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Journal ArticleDOI

A Method of Speed Control during Over-Ground Walking: Using a Digital Light-Emitting Diode Light Strip

01 Jul 2013-Advanced Materials Research (Trans Tech Publications)-pp 1371-1376
TL;DR: In this paper, a portable, inexpensive and programmable digital light-emitting diode (LED) system was introduced to control overground walking speed, which includes a custom-made 10 meters digital LED strip and a digital microcontroller.
Abstract: The purpose of this report was to introduce the design of a portable, inexpensive and programmable digital light-emitting diode (LED) system to control overground walking speed. The system includes a custom-made 10 meters digital LED strip and a digital microcontroller. By controlling the duration time of the power supply to each LED unit, a visible running lights signal can provide a visual cue for speed control. To evaluate this design, five subjects were asked to walk overground while following the LED visual cue at five different target speeds. The actual walking speeds were determined using Vicon motion capture system. The results of this evaluation showed a good match between the actual and desired speeds. The average percent difference was 2.51%, measured over 250 walking trials by the subjects. 98% of trials had an percent difference smaller than 6.5%, which is the maximum tolerated error within the literature. The inter-trial reliability for the LED speed control system ranged from 0.85 to 0.88 for faster speeds (1.6 m/s, 1.4 m/s), and slightly lower ranging from 0.74 to 0.79 at slower speeds (1.2 m/s, 1.0 m/s, 0.8 m/s).

Summary (1 min read)

Jump to: [Introduction][Results] and [Discussion]

Introduction

  • Walking speed is a very important parameter in gait analysis, which affects the magnitude of various kinematic and kinetic measures during walking.
  • Most treadmills are not equipped with embedded force plates, and ground reaction forces are not able to be collected.
  • The major disadvantage of these methods is that the participants’ do not have a clear visual guide during walking, so more practice trials are needed to help them adjust their speed to match the target.
  • By this way, the LED units are turning on quickly, one after another (Fig.2), creating a “running” effect by which the visual target (illuminated LED units) appears to move along the LED strip.
  • The timing of each heel strike was obtained from the forceplate data.

Results

  • The average measured speed and percent difference values for each subject are shown in Table 1.
  • A statistically significant difference in measured percent difference was only seen between the 0.8m/s group and 1.2m/s group (p=0.011).
  • Speeds (means ± SD), performing 10 walks for each speed.

Discussion

  • The LED system appears to be effective for speed control.
  • Based on the literature, two criteria have been proposed to assess the validity of walking speed based on error, the first being less that 3% [6], and the other less than 6.5% error is considered valid [5].
  • The result shows that compared to existing speed control system, the LED system has similar performance in terms of reliability and validity.
  • This is a potential issue that could affect the gait.
  • Because of its flexibility and portability, the LED strip system is easy to be elevated and supported by several rock stands, and the height is also adjustable.

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Content maybe subject to copyright    Report

