International Journal of Vehicular Technology
[SJR: 0.148] [H-I: 3] [4 followers] Follow
Open Access journal
ISSN (Print) 1687-5702 - ISSN (Online) 1687-5710
Published by Hindawi Publishing Corporation [399 journals]
- Design of Commute Carpooling Based on Fixed Time and Routes
Abstract: Although the private carpooling market of China has grown rapidly, it has been embarrassed by problems such as obstructed information, disordered expense, and frequent crimes currently. In this paper, a commute carpooling program based on fixed time and routes is designed and corresponding carpooling information platform is built to realize information retrieval, information matching, and mutual selection and evaluation. We have practiced the program in Huaian, China, and then evaluated it using the improved time-expense impedance model and VISSIM simulation system. The result shows that the carpooling program can reduce 65%~86% of the time-expense impedance and optimize some network parameters up to 20%~40%. Since it will help in reducing the travel time and cost greatly, improving safety and economy during carpooling, and easing the traffic congestion, it is a worthy carpooling mode to be extended in China.
PubDate: Wed, 31 Dec 2014 11:19:09 +000
- Traction Control of Electric Vehicles Using Sliding-Mode Controller with
Tractive Force Observer
Abstract: Traction control is an important element in modern vehicles to enhance drive efficiency, safety, and stability. Traction is produced by friction between tire and road, which is a nonlinear function of wheel slip. In this paper, a sliding-mode control approach is used to design a robust traction controller. The control objective is to operate vehicles such that a desired wheel slip ratio is achieved. A nonlinearity observer is employed to estimate tire tractive forces, which are used in the control law. Simulation and experimental results have illustrated the success of the proposed observer-based controller.
PubDate: Sun, 21 Dec 2014 06:26:53 +000
- A Review of Optimal Energy Management Strategies for Hybrid Electric
Abstract: Presence of an alternative energy source along with the Internal Combustion Engine (ICE) in Hybrid Electric Vehicles (HEVs) appeals for optimal power split between them for minimum fuel consumption and maximum power utilization. Hence HEVs provide better fuel economy compared to ICE based vehicles/conventional vehicle. Energy management strategies are the algorithms that decide the power split between engine and motor in order to improve the fuel economy and optimize the performance of HEVs. This paper describes various energy management strategies available in the literature. A lot of research work has been conducted for energy optimization and the same is extended for Plug-in Hybrid Electric Vehicles (PHEVs). This paper concentrates on the battery powered hybrid vehicles. Numerous methods are introduced in the literature and based on these, several control strategies are proposed. These control strategies are summarized here in a coherent framework. This paper will serve as a ready reference for the researchers working in the area of energy optimization of hybrid vehicles.
PubDate: Tue, 18 Nov 2014 08:47:26 +000
- Neck Moment Characterization of Restrained Child Occupant at Realistic
Nontest Standard Higher Impact Speed of 32.2 km/h
Abstract: The effects of bullet vehicle crash impact angle, child restraint system design, and restraint harness slack at side impact speed of 32.2 km/h (20 mph) on moments sustained at the neck by a three-year-old child are investigated. Mathematical models are built using the response surface method based on simulation results whereby good fitness is achieved. The singular and cross interactive effect of each predictor on the neck moment are analyzed. The number of significant parameters affecting the neck moment is shown to be the largest for wide impact angles and the impact angle parameter is largely revealed to be the most sensitive. An ideal safe range for low neck moment has been established to be within angles 45° and 65°. It is further shown that the nature of all parameters effect on the neck moment is highly dependent on the impact angle range.
