Effect of Combined Motion on Force Transmission of a Flexible Instrument

2014 ◽  
Author(s):  
J. P. Khatait ◽  
D. M. Brouwer ◽  
R. G. K. M. Aarts ◽  
J. L. Herder
Keyword(s):  
Friction Force ◽  
Velocity Ratio ◽  
Axial Direction ◽  
Experimental Results ◽  
Force Transmission ◽  
Rigid Tube ◽  
Combined Motion ◽  
Flexible Instrument ◽  
Translation Motion ◽  
Analytical Result

The force transmission of a flexible instrument through an endoscope is deteriorated due to friction between the contacting surfaces. Friction force along the axial direction can be reduced by combining the translation motion input with rotational motion input at the proximal end of the instrument. The effect of the combined motion on the force transmission is studied for a flexible instrument through a curved rigid tube. A mathematical formula is derived for the reduction in friction force along the axial direction due to the combined motion input. The force transmission of a flexible instrument through a curved rigid tube is analysed using the capstan equation. The ratio of the input and output forces is compared for the combined motion with that of the translation motion only. A ratio ζ is defined to measure the reduction in the friction force along the axial direction due to the combined motion input. The analytical result shows the reduction in the friction force for the combined motion input. A flexible multibody model is set up and various simulations are performed with different motion inputs. The simulation result showed a reduction in the value of ζ in accordance with the analytical result for the given velocity ratio. The results are further validated with the experimental results. The simulation and experimental results show an agreement with the analytical solutions. The knowledge of force transmission with a combination of motions can be used to increase the force fidelity of a flexible instrument in applications like robotic surgery with a flexible instrument.

Improved Force Transmission of a Flexible Surgical Instrument by Combining Input Motion

2015 ◽  
Vol 9 (1) ◽  
Author(s):  
Jitendra P. Khatait ◽  
Dannis M. Brouwer ◽  
Ronald G. K. M. Aarts ◽  
Just L. Herder
Keyword(s):  
Friction Force ◽  
Velocity Ratio ◽  
Translational Motion ◽  
Analytical Formula ◽  
Axial Direction ◽  
Force Transmission ◽  
Multibody Model ◽  
Combined Motion ◽  
Flexible Instrument ◽  
Input Motion

The force transmission of a flexible instrument through an endoscope is considerably deteriorated due to friction between the contacting surfaces. Friction force along the axial direction can be reduced by combining the translational motion input with rotation. A ratio ζ is defined to measure the reduction in the friction force along the axial direction due to the combined motion input at the proximal end of the instrument. An analytical formula is derived that shows the reduction in the friction force for the combined motion input. A flexible multibody model was setup and various simulations were performed with different motion inputs. The simulation result showed a reduction of 80% in the value of ζ in accordance with the analytical result for the given velocity ratio. Several experiments were performed with constant translational motion input combined with constant and sinusoidal rotational motion input. A maximum reduction of 84% is obtained in the value of ζ against a reduction of 89% calculated analytically. The knowledge of force transmission with a combination of motions can be used to increase the force fidelity of a flexible instrument in applications like robotic surgery with a flexible instrument.

Experimental Study of a Variable Pressure Damper on Automotive Valve Motion

1996 ◽  
Author(s):  
Jin-Jang Liou ◽  
Grodrue Huang ◽  
Wensyang Hsu
Keyword(s):  
Experimental Study ◽  
Friction Coefficient ◽  
Friction Force ◽  
High Speed ◽  
Experimental Results ◽  
Variable Pressure ◽  
Friction Forces ◽  
Valve Spring ◽  
Valve Motion

Abstract A variable pressure damper (VPD) is used here to adjusted the friction force on the valve spring to investigate the relation between the friction force and the valve bouncing phenomenon. The friction force on the valve spring is found experimentally, and the corresponding friction coefficient is also determined. Dynamic valve displacements at different speeds with different friction forces are calibrated. Bouncing and floating of the valve are observed when the camshaft reaches high speed. From the measured valve displacement, the VPD is shown to have significant improvement in reducing valve bouncing distance and eliminating floating. However, experimental results indicate that the valve bouncing can not be eliminated completely when the camshaft speed is at 2985 rpm.

Count Distribution and Precision in X-Ray Fluorescence Analysis

1959 ◽  
Vol 3 ◽  
pp. 95-107 ◽  
Author(s):  
Kurt F.J. Heinrich
Keyword(s):  
Standard Deviation ◽  
Poisson Distribution ◽  
Fluorescence Analysis ◽  
Experimental Results ◽  
X Ray ◽  
Statistical Fluctuations ◽  
Count Distribution ◽  
Analytical Result ◽  
Instrument Reliability

AbstractThe statistical fluctuations of photon counts arediscussedas a factor limiting the precision of the analytical result. Assuming a Poisson distribution, the theoretical standard deviation of the result can be calculated. While this prediction does not consider causes of variation other than the count statistics, it is useful in developing methods and checking instrument reliability. Practical examples using experimental results are given.

