7,554 research outputs found
Spacecraft formation flying using bifurcating potential fields
The distributed control of spacecraft flying in formation has been shown to have advantages over conventional single spacecraft systems. These include scalability, flexibility and robustness to failures. This paper considers the real problem of actuator saturation and shows how bound control laws can be developed that allow pattern formation and reconfigurability in a formation of spacecraft using bifurcating potential fields. In addition the stability of the system is ensured mathematically through dynamical systems theory
Automated driving and autonomous functions on road vehicles
In recent years, road vehicle automation has become an important and popular topic for research
and development in both academic and industrial spheres. New developments received
extensive coverage in the popular press, and it may be said that the topic has captured the
public imagination. Indeed, the topic has generated interest across a wide range of academic,
industry and governmental communities, well beyond vehicle engineering; these include computer
science, transportation, urban planning, legal, social science and psychology. While this
follows a similar surge of interest – and subsequent hiatus – of Automated Highway Systems
in the 1990’s, the current level of interest is substantially greater, and current expectations
are high. It is common to frame the new technologies under the banner of “self-driving cars”
– robotic systems potentially taking over the entire role of the human driver, a capability that
does not fully exist at present. However, this single vision leads one to ignore the existing
range of automated systems that are both feasible and useful. Recent developments are underpinned
by substantial and long-term trends in “computerisation” of the automobile, with
developments in sensors, actuators and control technologies to spur the new developments in
both industry and academia. In this paper we review the evolution of the intelligent vehicle
and the supporting technologies with a focus on the progress and key challenges for vehicle
system dynamics. A number of relevant themes around driving automation are explored in
this article, with special focus on those most relevant to the underlying vehicle system dynamics.
One conclusion is that increased precision is needed in sensing and controlling vehicle
motions, a trend that can mimic that of the aerospace industry, and similarly benefit from
increased use of redundant by-wire actuators
DFCV: A Novel Approach for Message Dissemination in Connected Vehicles using Dynamic Fog
Vehicular Ad-hoc Network (VANET) has emerged as a promising solution for
enhancing road safety. Routing of messages in VANET is challenging due to
packet delays arising from high mobility of vehicles, frequently changing
topology, and high density of vehicles, leading to frequent route breakages and
packet losses. Previous researchers have used either mobility in vehicular fog
computing or cloud computing to solve the routing issue, but they suffer from
large packet delays and frequent packet losses. We propose Dynamic Fog for
Connected Vehicles (DFCV), a fog computing based scheme which dynamically
creates, increments and destroys fog nodes depending on the communication
needs. The novelty of DFCV lies in providing lower delays and guaranteed
message delivery at high vehicular densities. Simulations were conducted using
hybrid simulation consisting of ns-2, SUMO, and Cloudsim. Results show that
DFCV ensures efficient resource utilization, lower packet delays and losses at
high vehicle densities
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