PubDate: Thu, 11 Sep 2014 08:10:17 +000
- Handover Performance over a Coordinated Contiguous Carrier Aggregation
Deployment Scenario in the LTE-Advanced System
Abstract: Although various carrier aggregation deployment scenarios (CADSs) have been introduced in the LTE-Advanced system, issues related to insufficient eNB coverage that leads to low throughput and high drop call have yet to be solved. This paper proposes a new deployment scenario called coordinated contiguous-CADS (CC-CADS), which utilizes two-component carriers (CCs) that operate on two frequencies located in a contiguous band. Each CC antenna is directed to a cell boundary of the other CC. The handover performance of users with various mobility speeds under CC-CADS has been investigated and compared with various deployment scenarios proposed by 3GPP. Simulation results show that the received signal reference power (RSRP) enhancement and performed handover, ping-pong, drop call, and outage probabilities reductions in CC-CADS outperformed the 3GPP’s CADSs, thus leading to reduced interruption time, improved spectral efficiency, and seamless handover.
PubDate: Sun, 31 Aug 2014 12:11:34 +000
- Driver’s Fatigue Detection Based on Yawning Extraction
Abstract: The increasing number of traffic accidents is principally caused by fatigue. In fact, the fatigue presents a real danger on road since it reduces driver capacity to react and analyze information. In this paper we propose an efficient and nonintrusive system for monitoring driver fatigue using yawning extraction. The proposed scheme uses face extraction based support vector machine (SVM) and a new approach for mouth detection, based on circular Hough transform (CHT), applied on mouth extracted regions. Our system does not require any training data at any step or special cameras. Some experimental results showing system performance are reported. These experiments are applied over real video sequences acquired by low cost web camera and recorded in various lighting conditions.
PubDate: Wed, 06 Aug 2014 00:00:00 +000
- Autonomous, Distributed Parking Lot Vacancy Management Using Intervehicle
Abstract: We have developed a method of managing vacancy information of a large parking lot in a distributed manner using only intervehicle communication. A group of parking spaces is defined as a cluster. Vacancy information of a cluster is managed by a vehicle in it. This vehicle is called a cluster head. The proposed method generates a communication path topology between cluster heads. The topology is a tree structure with the cluster head of the cluster nearest to the parking lot entrance as the root node. Cluster heads are ranked in order of the number of vacant spaces and the distance to the shop entrance. The vehicle entering the parking lot collects vacancy information of clusters. This information is transmitted along the tree structure from the lowest ranking cluster head. We have developed a simulation model for a parking lot that can accommodate nearly 1,000 vehicles and used it to evaluate the proposed method. We have confirmed that the proposed method generates less communication traffic and enables the vehicle entering a parking lot to collect vacancy information about the area near the shop entrance with a higher probability and in a shorter time.
PubDate: Mon, 21 Jul 2014 08:00:01 +000
- A Probabilistic Analysis of Path Duration Using Routing Protocol in VANETs
Abstract: In recent years, various routing metrics such as throughput, end-to-end delay, packet delivery ratio, path duration, and so forth have been used to evaluate the performance of routing protocols in VANETs. Among these routing metrics, path duration is one of the most influential metrics. Highly mobile vehicles cause frequent topology change in vehicular network environment that ultimately affects the path duration. In this paper, we have derived a mathematical model to estimate path duration using border node-based most forward progress within radius (B-MFR), a position based routing protocol. The mathematical model for estimation of path duration consists of probability of finding next-hop node in forwarding region, estimation of expected number of hops, probability distribution of velocity of nodes, and link duration between each intermediate pair of nodes. The analytical results for the path duration estimation model have been obtained using MATLAB. The model for path duration estimation has been simulated in NS2. Each of the analytical results has been verified through respective simulation results. The result analysis clearly reveals that path duration increases with the increase in transmission range and node density and decreases with the increase in the number of hops in the path and velocity of the nodes.
