Model-based prototyping of a controller for MR actuators

Magnetorheological (MR) actuators are semi-active devices that leverage the smart properties of the MR fluids whose rheology can be controlled by an external magnetic field. Within the presence of an external magnetic field, the magnetic domains of the MR fluid align with the external field, which results in the yield stress induced in the fluid, thus undergoing a transition from a fluid to a semi-solid. Thus, the control challenge for MR actuators is in controlling the rheology of the material by magnetic flux. Typically the control system is based on the coil’s current feedback. However, this approach based purely on the current control is not optimal since it is the magnetic stimuli that directly controls the material’s yield stress and not the current. Thus, this work investigates the capability of a flux controller in handling the non-linearities of the actuator, including magnetic hysteresis. A model of an MR actuator that incorporates the magnetic hysteresis and the control coil dynamics is developed. The flux controller is tuned to handle the addition of the hysteresis effect. The obtained results show that the chosen control topology is very effective for the considered flux commands inputs.info:eu-repo/semantics/publishedVersio

MODELLING OF AMPLITUDE-SELECTIVE-DAMPING VALVES

The so-called amplitude-selective-damping (ASD) valving is a relatively new approach for modifying the output of a hydraulic shock absorber. In the automotive industry ASD valves are known to improve isolation from road inputs. During more aggressive maneuvers the systems maintains the performance of a standard (non-ASD) shock absorber. In the paper, the author derives and analyzes a fairly complete state-space model of an exemplary piston-side ASD valve. The model includes key geometric and performance characteristics of the valve. The results are shown in the form of phase plane plots of force-displacement diagrams, respectively, for a twin-tube shock absorber configuration of choice

Modelling of amplitude-selective-damping valves Modelowanie zaworów o charakterystyce zależnej od amplitudy przemieszczenia /

Tyt. z nagłówka.Bibliogr. s. [64].W pracy przedstawiono model dwururowego amortyzatora samochodowego z zaworem o charakterystyce zależnej od amplitudy przemieszczenia. Zawór dodatkowy działa równolegle do zaworu głównego tłoka i pozwala na kształtowanie osiągów amortyzatora w zakresie małych przemieszczeń oraz średnich i wysokich częstotliwości wymuszenia. Model zawiera kluczowe zmienne geometryczne i materiałowe uwzględniające podstawowe osiągi zaworu w szerokim paśmie przemieszczeń i częstotliwości. Wyniki obliczeń zaprezentowano na płaszczyźnie fazowej siła-przemieszczenie w zakresie prędkości do 260 mm/s i częstotliwości wymuszenia do 12 Hz.The so-called amplitude-selective-damping (ASD) valving is a relatively new approach for modifying the output of a hydraulic shock absorber. In the automotive industry ASD valves are known to improve isolation from road inputs. During more aggressive maneuvers the systems maintains the performance of a standard (non-ASD) shock absorber. In the paper, the author derives and analyzes a fairly complete state-space model of an exemplary piston-side ASD valve. The model includes key geometric and performance characteristics of the valve. The results are shown in the form of phase plane plots of force-displacement diagrams, respectively, for a twin-tube shock absorber configuration of choice.Dostępny również w formie drukowanej.SŁOWA KLUCZOWE: zawór z tłumieniem zależnym od amplitudy przemieszczenia, amortyzator dwururowy, amortyzator hydrauliczny, modelowanie samochodowych amortyzatorów hydraulicznych. KEYWORDS: amplitude-selective-damping valve, twin-tube shock absorber, hydraulic shock absorber, automotive shock absorber modeling

Insight into magnetorheological shock absorbers

This book deals with magnetorheological fluid theory, modeling and applications of automotive magnetorheological dampers. On the theoretical side a review of MR fluid compositions and key factors affecting the characteristics of these fluids is followed by a description of existing applications in the area of vibration isolation and flow-mode shock absorbers in particular. As a majority of existing magnetorheological devices operates in a so-called flow mode a critical review is carried out in that regard. Specifically, the authors highlight common configurations of flow-mode magnetorheological shock absorbers, or so-called MR dampers that have been considered by the automotive industry for controlled chassis applications. The authors focus on single-tube dampers utilizing a piston assembly with one coil or multiple coils and at least one annular flow channel in the piston

