scholarly journals A Hybrid Control Policy for Semi-Active Vehicle Suspensions

2003 ◽  
Vol 10 (1) ◽  
pp. 59-69 ◽  
Author(s):  
Fernando D. Goncalves ◽  
Mehdi Ahmadian
Keyword(s):  
Steady State ◽  
Hybrid Control ◽  
Control Policy ◽  
Control Technique ◽  
Peak Acceleration ◽  
Alternative Control ◽  
Peak Displacement ◽  
Vehicle Suspensions ◽  
Magneto Rheological ◽  
Unsprung Mass

Various control policies, such as skyhook and groundhook control, have often been considered for semi-active vehicle suspensions. Past studies have shown the performance limitations of these policies, as well as others that have been considered for vehicle applications. This study will provide a look into an alternative control technique called "hybrid control", which attempts to merge the performance benefits of skyhook and groundhook control. The results of this study are based on an experimental evaluation of hybrid control using a quarter-car rig and a magneto-rheological damper. The control policy is employed and evaluated under a steady-state or pure tone input, and a transient or step input. Peak-to-peak displacement and peak-to-peak acceleration are used to evaluate performance. The results indicate that hybrid control can offer benefits to both the sprung mass and the unsprung mass. The steady-state results reveal that hybrid control can be used to reduce the peak-to- peak displacements and accelerations of both bodies. The transient evaluation shows that hybrid control can be effective at reducing the peak-to-peak displacement of the sprung mass.

In Search of a Suitable Control Policy for Intelligent Vehicle Suspensions

2002 ◽  
Author(s):  
Fernando D. Goncalves ◽  
Mehdi Ahmadian
Keyword(s):  
Steady State ◽  
Hybrid Control ◽  
Control Policy ◽  
Control Technique ◽  
Intelligent Vehicle ◽  
Alternative Control ◽  
Control Policies ◽  
Peak Displacement ◽  
Vehicle Suspensions ◽  
Magneto Rheological

Many control policies, such as skyhook and groundhook control, are now being considered for intelligent vehicle suspensions. Past studies have shown the performance limitations of these policies, as well as others that have been considered for vehicle applications. The performance of three semi-active control policies were studied experimentally under steady-state and transient inputs. Experimental results were obtained using a quarter-car rig and a magneto-rheological damper. The commonly considered skyhook and groundhook control policies were employed and evaluated under a steady-state, or pure tone, input and a transient, or step input. An alternative control technique called “hybrid control,” which attempts to merge the performance benefits of skyhook and groundhook control was also considered. Peak-to-peak displacement and peak-to-peak acceleration were used to evaluate performance. The results indicate that while skyhook and groundhook can offer benefits to either the sprung or unsprung masses, hybrid control can offer benefits to both masses. The compromise inherent in both skyhook and groundhook is eliminated with the use of hybrid control. Both the steady-state and transient dynamics of the sprung and unsprung masses can be reduced below those of passive using hybrid control with an α of 0.5. This corresponds to equal contributions from skyhook control and groundhook control.

Steady-State Energy Transfer of a Semi-Active Suspension Under Hybrid Control

2004 ◽  
Author(s):  
Christopher M. Boggs ◽  
Fernando D. Goncalves ◽  
Mehdi Ahmadian
Keyword(s):  
Steady State ◽  
Energy Dissipation ◽  
Yield Stress ◽  
Hybrid Control ◽  
Mr Damper ◽  
Control Policy ◽  
Mr Fluid ◽  
Mr Dampers ◽  
Field Dependent ◽  
System Energy

Magnetorheological (MR) fluids are often characterized by their field-dependent yield stress. Upon the activation of a magnetic field, the fluid has the ability to change from a fluid state to a semi-solid state in milliseconds. The field-dependent yield stress and the fluid’s fast response time make MR fluid an attractive technology for many applications. One such application that has gained considerable attention is in MR fluid dampers. The real-time control possibilities make MR dampers attractive alternatives to conventional viscous dampers. In comparing passive dampers with MR dampers, an equivalent viscous damping coefficient is often found from the energy dissipated by the MR damper with a fixed current applied to the damper. In contrast, this study investigates energy dissipation of the MR damper under a semi-active hybrid control policy. Hybrid control is a linear combination of skyhook and groundhook control. This study investigates the system energy under steady-state conditions at three frequencies, and how the system energy varies with varying contributions from skyhook and groundhook. A quarter-car rig was used to evaluate the dynamics of the hybrid suspension using an MR damper. Previous studies have shown that hybrid control can offer advantages to both the sprung and unsprung masses; however the relationship between energy dissipation and performance is not clear. In this study, we compare control policy performance to several energy-based measures. Results indicate that there is a strong correlation between sprung mass RMS acceleration and unsprung mass RMS acceleration to several of the energy-based measures.