PubDate: Thu, 17 Jul 2014 11:45:51 +000
- A Review of Active Yaw Control System for Vehicle Handling and Stability
Abstract: Yaw stability control system plays a significant role in vehicle lateral dynamics in order to improve the vehicle handling and stability performances. However, not many researches have been focused on the transient performances improvement of vehicle yaw rate and sideslip tracking control. This paper reviews the vital elements for control system design of an active yaw stability control system; the vehicle dynamic models, control objectives, active chassis control, and control strategies with the focus on identifying suitable criteria for improved transient performances. Each element is discussed and compared in terms of their underlying theory, strengths, weaknesses, and applicability. Based on this, we conclude that the sliding mode control with nonlinear sliding surface based on composite nonlinear feedback is a potential control strategy for improving the transient performances of yaw rate and sideslip tracking control.
PubDate: Thu, 12 Jun 2014 09:25:19 +000
- Nonlinear Controllers for a Light-Weighted All-Electric Vehicle Using
Chebyshev Neural Network
Abstract: Two nonlinear controllers are proposed for a light-weighted all-electric vehicle: Chebyshev neural network based backstepping controller and Chebyshev neural network based optimal adaptive controller. The electric vehicle (EV) is driven by DC motor. Both the controllers use Chebyshev neural network (CNN) to estimate the unknown nonlinearities. The unknown nonlinearities arise as it is not possible to precisely model the dynamics of an EV. Mass of passengers, resistance in the armature winding of the DC motor, aerodynamic drag coefficient and rolling resistance coefficient are assumed to be varying with time. The learning algorithms are derived from Lyapunov stability analysis, so that system-tracking stability and error convergence can be assured in the closed-loop system. The control algorithms for the EV system are developed and a driving cycle test is performed to test the control performance. The effectiveness of the proposed controllers is shown through simulation results.
PubDate: Tue, 22 Apr 2014 00:00:00 +000
- Dynamic Analysis and Design Optimization of Series Hydraulic Hybrid System
through Power Bond Graph Approach
Abstract: The availability of natural gas and crude oil resources has been declining over the years. In automobile sector, the consumption of crude oil is 63% of total crude oil production in the world. Hence, automobile industries are placing more emphasis on energy efficient hydraulic hybrid systems, which can replace their conventional transmission systems. Series hydraulic hybrid system (SHHS) is a multidomain mechatronics system with two distinct power sources that includes prime mover and hydropneumatic accumulator. It replaces the conventional transmission system to drive the vehicle. The sizing of the subsystems in SHHS plays a major role in improving the energy efficiency of the vehicle. In this paper, a power bond graph approach is used to model the dynamics of the SHHS. The obtained simulation results indicate the energy flow during various modes of operations. It also includes the dynamic response of hydropneumatic accumulator, prime mover, and system output speed. Further, design optimization of the system is carried out to optimize the process parameters for maximizing the system energy efficiency. This leads to increase in fuel economy and environmentally friendly vehicle.
PubDate: Tue, 01 Apr 2014 14:18:17 +000
- Stability Control of Vehicle Emergency Braking with Tire Blowout
Abstract: For the stability control and slowing down the vehicle to a safe speed after tire failure, an emergency automatic braking system with independent intellectual property is developed. After the system has received a signal of tire blowout, the automatic braking mode of the vehicle is determined according to the position of the failure tire and the motion state of vehicle, and a control strategy for resisting tire blowout additional yaw torque and deceleration is designed to slow down vehicle to a safe speed in an expected trajectory. The simulating test system is also designed, and the testing results show that the vehicle can be quickly stabilized and kept in the original track after tire blowout with the emergency braking system described in the paper.
PubDate: Tue, 11 Mar 2014 09:29:36 +000
- Broadcasting in Connected and Fragmented Vehicular Ad Hoc Networks
Abstract: This paper starts with an overview of vehicular ad hoc networks (VANETs) and their characteristics. Then this paper reviews diverse applications of VANETs and the requirements of these applications. In addition it reviews VANETs standards, different broadcasting presented in a variety of studies, and also associated issues with data dissemination in connected and fragmented vehicular networks to solve broadcast storm problem and temporary disconnected VANETs. The discussion will be about the encountered challenges and presented solutions with respect to the related issues, based on the literature and strength and weakness of each protocol.
