scholarly journals A Measurement of ‘Walking-the-Wall’ Dynamics: An Observational Study Using Accelerometry and Sensors to Quantify Risk Associated with Vertical Wall Impact Attenuation in Trampoline Parks

Sensors ◽  
2021 ◽  
Vol 21 (21) ◽  
pp. 7337
Author(s):  
Imam Hossain ◽  
Shilei Zhou ◽  
Karlos Ishac ◽  
Edward Lind ◽  
Lisa Sharwood ◽  
...  
Keyword(s):  
High Performance ◽  
Force Feedback ◽  
Reaction Force ◽  
Vertical Wall ◽  
Spatial Awareness ◽  
Rigid Surface ◽  
Fall From Height ◽  
Impact Attenuation ◽  
Vertical Walls ◽  
Rigid Walls

This study illustrates the application of a tri-axial accelerometer and gyroscope sensor device on a trampolinist performing the walking-the-wall manoeuvre on a high-performance trampoline to determine the performer dynamic conditions. This research found that rigid vertical walls would allow the trampolinist to obtain greater control and retain spatial awareness at greater levels than what is achievable on non-rigid vertical walls. With a non-rigid padded wall, the reaction force from the wall can be considered a variable force that is not constrained, and would not always provide the feedback that the trampolinist needs to maintain the balance with each climb up the wall and fall from height. This research postulates that unattenuated vertical walls are safer than attenuated vertical walls for walking-the-wall manoeuvres within trampoline park facilities. This is because non-rigid walls would provide higher g-force reaction feedback from the wall, which would reduce the trampolinist’s control and stability. This was verified by measuring g-force on a horizontal rigid surface versus a non-rigid surface, where the g-force feedback was 27% higher for the non-rigid surface. Control and stability are both critical while performing the complex walking-the-wall manoeuvre. The trampolinist experienced a very high peak g-force, with a maximum g-force of approximately 11.5 g at the bottom of the jump cycle. It was concluded that applying impact attenuation padding to vertical walls used for walking-the-wall and similar activities would increase the likelihood of injury; therefore, padding of these vertical surfaces is not recommended.

Direct Longitudinal Force Feedback for High-Performance Vehicle Dynamics Control Systems

2021 ◽  
Author(s):  
Giorgio Riva ◽  
Luca Mozzarelli ◽  
Matteo Corno ◽  
Simone Formentin ◽  
Sergio M. Savaresi
Keyword(s):  
Model Predictive Control ◽  
Control Systems ◽  
Predictive Control ◽  
Vehicle Dynamics ◽  
High Performance ◽  
Force Feedback ◽  
Longitudinal Force ◽  
Spiral Path ◽  
Comparable Performance ◽  
Vehicle Dynamics Control

Abstract State of the art vehicle dynamics control systems do not exploit tire road forces information, even though the vehicle behaviour is ultimately determined by the tire road interaction. Recent technological improvements allow to accurately measure and estimate these variables, making it possible to introduce such knowledge inside a control system. In this paper, a vehicle dynamics control architecture based on a direct longitudinal tire force feedback is proposed. The scheme is made by a nested architecture composed by an outer Model Predictive Control algorithm, written in spatial coordinates, and an inner longitudinal force feedback controller. The latter is composed by four classical Proportional-Integral controllers in anti-windup configuration, endowed with a suitably designed gain switching logic to cope with possible unfeasible references provided by the outer loop, avoiding instability. The proposed scheme is tested in simulation in a challenging scenario where the tracking of a spiral path on a slippery surface and the timing performance are handled simultaneously by the controller. The performance is compared with that of an inner slip-based controller, sharing the same outer Model Predictive Control loop. The results show comparable performance in presence of unfeasible force references, while higher robustness is achieved with respect to friction curve uncertainties.

