Publications
33 results found
Yu M, Evangelou S, Dini D, 2023, Advances in active suspension systems for road vehicles, Engineering, ISSN: 2095-8099
Active suspension systems (ASSs) have been proposed and developed for a few decades, and nowadays again become a thriving topic in both academia and industry, due to the high demand in driving comfort and safety, and the compatibility with vehicle electrification and autonomy. Existing review papers on ASSs are mainly about dynamics modelling and robust control, however, the gap between academic research outcomes and industrial application requirements is not yet bridged, hindering most ASS research knowledge from transferring to vehicle companies. This paper comprehensively reviews advances in ASSs for road vehicles, focusing on hardware structures and control strategies. Particularly, state-of-the-art ASSs that have been recently adopted in production cars are detailed, including representative solutions of Mercedes Active Body Control and Audi Predictive Active Suspension; novel concepts that could become alternative candidates are also introduced, including the Series Active Variable Geometry Suspension, and the Active Wheel Alignment System. The ASSs with compact structure, small mass increment, low power consumption, high frequency response, acceptable economic costs and high reliability are more likely to be adopted by car manufacturers. In terms of control strategies, future ASSs not only aim to stabilize the chassis attitude and attenuate the chassis vibration, moreover, but also cooperate with other bodies (e.g., steering and braking) and sensors (e.g., camera) within a car, and even with high-level decision (e.g., reference driving speed) in the overall transportation system – these strategies will be compatible with the rapidly developed electric and autonomous vehicles.
Feng Z, Yu M, Evangelou SA, et al., 2023, Mu-synthesis PID control of full-car with parallel active link suspension under variable payload, IEEE Transactions on Vehicular Technology, Vol: 72, Pages: 176-189, ISSN: 0018-9545
This paper presents a combined μ -synthesis PID control scheme, employing a frequency separation paradigm, for a recently proposed novel active suspension, the Parallel Active Link Suspension (PALS). The developed μ -synthesis control scheme is superior to the conventional H∞ control, previously designed for the PALS, in terms of ride comfort and road holding (higher frequency dynamics), with important realistic uncertainties, such as in vehicle payload, taken into account. The developed PID control method is applied to guarantee good chassis attitude control capabilities and minimization of pitch and roll motions (low frequency dynamics). A multi-objective control method, which merges the aforementioned PID and μ -synthesis-based controls is further introduced to achieve simultaneously the low frequency mitigation of attitude motions and the high frequency vibration suppression of the vehicle. A seven-degree-of-freedom Sport Utility Vehicle (SUV) full car model with PALS, is employed in this work to test the synthesized controller by nonlinear simulations with different ISO-defined road events and variable vehicle payload. The results demonstrate the control scheme's significant robustness and performance, as compared to the conventional passive suspension as well as the actively controlled PALS by conventional H∞ control, achieved for a wide range of vehicle payload considered in the investigation.
Feng Z, Yu M, Evangelou S, et al., 2022, Feedforward PID control of full-car with parallel active link suspension for improved chassis attitude stabilization, IEEE Conference on Control Technology and Applications (CCTA 2022), Publisher: IEEE
PID control is commonly utilized in an active suspension system to achieve desirable chassis attitude, where, due to delays, feedback information has much difficulty regulating the roll and pitch behavior, and stabilizing the chassis attitude, which may result in roll over when the vehicle steersat a large longitudinal velocity. To address the problem of the feedback delays in chassis attitude stabilization, in this paper, a feedforward control strategy is proposed to combine with a previously developed PID control scheme in the recently introduced Parallel Active Link Suspension (PALS). Numerical simulations with a nonlinear multi-body vehicle model areperformed, where a set of ISO driving maneuvers are tested. Results demonstrate the feedforward-based control scheme has improved suspension performance as compared to the conventional PID control, with faster speed of response in brakein a turn and step steer maneuvers, and surviving the fishhook maneuver (although displaying two-wheel lift-off) with 50 mph maneuver entrance speed at which conventional PID control rolls over.
