Force Evaluation of Tendon Routing for Underactuated Grasping

2021 ◽  
pp. 1-9
Author(s):  
Angus B. Clark ◽  
Lois Liow ◽  
Nicolas Rojas
Keyword(s):  
Optimum Condition ◽  
Theoretical Models ◽  
External Factors ◽  
Experimental Comparison ◽  
Adaptive Behaviour ◽  
Joint Torques ◽  
Contact Points ◽  
Single Finger ◽  
Modelling Analysis ◽  
Force Vectors

Abstract While the modelling analysis of the kinetostatic behaviour of underactuated tendon-driven robotic fingers has been largely addressed in the literature, tendon routing is often not considered by these theoretical models. Tendon routing path plays a fundamental role in defining joint torques, and subsequently the force vectors produced by the phalanxes. However, dynamic tendon behaviour is difficult to predict and is influenced by many external factors including tendon friction, the shape of the grasped object, the initial pose of the fingers, and finger contact points. In this paper, we present an experimental comparison of the force performance of nine fingers, with different tendon routing configurations. We use the concept of force-isotropy, in which forces are equal and distributed on each phalanx as the optimum condition for an adaptive grasp. Our results show only some of the finger designs surveyed exhibited a partial adaptive behaviour, showing distributed force for the proximal and distal phalanxes throughout grasping cycles, while other routings resulted in only a single finger remaining in contact with the object.

Improvement in the prevention of asbestos fibre release from ceiling materials by increasing the penetration of a silicate stabilizer through dilution

2017 ◽  
Vol 27 (7) ◽  
pp. 917-924
Author(s):  
Hyungyoo Shin ◽  
Youngkue Choi ◽  
Boram Jeon ◽  
Jooyeon Ha ◽  
Yleshik Sun ◽  
...  
Keyword(s):  
Optimum Condition ◽  
Dilution Rate ◽  
External Factors ◽  
Distilled Water ◽  
Asbestos Fibre ◽  
Fibre Concentration ◽  
Penetration Depths

The effect of diluting asbestos stabilizer on its performance of suppressing the asbestos fibre release has been investigated in terms of its penetrability into ceiling materials containing asbestos fibres. The performance of a silicate stabilizer was determined for cases where the ceiling material was damaged by external factors. The higher dilution rate of the stabilizer resulted in lower viscosities and hence greater penetration depths into asbestos ceiling materials. In addition, for cases in which the diluted stabilizer was sprayed several times onto the ceiling materials, the released asbestos fibre concentration was shown to be reduced by approximately 89% compared to the case of damaged ceiling material. Furthermore, this held true in cases where treated ceiling materials were damaged. The optimum condition, considering both performance and efficiency, is for a stabilizer with distilled water to be applied onto the damaged asbestos ceiling materials several times.

scholarly journals Optimal grasp planning for a dexterous robotic hand using the volume of a generalized force ellipsoid during accepted flattening

2017 ◽  
Vol 14 (1) ◽  
pp. 172988141668713 ◽  
Author(s):  
Peng Jia ◽  
Wei li Li ◽  
Gang Wang ◽  
Song Yu Li
Keyword(s):  
Simulation Analysis ◽  
Internal Force ◽  
Planning Method ◽  
Robotic Hand ◽  
Grasp Planning ◽  
Joint Torques ◽  
Contact Points ◽  
Generalized Force ◽  
Internal Forces ◽  
Dexterous Hand

A grasp planning method based on the volume and flattening of a generalized force ellipsoid is proposed to improve the grasping ability of a dexterous robotic hand. First, according to the general solution of joint torques for a dexterous robotic hand, a grasping indicator for the dexterous hand—the maximum volume of a generalized external force ellipsoid and the minimum volume of a generalized contact internal force ellipsoid during accepted flattening—is proposed. Second, an optimal grasp planning method based on a task is established using the grasping indicator as an objective function. Finally, a simulation analysis and grasping experiment are performed. Results show that when the grasping experiment is conducted with the grasping configuration and positions of contact points optimized using the proposed grasping indicator, the root-mean-square values of the joint torques and contact internal forces of the dexterous hand are at a minimum. The effectiveness of the proposed grasping planning method is thus demonstrated.