High performance force feedback mechanism for virtual reality training of endotracheal intubation

2004 ◽  
Vol 43 (1) ◽  
pp. 85-98 ◽  
Author(s):  
Jonathan D. French ◽  
James H. Mutti ◽  
Satish S. Nair ◽  
Michael Prewitt
Keyword(s):  
Virtual Reality ◽  
Endotracheal Intubation ◽  
High Performance ◽  
Force Feedback ◽  
Feedback Mechanism ◽  
Virtual Reality Training

scholarly journals Slit-type Breakwater; Box-type Wave Absorber

1976 ◽  
Vol 1 (15) ◽  
pp. 154 ◽  
Author(s):  
Shoshichiro Nagai ◽  
Shohachi Kakuno
Keyword(s):  
Cross Section ◽  
Water Depth ◽  
Vertical Wall ◽  
Bottom Wall ◽  
Front Wall ◽  
Type Wave ◽  
Composite Type ◽  
New Type ◽  
Vertical Walls ◽  
Horizontal Bottom

A box-type wave absorber, which is composed of a perforated vertical front-wall and a perforated, horizontal bottom-wall, has been proved by a number of experiments to show lower coefficients of reflection and more distinguished reduction of wave pressures than the perforated vertical- wall breakwater. A breakwater of composite-type, which is 1500 m long and to be built at a water depth of 10 to 11 m below the Datum Line in the Port of Osaka, is being designed to set this new type of wave absorber in the concrete caissons of the vertical-walls which is named "a slit-type breakwater". The typical cross-section of the breakwater and the advantages of the slit-type breakwater are presented herein.

The Effect of the Top Wall Temperature on the Laminar Natural Convection in Rectangular Cavities With Different Aspect Ratios

2009 ◽  
Vol 131 (5) ◽  
Author(s):  
Wenjiang Wu ◽  
Chan Y. Ching
Keyword(s):  
Natural Convection ◽  
Aspect Ratio ◽  
Wall Temperature ◽  
Vertical Wall ◽  
Flow Region ◽  
Temperature Profiles ◽  
Aspect Ratios ◽  
Vertical Walls ◽  
C And N ◽  
Laminar Natural Convection

The effect of the top wall temperature on the laminar natural convection in air-filled rectangular cavities driven by a temperature difference across the vertical walls was investigated for three different aspect ratios of 0.5, 1.0, and 2.0. The temperature distributions along the heated vertical wall were measured, and the flow patterns in the cavities were visualized. The experiments were performed for a global Grashof number of approximately 1.8×108 and nondimensional top wall temperatures from 0.52 (insulated) to 1.42. As the top wall was heated, the flow separated from the top wall with an undulating flow region in the corner of the cavity, which resulted in a nonuniformity in the temperature profiles in this region. The location and extent of the undulation in the flow are primarily determined by the top wall temperature and nearly independent of the aspect ratio of the cavity. The local Nusselt number was correlated with the local Rayleigh number for all three cavities in the form of Nu=C⋅Ran, but the values of the constants C and n changed with the aspect ratio.

scholarly journals A new solution approach to the Serre equations

2020 ◽  
Author(s):  
T S Jang
Keyword(s):  
Solitary Wave ◽  
Vertical Wall ◽  
High Amplitude ◽  
Solution Procedure ◽  
Linear Wave ◽  
Linear Interaction ◽  
Solution Approach ◽  
Non Linear ◽  
Vertical Walls ◽  
Wave Phenomena

Abstract This paper concerns constructing a semi-analytic solution procedure for integrating the fully non-linear Serre equations (or 1D Green–Naghdi equations for constant water depth). The validity of the solution procedure is checked by investigating a moving solitary wave for which the analytical solution is known. The semi-analytic procedure constructed in this study is confirmed to be good at observing non-linear wave phenomena of the collision of a sufficiently high-amplitude solitary wave with a vertical wall. The simulated results are in a good agreement with data of other authors. Further, the procedure simulates the non-linear interaction of four solitary waves, which enables us to investigate the repeated reflection of a single solitary wave between two vertical walls.

