Computer Simulation of Stick-Slip Friction in Mechanical Dynamic Systems

1985 ◽  
Vol 107 (1) ◽  
pp. 100-103 ◽  
Author(s):  
Dean Karnopp
Keyword(s):  
Computer Simulation ◽  
Dynamic Systems ◽  
Nonlinear Behavior ◽  
Stick Slip ◽  
Strongly Nonlinear ◽  
Zero Velocity ◽  
Straightforward Method ◽  
Performance Limitations ◽  
Almost All

Stick-slip friction is present to some degree in almost all actuators and mechanisms and is often responsible for performance limitations. Simulation of stick-slip friction is difficult because of strongly nonlinear behavior in the vicinity of zero velocity. A straightforward method for representing and simulating friction effects is presented. True zero velocity sticking is represented without equation reformulation or the introduction of numerical stiffness problems.

Development of a Laboratory Equipment for Dynamic Systems and Process Control Education

2014 ◽  
Author(s):  
Rafael E. Vásquez ◽  
Norha L. Posada ◽  
Fabio Castrillón ◽  
David Giraldo
Keyword(s):  
Process Control ◽  
Dynamic Systems ◽  
Sliding Mode ◽  
Control Strategies ◽  
Academic Research ◽  
Nonlinear Behavior ◽  
Industrial Training ◽  
Laboratory Equipment ◽  
Dynamic Matrix ◽  
Control Education

This paper addresses the development of an equipment to teach control engineering fundamentals. The design requirements were determined by users that perform academic, research and industrial training tasks in the area of dynamic systems and process control. Such requirements include: industrial instrumentation; measurement of controlled and manipulated variables, and disturbances; process reconfigurability; different control technologies; several control strategies; appropriate materials for visualization; and compact shape to optimize lab space. The selected process is a tank system that allows one to choose among several dynamic behaviors: first, second, and third order, linear and nonlinear behavior, and dead time; the mathematical model that represents the dynamics of the system is presented. A traditional 3-stage design methodology that includes conceptual, basic and detailed design was followed. The developed equipment allows the user to select from three different technological alternatives to control the system: a PLC, an industrial controller, and a computer. With such flexibility, several control strategies can be implemented: feedback, feedforward, PID, LQG, nonlinear control (gain scheduling, sliding mode, etc.), fuzzy logic, neural networks, dynamic matrix control, etc. The developed system is being used to teach undergrad courses, grad courses, and industrial training. Additionally, the equipment is useful in research projects where grad students and researches can implement and test several advanced control techniques.

Computer Simulation of Dynamic Systems

2020 ◽  
pp. 89-130
Author(s):  
Kirill Rozhdestvensky ◽  
Vladimir Ryzhov ◽  
Tatiana Fedorova ◽  
Kirill Safronov ◽  
Nikita Tryaskin ◽  
...  
Keyword(s):  
Computer Simulation ◽  
Dynamic Systems

Nonlinear behavior for periodically excited brushless motor

2019 ◽  
Vol 38 (2) ◽  
pp. 522-535
Author(s):  
Jianzhe Huang ◽  
Xingzhong Xiong
Keyword(s):  
Working Condition ◽  
Analytic Solution ◽  
Nonlinear Behavior ◽  
Analytic Solutions ◽  
Strong Nonlinearity ◽  
Periodic Motions ◽  
Content Type ◽  
Strongly Nonlinear ◽  
Brushless Motor ◽  
Analytic Expressions

Purpose Due to the coupling between the direct-axis current, quadrature-axis current and rotor speed, the dynamic response could be strongly nonlinear. Besides, if the working condition is severe, the loading is no longer constant and multiple harmonics could be introduced. In this paper, the periodic motions for brushless motor will be solved, and accurate analytic solution will be obtained through the proposed method. The purpose of this study is to provide accurate analytic solution of periodic motions for brushless motor with fluctuated loading, which is a dynamic system with strong nonlinearity. Design/methodology/approach A newly developed semi-analytic algorithm called discrete implicit maps is used to give analytic solutions for both stable and unstable motions for such a motor. Findings The accurate analytic expressions for stable and unstable periodic motions have been obtained. For unstable motion, it can stay on the unstable orbit for many periods without any controller. Through bifurcation analysis, the parameter sensitivity has been obtained which can be a suggestion for design and operation. Originality/value This paper provides all possible analytical solutions for period-1 motion as well as the unstable motions in a range of system parameters. It offers a chance to control the unstable motion for such a motor.

Wave-Based Control of a Nonlinear Flexible System

2006 ◽  
Author(s):  
William J. O’Connor ◽  
Francisco Ramos ◽  
Vicente Feliu
Keyword(s):  
Control Strategies ◽  
System Modeling ◽  
Nonlinear Behavior ◽  
Effective Control ◽  
Space Structures ◽  
Large Space ◽  
Flexible System ◽  
Strongly Nonlinear ◽  
Mechanical Waves ◽  
Actuator System

The motivation for this work is the control of flexible mechanical systems, such as long, light robot arms, gantry cranes, and large space structures, with an actuator at one end and a free boundary at the other. Very effective control strategies have recently been developed which are based on interpreting the actuator motion as launching mechanical “waves” (propagating motion) into the flexible system while absorbing returning “waves”. These control systems are robust to system changes and to actuator limitations. They are generic, require very little system modeling, need only local sensing, and are computationally light and easy to implement. In a flexible arm, when elastic deflections are large, frequently there is strongly nonlinear behavior. This paper investigates how such nonlinearities affect the wave-based control strategy. In summary, the news is good. It is found that errors arise only when trajectories are very demanding, and even then the errors are small. Some strategies for correcting these errors are explained: addition of a linear element at the actuator-system interface, error correction by second manoeuver, and redefinition of the waves in a less-than-optimal way. The paper presents these ideas and illustrates them with numerical simulations.