PubDate: Sun, 09 Mar 2014 09:56:17 +000
- Distributed Algorithm for Constructing Efficient Tree Topology for Message
Dissemination in Vehicular Networks
Abstract: Vehicular ad hoc network is an ad hoc network constituted among moving vehicles that have wireless dedicated short range communication (DSRC) devices in order to provide ubiquitous connectivity even if the road-side infrastructure is unavailable. Message dissemination in vehicular ad hoc networks is necessary for exchanging information about prevailing traffic information, so that the vehicles can take alternate routes to avoid traffic jam. A major challenge in broadcast protocols is that they result in flooding of messages that reduce the speed of dissemination due to collision. Dissemination of messages using tree topology reduces the number of rebroadcasts. Dynamicity Aware Graph Relabeling System model provides a framework to construct spanning tree in mobile wireless network. In this paper, we propose a new distributed algorithm for constructing an arbitrary spanning tree based on Dynamicity Aware Graph Relabeling System model, which develops a maximum leaf spanning tree in order to reduce the number of rebroadcasts and dissemination time. Our simulation results prove that the number of vehicles rebroadcasting the message is curtailed to 15% and the dissemination time required to achieve 100% reachability is curtailed by 10% under average vehicle density.
PubDate: Thu, 20 Feb 2014 07:21:17 +000
- Robust PID Steering Control in Parameter Space for Highly Automated
Abstract: This paper is on the design of a parameter space based robust PID steering controller. This controller is used for automated steering in automated path following of a midsized sedan. Linear and nonlinear models of this midsized sedan are presented in the paper. Experimental results are used to validate the longitudinal and lateral dynamic models of this vehicle. This paper is on automated steering control and concentrates on the lateral direction of motion. The linear model is used to design a PID steering controller in parameter space that satisfies -stability. The PID steering controller that is designed is used in a simulation study to illustrate the effectiveness of the proposed method. Simulation results for a circular trajectory and for a curved trajectory are presented and discussed in detail. This study is part of a larger research effort aimed at implementing highly automated driving in a midsized sedan.
PubDate: Tue, 04 Feb 2014 13:53:41 +000
- Control of Yaw Disturbance Using Fuzzy Logic Based Yaw Stability
Abstract: Yaw stability is an important consideration for the vehicle directional stability and handling behavior during emergency maneuvers. In order to maintain the desired path of the vehicle, in presence of disturbances due to cross wind, different road conditions, and tire deflections, a fuzzy logic based yaw stability controller is proposed in this paper. Proposed control system receives yaw rate error, steering angle given by the driver, and side slip angle as inputs, for calculating the additional steering angle as output, for maintaining the yaw stability of the vehicle. As the side slip angle cannot be measured directly in a vehicle, it was estimated using a model based Kalman observer. A two-degrees-of-freedom vehicle model is considered in the present work. The effect of disturbance on yaw rate and yaw rate error of the vehicle is simulated for sinusoidal, step maneuver and compared with the existing fuzzy control system which uses two inputs such as steering angle and yaw rate. The simulation results show better performance of the proposed fuzzy based yaw controller as compared with existing control system. Proposed fuzzy based yaw stability controller can be implemented in steer-by-wire system for an active front steering of a road vehicle.
PubDate: Tue, 04 Feb 2014 09:41:27 +000
- Driving Posture Recognition by Joint Application of Motion History Image
and Pyramid Histogram of Oriented Gradients
Abstract: In the field of intelligent transportation system (ITS), automatic interpretation of a driver’s behavior is an urgent and challenging topic. This paper studies vision-based driving posture recognition in the human action recognition framework. A driving action dataset was prepared by a side-mounted camera looking at a driver’s left profile. The driving actions, including operating the shift lever, talking on a cell phone, eating, and smoking, are first decomposed into a number of predefined action primitives, that is, interaction with shift lever, operating the shift lever, interaction with head, and interaction with dashboard. A global grid-based representation for the action primitives was emphasized, which first generate the silhouette shape from motion history image, followed by application of the pyramid histogram of oriented gradients (PHOG) for more discriminating characterization. The random forest (RF) classifier was then exploited to classify the action primitives together with comparisons to some other commonly applied classifiers such as NN, multiple layer perceptron, and support vector machine. Classification accuracy is over 94% for the RF classifier in holdout and cross-validation experiments on the four manually decomposed driving actions.