Zhang J, Yu M, Joedicke A, et al., 2022, Characterising the effects of simultaneous water and gasolinedilution on lubricant performance, Tribology International, ISSN: 0301-679X
Jia Y, Dou P, Zheng P, et al., 2022, High-accuracy ultrasonic method for in-situ monitoring of oil film thickness in a thrust bearing, Mechanical Systems and Signal Processing, Vol: 180, Pages: 109453-109453, ISSN: 0888-3270
Dou P, Zou L, Wu T, et al., 2022, Simultaneous measurement of thickness and sound velocity of porous coatings based on the ultrasonic complex reflection coefficient, NDT & E International, Vol: 131, Pages: 102683-102683, ISSN: 0963-8695
Yu M, Evangelou S, Dini D, 2022, Parallel active link suspension: full car application with frequency-dependent multi-objective control strategies, IEEE Transactions on Control Systems Technology, Vol: 30, Pages: 2046-2061, ISSN: 1063-6536
In this article, a recently proposed at basic level novel suspension for road vehicles, the parallel active link suspension (PALS), is investigated in the realistic scenario of a sport utility vehicle (SUV) full car. The involved rocker-pushrod assembly is generally optimized to maximize the PALS capability in improving the suspension performance. To fully release the PALS functions of dealing with both low- and high-frequency road cases, a PID control scheme is first employed for the chassis attitude stabilization, focusing on the minimization of both the roll and pitch angles; based on a derived linear equivalent model of the PALS-retrofitted full car, an H∞ control scheme is designed to enhance the ride comfort and road holding; moreover, a frequency-dependent multiobjective control strategy that combines the developed PID and H∞ control is proposed to enable: 1) chassis attitude stabilization at 0-1 Hz; 2) vehicle vibration attenuation at 1-8 Hz; and 3) control effort penalization (for energy saving) above 10 Hz. With a group of ISO-defined road events tested, numerical simulation results demonstrate that, compared to the conventional passive suspension, the PALS has a promising potential in full-car application, with up to 70% reduction of the chassis vertical acceleration in speed bumps and chassis leveling capability of dealing with up to 4.3-m/s² lateral acceleration.
Dou P, Wu T, Luo Z, et al., 2022, A finite-element-aided ultrasonic method for measuring central oil film thickness in a roller-raceway tribo-pair, Friction, Vol: 10, Pages: 944-962, ISSN: 2223-7690
Roller bearings support heavy loads by riding on an ultra-thin oil film (between the roller and theraceway), the thickness of which is critical as it reflects the lubrication performance. Ultrasonicinterfacial reflection, which facilitates a non-destructive measurement of oil film thickness, has beenwidely studied. However, insufficient spatial resolution around the rolling line contact zone remainsa barrier, despite the employment of miniature piezoelectric transducers. In this paper, a finiteelement-aided method is utilized to simulate wave propagation through a three-layered structureof roller-oil-raceway under elastohydrodynamic lubrication (EHL), with nonlinear characteristicsof i) the deformed curvature of the cylindrical roller and ii) the non-uniform distribution of fluid bulkmodulus along the circumference of the oil layer taken into account. A load- and speed-dependentlook-up table is then developed to establish an accurate relationship between the overall reflectioncoefficient (directly measured by an embedded ultrasonic transducer) and the objective variable ofcentral oil film thickness. Moreover, the proposed finite-element-aided method is verifiedexperimentally in a roller-raceway test rig, with the ultrasonic measured oil film thicknessessentially corresponding to the calculated values by EHL theory.