Experimental Investigation of the Energy Dissipated in a Magneto-Rheological Damper for Semi-Active Vehicle Suspensions

2003 ◽  
Author(s):  
Fernando D. Goncalves ◽  
Mehdi Ahmadian
Keyword(s):  
Yield Stress ◽  
Energy Input ◽  
Hybrid Control ◽  
Mr Damper ◽  
Energy Ratio ◽  
Mr Fluid ◽  
Vehicle Suspensions ◽  
Fluid Dampers ◽  
Magneto Rheological ◽  
Energy Dissipated

Magneto-rheological (MR) fluid dampers are often characterized by their field-dependent yield stress. This fielddependent yield stress and their fast response time make MR fluid dampers attractive alternatives to conventional viscous dampers. In comparing passive dampers with MR dampers, an equivalent viscous damping coefficient is often found from the energy dissipated by the MR damper. This study considers the energy dissipated by the MR damper under semi-active control. A hybrid control policy for semi-active vehicle suspensions is considered. A quarter car rig was used to evaluate the dynamics of the hybrid suspension using an MR damper. The steady-state performance of hybrid control is investigated with regard to the RMS displacements and accelerations of the sprung and unsprung masses. A frequency domain analysis is also presented. The transmissibilities of the sprung and unsprung masses are found using a range specific chirp signal. Results indicate that hybrid control with equal contributions from skyhook and groundhook can offer benefits to both the sprung and unsprung masses. With the performance of the hybrid semi-active suspension known, the study then considers the energy dissipated by the MR damper under hybrid control. An investigation into the possible correlation between performance and the energy dissipated by the MR damper is presented. Force-displacement curves are generated and an energy ratio is introduced. The energy ratio is the energy metric used to evaluate the energy dissipation of the MR damper. The energy ratio is defined as the ratio of the energy dissipated by the MR damper and the energy input into the system. The results indicate that the MR damper under hybrid control can dissipate nearly 70% of the energy input to the system.

Parametric Study of Damping Characteristics of Magneto-Rheological Damper: Mathematical and Experimental Approach

2020 ◽  
Vol 15 (3) ◽  
pp. 37-48
Author(s):  
Zubair Rashid Wani ◽  
Manzoor Ahmad Tantray
Keyword(s):  
Structural Control ◽  
Research Work ◽  
Testing Machine ◽  
Input Voltage ◽  
Damping Coefficient ◽  
Control Technique ◽  
Damping Force ◽  
Active Devices ◽  
Active Structural Control ◽  
Magneto Rheological

The present research work is a part of a project was a semi-active structural control technique using magneto-rheological damper has to be performed. Magneto-rheological dampers are an innovative class of semi-active devices that mesh well with the demands and constraints of seismic applications; this includes having very low power requirements and adaptability. A small stroke magneto-rheological damper was mathematically simulated and experimentally tested. The damper was subjected to periodic excitations of different amplitudes and frequencies at varying voltage. The damper was mathematically modeled using parametric Modified Bouc-Wen model of magneto-rheological damper in MATLAB/SIMULINK and the parameters of the model were set as per the prototype available. The variation of mechanical properties of magneto-rheological damper like damping coefficient and damping force with a change in amplitude, frequency and voltage were experimentally verified on INSTRON 8800 testing machine. It was observed that damping force produced by the damper depended on the frequency as well, in addition to the input voltage and amplitude of the excitation. While the damping coefficient (c) is independent of the frequency of excitation it varies with the amplitude of excitation and input voltage. The variation of the damping coefficient with amplitude and input voltage is linear and quadratic respectively. More ever the mathematical model simulated in MATLAB was in agreement with the experimental results obtained.

Improved Load Sharing Control Techniques for Inverters used in a Microgrid

2009 ◽  
Vol 10 (1) ◽  
Author(s):  
Wei Yao ◽  
Zhaoming Qian
Keyword(s):  
Steady State ◽  
Transient Response ◽  
Single Phase ◽  
Load Sharing ◽  
Power Sharing ◽  
Experimental Results ◽  
Control Technique ◽  
Transient Performance ◽  
Control Techniques ◽  
Control Scheme

In this paper, an improved load sharing control scheme is presented, which is able to improve the transient response and power sharing accuracy of parallel-connected inverters used in microgrid. It also shows how the improved droop method can be easily adapted to account for the operation of parallel-connected inverters, providing good performance under the variation and disturbance of loads, as well as achieving good steady-state objectives and transient performance. Two DSP-based single-phase Microgrid inverters are designed and implemented. Simulation and experimental results are all reported, confirming the validity of the proposed control technique.

scholarly journals Study on a Novel High-Efficiency Bridgeless PFC Converter

2014 ◽  
Vol 2014 ◽  
pp. 1-8
Author(s):  
Cao Taiqiang ◽  
Chen Zhangyong ◽  
Wang Jun ◽  
Sun Zhang ◽  
Luo Qian ◽  
...  
Keyword(s):  
Steady State ◽  
High Efficiency ◽  
Control Policy ◽  
Switching Frequency ◽  
Fast Recovery ◽  
Zero Current Switching ◽  
Zero Current ◽  
The One ◽  
Gain Characteristic ◽  
Conduction Mode

