15,500 research outputs found
Belief State Planning for Autonomously Navigating Urban Intersections
Urban intersections represent a complex environment for autonomous vehicles
with many sources of uncertainty. The vehicle must plan in a stochastic
environment with potentially rapid changes in driver behavior. Providing an
efficient strategy to navigate through urban intersections is a difficult task.
This paper frames the problem of navigating unsignalized intersections as a
partially observable Markov decision process (POMDP) and solves it using a
Monte Carlo sampling method. Empirical results in simulation show that the
resulting policy outperforms a threshold-based heuristic strategy on several
relevant metrics that measure both safety and efficiency.Comment: 6 pages, 6 figures, accepted to IV201
Analisis dan penilaian prestasi lengah lepas tangan menggunakan protokol pencetusan sesi (SIP) bagi sistem terintegrasi UMTS-WLAN
Teknologi rangkaian tanpa vvayar 4G merupakan penggabungan beberapa teknologi
rangkaian capaian yang berbeza seperti rangkaian Universal Mobile
Telecommunication System (UMTS) dan Rangkaian Kawasan Setempat Tanpa Wayar
(WLAN). Rangkaian 4G menyokong mobiliti tanpa kelim {seamless) dalam
menjanjikan perhubungan dan perkhidmatan yang terbaik kepada pelanggan. Protokol
Pencetusan Sesi (SIP) yang berada pada lapisan aplikasi telah diramalkan sebagai
calon terbaik bagi menguruskan mobiliti di dalam rangkaian 4G. Rangkaian 4G yang
menawarkan aplikasi multimedia dalam perkhidmatannya mesti mempunyai lengah
lepas tangan yang rendah bagi mencapai objektif penubuhannya. Tujuan utama
disertasi ini adalah untuk menilai lengah lepas tangan bagi sistem terintegrasi UMTSWLAN
yang menggunakan SIP sebagai protokol pengisyaratan. Model simulasi
menggunakan MATLAB dibangunkan untuk menilai prestasi lengah lepas tangan
tersebut. Model simulasi menggambarkan pergerakan hos mobil ke rangkaian UMTS
dan WLAN. Lengah lepas tangan yang berlaku diukur berdasarkan model analitik.
Prestasi lengah lepas tangan dinilai berdasarkan perubahan kadar ralat kerangka
(FER), kadar ketibaan sesi SIP dan halaju hos mobil (MIT) semasa MH bergerak ke
rangkaian UMTS dan WLAN. Keputusan simulasi menunjukkan bahawa lengah lepas
tangan meningkat dengan penambahan FER dan kadar ketibaan sesi SIP. Halaju
kebolehgerakan pengguna memberi kesan terhadap nilai lengah lepas tangan.
Keputusan juga menunjukkan lengah lepas tangan minimum yang berlaku sewaktu
MH bergerak ke rangkaian UMTS adalah 1.9565 saat dengan lebar jalur saluran
128kbps dan ke rangkaian WLAN adalah sekitar 0.8651 saat dengan lebar jalur
saluran 11 Mbps. Berdasarkan nilai ini, lengah lepas tangan semasa MH bergerak ke
rangkaian UMTS atau WLAN adalah tidak boleh diterima untuk penjurusan
multimedia. Di dalam kajian ini didapati capaian tanpa wayar GPRS menyumbang
lengah terbesar daripada keseluruhan lengah lepas tangan ke rangkaian UMTS
Functional Verification of Power Electronic Systems
This project is the final work of the degree in Industrial Electronics and
Automatic Engineering. It has global concepts of electronics but it focuses
in power electronic systems.
There is a need for reliable testing systems to ensure the good functionality of power electronic systems. The constant evolution of this products
requires the development of new testing techniques. This project aims to develop a new testing system to accomplish the functional verification of a new
power electronic system manufactured on a company that is in the power
electronic sector . This test system consists on two test bed platforms, one
to test the control part of the systems and the other one to test their functionality. A software to perform the test is also designed. Finally, the testing
protocol is presented.
This design is validated and then implemented on a buck converter and
an inverter that are manufactured at the company. The results show that
the test system is reliable and is capable of testing the functional verification
of the two power electronic system successfully.
In summary, this design can be introduced in the power electronic production process to test the two products ensuring their reliability in the
market
Using acoustic sensor technologies to create a more terrain capable unmanned ground vehicle
Unmanned Ground Vehicle’s (UGV) have to cope with the most complex range of dynamic and variable obstacles and therefore need to be highly intelligent in order to cope with navigating in such a cluttered environment. When traversing over different terrains (whether it is a UGV or a commercial manned vehicle) different drive styles and configuration settings need to be selected in order to travel successfully over each terrain type. These settings are usually selected by a human operator in manned systems on what they assume the ground conditions to be, but how can an autonomous UGV ‘sense’ these changes in terrain or ground conditions? This paper will investigate noncontact acoustic sensor technologies and how they can be used to detect different terrain types by listening to the interaction between the wheel and the terrain. The results can then be used to create a terrain classification list for the system so in future missions it can use the sensor technology to identify the terrain type it is trying to traverse, which creating a more autonomous and terrain capable vehicle. The technology would also benefit commercial driver assistive technologie
Connecting the World of Embedded Mobiles: The RIOT Approach to Ubiquitous Networking for the Internet of Things
The Internet of Things (IoT) is rapidly evolving based on low-power compliant
protocol standards that extend the Internet into the embedded world. Pioneering
implementations have proven it is feasible to inter-network very constrained
devices, but had to rely on peculiar cross-layered designs and offer a
minimalistic set of features. In the long run, however, professional use and
massive deployment of IoT devices require full-featured, cleanly composed, and
flexible network stacks.
