Kinematics and Friction in Grasping by Robotic Hands

1987 ◽  
Vol 109 (3) ◽  
pp. 398-404 ◽  
Author(s):  
E. N. Ohwovoriole
Keyword(s):  
Rigid Body ◽  
Kinematic Analysis ◽  
Screw Theory ◽  
Robotic Hands ◽  
Kinematic Theory ◽  
Novel Method ◽  
Total Freedom ◽  
The Stability

Using the extended screw theory, grasping is analyzed in terms of the complete and partial constraint of a rigid body. The underlying kinematic theory is first reviewed and illustrated. The extended screw theory is then used to determine the disturbing and nondisturbing external wrenches, and resulting disturbances for a grasped object. This is a new application of the concept of total freedom based on the idea of component motions and the wrenches that can cause them. Determining the disturbing and nondisturbing wrenches is tantamount to determining the stability of the grasp in regard to total freedom. Finally, a novel method of incorporating friction in the kinematic analysis of grasping using screw theory is also developed using the concepts of apparent normals and apparent motions.

Sir Robert Stawell Ball and methodologies of modern screw theory

2002 ◽  
Vol 216 (1) ◽  
pp. 1-11 ◽  
Author(s):  
H Lipkin ◽  
J Duffy
Keyword(s):  
Computational Geometry ◽  
Rigid Body ◽  
Lie Algebra ◽  
Screw Theory ◽  
Mechanical Design ◽  
Ball Screw ◽  
Dual Numbers ◽  
Body Dynamics ◽  
Rigid Body Mechanics ◽  
Multi Body

The theory of screws was largely developed by Sir Robert Stawell Ball over 100 years ago to investigate general problems in rigid body mechanics. Nowadays, screw theory is applied in many different but related forms including dual numbers, Plilcker coordinates and Lie algebra. An overview of these methodologies is presented along with a perspective on Ball. Screw theory has re-emerged after a hiatus to become an important tool in robot mechanics, mechanical design, computational geometry and multi-body dynamics.

Stability of a Rigid Body With an Oscillating Particle: An Application of MACSYMA

1985 ◽  
Vol 52 (3) ◽  
pp. 686-692 ◽  
Author(s):  
L. A. Month ◽  
R. H. Rand
Keyword(s):  
Angular Velocity ◽  
Rigid Body ◽  
Classical Problem ◽  
Moment Of Inertia ◽  
Model Parameters ◽  
Stability Chart ◽  
The Stability ◽  
Transition Curves ◽  
Minimum Moment ◽  
Small Angular Velocity

This problem is a generalization of the classical problem of the stability of a spinning rigid body. We obtain the stability chart by using: (i) the computer algebra system MACSYMA in conjunction with a perturbation method, and (ii) numerical integration based on Floquet theory. We show that the form of the stability chart is different for each of the three cases in which the spin axis is the minimum, maximum, or middle principal moment of inertia axis. In particular, a rotation with arbitrarily small angular velocity about the maximum moment of inertia axis can be made unstable by appropriately choosing the model parameters. In contrast, a rotation about the minimum moment of inertia axis is always stable for a sufficiently small angular velocity. The MACSYMA program, which we used to obtain the transition curves, is included in the Appendix.

Measurement of Angular Acceleration of a Rigid Body Using Linear Accelerometers

1975 ◽  
Vol 42 (3) ◽  
pp. 552-556 ◽  
Author(s):  
A. J. Padgaonkar ◽  
K. W. Krieger ◽  
A. I. King
Keyword(s):  
Experimental Data ◽  
Rigid Body ◽  
Simple Procedure ◽  
Three Dimensional ◽  
Angular Acceleration ◽  
Theory And Practice ◽  
Body Segments ◽  
Impact Biomechanics ◽  
The Stability ◽  
Definition Of

