Vehicle dynamics

About: Vehicle dynamics is a research topic. Over the lifetime, 12909 publications have been published within this topic receiving 204091 citations.

Distributed coordinated tracking via a variable structure approach - part I: Consensus tracking

Abstract: This is the first part of a two-part paper on distributed coordinated tracking for a group of autonomous vehicles via a variable structure approach. Here, the term coordinated tracking is used to refer to both consensus tracking and swarm tracking. In the first part of this paper, we focus on the consensus tracking problem where a group of autonomous vehicles can track a (time-varying) virtual leader when the state of the virtual leader is available to only a subset of the group of vehicles. In the case of first-order kinematics, we propose a distributed consensus tracking algorithm without velocity measurements under both fixed and switching network topologies. In particular, we show that distributed consensus tracking can be achieved in finite time. In the case of second-order dynamics, we propose two distributed consensus tracking algorithms without acceleration measurements under, respectively, a fixed and switching network topology. In particular, we show that the proposed algorithms guarantee at least global exponential tracking. For distributed consensus tracking in the case of both first-order kinematics and second-order dynamics, a mild connectivity requirement is proposed by adopting a connectivity maintenance mechanism in which the adjacency matrix is defined in a proper way.

EMBARC: error model based adaptive rate control for vehicle-to-vehicle communications

Abstract: Channel congestion is one of the major challenges for deployment of collision avoidance systems based on DSRC (Dedicated Short Range Communication) in large scale networks. If vehicles do not adapt to congestion conditions, DSRC transmissions could encounter extensive packet losses in areas of high vehicle density, leading to degradation in the performance of safety applications. In this paper, we propose a novel congestion control algorithm called Error Model Based Adaptive Rate Control (EMBARC) which adapts a vehicle's transmission rate as a function of channel load and vehicular dynamics. In particular, we extend Linear Integrated Message Rate Control (LIMERIC) algorithm's message rate adaptation with the capability to preemptively schedule messages based on the vehicle's movement. This leads to more transmission opportunities for vehicles with higher dynamics. The determination of a preemptive scheduling event is based on a novel suspected tracking error technique. Since LIMERIC maintains the channel load around a specific value, vehicles moving less dynamically will adapt to slightly reduced transmission rates in EMBARC. The extra transmit opportunities for highly dynamic vehicles reduce incidences of large tracking error compared to a pure LIMERIC approach. At the same time, EMBARC's use of adaptive rate control provides tracking error advantages over systems that transmit largely independent of channel load. We use simulations of a road with a winding segment to compare EMBARC with algorithms that do not take both channel load and vehicle dynamics into account. The results show that EMBARC has the best tracking accuracy among these algorithms over a wide range of node densities.

Stochastic model and connectivity dynamics for VANETs in signalized road systems

Abstract: The space and time dynamics of moving vehicles regulated by traffic signals governs the node connectivity and communication capability of vehicular ad hoc networks (VANETs) in urban environments. However, none of the previous studies on node connectivity has considered such dynamics with the presence of traffic lights and vehicle interactions. In fact, most of them assume that vehicles are distributed homogeneously throughout the geographic area, which is unrealistic. We introduce in this paper a stochastic traffic model for VANETs in signalized urban road systems. The proposed model is a composite of the fluid model and stochastic model. The former characterizes the general flow and evolution of the traffic stream so that the average density of vehicles is readily computable, while the latter takes into account the random behavior of individual vehicles. As the key contribution of this paper, we attempt to approximate vehicle interactions and capture platoon formations and dissipations at traffic signals through a density-dependent velocity profile. The stochastic traffic model with approximation of vehicle interactions is evaluated with extensive simulations, and the distributional result of the model is validated against real-world empirical data in London. In general, we show that the fluid model can adequately describe the mean behavior of the traffic stream, while the stochastic model can approximate the probability distribution well even when vehicles interact with each other as their movement is controlled by traffic lights. With the knowledge of the mean vehicular density dynamics and its probability distribution from the stochastic traffic model, we determine the degree of connectivity in the communication network and illustrate that system engineering and planning for optimizing both the transport (in terms of congestion) and communication networks (in terms of connectivity) can be carried out with the proposed model.

User-appropriate tyre-modelling for vehicle dynamics in standard and limit situations

Abstract: Summary When modelling vehicles for the vehicle dynamic simulation, special attention must be paid to the modelling of tyre-forces and -torques, according to their dominant influence on the results. This task is not only about sufficiently exact representation of the effective forces but also about user-friendly and practical relevant applicability, especially when the experimental tyre-input-data is incomplete or missing. This text firstly describes the basics of the vehicle dynamic tyre model, conceived to be a physically based, semi-empirical model for application in connection with multi-body-systems (MBS). On the basis of tyres for a passenger car and a heavy truck the simulated steady state tyre characteristics are shown together and compared with the underlying experimental values. In the following text the possibility to link the tyre model TMeasy to any MBS-program is described, as far as it supports the ‘Standard Tyre Interface’ (STI). As an example, the simulated and experimental data of a heav...