This paper introduces the networking architecture that turns RIOT into a
powerful IoT system, to enable low-power wireless scenarios. RIOT networking
offers (i) a modular architecture with generic interfaces for plugging in
drivers, protocols, or entire stacks, (ii) support for multiple heterogeneous
interfaces and stacks that can concurrently operate, and (iii) GNRC, its
cleanly layered, recursively composed default network stack. We contribute an
in-depth analysis of the communication performance and resource efficiency of
RIOT, both on a micro-benchmarking level as well as by comparing IoT
communication across different platforms. Our findings show that, though it is
based on significantly different design trade-offs, the networking subsystem of
RIOT achieves a performance equivalent to that of Contiki and TinyOS, the two
operating systems which pioneered IoT software platforms
Exoskeleton master controller with force-reflecting telepresence
A thorough understanding of the requirements for successful master-slave robotic systems is becoming increasingly desirable. Such systems can aid in the accomplishment of tasks that are hazardous or inaccessible to humans. Although a history of use has proven master-slave systems to be viable, system requirements and the impact of specifications on the human factors side of system performance are not well known. In support of the next phase of teleoperation research being conducted at the Armstrong Research Laboratory, a force-reflecting, seven degree of freedom exoskeleton for master-slave teleoperation has been concepted, and is presently being developed. The exoskeleton has a unique kinematic structure that complements the structure of the human arm. It provides a natural means for teleoperating a dexterous, possibly redundant manipulator. It allows ease of use without operator fatigue and faithfully follows human arm and wrist motions. Reflected forces and moments are remotely transmitted to the operator hand grip using a cable transmission scheme. This paper presents the exoskeleton concept and development results to date. Conceptual design, hardware, algorithms, computer architecture, and software are covered
ACon: A learning-based approach to deal with uncertainty in contextual requirements at runtime
Context: Runtime uncertainty such as unpredictable operational environment and failure of sensors that gather environmental data is a well-known challenge for adaptive systems.
Objective: To execute requirements that depend on context correctly, the system needs up-to-date knowledge about the context relevant to such requirements. Techniques to cope with uncertainty in contextual requirements are currently underrepresented. In this paper we present ACon (Adaptation of Contextual requirements), a data-mining approach to deal with runtime uncertainty affecting contextual requirements.
Method: ACon uses feedback loops to maintain up-to-date knowledge about contextual requirements based on current context information in which contextual requirements are valid at runtime. Upon detecting that contextual requirements are affected by runtime uncertainty, ACon analyses and mines contextual data, to (re-)operationalize context and therefore update the information about contextual requirements.
Results: We evaluate ACon in an empirical study of an activity scheduling system used by a crew of 4 rowers in a wild and unpredictable environment using a complex monitoring infrastructure. Our study focused on evaluating the data mining part of ACon and analysed the sensor data collected onboard from 46 sensors and 90,748 measurements per sensor.
Conclusion: ACon is an important step in dealing with uncertainty affecting contextual requirements at runtime while considering end-user interaction. ACon supports systems in analysing the environment to adapt contextual requirements and complements existing requirements monitoring approaches by keeping the requirements monitoring specification up-to-date. Consequently, it avoids manual analysis that is usually costly in today’s complex system environments.Peer ReviewedPostprint (author's final draft
A City-Scale ITS-G5 Network for Next-Generation Intelligent Transportation Systems: Design Insights and Challenges
As we move towards autonomous vehicles, a reliable Vehicle-to-Everything
(V2X) communication framework becomes of paramount importance. In this paper we
present the development and the performance evaluation of a real-world
vehicular networking testbed. Our testbed, deployed in the heart of the City of
Bristol, UK, is able to exchange sensor data in a V2X manner. We will describe
the testbed architecture and its operational modes. Then, we will provide some
insight pertaining the firmware operating on the network devices. The system
performance has been evaluated under a series of large-scale field trials,
which have proven how our solution represents a low-cost high-quality framework
for V2X communications. Our system managed to achieve high packet delivery
ratios under different scenarios (urban, rural, highway) and for different
locations around the city. We have also identified the instability of the
packet transmission rate while using single-core devices, and we present some
future directions that will address that.Comment: Accepted for publication to AdHoc-Now 201
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