Presentation of Assembly Condition and Subassembly Function Using Two Force Feedback Displays

2000 ◽  
Vol 12 (1) ◽  
pp. 2-10
Author(s):  
Ryoko Furusawa ◽  
◽  
Kazuaki Tanaka ◽  
Norihiro Abe ◽  
Katsuya Matsunaga ◽  
...  
Keyword(s):  
Force Feedback ◽  
Virtual Work ◽  
Daily Life ◽  
Reaction Force ◽  
The State ◽  
Work Space ◽  
Machine Parts ◽  
Haptic Sensation

Assembling is one of the important factors in our daily life. The aim of assembling is to obtain a particular function from the subassembly which is generated by putting some parts together. This fact shows that assembling machine parts is possibily the most appropriate example to exeute. If we assemble some machine parts, we decide the positions by their shapes, and then, make sure both the state of parts by reaction force fed back to the hand when a part touches other parts and the behavior of the subassembly. In addition, it is advisable to use both hands for assembly. In this research, we constructed a virtual work space using a force display which gives us haptic sensation returned from not only assembling operation but collaboration with both hands.

Dynamics of laser-induced cavitation bubbles near two perpendicular rigid walls

2018 ◽  
Vol 841 ◽  
pp. 28-49 ◽  
Author(s):  
Emil-Alexandru Brujan ◽  
Tatsuya Noda ◽  
Atsushi Ishigami ◽  
Toshiyuki Ogasawara ◽  
Hiroyuki Takahira
Keyword(s):  
High Speed ◽  
Vertical Wall ◽  
Bubble Surface ◽  
Bubble Collapse ◽  
High Speed Photography ◽  
Maximum Expansion ◽  
Toroidal Bubble ◽  
Horizontal Wall ◽  
The Moment ◽  
Rigid Walls

The behaviour of a laser-induced cavitation bubble near two perpendicular rigid walls and its dependence on the distance between bubble and walls is investigated experimentally. It was shown by means of high-speed photography with $100\,000~\text{frames}~\text{s}^{-1}$ that an inclined jet is formed during bubble collapse and the bubble migrates in the direction of the jet. At a given position of the bubble with respect to the horizontal wall, the inclination of the jet increases with decreasing distance between the bubble and the second, vertical wall. A bubble generated at equal distances from the walls develops a jet that is directed in their bisection. The penetration of the jet into the opposite bubble surface leads to the formation of an asymmetric toroidal bubble that is perpendicular to the jet direction. At a large distance from the rigid walls, the toroidal bubble collapses in the radial direction, eventually disintegrating into tiny microbubbles. When the bubble is in contact with the horizontal wall at its maximum expansion, the toroidal ring collapses in both radial and toroidal directions, starting from the bubble part opposite to the vertical wall, and the bubble achieves a crescent shape at the moment of second collapse. The bubble oscillation is accompanied by a strong migration along the horizontal wall.

Force Feedback Control of Lower Extremity Exoskeleton Assisting of Load Carrying Human

2014 ◽  
Vol 598 ◽  
pp. 546-550 ◽  
Author(s):  
Yusuf Şahin ◽  
Fatih Mehmet Botsalı ◽  
Mete Kalyoncu ◽  
Mustafa Tinkir ◽  
Ümit Önen ◽  
...  
Keyword(s):  
Feedback Control ◽  
Lower Extremity ◽  
Force Feedback ◽  
Reaction Force ◽  
Industrial Applications ◽  
Civil Defense ◽  
Weight Lifting ◽  
Wearable Robot ◽  
Joint Force ◽  
Load Carrying

Lower extremity exoskeletons are wearable robot manipulators that integrate human intelligence with the strength of legged robots. Recently, lower extremity exoskeletons have been specifically developed for rehabilitation, military, industrial applications and rescuing, heavy-weight lifting and civil defense applications. This paper presents controller design of a lower-extremity exoskeleton for a load carrying human to provide force feedback control against to external load carried by user during walking, sitting, and standing motions. Proposed exoskeleton system has two legs which are powered and controlled by two servo-hydraulic actuators. Proportional and Integral (PI) controller is designed for force control of system. Six flexible force sensors are placed in exoskeleton shoe and two load cells are mounted between the end of the piston rod and lower leg joint. Force feedback control is realized by comparing ground reaction force and applied force of hydraulic cylinder. This paper discusses control simulations and experimental tests of lower extremity exoskeleton system.

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