PubDate: Tue, 28 Jan 2014 07:50:19 +000
- Performance Comparison of IEEE 802.11p and IEEE 802.11b for
Vehicle-to-Vehicle Communications in Highway, Rural, and Urban Areas
Abstract: Communication between vehicles has recently been a popular research topic. Generally, the Vehicle-to-Vehicle (V2V), Vehicle-to-Infrastructure (V2I), and Infrastructure-to-Infrastructure (I2I) communications applications can be divided into two sections: (i) safety applications and (ii) nonsafety applications. In this study, we have investigated the performance of IEEE 802.11p and IEEE 802.11b based on real-world measurements and radio propagation models of V2V networks in different environments, including highway, rural, and urban areas. Furthermore, we have investigated the most used V2V mobility models and simulation tools. Comparative performance evaluations show that the IEEE 802.11p achieves higher network throughput, low end-to-end delay, and higher delivery ratio compared to IEEE 802.11b. Overall, our main objective is to describe potential advantages, research challenges, and applications of V2V networks and show how IEEE 802.11p and IEEE 802.11b will perform under different radio propagation environments.
PubDate: Wed, 06 Nov 2013 14:24:29 +000
- Advances of Human Factors Research for Future Vehicular Technology
PubDate: Mon, 30 Sep 2013 14:51:47 +000
- Analysis of Temporal Relationships between Eye Gaze and Peripheral Vehicle
Behavior for Detecting Driver Distraction
Abstract: A car driver’s cognitive distraction is a main factor behind car accidents. One’s state of mind is subconsciously exposed as a reaction reflecting it by external stimuli. A visual event that occurs in front of the driver when a peripheral vehicle overtakes the driver’s vehicle is regarded as the external stimulus. We focus on temporal relationships between the driver’s eye gaze and the peripheral vehicle behavior. The analysis result showed that the temporal relationships depend on the driver’s state. In particular we confirmed that the timing of the gaze toward the stimulus under the distracted state induced by a music retrieval task using an automatic speech recognition system is later than that under a neutral state while only driving without the secondary cognitive task. This temporal feature can contribute to detecting the cognitive distraction automatically. A detector based on a Bayesian framework using this feature achieves better accuracy than one based on the percentage road center method.
PubDate: Sun, 15 Sep 2013 13:31:47 +000
- Automotive Technology and Human Factors Research: Past, Present, and
Abstract: This paper reviews the history of automotive technology development and human factors research, largely by decade, since the inception of the automobile. The human factors aspects were classified into primary driving task aspects (controls, displays, and visibility), driver workspace (seating and packaging, vibration, comfort, and climate), driver’s condition (fatigue and impairment), crash injury, advanced driver-assistance systems, external communication access, and driving behavior. For each era, the paper describes the SAE and ISO standards developed, the major organizations and conferences established, the major news stories affecting vehicle safety, and the general social context. The paper ends with a discussion of what can be learned from this historical review and the major issues to be addressed. A major contribution of this paper is more than 180 references that represent the foundation of automotive human factors, which should be considered core knowledge and should be familiar to those in the profession.