A Method of Speed Control during Over-ground Walking: Using a Digital
Light-Emitting Diode Light Strip
Liang Huang
1,a
, Jie Zhuang
2,b
and Yanxin Zhang
1,c
1
Department of Sport & Exercise Science, the University of Auckland, New Zealand
2
School of kinesiology, Shanghai University of Sport, China
a
liang.huang@auckland.ac.nz,
b
zhuangjiesh@163.com,
c
yanxin.zhang@auckland.ac.nz
Keywords: Overground walking, LED, Gait analysis, Light strip, Microchip, PWM
Abstract. The purpose of this report was to introduce the design of a portable, inexpensive and
programmable digital light-emitting diode (LED) system to control overground walking speed. The
system includes a custom-made 10 meters digital LED strip and a digital microcontroller. By
controlling the duration time of the power supply to each LED unit, a visible running lights signal can
provide a visual cue for speed control. To evaluate this design, five subjects were asked to walk
overground while following the LED visual cue at five different target speeds. The actual walking
speeds were determined using Vicon motion capture system. The results of this evaluation showed a
good match between the actual and desired speeds. The average percent difference was 2.51%,
measured over 250 walking trials by the subjects. 98% of trials had an percent difference smaller than
6.5%, which is the maximum tolerated error within the literature. The inter-trial reliability for the
LED speed control system ranged from 0.85 to 0.88 for faster speeds (1.6 m/s, 1.4 m/s), and slightly
lower ranging from 0.74 to 0.79 at slower speeds (1.2 m/s, 1.0 m/s, 0.8 m/s).
Introduction
Walking speed is a very important parameter in gait analysis, which affects the magnitude of various
kinematic and kinetic measures during walking. There are various methods have been used for speed
control. The most direct way is by using a motor driven treadmill for which the speed is adjustable.
However, most treadmills are not equipped with embedded force plates, and ground reaction forces
are not able to be collected. Although force-plate-integrated treadmills are commercially available,
the cost of this type of treadmill is very high [1]. Moreover, it was reported that biomechanical
differences exist between treadmill and overground walking [2].
For overground walking, the speed is usually controlled by several photocells or timing lights
positioned along the walkway [3, 4]. The average speed is calculated after each trial. The major
disadvantage of these methods is that the participants’ do not have a clear visual guide during
walking, so more practice trials are needed to help them adjust their speed to match the target. Some
other studies have asked subjects to walk at a wide range of speeds and only the trials that were closest
(≈3%-6.5% errors) to the desired speed were chosen [5, 6]. In a recent report, Espy [7] provided the
subjects with a visible velocity target to follow during level walking. The target was a flag being
driven at a constant velocity by a motor running parallel to walkway. The results showed that the
velocity of walking was successfully manipulated. The disadvantages of this system are its low
mobility and relative complexity.
There is a need to develop a portable, inexpensive speed control system. The purpose of this report
was to introduce the design of a speed-adjustable and programmable digital light-emitting diode
(LED) light system, which can be used to control subjects’ speed during overground walking. The
reliability and accuracy of this equipment was also analyzed by comparing desired speeds and actual
walking speeds measured using motion capture system.
Advanced Materials Research Vols. 718-720 (2013) pp 1371-1376
© (2013) Trans Tech Publications, Switzerland
doi:10.4028/www.scientific.net/AMR.718-720.1371
All rights reserved. No part of contents of this paper may be reproduced or transmitted in any form or by any means without the written permission of TTP,
www.ttp.net. (ID: 130.216.199.155-25/06/13,03:24:49)

Methods
LEDs, a semiconductor light source, have been widely used in communication industry, media
industry and interior lighting for different purposes. With the development of microchip technology,
the visual effect of LED lights became diverse and programmable [8]. For example, LED lights can
create the “running” effect, which means a LED light signal can be transmitted from one location to
another along a strip smoothly. This motivated us to design a LED system to provide a visual cue for
walking speed control.
Our LED light system includes a custom-made 10 meter digital LED strip and a digital
microcontroller. The light strip is made up of 6.25 cm*1.2 cm*0.35 cm thin circuit boards with two
LED lights and a HL1606 microchip mounted on each board. The HL1606 microchip contains a four
pin input (DI, CI, SI, LI), which receives and copies the datasheet from microcontroller (Fig. 1). The
microchip signal can be transmitted through four output pins (DO, CO, SO, LO). In this way, two
LED units are connected and subsequently the signal can be transformed between LED units.
Fig. 1 Schematic of the “running” effect. The distance between each two adjacent LED unit is the
same. The duration time of power supply for each LED is also the same.
Duration=T
2
-T
1
=T
3
-T
2
=…=T
n
-T
n-1
.
A digital controller with STC90C52RC microcontroller (STC MCU Limited, China) was used to
control the LED strip. By controlling LED power supply using Pulse Width Modulation (PWM) [9]
technique, the first LED unit is turned on for a short duration of time then turned off at the same
moment the next LED unit is turned on. By this way, the LED units are turning on quickly, one after
another (Fig.2), creating a “running” effect by which the visual target (illuminated LED units) appears
to move along the LED strip.
1372 Advanced Measurement and Test III

