2,535 research outputs found
Computational intelligence approaches to robotics, automation, and control [Volume guest editors]
No abstract available
Past, Present, and Future of Simultaneous Localization And Mapping: Towards the Robust-Perception Age
Simultaneous Localization and Mapping (SLAM)consists in the concurrent
construction of a model of the environment (the map), and the estimation of the
state of the robot moving within it. The SLAM community has made astonishing
progress over the last 30 years, enabling large-scale real-world applications,
and witnessing a steady transition of this technology to industry. We survey
the current state of SLAM. We start by presenting what is now the de-facto
standard formulation for SLAM. We then review related work, covering a broad
set of topics including robustness and scalability in long-term mapping, metric
and semantic representations for mapping, theoretical performance guarantees,
active SLAM and exploration, and other new frontiers. This paper simultaneously
serves as a position paper and tutorial to those who are users of SLAM. By
looking at the published research with a critical eye, we delineate open
challenges and new research issues, that still deserve careful scientific
investigation. The paper also contains the authors' take on two questions that
often animate discussions during robotics conferences: Do robots need SLAM? and
Is SLAM solved
Development of bent-up triangular tab shear transfer (BTTST) enhancement in cold-formed steel (CFS)-concrete composite beams
Cold-formed steel (CFS) sections, have been recognised as an important
contributor to environmentally responsible and sustainable structures in developed
countries, and CFS framing is considered as a sustainable 'green' construction material
for low rise residential and commercial buildings. However, there is still lacking of data
and information on the behaviour and performance of CFS beam in composite
construction. The use of CFS has been limited to structural roof trusses and a host of nonstructural applications. One of the limiting features of CFS is the thinness of its section
(usually between 1.2 and 3.2 mm thick) that makes it susceptible to torsional,
distortional, lateral-torsional, lateral-distortional and local buckling. Hence, a reasonable
solution is resorting to a composite construction of structural CFS section and reinforced
concrete deck slab, which minimises the distance from the neutral-axis to the top of the
deck and reduces the compressive bending stress in the CFS sections. Also, by arranging
two CFS channel sections back-to-back restores symmetricity and suppresses lateraltorsional and to a lesser extent, lateral-distortional buckling. The two-fold advantages
promised by the system, promote the use of CFS sections in a wider range of structural
applications. An efficient and innovative floor system of built-up CFS sections acting
compositely with a concrete deck slab was developed to provide an alternative composite
system for floors and roofs in buildings. The system, called Precast Cold-Formed SteelConcrete Composite System, is designed to rely on composite actions between the CFS
sections and a reinforced concrete deck where shear forces between them are effectively
transmitted via another innovative shear transfer enhancement mechanism called a bentup triangular tab shear transfer (BTTST). The study mainly comprises two major
components, i.e. experimental and theoretical work. Experimental work involved smallscale and large-scale testing of laboratory tests. Sixty eight push-out test specimens and
fifteen large-scale CFS-concrete composite beams specimens were tested in this program.
In the small-scale test, a push-out test was carried out to determine the strength and
behaviour of the shear transfer enhancement between the CFS and concrete. Four major
parameters were studied, which include compressive strength of concrete, CFS strength,
dimensions (size and angle) of BTTST and CFS thickness. The results from push-out test
were used to develop an expression in order to predict the shear capacity of innovative
shear transfer enhancement mechanism, BTTST in CFS-concrete composite beams. The
value of shear capacity was used to calculate the theoretical moment capacity of CFSconcrete composite beams. The theoretical moment capacities were used to validate the
large-scale test results. The large-scale test specimens were tested by using four-point
load bending test. The results in push-out tests show that specimens employed with
BTTST achieved higher shear capacities compared to those that rely only on a natural
bond between cold-formed steel and concrete and specimens with Lakkavalli and Liu
bent-up tab (LYLB). Load capacities for push-out test specimens with BTTST are
ii
relatively higher as compared to the equivalent control specimen, i.e. by 91% to 135%.
When compared to LYLB specimens the increment is 12% to 16%. In addition, shear
capacities of BTTST also increase with the increase in dimensions (size and angle) of
BTTST, thickness of CFS and concrete compressive strength. An equation was
developed to determine the shear capacity of BTTST and the value is in good agreement
with the observed test values. The average absolute difference between the test values
and predicted values was found to be 8.07%. The average arithmetic mean of the
test/predicted ratio (n) of this equation is 0.9954. The standard deviation (a) and the
coefficient of variation (CV) for the proposed equation were 0.09682 and 9.7%,
respectively. The proposed equation is recommended for the design of BTTST in CFSconcrete composite beams. In large-scale testing, specimens employed with BTTST
increased the strength capacities and reduced the deflection of the specimens. The
moment capacities, MU ) e X p for all specimens are above Mu>theory and show good agreement
with the calculated ratio (>1.00). It is also found that, strength capacities of CFS-concrete
composite beams also increase with the increase in dimensions (size and angle) of
BTTST, thickness of CFS and concrete compressive strength and a CFS-concrete
composite beam are practically designed with partial shear connection for equal moment
capacity by reducing number of BTTST. It is concluded that the proposed BTTST shear
transfer enhancement in CFS-concrete composite beams has sufficient strength and is
also feasible. Finally, a standard table of characteristic resistance, P t a b of BTTST in
normal weight concrete, was also developed to simplify the design calculation of CFSconcrete composite beams
- …