PubDate: Wed, 04 Sep 2013 15:01:57 +000
- Fuel Efficiency by Coasting in the Vehicle
Abstract: This paper investigates the possibility of improving the fuel efficiency by decreasing the engine speed during the coasting phase of the vehicle. The proposed approach is stimulated by the fact that the engine losses increase with the engine speed. If the engine speed is retained low, the engine losses will be reduced and subsequently the tractive torque will be increased, enabling the vehicle to remain moving for longer duration while coasting. By increasing the time period of the coasting the fuel efficiency can be increased, especially travelling downhill, since it can benefit from the kinematic energy stored in the vehicle to continue coasting for a longer duration. It is already industry standard practice to cut fuel during coasting and refuel at low engine speed. The substantial difference proposed in this paper is the controlled reduction of engine speed during this phase and thus reduction in the engine losses, resulting in improved fuel economy. The simulation model is tested and the results illustrating an improvement to the fuel efficiency through the proposed method are presented. Some results of the experimental tests with a real vehicle through the proposed strategy are also presented in the paper.
PubDate: Mon, 26 Aug 2013 14:41:22 +000
- Improving Energy Conversion Efficiency by means of Power Splitting in Dual
Drive Train EV Applications
Abstract: The limited amount of energy stored on board of battery electric vehicles (BEV) spurs research activities in the field of efficiency optimization for electric drive train applications in order to achieve an enhanced mileage. In this work a control method for BEV applications with two drive trains (e.g., one at the front and one at the rear axle) is presented. Herein, a simple optimization algorithm is introduced enabling to operate the two drives with different torque values, depending on the instantaneous operation point, leading to a reduction of apparent power losses on board. Simulations on a virtual BEV yield a decrease in the cumulated energy consumptions during typical BEV operation, leading to an increase in the achievable mileage.
PubDate: Mon, 26 Aug 2013 08:29:19 +000
- The Front Seat Passenger: How to Transfer Qualitative Findings into Design
Abstract: While the field of automotive HCI research abounds in driver-focused design and studies of driver distraction, relatively little attention has been directed to the front seat passengers. A challenge for designers and researchers is the ideation through exploration of passenger experiences and needs and the question of how to integrate them in design solutions. In this paper, we ground an ideation exercise based on results of a probing study conducted at two petrol stations. A probing package for front seat passengers was designed and distributed in cooperation with a petrol station company. Approximately 700 customers were approached randomly and 90 probe packages were handed out. 30 probing packages were returned and a segment clustering and a qualitative analysis were performed. The results gave insights into the activities and needs of front seat passengers and were then used in a design workshop together with a group of industrial designers. A set of ideas for novel interface solutions for front seat passengers were developed such as the invisible engine (look through the motor block with a display-based camera system). We further discuss the challenges and shortcomings of how to interpret and express ideas when transferring qualitative research findings into design.
PubDate: Tue, 09 Jul 2013 09:20:59 +000
- Identification of Cognitive Distraction Using Physiological Features for
Adaptive Driving Safety Supporting System
Abstract: It was identified that traffic accidents relate closely to the driver’s mental and physical states immediately before the accident by our questionnaire survey. Distraction is one of the key human factors involved in traffic accidents. We reproduced driver’s cognitive distraction on a driving simulator by means of imposing cognitive loads such as doing arithmetic and having conversation while driving. Visual features such as test subjects’ gaze direction, pupil diameter, and head orientation, together with heart rate from ECG, were used in this study to detect the cognitive distraction. We improved detection accuracy obtained from earlier studies by using the AdaBoost. This paper also suggests a multiclass identification using Error-Correcting Output Coding, which can identify the degree of cognitive load. Finally, we verified the effectiveness of the multiclass identification by conducting a series of experiments. All these aimed at developing a constituent technology of a driver monitoring system that is expected to create adaptive driving safety supporting system to lower the number of traffic accidents.
