Analysis of the Effect of Coulomb Friction on Haptic Systems Dynamics

2016 ◽  
Author(s):  
Csaba Budai ◽  
László L. Kovács ◽  
József Kövecses
Keyword(s):  
Coulomb Friction ◽  
Dynamic Behaviour ◽  
Systems Dynamics ◽  
Data Systems ◽  
Sampled Data ◽  
Complex Dynamic ◽  
System Parameters ◽  
Human Machine Interfaces ◽  
And Performance ◽  
Experiment Analysis

Dissipation mechanisms and dissipative forces play a pivotal role in the operations and performance of human-machine interfaces and particularly in haptic systems. Dissipation is a very difficult phenomenon to model. Coulomb friction in general can be the most influential element in systems involving multiple direct contact connections such as joints with transmissions or mechanically guided components. Coulomb friction includes non-smooth discontinuity and can induce complex dynamic behaviours. Very little attention has been paid to the analysis of the effects of Coulomb friction in haptic devices. In this paper we illustrate, by experiment, analysis and simulation, the nature of the dynamic behaviour caused by Coulomb friction in haptic sampled-data systems. We demonstrate that a simple model can represent this behaviour, and show the effects of the haptic system parameters on this dynamics.

Combined Effect of Sampling and Coulomb Friction on Haptic Systems Dynamics

2018 ◽  
Vol 13 (6) ◽  
Author(s):  
Csaba Budai ◽  
László L. Kovács ◽  
József Kövecses
Keyword(s):  
Coulomb Friction ◽  
Friction Compensation ◽  
Systems Dynamics ◽  
Data Systems ◽  
Sampled Data ◽  
Complex Dynamic ◽  
System Parameters ◽  
Human Machine Interfaces ◽  
And Performance ◽  
Experiment Analysis

Dissipation mechanisms and dissipative forces play a pivotal role in the operations and performance of human-machine interfaces and particularly in haptic systems. Dissipation is a very difficult phenomenon to model. Coulomb friction in general can be the most influential element in systems involving multiple direct contact connections such as joints with transmissions or mechanically guided components. Coulomb friction includes nonsmooth discontinuity and can induce complex dynamic behaviors. The effect of Coulomb friction is often neglected in haptics. The part of the literature which deals with friction mainly focuses on friction compensation and/or simulation of friction for haptic rendering. In this paper, the nature of the dynamic behavior caused by Coulomb friction in haptic sampled-data systems is illustrated by experiment, analysis, and simulation. It is also demonstrated that a simple model can represent this behavior and show the effects of the haptic system parameters on this dynamics.

scholarly journals Effects of heterogeneity in infection-exposure history and immunity on the dynamics of a protozoan parasite

2007 ◽  
Vol 4 (16) ◽  
pp. 841-849 ◽  
Author(s):  
Maite Severins ◽  
Don Klinkenberg ◽  
Hans Heesterbeek
Keyword(s):  
Dynamic Behaviour ◽  
Protozoan Parasite ◽  
Host Population ◽  
Infection Process ◽  
Control Measures ◽  
Complex Dynamic ◽  
Systems Models ◽  
Exposure History ◽  
The Relationship ◽  
Initial Contamination

Infection systems where traits of the host, such as acquired immunity, interact with the infection process can show complex dynamic behaviour with counter-intuitive results. In this study, we consider the traits ‘immune status’ and ‘exposure history’, and our aim is to assess the influence of acquired individual heterogeneity in these traits. We have built an individual-based model of Eimeria acervulina infections, a protozoan parasite with an environmental stage that causes coccidiosis in chickens. With the model, we simulate outbreaks of the disease under varying initial contaminations. Heterogeneity in the traits arises stochastically through differences in the dose and frequency of parasites that individuals pick up from the environment. We find that the relationship between the initial contamination and the severity of an outbreak has a non-monotonous ‘wave-like’ pattern. This pattern can be explained by an increased heterogeneity in the host population caused by the infection process at the most severe outbreaks. We conclude that when dealing with these types of infection systems, models that are used to develop or evaluate control measures cannot neglect acquired heterogeneity in the host population traits that interact with the infection process.

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