Fig. 2 Schematic of the LED system. The system includes a LED strip with HL1606 microchips and a
PWM build-in microcontroller. The data is firstly sent and copied on the DI (data in), CI (clock in)
and SI (speed clock input) lines. Under control of the LI (latch in), the data was pushed down the line
to the next microchip through the DO (data out) pin, CO (clock out), SO (speed clock output) and LO
(latch out) pins. In this way, two LED units were connected and each one can be controlled
individually.
To generate one target speed, one need the duration of the light on each LED unit and distance
between adjacent LED units. By assigning a value to the duration in PWM datasheet, the speed can be
calculated as the ratio of the distance between two LED units (3.125 cm) and the duration time.
According to the source code of the PWM built-in module, the minimum duration of each LED unit is
0.008 s. Each incremental increase in walking speed (total of 100 levels) this time duration increases
by 0.001 s. The equation is
Target Speed
=
0
.
03125
0
.
008
+
0
.
001
×
(

1
)
m/s
(1)
The LED speed ranges from 0.10m/s to 3.90 m/s, which can cover the possible human walking
speed range. In addition, the PWM module enables the user to set the number of LED units working as
a group, that is, we can select either just one dot or a beam of light moving forward.
An Evaluation of method was designed to evaluate the accuracy of controlling walking speed control
using the LED system. Experiments were carried out at the Biomechanics Laboratory of the
University of Auckland. The experiment protocol was approved by The University of Auckland’s
Human Research Ethics committee. Five healthy subjects, (age: 24.8±3.6 years, height: 166.2 ±7.5
cm, three males and two females) were each asked to walk down a 10 meter walkway at five given
speeds (0.8 m/s, 1.0 m/s, 1.2 m/s, 1.4 m/s and 1.6 m/s) by following the light cue. The 10 meters
digital LED light strip was installed on the side of the walkway and connected to the digital controller
and power supply (12 volt Direct-Current). In order to increase the visual target, we set 16 serial LED
units working together. The reflective markers were placed on the heel and the toe positions of the
shoes (Fig. 3). The eight cameras Vicon motion analysis system (Oxford Metrics, UK) was used to
record the displacement of the markers in three-dimension at a frequency of 100 Hz. Ground reaction
forces were measured by two in-ground AMTI force plates at a frequency of 1000 Hz. Heel-strike and
toe-off times were detected from the force plate data with a threshold value of 20 N.
During each trail, the visual target (the set of 16 LED units), moved along the LED strip at the
desired walking speed. The subjects were able to view the lights running in front of them without
bending their heads (Fig. 3). Before capture, the participants carried out 5 to 10 times of practices at
each LED-controlled speed. A researcher was walking along side to help subjects to match the speed
during practices. After participants become familiar with the speed, they then performed ten
Advanced Materials Research Vols. 718-720 1373

successful walking at each desired speed by themselves. The stride length was determined by
measuring the distance between heel marker positions during consecutive ground contacts of the same
foot. The stride time was determined by measure the time from heel strike to heel strike of same foot.
The timing of each heel strike was obtained from the forceplate data. The actual walking speed was
computed as stride time divided by stride length. All data was processed by using Vicon Workstation
software (Oxford Metrics, UK).
Fig. 3 The experimental set-up of the evaluation tests. The subjects followed the running lights along
the 10m walkway with two force-plates. Toe and heel markers were positioned to determine the feet
segment.
The percent difference was calculated to explain the validity of each walking speed using the
following equation:
D
ifference % =
measured


