Understanding suspension rheology of anisotropically-charged platy minerals from direct interaction force measurement using AFM

2013 ◽  
Vol 18 (2) ◽  
pp. 149-156 ◽  
Author(s):  
Lujie Yan ◽  
Jacob H. Masliyah ◽  
Zhenghe Xu
1998 ◽  
Vol 538 ◽  
Author(s):  
A. El-Azab

AbstractThe present work aims at studying the image stress and image Peach-Koehler force fields for three-dimensional dislocation configurations in a single crystal of finite volume. It is shown that the image stress field is significant within the entire crystal volume, and that the image Peach-Koehler force can be of the same order of magnitude as the direct interaction force calculated from the infinite domain solution. The results demonstrate that image stress gives rise to long-range interaction forces that are important in meso-scale dynamics of dislocation structures.


2009 ◽  
Vol 79-82 ◽  
pp. 7-10 ◽  
Author(s):  
Ying Song ◽  
Yan Liang Du ◽  
Bao Chen Sun

Measurement of wheel/rail contact forces is of importance. Traditional methods for wheel/rail interaction force measurement all need strain gauges on wheel sets and/or rails. Because strain gauges have the performances of zero-drift, poor anti-interference property and instability of test system, they can’t meet wheel/rail force test requirements in high-speed and heavy haul railways. A new method based on PVDF piezoelectric sensing technology is presented for the test of vertical and horizontal wheel/rail force in this paper. Firstly, based on the wheel/rail interaction characteristics, the restriction condition of track and strain sensing principle of PVDF films, principle for measuring vertical and lateral wheel/rail interaction forces is proposed. Then a series of tests were carried out to compare the performance of PVDF strain sensors with the one of strain gauges. The results show that the PVDF strain sensor has better reliability in wheel/rail force monitoring. Finally numerical analysis by Finite Element Method has been carried out to verify the feasibility of the method presented in this paper.


2020 ◽  
Vol 172 ◽  
pp. 107791 ◽  
Author(s):  
Gi Young Kim ◽  
Suguna Perumal ◽  
Soon Cheon Kim ◽  
Sang-Ho Lee ◽  
Seung Man Noh ◽  
...  

2019 ◽  
Vol 9 (12) ◽  
pp. 2573
Author(s):  
Jing Guo ◽  
Bo Xiao ◽  
Hongliang Ren

Force sensing in robotic-assisted minimally invasive surgery (RMIS) is crucial for performing dedicated surgical procedures, such as bilateral teleoperation and palpation. Due to the bio-compatibility and sterilization requirements, a specially designed surgical tool/shaft is normally attached to the sensor while contacting the organ targets. Through this design, the measured force from the sensor usually contains uncertainties, such as noise, inertial force etc., and thus cannot reflect the actual interaction force with the tissue environment. Motivated to provide the authentic contact force between a robotic tool and soft tissue, we proposed a data-driven force compensation scheme without intricate modeling to reduce the effects of force measurement uncertainties. In this paper, a neural-network-based approach is utilized to automatically model the inertial force subject to noise during the robotic palpation procedure, then the exact contact force can be obtained through the force compensation method which cancels the noise and inertial force. Following this approach, the genuine interaction force during the palpation task can be achieved furthermore to improve the appraisal of the tumor surrounded by the soft tissue. Experiments are conducted with robotic-assisted palpation tasks on a silicone-based soft tissue phantom and the results verify the effectiveness of the suggested method.


Sensors ◽  
2021 ◽  
Vol 21 (19) ◽  
pp. 6545
Author(s):  
Sun’an Wang ◽  
Binquan Zhang ◽  
Zhenyuan Yu ◽  
Yu’ang Yan

With the emerging of wearable robots, the safety and effectiveness of human-robot physical interaction have attracted extensive attention. Recent studies suggest that online measurement of the interaction force between the robot and the human body is essential to the aspects above in wearable exoskeletons. However, a large proportion of existing wearable exoskeletons monitor and sense the delivered force and torque through an indirect-measure method, in which the torque is estimated by the motor current. Direct force/torque measuring through low-cost and compact wearable sensors remains an open problem. This paper presents a compact soft sensor system for wearable gait assistance exoskeletons. The contact force is converted into a voltage signal by measuring the air pressure within a soft pneumatic chamber. The developed soft force sensor system was implemented on a robotic hip exoskeleton, and the real-time interaction force between the human thigh and the exoskeleton was measured through two differential soft chambers. The delivered torque of the hip exoskeleton was calculated based on a characterization model. Experimental results suggested that the sensor system achieved direct force measurement with an error of 10.3 ± 6.58%, and torque monitoring for a hip exoskeleton which provided an understanding for the importance of direct force/torque measurement for assistive performance. Compared with traditional rigid force sensors, the proposed system has several merits, as it is compact, low-cost, and has good adaptability to the human body due to the soft structure.


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