PubDate: Mon, 08 Jul 2013 11:09:45 +000
- A Robust Fuzzy Sliding Mode Controller Synthesis Applied on Boost DC-DC
Converter Power Supply for Electric Vehicle Propulsion System
Abstract: The development of electric vehicles power electronics system control comprising of DC-AC inverters and DC-DC converters takes a great interest of researchers in the modern industry. A DC-AC inverter supplies the high power electric vehicle motors torques of the propulsion system and utility loads, whereas a DC-DC converter supplies conventional low-power, low-voltage loads. However, the need for high power bidirectional DC-DC converters in future electric vehicles has led to the development of many new topologies of DC-DC converters. Nonlinear control of power converters is an active area of research in the fields of power electronics. This paper focuses on a fuzzy sliding mode strategy (FSMS) as a control strategy for boost DC-DC converter power supply for electric vehicle. The proposed fuzzy controller specifies changes in the control signal based on the surface and the surface change knowledge to satisfy the sliding mode stability and attraction conditions. The performances of the proposed fuzzy sliding controller are compared to those obtained by a classical sliding mode controller. The satisfactory simulation results show the efficiency of the proposed control law which reduces the chattering phenomenon. Moreover, the obtained results prove the robustness of the proposed control law against variation of the load resistance and the input voltage of the studied converter.
PubDate: Thu, 23 May 2013 16:23:49 +000
- Multiple-Observation-Based Robust Channel and Doppler Estimation in High
Abstract: Channel estimation is a challenging task, especially in high mobility applications due to the rapid variation of the propagation environment. This paper presents a new technique that exploits past channel impulse responses (CIRs) in order to trace and compensate Doppler frequency in mobile applications, enabling robust estimation of time-varying channel. Based on the fact that channel taps at different time instants can be fitted with a sinusoidal wave, a joint estimator is proposed to estimate the channel parameters. Therefore, the efficiency of the channel estimation can be improved and stringent delay requirements for the communication systems can also be satisfied. Simulation results show that system performance in terms of bit error rate (BER) is significantly improved with the proposed algorithm.
PubDate: Mon, 13 May 2013 18:16:38 +000
- ICT Innovations in Future Smart Cars
PubDate: Mon, 13 May 2013 16:09:00 +000
- Performance Evaluation of IEEE 1609 WAVE for Vehicular Communications
Abstract: In IEEE 1609, it uses IEEE 802.11 Enhanced Distributed Channel Access (EDCA) mechanism to access the channel. IEEE 802.11 EDCA is a new wireless technology for wireless access in the vehicular environment (WAVE). It defines a new supplement to the existing IEEE 802.11 MAC protocol. In IEEE 802.11 EDCA, the aim is providing a QoS support. While the system serves different access categories (ACs), EDCA does not perform well under high load conditions. In order to improve the efficiency, we pay attention to the EDCA with transmit opportunity (TXOP) mechanism. We first proposed a Markov chain model and studied the behavior. We extend the model to support IEEE 802.11 EDCA and presented a more accurate analysis under nonideal channel environment. We also compared it with that without TXOP mechanism under channel error environment.
PubDate: Tue, 07 May 2013 10:37:48 +000
- Vehicle Yaw Rate Estimation Using a Virtual Sensor
Abstract: Road vehicle yaw stability control systems like electronic stability program (ESP) are important active safety systems used for maintaining lateral stability of the vehicle. Vehicle yaw rate is the key parameter that needs to be known by a yaw stability control system. In this paper, yaw rate is estimated using a virtual sensor which contains kinematic relations and a velocity-scheduled Kalman filter. Kinematic estimation is carried out using wheel speeds, dynamic tire radius, and front wheel steering angle. In addition, a velocity-scheduled Kalman filter utilizing the linearized single-track model of the road vehicle is used in the dynamic estimation part of the virtual sensor. The designed virtual sensor is successfully tested offline using a validated, high degrees of freedom, and high fidelity vehicle model and using hardware-in-the-loop simulations. Moreover, actual road testing is carried out and the estimated yaw rate from the virtual sensor is compared with the actual yaw rate obtained from the commercial yaw rate sensor to demonstrate the effectiveness of the virtual yaw rate sensor in practical use.
PubDate: Wed, 24 Apr 2013 14:43:45 +000