Using a Timescale Ensemble on Moving Platforms

2021 ◽  
Author(s):  
Marc A. Weiss ◽  
Steven Wilkinson
Keyword(s):  
Moving Platforms

The Optimum Quality Index for the Stability of In-Parallel Planar Platform Devices

1999 ◽  
Vol 121 (1) ◽  
pp. 15-20 ◽  
Author(s):  
J. Lee ◽  
J. Duffy ◽  
M. Keler
Keyword(s):  
Optimal Design ◽  
Equilateral Triangle ◽  
Quality Index ◽  
Optimal Shape ◽  
Geometrical Meaning ◽  
Moving Platforms ◽  
Maximum Value ◽  
Dimensionless Ratio ◽  
Parallel Platform ◽  
The Stability

The paper investigates primarily the geometrical meaning of the determinant of the Jacobian (det j) of the three connector lines of a planar in-parallel platform device using reciprocity. A remarkably simple result is deduced: The maximum value of det j namely, det jm is simply one-half of the sum of the lengths of the sides of the moving triangular platform. Further, this result is shown to be independent of the location of the fixed pivots in the base. A dimensionless ratio λ = |det j|/det jm is defined as the quality index (0 ≤ λ ≤ 1) and it is proposed here to use it to measure “closeness” to a singularity. An example which determines the optimal design by comparing different shaped moving platforms having the same det jm is given and demonstrates that the optimal shape is in fact an equilateral triangle

scholarly journals Energy cost associated with moving platforms

PeerJ ◽  
2018 ◽  
Vol 6 ◽  
pp. e5439 ◽  
Author(s):  
Carolyn A. Duncan ◽  
Scott N. MacKinnon ◽  
Jacques F. Marais ◽  
Fabien A. Basset
Keyword(s):  
Energy Cost ◽  
Postural Stability ◽  
Commercial Fishing ◽  
Moving Platforms ◽  
Metabolic Costs ◽  
Significant Performance ◽  
Operator Fatigue ◽  
Exact Effect ◽  
Experienced Personnel ◽  
Platform Motions

BackgroundPrevious research suggests motion induced fatigue contributes to significant performance degradation and is likely related to a higher incidence of accidents and injuries. However, the exact effect of continuous multidirectional platform perturbations on energy cost (EC) with experienced personnel on boats and other seafaring vessels remains unknown.ObjectiveThe objective of this experiment was to measure the metabolic ECs associated with maintaining postural stability in a motion-rich environment.MethodsTwenty volunteer participants, who were free of any musculoskeletal or balance disorders, performed three tasks while immersed in a moving environment that varied motion profiles similar to those experienced by workers on a mid-size commercial fishing vessel (static platform (baseline), low and high motions (HMs)). Cardiorespiratory parameters were collected using an indirect calorimetric system that continuously measured breath-by-breath samples. Heart rate was recoded using a wireless heart monitor.ResultsResults indicate a systematic increase in metabolic costs associated with increased platform motions. The increases were most pronounced during the standing and lifting activities and were 50% greater during the HM condition when compared to no motion. Increased heart rates were also observed.DiscussionPlatform motions have a significant impact on metabolic costs that are both task and magnitude of motion dependent. Practitioners must take into consideration the influence of motion-rich environments upon the systematic accumulation of operator fatigue.

scholarly journals Proactive Guidance for Accurate UAV Landing on a Dynamic Platform: A Visual–Inertial Approach

Sensors ◽  
2022 ◽  
Vol 22 (1) ◽  
pp. 404
Author(s):  
Ching-Wei Chang ◽  
Li-Yu Lo ◽  
Hiu Ching Cheung ◽  
Yurong Feng ◽  
An-Shik Yang ◽  
...  
Keyword(s):  
Trajectory Optimization ◽  
Control Method ◽  
Guidance System ◽  
Autonomous Landing ◽  
Ground Vehicle ◽  
Ground Station ◽  
Moving Platforms ◽  
Promising Solution ◽  
Long Endurance ◽  
Indoor And Outdoor

This work aimed to develop an autonomous system for unmanned aerial vehicles (UAVs) to land on moving platforms such as an automobile or a marine vessel, providing a promising solution for a long-endurance flight operation, a large mission coverage range, and a convenient recharging ground station. Unlike most state-of-the-art UAV landing frameworks that rely on UAV onboard computers and sensors, the proposed system fully depends on the computation unit situated on the ground vehicle/marine vessel to serve as a landing guidance system. Such a novel configuration can therefore lighten the burden of the UAV, and the computation power of the ground vehicle/marine vessel can be enhanced. In particular, we exploit a sensor fusion-based algorithm for the guidance system to perform UAV localization, whilst a control method based upon trajectory optimization is integrated. Indoor and outdoor experiments are conducted, and the results show that precise autonomous landing on a 43 cm × 43 cm platform can be performed.

scholarly journals Experimental evaluation of a linear angular momentum multiplexed radio link for moving platforms