scholarly journals Experimental Comparison of PID Based RPM Control for Long Horizontal vs. Vertical Drillstring

2021 ◽  
Author(s):  
Aditya Sharma ◽  
Saket Srivastava ◽  
Catalin Teodoriu ◽  
Marius Stan
Keyword(s):  
Active Control ◽  
Closed Loop ◽  
Vibration Suppression ◽  
Rotation Speed ◽  
Experimental Comparison ◽  
Pid Tuning ◽  
Contact Points ◽  
Loop Feedback ◽  
Closed Loop Feedback ◽  
Field Deployment

Drilling vibrations has been identified as a key performance limiter that prevents successful energy transfer from the surface to the bit. The resultant irregular bit rotation speed causes drilling challenges like poor hole quality and reduction in rate of penetration to name a few. Amongst other vibration suppression techniques, active control of vibrations is widely used and recommended. Active control system utilizes a closed loop feedback control to continuously adapt to downhole vibrations detected at the surface. The system requires regular tuning and upgrades which is done experimentally before field deployment. The paper presents a PID based experimental tuning of horizontal and vertical strings for irregular RPM. In doing so, the paper highlights the need of having horizontal experimental setups for state-of-the-art PID tuning for downhole RPM. The settling time of irregular RPM for horizontal setup is found to be lower than the vertical configuration due to multiple contact points and increased friction coefficient.

Predictive Simulation of Human Ladder Climbing

2013 ◽  
Author(s):  
Hyun-Joon Chung ◽  
Yujiang Xiang ◽  
Mahdiar Hariri ◽  
Rajan Bhatt ◽  
Jasbir S. Arora ◽  
...  
Keyword(s):  
Degrees Of Freedom ◽  
Motion Tracking ◽  
Mechanical Energy ◽  
Joint Torque ◽  
Human Model ◽  
Joint Torques ◽  
Contact Points ◽  
Design Variables ◽  
Reaction Forces ◽  
Hands And Feet

An optimization formulation for human ladder climbing simulation is presented. The human model has 55 degrees of freedom — 49 revolute joints and 6 global translation & rotation joints. It is assumed that the ladder climbing motion is symmetric and periodic. The formulation starts with four contact points with both hands and feet. Then, hand and foot moves up and it ends with four contact points again. Design variables are the joint angle profiles and contact reaction forces. The objective function is combined with dynamic efforts and motion tracking. The dynamic efforts are joint torque square which is proportional to the mechanical energy. The motion tracking is the motion capture data tracking so that the motion follows the natural ladder climb motion as well. The dynamics results with joint torques and reaction forces are recovered and analyzed from the simulation.

A Conceptual Model for Examining E-Government Adoption in Jordan

2012 ◽  
Vol 8 (2) ◽  
pp. 1-31 ◽  
Author(s):  
Mohammad Alryalat ◽  
Yogesh K. Dwivedi ◽  
Michael D. Williams
Keyword(s):  
Technology Acceptance ◽  
Conceptual Model ◽  
Diffusion Of Innovation ◽  
Empirical Studies ◽  
Theoretical Models ◽  
Developed Countries ◽  
External Factors ◽  
Factors Affecting ◽  
Depth Analysis ◽  
Research Frameworks