Dou P, Zheng P, Jia Y, et al., 2022, Ultrasonic measurement of oil film thickness in a four-layer structure for applications including sliding bearings with a thin coating, NDT & E International, Pages: 102684-102684, ISSN: 0963-8695
Yu M, Zhang J, Kirkby T, et al., 2022, Electrical impedance spectroscopy enabled in-depth lubrication condition monitoring, The 2022 STLE Annual Meeting & Exhibition
Electrical contact resistance or capacitance as measured between twointerfaces of a lubricated contact has been used in tribometers, partiallyreflecting the lubrication condition. In contrast, the electrical impedancespectroscopy (EIS) provides rich information of magnitude/phase spectrum,which is thoroughly investigated using a combination of electrical circuitmodels (equivalent to the lubricated contact) and in-situ measurements with aball-on-disc contact. Results indicate a promising potential of EIS inlubrication condition monitoring, including the variation of lubricant filmthickness as estimated using high-frequency magnitude response; thetransition between full-film, mixed, and boundary lubrication regimes, asdifferentiated using extracted electrical resistance together with phasespectrum; the forming of anti-wear boundary film, where extraresistor/capacitor are added; and the degradation of lubricant, such as fueldilution, oil oxidization, and water emulsifying.
Yu M, Reddyhoff T, Dini D, et al., 2022, Acoustic emission enabled particle size estimation via low stress-varied axial interface shearing, IEEE Transactions on Instrumentation and Measurement, Vol: 71, ISSN: 0018-9456
Acoustic emission (AE) refers to a rapid release of localized stress energy that propagates as a transient elastic wave and is typically used in geotechnical applications to study stick-slip during shearing, and breakage and fracture of particles. This article develops a novel method of estimating the particle size, an important characteristic of granular materials, using axial interface shearing-induced AE signals. Specifically, a test setup that enables axial interface shearing between a one-dimensional compression granular deposit and a smooth shaft surface is developed. The interface sliding speed (up to 3mm/s), the compression stress (0-135kPa), and the particle size (150μm-5mm) are varied to test the acoustic response. The start and end moments of a shearing motion, between which a burst of AE data is produced, are identified through the variation of the AE count rates, before key parameters can be extracted from the bursts of interests. Linear regression models are then built to correlate the AE parameters with particle size, where a comprehensive evaluation and comparison in terms of estimation errors is performed. For granular samples with a single size, it is found that both the AE energy related parameters and AE counts, obtained using an appropriate threshold voltage, are effective in differentiating the particle size, exhibiting low fitting errors. The value of this technique lies in its potential application to field testing, for example as an add-on to cone penetration test systems and to enable in-situ characterization of geological deposits.
Dou P, Jia Y, Zheng P, et al., 2022, Review of ultrasonic-based technology for oil film thickness measurement in lubrication, Tribology International, Vol: 165, ISSN: 0301-679X
Lubricant film thickness is the most informative variable that reflects lubrication conditions and transmission efficiency in the mechanical equipment, therefore its measurement is highly important. Despite a large number of theoretical models that have been developed to describe the lubricant film, complexities and uncertainties in a real tribo-pair contact still hinder the implementation of accurate and robust methods of in-situ film thickness measurements. Recently, ultrasonic-based measurement has been widely studied, showing promising potential owing to its non-destructive characteristics, high sensitivity, and limited physical modifications. This paper comprehensively reviews basic principles of ultrasonic-based oil film measurement; summarizes progress on calculation models and associated signal processing methods; exhibits in-lab demonstrations and in-situ applications; and discusses key technical issues and possible solutions.
Yu M, Reddyhoff T, Dini D, et al., 2021, Using ultrasonic reflection resonance to probe stress wave velocity in assemblies of spherical particles, IEEE Sensors Journal, Vol: 21, Pages: 22489-22498, ISSN: 1530-437X
A high-sensitivity method to measure acousticwave speed in soils by analyzing the reflected ultrasonic signalfrom a resonating layered interface is proposed here.Specifically, an ultrasonic transducer which can be used to bothtransmit and receive signals is installed on a low-high acousticimpedance layered structure of hard PVC and steel, which in turnis placed in contact with the soil deposit of interest. The acousticimpedance of the soil (the product of density and wave velocity)is deduced from analysis of the waves reflected back to thetransducer. A system configuration design is enabled bydeveloping an analytical model that correlates the objectivewave speed with the measurable reflection coefficient spectrum.The physical viability of this testing approach is demonstratedby means of a one-dimensional compression device that probesthe stress-dependence of compression wave velocity of differentsizes of glass ballotini particles. Provided the ratio of thewavelength of the generated wave to the soil particle size issufficiently large the data generated are in agreement with dataobtained using conventional time-of-flight measurements. Inprinciple, this high-sensitivity approach avoids the need for thewave to travel a long distance between multiple transmitterreceiver sensors as is typically the case in geophysical testingof soil. Therefore it is particularly suited to in-situ observation ofsoil properties in a highly compact setup, where only a single transducer is required. Furthermore, high spatialresolution of local measurements can be achieved, and the data are unaffected by wave attenuation as transmitted insoil.
