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In this paper, three different environmental monitoring application classes are investigated. The first class requires equal sensor density as in the case of a random incident source. The second class requires the sensors to be concentrated in the outer regions as in the case of a central incident source. The third class requires the sensors to be concentrated more in the center as in a case where...
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...
In this paper, a performability model is developed to analyze the effect of Access Point failures on the performance of a WiFi communication system. The system consists of seven Access Points in which mobile nodes (vehicles) travel at speeds up to 60 Km/hr. Traffic information is continuously sent by the infrastructure to the vehicles (I2V) in the form of bursts of identical packets to decrease packet...
In this paper, the repair process for fault-tolerant industrial production lines is investigated. The type of failure may significantly affect the repair time because of travel time, customs,... A modified Markov model is developed that takes into account these different repair times. The availability of a two-machine production line is then calculated using this model and is compared to the availability...
This paper presents a mechanism to evaluate fault-tolerant WiFi network performance in a mobile environment. Fault-tolerance at the access point (AP) level is presented in a degraded performance mode. In case of an access point (AP) failure the surrounding APs increase their power to compensate for this failure. Mobile IPv6 is used as mobile protocol for the moving entities. A new metric is introduced...
The use of Ethernet protocol for railway vehicle on-board networks is considered. It is shown that a single Ethernet network can carry real-time control data, thus replacing existing train control networks. In addition, this network can also carry entertainment data for passengers as well as data coming from mobile wireless devices carried on-board. OPNET simulations are used to estimate the maximum...
This paper focuses on the wireless communication aspect of the traffic control problem in urban areas. The IEEE 802.11b standard is used and an architecture is developed that produces zero packet loss at vehicle speeds of up to 60 Km/hr. A quantitative comparison is made between the Mobile Internet Protocol v4 (MIPv4) and MIPv6. It is shown that MIPv6 produces much less packet losses than MIPv4. Burst...
In this research, three honeycell WiFl architectures using the 802.11b and 802.11g protocols are studied. These architectures are designed to provide high mobility for dynamic data applications and are optimized for deployment in moderately populated areas. OPNET is used in the study as the network simulator. At the OPNET default value of the packet reception power threshold, it is found that the...
This paper introduces the idea of using the stigmergic approach to solve traffic problems in congested urban areas and focuses on the communications aspect of the problem. V2I and I2V are based on IEEE 802.11 standard. The urban area is equipped with access points that are wired to a central node. The number of packets lost is investigated at different vehicle speeds as well as different I2V broadcast...
Automotive industry is in continuous evolution. Luxury as well as comfort is important. Safety measures are the most important in designing a moving vehicle. Safety can be studied from a mechanical point of view as well as from an electrical point of view. This paper presents a simulation study for fault-tolerant sensor networks for cars' on-board control. On-board communication and control networks...
This research investigates the mean time to failure (MTTF) of a fault-tolerant two-machine production line in the context of networked control systems (NCS). A conventional Markov model is used. A special metric is introduced and used to find the most cost-efficient and practical way of simultaneously decreasing controller failure rate and increasing repair rate and coverage in order to increase MTTF...
Networks play an important role in hierarchical implementation of distributed control networks. In previous studies, Gigabit Ethernet was used to build such control systems. OPNET simulations were successful for such systems from the point of view of network traffic. They also showed the need to have a higher computational power for the supervisory node relative to the normal control nodes. This was...
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...
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...
This paper presents the design of a low-cost, robust and fault-secure fire protection system for trains. This system consists of three temperature detectors and three smoke detectors whose outputs are connected to a controller. The system produces three warning signals: fire, alarm and cigarette. The system takes into account the presence or absence of wind and is expected to be extremely useful in...
In this paper, a model for a code division multiple access (CDMA) transceiver, using a special type of pseudorandom noise (PN) code, is developed. The simulation results obtained using ModelSim 5.7 and ISE 5.1 are presented. The VHDL model is programmed on a Xilinx FPGA, "Virtex XCV800", and tested successfully. The transceiver represents the core for a wireless device attached to the serial...
This paper investigates the effect of failures on the productivity of fault-tolerant networked control systems under varying loads. Higher speeds of operation are sometimes used to increase production and compensate for down time due to component failures. Improved Markov models are developed and used to calculate system probabilities. When these probabilities are combined with the maximum speed of...
In this paper, the use of Fast and Gigabit Ethernet in networked control systems is tested. Real-time traffic and non-real time traffic are integrated without changing the IEEE 802.3 protocol packet format. In a mixed traffic industrial environment, it is found that standard Gigabit Ethernet switches succeed to meet time constraints that Fast Ethernet failed to meet
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