The computation of angular acceleration of a rigid body from measured linear accelerations is a simple procedure, based on well-known kinematic principles. It can be shown that, in theory, a minimum of six linear accelerometers are required for a complete definition of the kinematics of a rigid body. However, recent attempts in impact biomechanics to determine general three-dimensional motion of body segments were unsuccessful when only six accelerometers were used. This paper demonstrates the cause for this inconsistency between theory and practice and specifies the conditions under which the method fails. In addition, an alternate method based on a special nine-accelerometer configuration is proposed. The stability and superiority of this approach are shown by the use of hypothetical as well as experimental data.

scholarly journals Experimental and Numerical Investigation on the Stability of Loess Embankment Treated by Chemical Solution under Freezing-Thawing Conditions

2021 ◽  
Author(s):  
Hua Liu ◽  
Zelin Niu ◽  
Yuanhong Dong ◽  
Naifei Liu ◽  
Shuocheng Zhang
Keyword(s):  
Shear Strength ◽  
Safety Factor ◽  
Limit Equilibrium ◽  
Solution Concentration ◽  
Chemical Solution ◽  
Compression Index ◽  
Limit Equilibrium Methods ◽  
Novel Method ◽  
The Stability ◽  
Embankment Stability

Abstract In order to study the influence of chemical solution on the stability of loess embankment in seasonally frozen regions, the compression index, shear strength index and embankment safety factor of compacted loess fillings that were treated by different concentrations of chemical solution were analyzed through laboratory test and slope stability analysis program. The experimental results showed that the collapsible coefficients of remolded loess treated by different chemical solution will all increase which comparing the distilled water, and then will change again after freezing-thawing cycles (FTCs). The compression index of undisturbed loess will show regularity with the increase of chemical solution concentration. The shear strength of remolded loess also changed under the chemical solution and FTCs. Besides, simulation of the strength parameters by limit equilibrium methods showed that the safety factor of loess embankment with treatment of solution was significantly higher than that of untreated one, and the FTC would cause a further deterioration. The embankment stability improved after treated by chemical solution without considering seepage of rainwater. These results would provide a novel method to the problem of embankment stability related to environmental condition changes.

scholarly journals On the Stability Analysis of a Coupled Rigid Body

2018 ◽  
Vol 09 (03) ◽  
pp. 210-222
Author(s):  
Olaniyi S. Maliki ◽  
Victor O. Anozie
Keyword(s):  
Stability Analysis ◽  
Rigid Body ◽  
The Stability

scholarly journals Poly(catecholamine) Coating and Biofunctionalization of CsPbBr3 Microcrystals

2021 ◽  
Author(s):  
Sangyeon Cho ◽  
Seok-Hyun Yun
Keyword(s):  
Lipid Bilayers ◽  
Environmental Stability ◽  
Live Cells ◽  
Functional Coatings ◽  
Common Strategy ◽  
Novel Method ◽  
Halide Perovskites ◽  
The Stability ◽  
New Applications

<p>Lead halide perovskites (LHP) microcrystals are promising materials for various optoelectronic applications. Surface coating on particles is a common strategy to improve their functionality and environmental stability, but LHP is not amenable to most coating chemistries because of its intrinsic weakness against polar solvents. Here, we describe a novel method of synthesizing LHP microcrystals in a super-saturated polar solvent using sonochemistry and applying various functional coatings on individual microcrystals <i>in situ</i>. We synthesize cesium lead bromine perovskite (CsPbBr<sub>3</sub>) microparticles capped with organic poly-norepinephrine (pNE) layers. The catechol group of pNE coordinates to bromine-deficient lead atoms, forming a defect-passivating and diffusion-blocking shell. The pNE layer enhances the stability of CsPbBr<sub>3</sub> in water by 2,000-folds, enabling bright luminescence and lasing from single microcrystals in water. Furthermore, the pNE shell permits biofunctionalization with proteins, small molecules, and lipid bilayers. Luminescence from CsPbBr<sub>3</sub> microcrystals is sustained in water over 1 hour and observed in live cells. The functionalization method may enable new applications of LHP particles in water-rich environments.<b></b></p>

An algorithm for the 3D ROck Slope Kinematic Analysis (ROKA) based on RPAS digital photogrammetry data.