Assessment of the Magnetic Hysteretic Behaviour of MR Dampers through Sensorless Measurements

Magnetorheological (MR) dampers are well-known devices based on smart fluids. The dampers exhibit nonlinear hysteretic behaviour which affects their performance in control systems. Hence, an effective control scheme must include a hysteresis compensator. The source of hysteresis in MR dampers is twofold. First, it is due to the compressibility and inertia of the fluid. Second, magnetic hysteresis is the inherent property of ferromagnetic materials that form the control circuit of the valve including MR fluid. While the former was studied extensively over the past years using various phenomenological models, the latter has attracted less attention. In this paper, we analyze the magnetic hysteretic behaviour of three different MR dampers by investigating their current-flux relationships. Two dampers operate in flow mode, whereas the third one is a shear-mode device (brake). The approach is demonstrated using a sensorless magnetic flux estimation technique. We reveal the response of the dampers when subjected to sinusoidal inputs across a wide range of operating conditions and excitation inputs. Our observations of the flux data showed that the hysteresis is influenced by both amplitude and the frequency of the excitation input. The procedure allows to analyze the magnetic hysteresis independently of other sources of hysteresis in MR dampers; on this basis, more effective damper models and control algorithms can be developed in the future

On the Application of Support Vector Method for Predicting the Current Response of MR Dampers Control Circuit

Magnetorheological (MR) dampers are controlled energy-dissipating devices utilizing smart fluids. They operate in a fast and valveless manner by taking advantage of the rheological properties of MR fluids. The magnitude of the response of MR fluids, when subjected to magnetic fields, is of sufficient magnitude to employ them in various applications, namely, vibration damping, energy absorption, exoskeletons, etc. At the same time, predicting their response to arbitrary mechanical and electrical inputs is still a research challenge. Due to the non-linearities involved in material properties or the design of the solenoid used for activating the fluid modeling the relationships between the control circuit and the material’s response is complex. Modeling studies can be classified into two categories. The parametric approach requires the knowledge of the internal material’s properties and takes advantage of physics formulas to infer the I/O relationships present in the damper. For comparison, the non-parametric approach harnesses various data mapping techniques to describe the device’s behavior. While the latter is more suited for design studies, the former seems ideal for control algorithm prototyping and the like. In this study, based on the so-called Support Vector Method (SVM), the authors develop a non-parametric model of the control circuit of an exemplary rotary MR damper. To the best of the author’s knowledge, it is the first attempt at an SVM application for MR dampers’ control circuit modeling. Using the acquired experimental data, the I/O relationships are inferred using the SVM algorithm, and its performance is verified across a wide range of excitation frequencies. The obtained results are satisfactory, and the current response of the MR damper is well-predicted. The model performance shows the potential for incorporating it into model-based prototyping and designing of MR control systems

On the Application of Support Vector Method for Predicting the Current Response of MR Dampers Control Circuit

Magnetorheological (MR) dampers are controlled energy-dissipating devices utilizing smart fluids. They operate in a fast and valveless manner by taking advantage of the rheological properties of MR fluids. The magnitude of the response of MR fluids, when subjected to magnetic fields, is of sufficient magnitude to employ them in various applications, namely, vibration damping, energy absorption, exoskeletons, etc. At the same time, predicting their response to arbitrary mechanical and electrical inputs is still a research challenge. Due to the non-linearities involved in material properties or the design of the solenoid used for activating the fluid modeling the relationships between the control circuit and the material’s response is complex. Modeling studies can be classified into two categories. The parametric approach requires the knowledge of the internal material’s properties and takes advantage of physics formulas to infer the I/O relationships present in the damper. For comparison, the non-parametric approach harnesses various data mapping techniques to describe the device’s behavior. While the latter is more suited for design studies, the former seems ideal for control algorithm prototyping and the like. In this study, based on the so-called Support Vector Method (SVM), the authors develop a non-parametric model of the control circuit of an exemplary rotary MR damper. To the best of the author’s knowledge, it is the first attempt at an SVM application for MR dampers’ control circuit modeling. Using the acquired experimental data, the I/O relationships are inferred using the SVM algorithm, and its performance is verified across a wide range of excitation frequencies. The obtained results are satisfactory, and the current response of the MR damper is well-predicted. The model performance shows the potential for incorporating it into model-based prototyping and designing of MR control systems