In order to implement a high-efficiency bridgeless power factor correction converter, a new topology and operation principles of continuous conduction mode (CCM) and DC steady-state character of the converter are analyzed, which show that the converter not only has bipolar-gain characteristic but also has the same characteristic as the traditional Boost converter, while the voltage transfer ratio is not related with the resonant branch parameters and switching frequency. Based on the above topology, a novel bridgeless Bipolar-Gain Pseudo-Boost PFC converter is proposed. With this converter, the diode rectifier bridge of traditional AC-DC converter is eliminated, and zero-current switching of fast recovery diode is achieved. Thus, the efficiency is improved. Next, we also propose the one-cycle control policy of this converter. Finally, experiments are provided to verify the accuracy and feasibility of the proposed converter.

Predictability of strong motions from the Northridge, California, earthquake

1996 ◽  
Vol 86 (1B) ◽  
pp. S100-S114 ◽  
Author(s):  
John G. Anderson ◽  
Guang Yu
Keyword(s):  
Vertical Component ◽  
Source Model ◽  
Statistical Characteristics ◽  
Peak Acceleration ◽  
Blind Test ◽  
Peak Displacement ◽  
Velocity Models ◽  
Maximum Bias ◽  
Standard Deviations ◽  
A Site

Abstract The composite source model for generating synthetic strong ground motions is tested for its ability to predict the statistical characteristics of Northridge accelerograms recorded in or adjacent to the San Fernando valley. The general problem is prediction of strong motions at a site of engineering interest with sufficient realism to be useful for engineering applications. The strongest test of any proposed method is a blind prediction. For this study, a completely blind test was not possible. Our objective was to use only a preliminary description of fault geometry and magnitude and previously published velocity models and, without iteration to improve the quality of fit, to evaluate the differences between predicted and observed accelerograms. The parameters that we predict are peak acceleration, peak velocity, peak displacement, Fourier spectra at seven frequencies, and pseudorelative velocity response (5% damping) at seven periods. Our results are given for 14 stations. For the horizontal components, these parameters are all predicted with a maximum bias of under 50% and an average bias of observations exceeding predictions by 6%. For peak acceleration and some response spectral periods, the bias for this model is smaller than at least some regressions, when applied to this specific earthquake. On the vertical component, the maximum bias is a factor of 2, and the average gives predictions exceeding observations by 25%. Standard deviations of the common logarithm of the ratio of observed-to-predicted parameters are typically about 0.3, which is perhaps 50% greater than the standard deviations typical of regressions but comparable to standard deviations of observations from this earthquake compared to regressions. In the future, it is likely that, in some cases, traditional regressions will be replaced with synthetic calculations of some type, such as the method used here. Based on the results of this study, the amount of progress that has been made in obtaining that goal is very encouraging.

Comparison of Controllers for a UAV with Integral Effect and Kalman Estimator: By Bessel Polynomials and LQR

2013 ◽  
Vol 436 ◽  
pp. 54-60 ◽  
Author(s):  
Wenceslao Eduardo Rodríguez ◽  
Ramiro Ibarra ◽  
Gerardo Romero ◽  
David Lara ◽  
Jaime Arredondo ◽  
...  
Keyword(s):  
Steady State ◽  
Pole Placement ◽  
Control Technique ◽  
State Estimator ◽  
Control Laws ◽  
State Response ◽  
Integral Effect ◽  
Aerial Vehicle ◽  
Pole Placement Controller ◽  
Selection Of

This paper presents the development of two different control techniques as an approach having to remove steady-state error present in the response of attitude of a mini unmanned aerial vehicle. A problem that arises when performing pole placement controller is the selection of the poles, the Bessel approximation allows the selection of the eigenvalues in function to a specified response time for a feedback pole placement controller and state estimator (observer). On the other hand presents an optimal control technique combined with Kalman filter to estimate the state affected by perturbations in the system, both cases using the integral effect to eliminate the steady state error.These two control laws has the property of responding to a desired response according to a time or state response desired.

Magnetic field dependent steady-state shear response of Fe3O4 micro-octahedron based magnetorheological fluids

2018 ◽  
Vol 20 (30) ◽  
pp. 20247-20256 ◽  
Author(s):  
A. V. Anupama ◽  
V. B. Khopkar ◽  
V. Kumaran ◽  
B. Sahoo
Keyword(s):  
Magnetic Field ◽  
Steady State ◽  
Yield Stress ◽  
Applied Magnetic Field ◽  
Rheological Behaviour ◽  
Magnetorheological Fluids ◽  
Shear Response ◽  
Field Dependent ◽  
Dynamic Yield ◽  
Magneto Rheological

The magneto-rheological behaviour of fluids containing soft-ferrimagnetic Fe3O4 micro-octahedrons (M = magnetization, τY = dynamic yield-stress and H = applied-magnetic-field).

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