A New View on Grasping

Motor Control ◽  
1999 ◽  
Vol 3 (3) ◽  
pp. 237-271 ◽  
Author(s):  
Jeroen B.J. Smeets ◽  
Eli Brenner
Keyword(s):  
Surface Roughness ◽  
Visual Information ◽  
Experimental Studies ◽  
Movement Speed ◽  
Object Size ◽  
Extensive Review ◽  
Minimum Jerk ◽  
Alternative Description ◽  
Position And Orientation ◽  
Shape And Size

Reaching out for an object is often described as consisting of two components that are based on different visual information. Information about the object's position and orientation guides the hand to the object, while information about the object's shape and size determines how the fingers move relative to the thumb to grasp it. We propose an alternative description, which consists of determining suitable positions on the object—on the basis of its shape, surface roughness, and so on—and then moving one's thumb and fingers more or less independently to these positions. We modeled this description using a minimum-jerk approach, whereby the finger and thumb approach their respective target positions approximately orthogonally to the surface. Our model predicts how experimental variables such as object size, movement speed, fragility, and required accuracy will influence the timing and size of the maximum aperture of the hand. An extensive review of experimental studies on grasping showed that the predicted influences correspond to human behavior.

scholarly journals Experimental Investigation and Comparison of the Thermal Performance of Additively and Conventionally Manufactured Heat Exchangers

Metals ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 574
Author(s):  
Ana Vafadar ◽  
Ferdinando Guzzomi ◽  
Kevin Hayward
Keyword(s):  
Surface Roughness ◽  
Thermal Performance ◽  
Heat Exchangers ◽  
High Efficiency ◽  
Cooling System ◽  
Fluid Dynamic ◽  
Dynamic Performance ◽  
Experimental Studies ◽  
Manufacturing Method ◽  
Industrial Sectors

Air heat exchangers (HXs) are applicable in many industrial sectors because they offer a simple, reliable, and cost-effective cooling system. Additive manufacturing (AM) systems have significant potential in the construction of high-efficiency, lightweight HXs; however, HXs still mainly rely on conventional manufacturing (CM) systems such as milling, and brazing. This is due to the fact that little is known regarding the effects of AM on the performance of AM fabricated HXs. In this research, three air HXs comprising of a single fin fabricated from stainless steel 316 L using AM and CM methods—i.e., the HXs were fabricated by both direct metal printing and milling. To evaluate the fabricated HXs, microstructure images of the HXs were investigated, and the surface roughness of the samples was measured. Furthermore, an experimental test rig was designed and manufactured to conduct the experimental studies, and the thermal performance was investigated using four characteristics: heat transfer coefficient, Nusselt number, thermal fluid dynamic performance, and friction factor. The results showed that the manufacturing method has a considerable effect on the HX thermal performance. Furthermore, the surface roughness and distribution, and quantity of internal voids, which might be created during and after the printing process, affect the performance of HXs.

scholarly journals Experimental research on processing incomplete spherical surfaces of machine parts

2021 ◽  
Vol 346 ◽  
pp. 01031
Author(s):  
Andrei Katunin ◽  
Mikhail Burnashov ◽  
Anton Tryastsin ◽  
Alexander Edapin
Keyword(s):  
Surface Roughness ◽  
Experimental Research ◽  
Experimental Studies ◽  
Spherical Surfaces ◽  
Machine Parts ◽  
Ball Joints

Improving the durability and reliability of such components as ball joints of cars is very important. The article presents experimental studies to determine surface roughness of incomplete spherical surfaces of machine parts.

scholarly journals INVESTIGATION OF THE METHOD OF PROCESSING HOLES WITH A ROTARY CUP CUTTER WITH SURFACING

2021 ◽  
pp. 1-6
Author(s):  
Bakytzhan Donenbayev ◽  
Karibek Sherov ◽  
Assylkhan Mazdubay ◽  
Aybek Sherov ◽  
Medgat Mussayev ◽  
...  
Keyword(s):  
Surface Roughness ◽  
Cutting Tool ◽  
Large Diameter ◽  
Cutting Tools ◽  
Experimental Studies ◽  
Surface Hardness ◽  
Hard Metal ◽  
Metal Plates ◽  
Study Results ◽  
The Cost

This article presents the experimental study results of the process of rotational friction holes boring using a cup cutter surfaced by STOODY M7-G material. As a result of experimental studies, the following quality indicators were achieved: surface roughness within Ra=10÷1,25 micrometer; surface hardness within HB 212-248. Using a cup cutter surfaced by STOODY M7-G material in case of rotational friction boring of large-diameter holes for large-sized parts can improve processing performance in comparison with cutting tools equipped with hard metal plates and provided the required surface roughness. Preliminary calculations showed that the manufacture of cup cutters from non-instrumental materials reduces the cost of the cutting tool by 5-7 times and the cost of the operation by 1.5-2 times.

