scholarly journals Dynamics of an Autoparametric Pendulum-Like System with a Nonlinear Semiactive Suspension

2011 ◽  
Vol 2011 ◽  
pp. 1-15 ◽  
Author(s):  
Krzysztof Kecik ◽  
Jerzy Warminski
Keyword(s):  
Vibration Analysis ◽  
Dynamic Behaviour ◽  
Resonance Region ◽  
Nonlinear Damping ◽  
Harmonic Excitation ◽  
Magnetorheological Damper ◽  
Nonlinear Spring ◽  
Dynamics And Control ◽  
And Control ◽  
Experimental Rig

This paper presents vibration analysis of an autoparametric pendulum-like mechanism subjected to harmonic excitation. To improve dynamics and control motions, a new suspension composed of a semiactive magnetorheological damper and a nonlinear spring is applied. The influence of essential parameters such as the nonlinear damping or stiffness on vibration, near the main parametric resonance region, are carried out numerically and next verified experimentally in a special experimental rig. Results show that the magnetorheological damper, together with the nonlinear spring can be efficiently used to change the dynamic behaviour of the system. Furthermore, the nonlinear elements applied in the suspension of the autoparametric system allow to reduce the unstable areas and chaotic or rotating motion of the pendulum.

Influence of the Load Occupancy Ratio on the Dynamic Response of an Elevator Car System

2014 ◽  
Vol 706 ◽  
pp. 128-136 ◽  
Author(s):  
Ignacio Herrera ◽  
Hui Su ◽  
Stefan Kaczmarczyk
Keyword(s):  
Dynamic Response ◽  
Simulation Model ◽  
Dynamic Behaviour ◽  
Experimental Tests ◽  
Harmonic Excitation ◽  
Ride Quality ◽  
Model Predictions ◽  
Dynamic Absorber ◽  
Experimental Rig ◽  
Load Conditions

In predictions of the dynamic behaviour of an elevator car system, it is important to take into account the influence of passengers’ behaviour in the car. In this paper a simulation model to analyse the influence of various loading car conditions on the dynamic response of the elevator system is developed. This involves the investigation of the dynamic response of the car with different loads. An experimental rig with a rectangular elevator platform fixed on the top of four silent blocks attached to a shaker is designed to conduct experimental tests. The car is excited over a range of frequencies and amplitudes. A number of passengers wearing different type of shoes in the car are investigated. The transmissibility measurements are carried out with a harmonic excitation applied first to an empty car and then to the car with a number of passengers. An excellent agreement from experimental tests with the model predictions is achieved. The passenger’s role to act as a dynamic absorber is assessed and recommendations to achieve the best ride quality under load conditions are provided and summarised.

Design, modeling, and control of a magnetorheological rotary damper for scissor seat suspension

2020 ◽  
Vol 234 (9) ◽  
pp. 2402-2416
Author(s):  
Jianqiang Yu ◽  
Xiaomin Dong ◽  
Xuhong Wang ◽  
Junli Li ◽  
Biao Li
Keyword(s):  
Experimental Tests ◽  
Nonlinear Damping ◽  
Magnetorheological Damper ◽  
Hysteretic Model ◽  
Active System ◽  
Backbone Curve ◽  
Modeling And Control ◽  
Seat Suspension ◽  
Damping Characteristics ◽  
And Control

This research investigates the design, modeling, and control of an improved magnetorheological rotary damper for seat suspension. A magnetorheological damper with optimized flux path is developed to improve the distribution of magnetic field. Its dynamic damping characteristics are tested by MTS machine under sinusoidal excitations. To describe the nonlinear damping characteristics of magnetorheological damper, a hysteretic model based on backbone curve is selected by comparing with other models. To verify the feasibility of seat suspension with the proposed magnetorheological damper, the simulated analysis and experimental tests are conducted. A dynamic model of scissor seat suspension with rotary damper is constructed and simplified. The performances of semi-active system show that the seat suspension with the proposed damper can reduce vibration efficiently.