×100 %
(2)
Where V
measured
is the measured walking speed using Vicon system and V
target
is the LED target
speed. A one way ANOVA was used to determine whether difference% was significant different
between each two speeds. Intra-class correlation coefficient (ICC) was also calculated to test the
reliability of the LED speed control system, by using SPSS software. A p-value of <0.05 was
considered to be statistically significant.
Results
The average measured speed and percent difference values for each subject are shown in Table 1. The
measured percent difference ranged from 0.01% to 7.55%. A statistically significant difference in
measured percent difference was only seen between the 0.8m/s group and 1.2m/s group (p=0.011).
There were no statistical differences found in the other 9 pairs of data. Over the 250 trials of the five
subjects, 64.4% (161/250) of the trials had the percent difference of less than 3%, 33.6% (84/250)
between 3% and 6.5%, and only 2% (5/250) had the percent difference larger than 6.5%.
1374 Advanced Measurement and Test III

Table 1 The measured speed and percent difference for five subjects (Subject 1-5) at five different
speeds (means ± SD), performing 10 walks for each speed.
Difference %
0.8m/s 1.0 m/s 1.2 m/s 1.4 m/s 1.6 m/s
Subject1 2.14±1.60 2.03±1.42 2.56±1.84 1.93±1.52 2.56±1.63
Subject2 2.38±1.77 3.51±2.45 3.69±1.80 4.24±2.22 1.28±1.32
Subject3 1.29±1.38 1.13±1.15 2.68±1.30 2.07±1.07 2.86±1.64
Subject4 3.14±2.05 4.58±1.87 3.36±1.54 1.83±1.08 2.76±1.63
Subject5 2.79±1.46 1.82±0.69 1.32±1.03 1.99±1.83 2.26±1.79
overall 2.29±1.74 2.67±2.06 2.84±1.65 2.37±1.72 2.40±1.62
The ICC for the LED speed control system at five speeds, ranging from 0.85 to 0.88 for fast speeds
level (1.6 m/s, 1.4 m/s), and slightly lower ranging from 0.74 to 0.79 at slower speeds (1.2 m/s, 1.0
m/s, 0.8 m/s).
Discussion
The LED system appears to be effective for speed control. All the subjects were able to follow the
visible running lights signal, resulting in a good match of each desired speed. The average percent
difference of this LED speed control system was 2.58%. Based on the literature, two criteria have
been proposed to assess the validity of walking speed based on error, the first being less that 3% [6],
and the other less than 6.5% error is considered valid [5]. Under these criteria, 63% and 97.5% of
trials, respectively, are valid. The repeatability results for preferred walking speed were in the
excellent range.
The result shows that compared to existing speed control system, the LED system has similar
performance in terms of reliability and validity. Compared with the motor driven system [7], the LED
system is easier to install or move. Thus walking speeds can be controlled directly without additional
calculations, human resources and time are saved.
In studies which investigate both mechanical and metabolic cost of walking, these two parts are
usually tested separately if force-plate-integrated treadmills are not available. In this case, the
flexibility of the LED light strip enables itself to be wired to form a digital track that has built in
force-plates. The subjects’ walking speed can be kept steady under the guiding of the lights. Then the
kinematic, kinetic and metabolic data can be measured simultaneously.
Although it is expected that the LED speed control system will improve present experimental
methodologies of gait analysis, evidence is also needed to evaluate whether other population groups
are able to follow the lights to achieve target velocities. In present study design, subjects were allowed
to slightly look down at the running light during walking, in order to keep the pace. This is a potential
issue that could affect the gait. It suggested that the LED strip can be raised to the subject’s eye level
in future experimental set-up. Because of its flexibility and portability, the LED strip system is easy to
be elevated and supported by several rock stands, and the height is also adjustable. Another factor
worth further consideration is that providing a visual cue could affect the gait of many pathologies
including Parkinson's disease and therefore give a false impression of their gait. During walking in
healthy subjects without any cognition problem, however, it is not expected to be a major concern.
Acknowledgement
This research was supported by Key Laboratory of Exercise and Health Sciences of Ministry of
Education, Shanghai University of Sport. This work was also supported by Program for New Century
Excellent Talents in University (NCET).
Advanced Materials Research Vols. 718-720 1375