scholarly journals INFLUENCE OF CONSTRUCTIVE AND TECHNOLOGICAL PARAMETERS OF THE UNIT FOR STRIP TILL ON THE LUMPINESS

2020 ◽  
Author(s):  
G. Golub ◽  
◽  
A. Dvornyk
Keyword(s):  
Winter Wheat ◽  
Relative Position ◽  
Experimental Studies ◽  
Movement Speed ◽  
Technological Parameters ◽  
Depth Of Processing ◽  
Processing Depth ◽  
Economic Methods ◽  
Strip Tillage

The goal of the work. Investigate the influence of the relative position of the depth of processing with a chisel, the speed of movement of the unit and the distance between the cutting side discs on the lumpiness of the processed strip. Methods of research: analytical - quantitative determination of the quality of strip tillage; laboratory-field - for research, an experimental installation was completed with an MTZ-892 tractor and a section of the unit for strip tillage; statistical with generally accepted agronomic and economic methods. Results. Experimental studies of changes in the design and technological parameters of the unit for strip processing with the determination of lumpiness have been carried out. To study the main parameters, the depth of processing of the subsoiler (chisel) is taken from 13 to 27 cm, the distance between the cutting side discs is from 10 to 30 cm, the speed of the MTA is from 4 to 11 km/h. Unchanged parameters during the study: the distance from the axis of the front disc to the chisel is 50 cm, the distance from the chisel to the axis of the cutting side discs is 50 cm, the immersion depth of the cutting side discs is 10 cm. Experimental background is winter wheat stubble. Soil cultivation for winter wheat - deep (18 cm) disking, before that plowing to a depth of 25 cm. According to the research results, graphs of the dependence of lumpiness on the relative position of the chisel, cutting side discs and changes in the speed of the MTA were built. As the speed and distance between the side cutting discs increase, the lumpiness value decreases. Conclusions. Based on the results of the studies, the dependences of lumpiness on the relative position of the chisel and cutting side disks were obtained when the speed of the MTA was changed. It was determined that with an increase in the processing depth, the distance between the cutting side discs of 20 cm and the MTA movement speed of 7.5 km / h, a uniform increase in lumpiness is observed. The distance between the side cutting discs of 10 cm is not suitable for work.

scholarly journals Experimental Research on Discharge Forming Cutting-Electrochemical Machining of Single-Crystal Silicon

2021 ◽  
Vol 2021 ◽  
pp. 1-13
Author(s):  
Bin Xin ◽  
Wei Liu
Keyword(s):  
Surface Roughness ◽  
Single Crystal ◽  
Electrical Discharge ◽  
Electrical Discharge Machining ◽  
Electrochemical Machining ◽  
Single Crystal Silicon ◽  
Recast Layer ◽  
Movement Speed ◽  
Crystal Silicon ◽  
Wedm Process

During the wire electrical discharge machining (WEDM) process, a large number of discharge pits and a recast layer are easily generated on the workpiece surface, resulting in high surface roughness. A discharge forming cutting-electrochemical machining method for fabricating single-crystal silicon is proposed in this study to solve this problem. On the same processing equipment, single-crystal silicon is first cut using the discharge forming cutting method. Second, electrochemical anodic reaction technology is used to dissolve the discharge pits and recast layer on the single-crystal silicon surface. The machining mechanism of this process, the surface elements of the processed single-crystal silicon and a comparison of the kerf width are analyzed through experiments. On this basis, the influence of the movement speed of the copper foil electrode during electrochemical anodic dissolution on the final surface roughness is qualitatively analyzed. The experimental results show that discharge forming cutting-electrochemical machining can effectively eliminate the electrical discharge pits and recast layer, which are caused by electric discharge cutting, on the surface of single-crystal silicon, thereby reducing the surface roughness of the workpiece.

Statistical Analysis of Process Parameters in Drilling of Al/Al2O3p Metal Matrix Composites

2014 ◽  
Vol 14 (3) ◽  
pp. 171-175 ◽  
Author(s):  
Yashvir Singh ◽  
Amneesh Singla ◽  
Ajay Kumar
Keyword(s):  
Surface Roughness ◽  
Statistical Analysis ◽  
Process Parameters ◽  
Metal Matrix ◽  
Design Method ◽  
Experimental Studies ◽  
Cutting Speed ◽  
Depth Of Cut ◽  
Signal To Noise ◽  
Drilling Parameters

AbstractThis paper presents a statistical analysis of process parameters for surface roughness in drilling of Al/Al2O3p metal matrix composite. The experimental studies were conducted under varying spindle speed, feed rate, point angle of drill. The settings of drilling parameters were determined by using Taguchi experimental design method. The level of importance of the drilling parameters is determined by using analysis of variance. The optimum drilling parameter combination was obtained by using the analysis of signal-to-noise ratio. Through statistical analysis of response variables and signal-to-noise ratios, the determined significant factors are depth of cut and drill point angle with the contributions of 87% and 12% respectively, whereas the cutting speed is insignificant contributing by 1% only. Confirmation tests verified that the selected optimal combination of process parameter through Taguchi design was able to achieve desired surface roughness.

scholarly journals Experimental studies of the quality of embossed characters of the Braille alphabet