In this paper, the authors propose and discuss a conceptual model for examining factors affecting e-government adoption in Jordan. This study evaluates existing empirical studies that examine e-government adoption in developing and under-developed countries. These studies were based on pre-existing theoretical models for explaining and guiding their research frameworks. An in-depth analysis of such models revealed that the technology acceptance model (TAM), the diffusion of innovation (DOI) theory, the theory of planned behaviour (TPB), and the unified theory of acceptance and use of technology (UTAUT) were among some of the most frequently used. As the UTAUT is a unified model based on the mapping of eight models, it was deemed appropriate to use the UTAUT as a guiding model for this research. A comprehensive analysis of all studies and constructs revealed that some external factors were also important for explaining e-gov adoption in developing countries. Hence, such external factors also considered relevant were integrated with UTAUT constructs as examining factors affecting e-gov adoption in Jordan. The theoretical and logical arguments and prior empirical validation of the constructs and their relationships allowed for the justification of the proposed integrated model and formulation of the associated hypotheses.

scholarly journals Change Factors and the Adaptability of Buildings

2020 ◽  
Vol 12 (16) ◽  
pp. 6585
Author(s):  
John M. Kamara ◽  
Oliver Heidrich ◽  
Vincenza E. Tafaro ◽  
Sebastiano Maltese ◽  
Mario C. Dejaco ◽  
...  
Keyword(s):  
Case Studies ◽  
Wide Spectrum ◽  
Theoretical Models ◽  
External Factors ◽  
Change Factors ◽  
Building Systems ◽  
Depth Study ◽  
Building Factors ◽  
The Creation ◽  
Or Organization

The adaptability of buildings addresses the responses of buildings to the changing needs of owners/users and the demands of external factors, over their lifecycle. An understanding of these changes is therefore key to the creation of adaptable buildings. This paper reports research which was aimed at modelling building changes to better understand the challenges for their adaptability. An in-depth study of the changes in selected case studies was conducted to understand the nature, characteristics, and implications of these changes for buildings and their ability to adapt. The findings from these case studies were analyzed against theoretical models reported in the literature on change and adaptability. As a result, a model was developed that identified and categorized a wide spectrum of changes to the building fabric within the broad remit of adaptability that are triggered by many factors, which are sometimes external to the building or organization. In the cases investigated, it was found that the factors that lead to actual changes to buildings were not necessarily due to the ease of making those changes, but rather the organizational will and means to make the changes. Similarly, changes were made not because the building systems were obsolete, but because of non-building factors. The timings of changes therefore did not correspond to the assumed lifespan models of different building layers, suggesting that a new way of predicting and/or categorizing building changes is needed. Furthermore, the interrelationships and nature of the triggers for change suggest that the adaptability of buildings is not just about building systems, but also about non-building factors. Thus, the further exploration of non-building triggers and enablers for change using the developed model presented here, will further enhance the creation of more adaptable buildings.

scholarly journals An Experimental Comparison of Quantum Decision Theoretical Models of Intertemporal Choice for Gain and Loss

2012 ◽  
Vol 02 (04) ◽  
pp. 119-122
Author(s):  
Taiki Takahashi ◽  
Hiroshi Nishinaka ◽  
Takaki Makino ◽  
Ruokang Han ◽  
Hiroki Fukui
Keyword(s):  
Intertemporal Choice ◽  
Theoretical Models ◽  
Experimental Comparison ◽  
Gain And Loss

scholarly journals Effects of neuromuscular lags on controlling contact transitions

2009 ◽  
Vol 367 (1891) ◽  
pp. 1163-1179 ◽  
Author(s):  
Madhusudhan Venkadesan ◽  
Francisco J Valero-Cuevas
Keyword(s):  
Neural Control ◽  
Deterministic Model ◽  
Optimal Solution ◽  
Trade Off ◽  
Joint Torques ◽  
Human Data ◽  
Force Magnitude ◽  
Trade Offs ◽  
Speed Accuracy ◽  
Force Vectors