Force Analysis of the Film in a COF Chip Mounter’s Loader

2004 ◽  
Author(s):  
Dein Shaw ◽  
H. C. Lin
Keyword(s):  
Friction Force ◽  
Relative Motion ◽  
Lower Layer ◽  
Axial Direction ◽  
Tension Force ◽  
Force Distribution ◽  
Force Analysis ◽  
Transportation Vehicle

In this study, the tension force distributions in the film of COF cartridge are studied. It is noted that if the tension force on the film is too high, the interface between chip and film cracked. If the force is too low, there is no enough friction force to keep the COF in fix position when the cartridge is on the transportation vehicle. The relative motion between the chips of lower layer and the film of upper layer will cause the fatigue of interface of chips and film. It is also important to note that due to the friction the tension force at any section of the film is different. To fine the force distribution, a method to determine the tension force is developed and only effect of axial direction is considered. The assumption makes the film behave like a string. The results show that the forces on the film are different whenever the film passes a chip underneath.

scholarly journals Design and Analysis of a Novel Articulated Drive Mechanism for Multifunctional NOTES Robot

2015 ◽  
Vol 7 (1) ◽  
Author(s):  
Tao Shen ◽  
Carl A. Nelson ◽  
Kevin Warburton ◽  
Dmitry Oleynikov
Keyword(s):  
Endoscopic Surgery ◽  
Robotic Manipulator ◽  
Experimental Results ◽  
Force Transmission ◽  
Natural Orifice ◽  
Drive Mechanism ◽  
Dc Motors ◽  
Preliminary Validation ◽  
Complex Shapes

This paper presents a novel articulated drive mechanism (ADM) for a multifunctional natural orifice transluminal endoscopic surgery (NOTES) robotic manipulator. It consists mainly of three major components including a snakelike linkage, motor housing, and an arm connector. The ADM can articulate into complex shapes for improved access to surgical targets. A connector provides an efficient and convenient modularity for insertion and removal of the robot. Four DC motors guide eight cables to steer the robot. The workspace, cable displacement and force transmission relationships are derived. Experimental results give preliminary validation of the feasibility and capability of the ADM system.

CHAOTIC BEHAVIOR OF FRICTION FORCE

1992 ◽  
Vol 02 (01) ◽  
pp. 205-209 ◽  
Author(s):  
JERZY WOJEWODA ◽  
RONALD BARRON ◽  
TOMASZ KAPITANIAK
Keyword(s):  
Mechanical System ◽  
Friction Force ◽  
Relative Velocity ◽  
Chaotic Behavior ◽  
Experimental Results ◽  
Velocity Dependence ◽  
Force Velocity

Experimental results of friction in a mechanical system are reported. Strange properties of the friction force-velocity dependence are shown, where this relationship does not follow the typical assumption of the force proportional to the sign of the relative velocity.

Theoretical Model of Plastic Hysteresis in Spherical Contact Under Combined Normal and Tangential Loading

2008 ◽  
Author(s):  
Yuri Kligerman ◽  
Izhak Etsion
Keyword(s):  
Theoretical Model ◽  
Stress State ◽  
Friction Force ◽  
Contact Area ◽  
Contact Condition ◽  
Experimental Results ◽  
Tangential Displacement ◽  
Elastic Plastic ◽  
Plastic Sphere ◽  
Good Agreement

The behavior of an elastic-plastic contact between a deformable sphere and a rigid flat under combined constant normal and reciprocating tangential loading is investigated in the present work. The theoretical model is based on the assumptions of full stick contact condition and two kinds of the sphere material hardening. Hysteretic change of friction force versus tangential displacement during reciprocating tangential loading is investigated along with the study of the change of the contact area and stress state in the elastic-plastic sphere. Good agreement between theoretical and experimental results is obtained.

Force Transfer Behavior of Mechanically Fastened Structures in Light Weight Design

2008 ◽  
Author(s):  
C. Friedrich ◽  
D. Koch ◽  
G. Dinger
Keyword(s):  
Axial Direction ◽  
Light Weight ◽  
Force Transmission ◽  
Transmission Design ◽  
Component Systems ◽  
Mechanical Fastening ◽  
Mechanically Fastened ◽  
Transfer Behavior ◽  
Weight Design ◽  
Increased Sensitivity

Light weight design gets more and more important regarding mass inertia of moved component systems. By this reason new products are using more and more light materials which exhibit an increased sensitivity due to force transmission in component contact zones. This paper gives an overview about related criteria when designing fastened component systems with transverse loading. Numeric stress analysis with FEA calculates a detailed stress distribution with significant inhomogeneities. The reasons for increased sensitivity of light materials get obvious. Often bolted joints are used to realize friction-based transverse force transmission – design criteria which become important in light weight design are shown (e.g. self loosening). Forces can also be transmitted in axial direction; an example is proposed with an effective mechanical fastening system of long composite components without adhesives. Finally, conclusions for future engineering design are drawn.

Study on Isolation Device for Decrease of Displacement by Using Control of Friction

2005 ◽  
Author(s):  
Masanori Shintani ◽  
Yuichi Hattori ◽  
Tadashi Kotera
Keyword(s):  
Natural Frequency ◽  
Analytical Model ◽  
Friction Force ◽  
External Force ◽  
Simulation Analysis ◽  
Relative Displacement ◽  
Earthquake Damage ◽  
Experimental Results ◽  
Isolation Device ◽  
Analytical Program

This paper deals with an isolation device by using friction force. An isolation device decreases response acceleration and external force. Therefore, earthquake damage is reduced. However, an isolation device has a demerit for large relative displacement. A low horizontal natural frequency decreases the response acceleration. Therefore, in this research, a soft spring is attached to the base of the structure. The purpose of this research is to decrease the relative displacement by using the friction force. Then, an analytical model in consideration of the friction force is proposed, and a simulation is analyzed with well-known earthquake waves. Consequently, as the friction force increases, the results show that the relative displacement decreases. However, it is found that the response acceleration increases. But it is thought that optimal friction force exists, and this force decreases both the response acceleration and the relative displacement. This is considered to change with the properties of earthquake waves. Therefore, it is thought that the response acceleration and the relative displacement are decreased by changing the friction force to the most suitable value for earthquakes. This isolation device is examined with simulation analysis. An experimental device is made under the same conditions as the proposed analytical model. The analytical results are compared with the experimental results, and the validity of an analytical program is examined.

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