Yu M, Cheng C, Evangelou S, et al., 2021, Series active variable geometry suspension: full-car prototyping and road testing, IEEE-ASME Transactions on Mechatronics, Vol: 27, ISSN: 1083-4435
In this paper, afull-car prototype of the recently proposed mechatronic suspension, Series Active Variable Geometry Suspension (SAVGS), is developed for on-road driving experimental proof of concept, aiming to be adopted by suspension OEMs (original equipment manufacturers) as an alternative solution to fully active suspensions. Particularly, mechanical modifications are performed to both corners of the front double-wishbone suspensionof a production car, with active single-links attached to the upper-ends of the spring-damper units, while both corners of the rear suspension remain inthe original (passive) configurations.The mechanical modifications involve innovatively designed parts to enable the desired suspension performance improvements, while maintaining ride harshness at conventional levels.Areal-time embedded system is further developed to primarily implement:1) power supply, data acquisition and measurementsof the vehicle dynamics related variables, and 2) robust control application for the ride comfort and road holding enhancement, which is based on a derived linearized model of the full-car dynamics and a newly synthesizedH-infinity control scheme. Results obtained from on-road driving experiments are inessential agreement with numerical simulation results also produced. Overall, the full-car prototypeof SAVGS demonstrates promising suspension performance,with anaverage 3 dB attenuation (or equivalently 30% reduction) of the chassis vertical acceleration at aroundthe human-sensitive frequencies (2-5Hz),as compared to the original vehicle with the passive suspension system. More importantly, the prototype also indicatesthe practicality of the solution, as the SAVGS retrofit to a real car is achieved by simple mechanical modifications, compact actuator packaging, smallmass increment(21.5kg increase with respect to the original vehicle), limited power usage
Yu M, Zhang J, Joedicke A, et al., 2021, Experimental investigation into the effects of diesel dilution on engine lubrication, Tribology International, Vol: 156, Pages: 1-9, ISSN: 0301-679X
The dilution of lubricant due to contamination with diesel fuel is an increasingly prevalent, potentially importantand poorly understood issue. Thisstudy addressestwo fundamental questions: 1) How doesthe change in lubricantrheology due to diesel dilution affect engine lubrication? 2) How is the chemical performance of lubricantcomponents (base oil and performance additives) impacted by diesel dilution under different lubrication regimes(boundary/full film, hydrodynamic/elastohydrodynamic). This is achieved by testing three lubricant samples: 1)neat fully formulated 0W-30 engine oil, 2) fully formulated 0W-30 oil diluted with diesel at a concentration of15%, denoted “0W-30D”, and 3) neat, fully-formulated 0W-16, with the same base oil components andperformance additives as the 0W-30, but blended to give a viscosity equal to that of the diluted an equivalent“0W-30D”. Tribometer tests, including 1) low pressure, low shear viscosity, 2) Ultra-high Shear Viscosity (USV),3) elastohydrodynamic film thickness, 4) Stribeck friction and 5) boundary friction and wear, are then conducted.To further emulate engine lubrication conditions, Stribeck curve measurements are performed on the threelubricants using a journal bearing test rig, fitted with a connecting-rod and commercial diesel engine shells.Results suggest that diesel dilution only slightly affects chemical additive performance (with friction modifiersbeing more inhibited than anti-wear additives) but does reduce both viscosity and film thickness. However, caremust be taken in using viscometrics to predict dilution behaviour because 1) the pressure viscosity coefficient isalso affected by diesel dilution which has implications for elastohydrodynamically lubrication contacts, 2) shearthinning means that viscosity modifier additives effects lose their functions at high shear rates; whereas dieselcontamination affects viscosity behaviour throughout the whole shear rate range.