We present a numerical exploration of contact transitions with the fingertip. When picking up objects our fingertips must make contact at specific locations, and—upon contact—maintain posture while producing well-directed force vectors. However, the joint torques for moving the fingertip towards a surface ( τ m ) are different from those for producing static force vectors ( τ f ). We previously described the neural control of such abrupt transitions in humans, and found that unavoidable errors arise because sensorimotor time delays and lags prevent an instantaneous switch between different torques. Here, we use numerical optimization on a finger model to reveal physical bounds for controlling such rapid contact transitions. Resembling human data, it is necessary to anticipatorily switch joint torques to τ f at about 30 ms before contact to minimize the initial misdirection of the fingertip force vector. This anticipatory strategy arises in our deterministic model from neuromuscular lags, and not from optimizing for robustness to noise/uncertainties. Importantly, the optimal solution also leads to a trade-off between the speed of force magnitude increase versus the accuracy of initial force direction. This is an alternative to prevailing theories that propose multiplicative noise in muscles as the driver of speed–accuracy trade-offs. We instead find that the speed–accuracy trade-off arises solely from neuromuscular lags. Finally, because our model intentionally uses idealized assumptions, its agreement with human data suggests that the biological system is controlled in a way that approaches the physical boundaries of performance.

scholarly journals Internal and External Factors’ Influence on Recycling: Insights From a Laboratory Experiment With Observed Behavior

2021 ◽  
Vol 12 ◽  
Author(s):  
Noah Linder ◽  
Sonny Rosenthal ◽  
Patrik Sörqvist ◽  
Stephan Barthel
Keyword(s):  
Laboratory Experiment ◽  
Physical Environment ◽  
Psychological Factors ◽  
Environmental Behavior ◽  
Theoretical Models ◽  
External Factors ◽  
Personal Norms ◽  
Choice Context ◽  
Physical Context ◽  
Spatial Positioning

Internal psychological factors, such as intentions and personal norms, are central predictors of pro-environmental behavior in many theoretical models, whereas the influence from external factors such as the physical environment is seldom considered. Even rarer is studying how internal factors interact with the physical context in which decisions take place. In the current study, we addressed the relative influence and interaction of psychological and environmental factors on pro-environmental behavior. A laboratory experiment presented participants (N = 399) with a choice to dispatch a used plastic cup in a recycling or general waste bin after participating in a staged “yogurt taste test.” Results showed how the spatial positioning of bins explained more than half of the variance in recycling behavior whilst self-reported recycling intentions were not related to which bin they used. Rinsing cups (to reduce contamination) before recycling, on the other hand, was related to both behavioral intention and external factors. These results show that even seemingly small differences in a choice context can influence how well internal psychological factors predict behavior and how aspects of the physical environment can assist the alignment of behavior and intentions, as well as steering behavior regardless of motivation.

New type electron gun with electrostatic and electromagnetic lenses

1978 ◽  
Vol 36 (1) ◽  
pp. 62-63
Author(s):  
T. Ichinokawa ◽  
H. Maeda
Keyword(s):  
Electron Microscopy ◽  
Electron Beam ◽  
Optimum Condition ◽  
Bias Voltage ◽  
Electron Gun ◽  
Charge Effect ◽  
Micro Fabrication ◽  
Maximum Brightness ◽  
New Type ◽  
The Ideal

I. IntroductionThermionic electron gun with the Wehnelt grid is popularly used in the electron microscopy and electron beam micro-fabrication. It is well known that this gun could get the ideal brightness caluculated from the Lengumier and Richardson equations under the optimum condition. However, the design and ajustment to the optimum condition is not so easy. The gun has following properties with respect to the Wehnelt bias; (1) The maximum brightness is got only in the optimum bias. (2) In the larger bias than the optimum, the brightness decreases with increasing the bias voltage on account of the space charge effect. (3) In the smaller bias than the optimum, the brightness decreases with bias voltage on account of spreading of the cross over spot due to the aberrations of the electrostatic immersion lens.In the present experiment, a new type electron gun with the electrostatic and electromagnetic lens is designed, and its properties are examined experimentally.

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