating frequency band used by the control nodes. All simulations are conducted on OPNET Network Modeler and system performance is measured in terms of packet end-to-end delay and correct packet transmission/reception. All results are subjected to a 95% confidence analysis. The results show that intentional jamming is more damaging than medium congestion, which in turn is more damaging than network congestion.