Citations
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Abstract: Purpose: This study aimed to investigate the influence of childhood obesity on energetic cost during normal walking and to determine if obese children choose a walking strategy optimizing their gait pattern. Method: Sixteen obese children with no functional abnormalities were matched by age and gender with 16 normal-weight children. All participants were asked to walk along a nearly circular track 30 m in length at a self-selected speed. Spatiotemporal data, kinematics, and ground reaction force were collected during walking using a three-dimensional motion analysis system. Metabolic cost was collected by a portable gas analyzer simultaneously. Results: The mechanical energy expenditure (MEE) was 72.7% higher in obese children than in normal-weight children. The net metabolic cost was 65.7% higher in obese children. No difference was found in the metabolic rate (J·kg− 1·m− 1), normalized MEE (J·kg− 1·m− 1) and mechanical efficiency between the obese and normal-weight groups. The obese children walked with...

39 citations

Patent
05 Sep 2017
TL;DR: In this article, a motion capture movement reference system includes a light strip with lights positioned in series along a length of the elongated substrate and a computing device configured to program the lights with an illumination protocol.
Abstract: The system provides movement guidance to an actor using a motion capture movement reference system. The motion capture movement reference system includes a light strip having an elongated substrate with lights positioned in series along a length of the elongated substrate and a computing device configured to program the lights with an illumination protocol. Operationally, a user inputs into the computing device one or more variables to establish a number of lights to simultaneously activate and/or a rate of activating and deactivating the lights along the length of the elongated substrate. The light strip is programmed based upon the one or more variables. When the lights are activated and deactivated along the length of the elongated substrate, an actor chases the lights.
References
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Abstract: The goal of this study was to compare treadmill walking with overground walking in healthy subjects with no known gait disorders. Nineteen subjects were tested, where each subject walked on a split-belt instrumented treadmill as well as over a smooth, flat surface. Comparisons between walking conditions were made for temporal gait parameters such as step length and cadence, leg kinematics, joint moments and powers, and muscle activity. Overall, very few differences were found in temporal gait parameters or leg kinematics between treadmill and overground walking. Conversely, sagittal plane joint moments were found to be quite different, where during treadmill walking trials, subjects demonstrated less dorsiflexor moments, less knee extensor moments, and greater hip extensor moments. Joint powers in the sagittal plane were found to be similar at the ankle but quite different at the knee and hip joints. Differences in muscle activity were observed between the two walking modalities, particularly in the tibialis anterior throughout stance, and in the hamstrings, vastus medialis and adductor longus during swing. While differences were observed in muscle activation patterns, joint moments and joint powers between the two walking modalities, the overall patterns in these behaviors were quite similar. From a therapeutic perspective, this suggests that training individuals with neurological injuries on a treadmill appears to be justified.

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"A Method of Speed Control during Ov..." refers background in this paper

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TL;DR: This study provides reference data for muscle contributions to support and progression over a wide range of walking speeds and highlights the importance of walking speed when evaluating muscle function.

402 citations


"A Method of Speed Control during Ov..." refers background in this paper

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TL;DR: The development of high-performance visible-spectrum light-emitting diodes (LEDs) has occurred over a period of over 60 years, beginning with the discovery of the first semiconductor p-n junction in 1940, the development of solid-state electronic band theory in the 1940s, the invention of bipolar transistor in 1947, and the demonstration of efficient light generation from III-V alloys in the 1950s and 1960s.
Abstract: In a practical sense, the development of high-performance visible-spectrum light-emitting diodes (LEDs) has occurred over a period of over 60 years, beginning with the discovery of the first semiconductor p-n junction in 1940, the development of solid-state electronic band theory in the 1940s, the invention of the first bipolar transistor in 1947, and the demonstration of efficient light generation from III-V alloys in the 1950s and 1960s. This paper reviews some of the major scientific and technological developments and observations that have created the materials and device technologies currently used in the commercial mass production of high-brightness visible-spectrum LEDs and that have culminated in white-light sources exhibiting luminous efficacies of over 150 lm/W, far beyond what has been achieved with conventional lighting technologies.