2021 ◽  
Vol 477 (2254) ◽  
Author(s):  
Ben Allen ◽  
Tim W. C. Brown ◽  
Timothy D. Drysdale
Keyword(s):  
Angular Momentum ◽  
Spectral Efficiency ◽  
Experimental System ◽  
Antenna System ◽  
Radio Link ◽  
Translation Invariance ◽  
Video Streams ◽  
Moving Platforms ◽  
High Spectral Efficiency ◽  
Performance Results

Linear angular momentum multiplexing (LAMM) has recently been proposed for high spectral-efficiency communications between moving platforms, such as between trains and ground infrastructure. We present performance results obtained from a scale experimental system comprising a 2 × 2 antenna system operating at 2.35 GHz. The link transmitted two independent video streams, using RF pre-coding and software-defined radios to modulate and up/down-convert the signals. Linear motion is introduced to demonstrate the translation-invariance of the technique. We interpret the measured data with the aid of an analytical model to show that crosstalk between the two channels is at levels low enough to consistently support the video streams without interruption. Specifically, our results show spectral efficiency is consistently higher when LAMM coding is enabled compared with an uncoded channel.

scholarly journals A Precise and GNSS-Free Landing System on Moving Platforms for Rotary-Wing UAVs

Sensors ◽  
2019 ◽  
Vol 19 (4) ◽  
pp. 886 ◽  
Author(s):  
Francisco Alarcón ◽  
Manuel García ◽  
Ivan Maza ◽  
Antidio Viguria ◽  
Aníbal Ollero
Keyword(s):  
Relative Position ◽  
Unmanned Helicopter ◽  
Landing Position ◽  
Moving Platforms ◽  
Landing Platform ◽  
Aerial Vehicle ◽  
The Stability ◽  
Novel Concept ◽  
High Level ◽  
Rotary Wing

This article presents a precise landing system that allows rotary-wing UAVs to approach and land safely on moving platforms, without using GNSS at any stage of the landing maneuver, and with a centimeter level accuracy and high level of robustness. This system implements a novel concept where the relative position and velocity between the aerial vehicle and the landing platform are calculated from the angles of a cable that physically connects the UAV and the landing platform. The use of a cable also incorporates a number of extra benefits, such as increasing the precision in the control of the UAV altitude. It also facilitates centering the UAV right on top of the expected landing position, and increases the stability of the UAV just after contacting the landing platform. The system was implemented in an unmanned helicopter and many tests were carried out under different conditions for measuring the accuracy and the robustness of the proposed solution. Results show that the developed system allowed landing with centimeter accuracy by using only local sensors and that the helicopter could follow the landing platform in multiple trajectories at different velocities.

A novel five-degrees-of-freedom decoupled robot

Robotica ◽  
2009 ◽  
Vol 28 (6) ◽  
pp. 909-917 ◽  
Author(s):  
Jaime Gallardo-Alvarado ◽  
Horacio Orozco-Mendoza ◽  
José M. Rico-Martínez
Keyword(s):  
Machine Tools ◽  
Degrees Of Freedom ◽  
Parallel Manipulators ◽  
Solar Panels ◽  
Spatial Mechanism ◽  
Moving Platforms ◽  
Parallel Kinematic ◽  
Radar Antennas

SUMMARYIn this work a new nonoverconstrained redundant decoupled robot, free of compound joints, formed from three parallel manipulators, with two moving platforms and provided with six active limbs connected to the fixed platform, called LinceJJP, is presented. Interesting applications such as multi-axis machine tools with parallel kinematic architectures, solar panels, radar antennas, and telescopes are available for this novel spatial mechanism.

Pedestrian classification from moving platforms using cyclic motion pattern

2005 ◽  
Author(s):  
Yang Ran ◽  
Qinfen Zheng ◽  
I. Weiss ◽  
L.S. Davis ◽  
W. Abd-Almageed ◽  
...  
Keyword(s):  
Motion Pattern ◽  
Moving Platforms ◽  
Cyclic Motion

Postural Stability of Stand-Up Forklift Operators in Response to Normal Braking Procedures

2005 ◽  
Author(s):  
Chimba Mkandawire ◽  
Mark A. Nicosia ◽  
Tara L. A. Moor ◽  
Catherine F. Corrigan
Keyword(s):  
Americans With Disabilities Act ◽  
Postural Stability ◽  
Peak Acceleration ◽  
Moving Platforms ◽  
Poor Predictor

Balance retention and postural stability of forklift operators have not been well investigated in the literature. Our testing shows that forklift operators can maintain postural stability during routine braking procedures while using standup lift trucks, and that peak acceleration levels generated by lift trucks are below the peak acceleration levels mandated by the Americans with Disabilities Act for moving platforms. Our review of studies involving balance retention has shown that acceleration levels experienced by subjects who maintained postural stability were greater than the peak accelerations during forklift braking operation. In addition, acceleration levels alone are a poor predictor of a subject’s ability to maintain postural stability.

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