scholarly journals Nonlinear Heat Transport in Superlattices with Mobile Defects

Entropy ◽  
2019 ◽  
Vol 21 (12) ◽  
pp. 1200 ◽  
Author(s):  
David Jou ◽  
Liliana Restuccia
Keyword(s):  
Thermal Conductivity ◽  
Heat Flux ◽  
Heat Conduction ◽  
Thermal Resistance ◽  
Heat Transport ◽  
Concentration Dependence ◽  
Transport Coefficients ◽  
Nonlinear Behavior ◽  
Strongly Nonlinear

We consider heat conduction in a superlattice with mobile defects, which reduce the thermal conductivity of the material. If the defects may be dragged by the heat flux, and if they are stopped at the interfaces of the superlattice, it is seen that the effective thermal resistance of the layers will depend on the heat flux. Thus, the concentration dependence of the transport coefficients plus the mobility of the defects lead to a strongly nonlinear behavior of heat transport, which may be used in some cases as a basis for thermal transistors.

The Evaluation of Agreement Between Dynamics of Electric Wheelchair and Human Behavior

2004 ◽  
Vol 16 (4) ◽  
pp. 434-442 ◽  
Author(s):  
Shigenobu Shimada ◽  
◽  
Kosei Ishimura ◽  
Mitsuo Wada ◽  
Keyword(s):  
Mathematical Model ◽  
Computer Simulation ◽  
Stability Analysis ◽  
Human Behavior ◽  
User Behavior ◽  
Electric Wheelchair ◽  
Straight Line ◽  
Almost All

We studied the problem of interaction of movement between the electric wheelchair and the user. Almost all current products have indexes such as roll stability and operability, but such indexes do not always agree with user behavior because such indexes are static. Another problem arises from the fact that the disagreement of movement causes uncontrollable situations and turnover of the wheelchairs. We evaluated wheelchairs that consider user behavior, first in an experiment to understand the cause of disagreement among users during movement by measuring straight line ands turning, then, based on this result, derived a mathematical model for disagreement in wheelchair motion. Computer simulation, showed that vibration occurred within certain parameters. We present simple roll stability analysis of wheelchairs turning. Simulation confirmed the viability of our proposals.

scholarly journals Computer Simulation of Dynamic Systems

1973 ◽  
Vol 95 (4) ◽  
pp. 441-442
Author(s):  
Ralph J. Kochenburger ◽  
David M. Auslander
Keyword(s):  
Computer Simulation ◽  
Dynamic Systems

A Numerical Study of Non-Symmetric Joints

2007 ◽  
Author(s):  
Edward Berger
Keyword(s):  
Dynamic Systems ◽  
Frequency Tuning ◽  
Numerical Study ◽  
Relative Displacement ◽  
Stick Slip ◽  
Small Perturbations ◽  
Important Indicator ◽  
Frequency Domains ◽  
Displacement Profile

A great deal of analytical, numerical, and experimental research has focused on characterizing symmetric lap-type joints, in which the joint connects dynamic systems with nominally the same descriptions. In this paper, we numerically examine dynamically non-symmetric jointed structures. Starting with the analytical treatments of Pratt and Williams (1981) as verification of our simulation model and approach, we then introduce structural stiffness asymmetries ranging from small perturbations to large differences. The results are presented in both the time and frequency domains, and the role of the dynamic asymmetry is critically examined. The results of this numerical study suggest that both the relative displacement profile and the stick-slip behavior at the joint are sensitive to the dynamics of the two substructures, with frequency tuning of the substructures being an important indicator of joint performance.

scholarly journals Adaptation in cone photoreceptors contributes to an unexpected insensitivity of On parasol retinal ganglion cells to spatial structure in natural images

2021 ◽  
Author(s):  
Zhou Yu ◽  
Maxwell H Turner ◽  
Fred Rieke
Keyword(s):  
Spatial Structure ◽  
Retinal Ganglion Cells ◽  
Neural Circuits ◽  
Ganglion Cells ◽  
Nonlinear Behavior ◽  
Building Blocks ◽  
Retinal Ganglion ◽  
Cone Photoreceptors ◽  
Strongly Nonlinear ◽  
Visual Inputs

Neural circuits are constructed from nonlinear building blocks, and not surprisingly overall circuit behavior is often strongly nonlinear. But neural circuits can also behave near linearly, and some circuits shift from linear to nonlinear behavior depending on stimulus conditions. Such control of the linearity or nonlinearity of circuit behavior is fundamental to neural computation. Here we study a surprising stimulus dependence of the responses of On (but not Off) parasol retinal ganglion cells: these cells respond nonlinearly to spatial structure in temporally-modulated grating stimuli but linearly to spatial structure in flashed gratings and natural visual inputs. We show that this unexpected response linearity can be explained by a shift in the balance of excitatory and inhibitory synaptic inputs that originates at least in part from adaptation in the cone photoreceptors. More generally, this highlights how subtle asymmetries in signaling - here in the cone signals - can qualitatively alter circuit computation.

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