236 citations


Additional excerpts

  • ...With the development of microchip technology, the visual effect of LED lights became diverse and programmable [8]....

    [...]

Book
01 Jan 1998
TL;DR: In this paper, the authors present an analytical solution to calculate the current waveform of an AC-to-AC converter and demonstrate the effect of current waveforms on the performance of the converter.
Abstract: Preface. 1 Principles and Methods of Electric PowerConversion. 1.1 What Is Power Electronics? 1.2 Generic Power Converter. 1.3 Waveform Components and Figures of Merit. 1.4 Phase Control. 1.5 Pulse Width Modulation. 1.6 Calculation of Current Waveforms. 1.6.1 Analytical Solution. 1.6.2 Numerical Solution. 1.6.3 Practical Examples: Single-Phase Diode Rectifiers. 1.7 Summary. Example. Problems. Computer Assignments. Literature. 2 Semiconductor Power Switches. 2.1 General Properties of Semiconductor Power Switches. 2.2 Power Diodes. 2.3 Semicontrolled Switches. 2.3.1 SCRs. 2.3.2 Triacs. 2.4 Fully Controlled Switches. 2.4.1 GTOs. 2.4.2 IGCTs. 2.4.3 Power BJTs. 2.4.4 Power MOSFETs. 2.4.5 IGBTs. 2.5 Comparison of Semiconductor Power Switches. 2.6 Power Modules. 2.7 Summary. Literature. 3 Supplementary Components and Systems. 3.1 What Are Supplementary Components and Systems? 3.2 Drivers. 3.2.1 Drivers for SCRs, Triacs, and BCTs. 3.2.2 Drivers for GTOs and IGCTs. 3.2.3 Drivers for BJTs. 3.2.4 Drivers for Power MOSFETs and IGBTs. 3.3 Overcurrent Protection Schemes. 3.4 Snubbers. 3.4.1 Snubbers for Power Diodes, SCRs, and Triacs. 3.4.2 Snubbers for GTOs and IGCTs. 3.4.3 Snubbers for Transistors. 3.4.4 Energy Recovery from Snubbers. 3.5 Filters. 3.6 Cooling. 3.7 Control. 3.8 Summary. Literature. 4 AC-to-DC Converters. 4.1 Diode Rectifiers. 4.1.1 Three-Pulse Diode Rectifier. 4.1.2 Six-Pulse Diode Rectifier. 4.2 Phase-Controlled Rectifiers. 4.2.1 Phase-Controlled Six-Pulse Rectifier. 4.2.2 Dual Converters. 4.3 PWM Rectifiers. 4.3.1 Impact of Input Filter. 4.3.2 Principles of Pulse Width Modulation. 4.3.3 Current-Type PWM Rectifier. 4.3.4 Voltage-Type PWM Rectifier. 4.4 Device Selection for Rectifiers. 4.5 Common Applications of Rectifiers. 4.6 Summary. Examples. Problems. Computer Assignments. Literature. 5 AC-to-AC Converters. 5.1 AC Voltage Controllers. 5.1.1 Phase-Controlled Single-Phase AC Voltage Controller. 5.1.2 Phase-Controlled Three-Phase AC Voltage Controllers. 5.1.3 PWM AC Voltage Controllers. 5.2 Cycloconverters. 5.3 Matrix Converters. 5.4 Device Selection for AC-to-AC Converters. 5.5 Common Applications of AC-to-AC Converters. 5.6 Summary. Examples. Problems. Computer Assignments. Literature. 6 DC-to-DC Converters. 6.1 Static DC Switches. 6.2 Step-Down Choppers. 6.2.1 First-Quadrant Chopper. 6.2.2 Second-Quadrant Chopper. 6.2.3 First-and-Second-Quadrant Chopper. 6.2.4 First-and-Fourth-Quadrant Chopper. 6.2.5 Four-Quadrant Chopper. 6.3 Step-Up Chopper. 6.4 Current Control in Choppers. 6.5 Device Selection for Choppers. 6.6 Common Applications of Choppers. 6.7 Summary. Example. Problems. Computer Assignments. Literature. 7 DC-to-AC Converters. 7.1 Voltage-Source Inverters. 7.1.1 Single-Phase Voltage-Source Inverter. 