Experimental Investigation on the Dynamic Behavior of Chaotic Jumping in Inverted Flexible Pendulum Under Harmonic Excitation

2018 ◽  
Author(s):  
Hartiny A. Kahar ◽  
Elmira Madadi ◽  
Dirk Söffker
Keyword(s):  
Multiple Equilibria ◽  
Dynamical Behavior ◽  
Harmonic Excitation ◽  
Control Parameters ◽  
Pendulum System ◽  
Dynamics And Control ◽  
Design Requirements ◽  
And Control ◽  
Two Equilibria ◽  
Stimulation Of

Control of flexible systems is effected by design requirements and also manufacturing aspects. The dynamics and control of such systems are challenging, especially in the case of an inverted flexible pendulum system. The experimental study of the dynamical behavior of this kind of system showing jumping phenomenon between three equilibria is not considered in detail in literatures so far. The paper focuses on studying the effects of some parameters to the dynamics of the flexible pendulum. By varying the excitation parameters, control parameters, as well as other distinguished mechanical parameters, different phenomena are observed in experiments discussed in this contribution. In this study, a custom built inverted flexible pendulum on cart system under PID-controlled harmonic excitation is considered. Data are collected from both cart excitation signal and displacement of the pendulum, also to observe their correlation towards jumping behavior. Effects of the variation of the parameters leading to changes in chaotic jumping patterns. Multiple equilibria are observed and analyzed. It can be concluded that depending on the excitation amplitudes, frequencies, and controller parameters, the minimum of two equilibria with an unstable third equilibrium can be detected while jumping phenomena between the equilibria are observed. Questions about the stimulation of the jumping by impulses resulting from imperfect sinusoidal excitation due to control limitations are discussed.

Nonlinear dynamics and control of helicopter ground resonance

2021 ◽  
pp. 107754632199693
Author(s):  
Jayachandran Warrier ◽  
Shaikh Faruque Ali
Keyword(s):  
Control Strategies ◽  
Operating Conditions ◽  
Magnetorheological Damper ◽  
Mechanical Instability ◽  
Logic Control ◽  
Ground Resonance ◽  
Dynamics And Control ◽  
Bang Bang Control ◽  
And Control ◽  
Lag Dampers

Ground resonance is an aero-mechanical instability in helicopters that use soft in-plane rotors. Traditionally, ground resonance is mitigated by using passive lead–lag dampers that provide sufficient in-plane damping. However, these dampers because of their passive nature cannot adapt to all operating conditions. In this work, a magnetorheological fluid–based semi-active lead–lag damper is proposed to offer controllable damping. Two nonlinear control strategies are reported to operate the voltage to be supplied to the magnetorheological damper. The first strategy is a model-based control using dynamic inversion. The second is a fuzzy logic control integrated with a particle swarm optimization algorithm to optimize the control parameters. Both control strategies are shown to be effective in eliminating ground resonance. Unlike bang–bang control, the prescribed control algorithms can make use of complete voltage level available in the magnetorheological damper with smooth voltage updates. A comparative study of the controller performances is made through appropriate performance indices and system responses. Finally, the most optimum control strategy to mitigate ground resonance is inferred.

PROJECT ON ELECTRONIC STEERING SYSYTEM

2018 ◽  
Vol 4 (5) ◽  
pp. 7
Author(s):  
Shivam Dwivedi ◽  
Prof. Vikas Gupta
Keyword(s):  
Steering System ◽  
Essential Elements ◽  
Variable Pressure ◽  
Passenger Cars ◽  
Control Techniques ◽  
Steering Mechanism ◽  
Dynamics And Control ◽  
Active Research ◽  
Electronic Steering ◽  
And Control

As the four-wheel steering (4WS) system has great potentials, many researchers' attention was attracted to this technique and active research was made. As a result, passenger cars equipped with 4WS systems were put on the market a few years ago. This report tries to identify the essential elements of the 4WS technology in terms of vehicle dynamics and control techniques. Based on the findings of this investigation, the report gives a mechanism of electronically controlling the steering system depending on the variable pressure applied on it. This enhances the controlling and smoothens the operation of steering mechanism.

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