2016 ◽  
Vol 64 (3) ◽  
pp. 607-614
Author(s):  
R. Barczyk ◽  
D. Jasińska-Choromańska
Keyword(s):  
Surface Roughness ◽  
Statistical Analysis ◽  
3D Printing ◽  
Rapid Prototyping ◽  
Experimental Studies ◽  
Printed Text ◽  
Blind Persons ◽  
Blind Individuals

Abstract The paper presents studies pertaining to the quality of embossed characters of the Braille alphabet used, among other applications, for tagging drug labels. The following parameters of embossed inscriptions were measured: height, diameter of the dots and surface roughness (18 samples with various combinations of their values). 48 blind individuals assessed the quality of the printed text. Statistical analysis proved that a text with dots having height of 0.9 millimeter, diameter of 1.6 millimeters and roughness Ra of about 1 micrometer to be the best. The samples had been made using two different methods of rapid prototyping: PolyJet and SLS. 3D printing is increasingly popular and the studies proved the usefulness of these methods for labeling with embossed inscriptions, due to the repeatability, durability and quality they ensure. The assessing group of blind individuals was comprised of 24 persons 14–17 years old and other 24 persons aged over 60 who were not proficient in reading Braille alphabet, This allows to conclude that a text featuring the above values of the parameters will be easy to read for the majority of blind persons.

Experimental Studies on Surface Roughness in Drilling MDF Composite Panels using Taguchi and Regression Analysis Method

2012 ◽  
Vol 12 (10) ◽  
pp. 978-984 ◽  
Author(s):  
S. Prakash ◽  
J. Lilly Mercy ◽  
K. Palanikuma ◽  
S. Ramesh ◽  
M.I. Rizwan Jamal ◽  
...  
Keyword(s):  
Surface Roughness ◽  
Regression Analysis ◽  
Experimental Studies ◽  
Composite Panels ◽  
Analysis Method

scholarly journals Transformation of Surface Roughness of Mg Alloy Tubes During Laser Dieless Drawing

2020 ◽  
Vol 29 (11) ◽  
pp. 7736-7743
Author(s):  
Andrij Milenin ◽  
Tsuyoshi Furushima ◽  
Jiří Němeček
Keyword(s):  
Surface Roughness ◽  
Longitudinal Strain ◽  
Maximum Stress ◽  
Experimental Studies ◽  
Strain Curve ◽  
Surface Roughening ◽  
Drawing Process ◽  
Stress Strain Curve ◽  
Stress Strain ◽  
Dieless Drawing

AbstractThe paper investigates the transformation of surface roughness of tubes made from magnesium and magnesium alloys as a function of their longitudinal strain during laser dieless drawing. Experimental studies on three materials (AZ31, MgCa08, and pure Mg) have shown that the dependence of roughness on the longitudinal strain is nonlinear and exhibits a minimum. The proposed explanation for this is that the transformation of surface roughness occurs following two mechanisms. The first mechanism involves stretching of the tube and the decreasing of existing roughness with the increasing elongation. The second mechanism is based on the strain-induced surface roughening phenomenon. This mechanism leads to an increase in roughness with the increasing elongation. To analyze these mechanisms, a numerical model of roughness formation is used. It is experimentally shown that the position of the minimum roughness concerning the tube longitudinal strain is correlated with the stress-strain curve of the material under laser dieless drawing conditions. The obtained results provide a practical way to reduce surface roughness of tubes produced by the laser dieless drawing process. According to the proposed method, to achieve minimum roughness, it is necessary to keep the longitudinal strain under a specific value. This value is close to the strain, which corresponds to the maximum stress on the stress-strain curve of the material for temperature and strain rate, corresponding laser dieless drawing conditions.

ROUGHNESS EFFECT OF DIFFERENT GEOMETRIES ON MICRO GAS FLOWS BY LATTICE BOLTZMANN SIMULATION

2009 ◽  
Vol 20 (06) ◽  
pp. 953-966 ◽  
Author(s):  
CHAOFENG LIU ◽  
YUSHAN NI ◽  
YONG RAO
Keyword(s):  
Surface Roughness ◽  
Lattice Boltzmann ◽  
Experimental Studies ◽  
Resistance Coefficient ◽  
Lattice Boltzmann Model ◽  
Gas Flows ◽  
Fractal Boundary ◽  
Roughness Effects ◽  
Roughness Effect ◽  
Relative Roughness

The roughness effects of the gas flows of nitrogen and helium in microchannels with various relative roughnesses and different geometries are studied and analyzed by a lattice Boltzmann model. The shape of surface roughness is simulated to be square, sinusoidal, triangular, and fractal. Numerical computations compared with theoretical and experimental studies show that the roughness geometry is an important factor besides the relative roughness in the study of the effects of surface roughness. The fractal boundary presents a higher influence on the velocity field and the resistance coefficient than other regular boundaries at the same Knudsen number and relative roughness. In addition, the effects of rarefaction, compressibility, and roughness are strongly coupled, and the roughness effect should not be ignored in studying rarefaction and compressibility of the microchannel as the relative roughness increases.

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