2021 ◽  
Author(s):  
Niccolò Menegoni ◽  
Daniele Giordan ◽  
Cesare Perotti
Keyword(s):  
Kinematic Analysis ◽  
Rock Slope ◽  
Traditional Approach ◽  
Rock Slopes ◽  
Digital Photogrammetry ◽  
Modes Of Failure ◽  
Wedge Sliding ◽  
Flexural Toppling ◽  
The Stability ◽  
Digital Outcrop

&lt;p&gt;Among the several adopted methods for the kinematic analysis of the possible modes of failure that could affect a rock slope, the Markland test is the most used. Whereas, it has the advantage of being simple and fast, it has some limits, as the impossibility to manually consider the several different slope orientations and their interaction with the discontinuity dimensions and positions.&lt;/p&gt;&lt;p&gt;Recently, the improvements in the Remote Piloted Aerial System (RPAS) digital photogrammetry techniques for the development and mapping of Digital Outcrop Models (DOMs) have given the possibility of developing new automatized digital approaches. In this study, ROKA (ROck slope Kinematic Analysis) algorithm is presented. It is an open-source algorithm, written in MATLAB language, which aims to perform the kinematic analysis of the stability of a rock slope using the discontinuity measurements collected onto 3D DOMs. Its main advantage is the possibility to identify the possible critical combination between the 3D georeferenced discontinuities and the local surface of the slope. In particular, the critical combinations that can activate the planar sliding, flexural toppling, wedge sliding and direct toppling modes of failures can be detected and highlighted directly on the DOM. Hence, the ROKA algorithm can make the traditional approach for the kinematic analysis of a rock slope more effective, allowing not only to simplify the analysis, but also to increase its detail. This can be very important, in particular, for the analysis of large and complex rock slopes.&lt;/p&gt;

scholarly journals SYNTHESIS AND STABILITY OF RESVERATROL-CONJUGATED GOLD NANOPARTICLES MODIFIED WITH POLYETHYLENE GLYCOL

2020 ◽  
pp. 230-236
Author(s):  
RADITYA ISWANDANA ◽  
RICHA NURSELVIANA ◽  
SUTRIYO SUTRIYO
Keyword(s):  
Particle Size ◽  
Gold Nanoparticles ◽  
Polyethylene Glycol ◽  
Zeta Potential ◽  
High Performance ◽  
Entrapment Efficiency ◽  
Test Results ◽  
Novel Method ◽  
The Stability ◽  
Phosphate Buffered Saline

Objective: Gold nanoparticles (AuNPs) are highly useful for drug delivery, but their application is limited by their stability as they readily aggregate.This issue can be prevented by adding a stabilizing agent such as resveratrol (RSV), which is a polyphenol derived from plants, that is used to preventcancer. Therefore, we propose a novel method to prepare stable RSV-conjugated nanoparticles modified with polyethylene glycol (RSV-AuNP-PEG).Methods: In the first step, the Turkevich method was used to synthesize the AuNPs. Then, PEG was added as stabilizer agent and conjugated with RSV.The synthesized conjugates were characterized using ultraviolet-visible spectrophotometry, Fourier transform infrared spectroscopy, particle sizeanalysis, and high-performance liquid chromatography.Results: The obtained RSV-AuNP-PEG had a particle size of 83.93 nm with a polydispersity index (PDI) of 0.562 and formed a translucent purple-redfluid in solution. The zeta potential was −22.9 mV, and the highest entrapment efficiency was 75.86±0.66%. For comparison, the RSV-AuNP solutionwas purple and turbid, the particle size was 51.97 nm with a PDI of 0.694, and the zeta potential was −24.6 mV. The stability test results showed thatthe storage stability of RSV-AuNP-PEG was better than that of AuNP-RSV. Further, the RSV-AuNP-PEG was shown to be most stable in 2% bovine serumalbumin (BSA) while the AuNP-RSV was most stable in 2% BSA in phosphate-buffered saline pH 7.4.Conclusion: These results show that modification of RSV-conjugated AuNPs with PEG effectively prevents their aggregation in storage, but only incertain mediums.

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