Due to hundreds of fatalities annually at unprotected railroad crossings (mostly because of collisions with passenger
vehicles and derailments resulting from improperly maintained tracks and mechanical failures), supplying a reliable
source of electrical energy to power crossing lights and distributed sensor networks is essential to improve safety. With
regard to the high cost of electrical infrastructure for railroad crossings in remote areas and the lack of reliability and
robustness of solar and wind energy solutions, development of alternative energy harvesting devices is of interest. In this
paper, improvements to a mechanical energy harvesting device are presented. The device scavenges electrical energy
from deflection of railroad track due to passing railcar traffic. It is mounted to and spans two rail ties and converts and
magnifies the track's entire upward and downward displacement into rotational motion of a PMDC generator. The
major improvements to the new prototype include: harvesting power from upward displacement in addition to
downward, changing the gearing and generator in order to maximize power production capacity for the same shaft speed,
and improving the way the system is stabilized for minimizing lost motion. The improved prototype was built, and
simulations and tests were conducted to quantify the effects of the improvements.
KEYWORDS: Prototyping, Control systems, Control systems design, Wind energy, Computer simulations, Energy harvesting, Device simulation, Resistance, Sensor networks, Resistors
With the vastness of existing railroad infrastructure, there exist numerous road crossings which are lacking warning
light systems and/or crossing gates due to their remoteness from existing electrical infrastructure. Along with
lacking warning light systems, these areas also tend to lack distributed sensor networks used for railroad track health
monitoring applications. With the power consumption required by these systems being minimal, extending electrical
infrastructure into these areas would not be an economical use of resources. This motivated the development of an
energy harvesting solution for remote railroad deployment. This paper describes a computer simulation created to
validate experimental on-track results for different mechanical prototypes designed for harvesting mechanical power
from passing railcar traffic. Using the Winkler model for beam deflection as its basis, the simulation determines the
maximum power potential for each type of prototype for various railcar loads and speeds. Along with calculating the
maximum power potential of a single device, the simulation also calculates the optimal number and position of the
devices needed to power a standard railroad crossing light signal. A control system was also designed to regulate
power to a battery, monitor and record power production, and make adjustments to the duty cycle of the crossing
lights accordingly. On-track test results are compared and contrasted with results from the simulation, discrepancies
between the two are examined and explained, and conclusions are drawn regarding suitability of the device for
powering high-efficiency LED lights at railroad crossings and powering track-health sensor networks.
A considerable proportion of railroad infrastructure exists in regions which are comparatively remote. With regard to the
cost of extending electrical infrastructure into these areas, road crossings in these areas do not have warning light
systems or crossing gates and are commonly marked with reflective signage. For railroad track health monitoring
purposes, distributed sensor networks can be applicable in remote areas, but the same limitation regarding electrical
infrastructure is the hindrance. This motivated the development of an energy harvesting solution for remote railroad
deployment. This paper describes on-track experimental testing of a mechanical device for harvesting mechanical power
from passing railcar traffic, in view of supplying electrical power to warning light systems at crossings and to remote
networks of sensors. The device is mounted to and spans two rail ties and transforms the vertical rail displacement into
electrical energy through mechanical amplification and rectification into a PMDC generator. A prototype was tested
under loaded and unloaded railcar traffic at low speeds. Stress analysis and speed scaling analysis are presented, results
of the on-track tests are compared and contrasted to previous laboratory testing, discrepancies between the two are
explained, and conclusions are drawn regarding suitability of the device for illuminating high-efficiency LED lights at railroad crossings and powering track-health sensor networks.
A significant portion of railroad infrastructure exists in areas that are relatively remote. Railroad crossings in these areas
are typically only marked with reflective signage and do not have warning light systems or crossbars due to the cost of
electrical infrastructure. Distributed sensor networks used for railroad track health monitoring applications would be
useful in these areas, but the same limitation regarding electrical infrastructure exists. This motivates the search for a
long-term, low-maintenance power supply solution for remote railroad deployment. This paper describes the
development of a mechanical device for harvesting mechanical power from passing railcar traffic that can be used to
supply electrical power to warning light systems at crossings and to remote networks of sensors via rechargeable
batteries. The device is mounted to and spans two rail ties such that it directly harnesses the vertical displacement of the
rail and attached ties and translates the linear motion into rotational motion. The rotational motion is amplified and
mechanically rectified to rotate a PMDC generator that charges a system of batteries. A prototype was built and tested in
a laboratory setting for verifying functionality of the design. Results indicate power production capabilities on the order
of 10 W per device in its current form. This is sufficient for illuminating high-efficiency LED lights at a railroad
crossing or for powering track-health sensor networks.
One of the most limiting factors for distributed sensor networks used for railroad track health monitoring applications is
the lack of a long-term, low-maintenance power supply. Most existing systems still require a change of battery, and
remoteness of location and low frequency of maintenance can limit their practical deployment. In this paper we describe
an investigation of two principal methods for harvesting mechanical power from passing railcars in order to supply
electrical power to remote networks of sensors. We first considered an inductive voice coil device directly driven by
vertical rail displacement. We then considered a piezoelectric device that is attached to the bottom of the rail and is
driven by the longitudinal strain produced by rail bending due to passing railcars. Theoretical models of the behavior of
these devices were integrated with an analytical model of rail track deflection to perform numerical simulations of both
of these power scavenging techniques. Lab and field tests were also performed to validate the simulation results.
Resulting values of average power production show promise for scavenging near the targeted level of 1 mW, and the
field data matched well with the simulations.
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