7.1.2 Three-Phase Voltage-Source Inverter. 7.1.3 Voltage Control Techniques for Voltage-SourceInverters. 7.1.4 Current Control Techniques for Voltage-SourceInverters. 7.2 Current-Source Inverters. 7.2.1 Three-Phase Square-Wave Current-Source Inverter. 7.2.2 Three-Phase PWM Current-Source Inverter. 7.3 Multilevel Inverters. 7.4 Soft-Switching Inverters. 7.5 Device Selection for Inverters. 7.6 Common Applications of Inverters. 7.7 Summary. Examples. Problems. Computer Assignments. Literature. 8 Switching Power Supplies. 8.1 Basic Types of Switching Power Supplies. 8.2 Nonisolated Switched-Mode DC-to-DC Converters. 8.2.1 Buck Converter. 8.2.2 Boost Converter. 8.2.3 Buck Boost Converter. 8.2.4 uk Converter. 8.2.5 SEPIC and Zeta Converters. 8.2.6 Comparison of Nonisolated Switched-Mode DC-to-DCConverters. 8.3 Isolated Switched-Mode DC-to-DC Converters. 8.3.1 Single-Switch Isolated DC-to-DC Converters. 8.3.2 Multiple-Switch Isolated DC-to-DC Converters. 8.3.3 Comparison of Isolated Switched-Mode DC-to-DCConverters. 8.4 Resonant DC-to-DC Converters. 8.4.1 Quasi-Resonant Converters. 8.4.2 Load-Resonant Converters. 8.4.3 Comparison of Resonant DC-to-DC Converters. 8.5 Summary. Examples. Problems. Computer Assignments. Literature. 9 Power Electronics and Clean Energy. 9.1 Why Is Power Electronics Indispensable in Clean EnergySystems? 9.2 Solar and Wind Renewable Energy Systems. 9.2.1 Solar Energy Systems. 9.2.2 Wind Energy Systems. 9.3 Fuel Cell Energy Systems. 9.4 Electric and Hybrid Cars. 9.5 Power Electronics and Energy Conservation. 9.6 Summary. Literature. Appendix A PSpice Simulations. Appendix B Fourier Series. Appendix C Three-Phase Systems. Index.

168 citations

Journal ArticleDOI
TL;DR: Four different methods of identifying the times of foot-strike and toe-off during running based on gait marker trajectories were presented and the event times predicted by the methods were compared to those identified using a force plate for both over-ground and treadmill running.

68 citations


"A Method of Speed Control during Ov..." refers background in this paper

  • ...Although force-plate-integrated treadmills are commercially available, the cost of this type of treadmill is very high [1]....

    [...]

Frequently Asked Questions (2)
Q1. What contributions have the authors mentioned in the paper "A method of speed control during over-ground walking: using a digital light-emitting diode light strip" ?

The purpose of this report was to introduce the design of a portable, inexpensive and programmable digital light-emitting diode ( LED ) system to control overground walking speed. By controlling the duration time of the power supply to each LED unit, a visible running lights signal can provide a visual cue for speed control. To evaluate this design, five subjects were asked to walk overground while following the LED visual cue at five different target speeds. 

It suggested that the LED strip can be raised to the subject ’ s eye level in future experimental set-up. Another factor worth further consideration is that providing a visual cue could affect the gait of many pathologies including Parkinson 's disease and therefore give a false impression of their gait.