115,049 research outputs found
Movers and Shakers: Kinetic Energy Harvesting for the Internet of Things
Numerous energy harvesting wireless devices that will serve as building
blocks for the Internet of Things (IoT) are currently under development.
However, there is still only limited understanding of the properties of various
energy sources and their impact on energy harvesting adaptive algorithms.
Hence, we focus on characterizing the kinetic (motion) energy that can be
harvested by a wireless node with an IoT form factor and on developing energy
allocation algorithms for such nodes. In this paper, we describe methods for
estimating harvested energy from acceleration traces. To characterize the
energy availability associated with specific human activities (e.g., relaxing,
walking, cycling), we analyze a motion dataset with over 40 participants. Based
on acceleration measurements that we collected for over 200 hours, we study
energy generation processes associated with day-long human routines. We also
briefly summarize our experiments with moving objects. We develop energy
allocation algorithms that take into account practical IoT node design
considerations, and evaluate the algorithms using the collected measurements.
Our observations provide insights into the design of motion energy harvesters,
IoT nodes, and energy harvesting adaptive algorithms.Comment: 15 pages, 11 figure
Motion Detecting Method And Device
In some embodiments, a motion detecting device is configured to detect whether one or more movement events have occurred. The motion detecting device can include: (a) a processing module configured to run on a computational unit; and (b) a sensing device having: (1) one or more pressure sensors configured to provide two or more pressure measurements; and (2) a transmitter electrically coupled to the one or more pressure sensors and configured to transmit the two or more pressure measurements to the computational unit. The processing module is configured to use the two or more pressure measurements to determine whether the one or more movement events have occurred. The sensing device can be configured to be placed in at least one of ductwork of a heating, ventilation, and air conditioning system or an air handler of the heating, ventilation, and air conditioning system. Other embodiments are disclosed.Georgia Tech Research Corporatio
Shear-invariant Sliding Contact Perception with a Soft Tactile Sensor
Manipulation tasks often require robots to be continuously in contact with an
object. Therefore tactile perception systems need to handle continuous contact
data. Shear deformation causes the tactile sensor to output path-dependent
readings in contrast to discrete contact readings. As such, in some
continuous-contact tasks, sliding can be regarded as a disturbance over the
sensor signal. Here we present a shear-invariant perception method based on
principal component analysis (PCA) which outputs the required information about
the environment despite sliding motion. A compliant tactile sensor (the TacTip)
is used to investigate continuous tactile contact. First, we evaluate the
method offline using test data collected whilst the sensor slides over an edge.
Then, the method is used within a contour-following task applied to 6 objects
with varying curvatures; all contours are successfully traced. The method
demonstrates generalisation capabilities and could underlie a more
sophisticated controller for challenging manipulation or exploration tasks in
unstructured environments. A video showing the work described in the paper can
be found at https://youtu.be/wrTM61-pieUComment: Accepted in ICRA 201
Variable Powder Flow Rate Control in Laser Metal Deposition Processes
This paper proposes a novel technique, called Variable Powder Flow Rate Control (VPFRC), for
the regulation of powder flow rate in laser metal deposition processes. The idea of VPFRC is to
adjust the powder flow rate to maintain a uniform powder deposition per unit length even when
disturbances occur (e.g., the motion system accelerates and decelerates). Dynamic models of the
powder delivery system motor and the powder transport system (i.e., five–meter pipe, powder
dispenser, and cladding head) are first constructed. A general tracking controller is then designed
to track variable powder flow rate references. Since the powder flow rate at the nozzle exit
cannot be directly measured, it is estimated using the powder transport system model. The input
to this model is the DC motor rotation speed, which is estimated on–line using a Kalman filter.
Experiments are conducted to examine the performance of the proposed control methodology.
The experimental results demonstrate that VPFRC is successful in maintaining a uniform track
morphology, even when the motion control system accelerates and decelerates.Mechanical Engineerin
Multimode laser cooling and ultra-high sensitivity force sensing with nanowires
Photo-induced forces can be used to manipulate and cool the mechanical motion
of oscillators. When the oscillator is used as a force sensor, such as in
atomic force microscopy, active feedback is an enticing route to enhancing
measurement performance. Here, we show broadband multimode cooling of dB
down to a temperature of ~K in the stationary regime. Through the use
of periodic quiescence feedback cooling, we show improved signal-to-noise
ratios for the measurement of transient signals. We compare the performance of
real feedback to numerical post-processing of data and show that both methods
produce similar improvements to the signal-to-noise ratio of force
measurements. We achieved a room temperature force measurement sensitivity of
N with integration time of less than ms. The high
precision and fast force microscopy results presented will potentially benefit
applications in biosensing, molecular metrology, subsurface imaging and
accelerometry.Comment: 16 pages and 3 figures for the main text, 14 pages and 5 figures for
the supplementary informatio
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