Dou P, Wu T, Jia Y, et al., 2021, High-accuracy incident signal reconstruction for in-situ ultrasonic measurement of oil film thickness, Mechanical Systems and Signal Processing, Vol: 156, Pages: 107669-107669, ISSN: 0888-3270
Yu M, Zhang J, Reddyhoff T, 2021, Characterizing Fuel Dilution Effects on Rheological and Tribological Behavior of Engine Lubricant, the 7th World Tribology Congress (WTC2021)
Jia Y, Wu T, Dou P, et al., 2020, Temperature Compensation Strategy for Ultrasonic-based Measurement of Oil Film Thickness, Wear, ISSN: 0043-1648
Yu M, Shen L, Mutasa T, et al., 2020, Exact analytical solution to ultrasonic interfacial reflection enabling optimal oil film thickness measurement, Tribology International, Vol: 151, Pages: 1-10, ISSN: 0301-679X
The ultrasonic reflection from a lubricated interface has been widely analyzed to measure fluid film thickness, with different algorithms being applied to overcome measurement accuracy and resolution issues. Existing algorithms use either the amplitude or the phase angle of the ultrasonic interfacial reflection. In this paper, a new algorithm (named the “exact model – complex”) that simultaneously utilizes both the amplitude and the phase of the complex ultrasonic reflection coefficient is proposed and mathematically derived. General procedures for theoretical analysis in terms of measurement accuracy and uncertainty are proposed and applied to the new algorithm, the beneficial features of which (as compared to other existing algorithms) can be summarized as: 1) a direct calculation, instead of an iterative approximation, 2) guaranteed maximum measurement accuracy, and 3) acceptable measurement uncertainty. None of the existing methods have showed this combination of benefits. Moreover, two groups of raw data from previous experimental studies are utilized to further validate the practical feasibility of the new algorithm. Overall, the proposed “exact model – complex” algorithm fully exploits the potential of ultrasonic reflection for oil film thickness measurement, with an accurate and a convenient calculation suited to practical implementation.
HONG H-C, ZHANG B, YU M, et al., 2020, Analysis and optimization on u-shaped damping groove for flow ripple reduction of fixed displacement axial-piston pump, International Journal of Fluid Machinery and Systems, Vol: 13, Pages: 126-135, ISSN: 1882-9554
The periodic flow ripples and pressure pulsations in a fixed-displacement axial-piston pump will directly impact its dynamic characteristics. To reduce the discharge flow ripples and pressure pulsations is one of the design challenges. An optimizing method is investigated herein using numerical models. The U-shaped damping groove at the discharge kidney groove is the primary optimized object. The numerical models of a fixed-displacement axial-piston pump with nine pistons are proposed and developed by MATLAB/Simulink. The effects of width radius, groove depth and groove length angle on flow dynamics are discussed. The optimization models based on the root-mean-square, the pulsation and the suction-extrusion ratio are proposed. As results show that the optimized structure can decrease the flow ripples from 31.08% to 20.33%.
Yu M, Cheng C, Evangelou S, et al., 2020, Robust control for a full-car prototype of series active variable geometry suspension, 2019 IEEE 58th Conference on Decision and Control, Publisher: IEEE
The Series Active Variable Geometry Suspension (SAVGS) which has been recently proposed shows promising potential in terms of suspension performance enhancement, limited power consumption and so on. In this paper, the control aspects of a full-car prototype with the front axle retrofitted by the SAVGS, which is developed to validate the practical feasibility of the novel mechatronic suspension, are addressed. Two 12 Vdc batteries and one DC/AC inverter constitute an independent power source that supplies the overall embedded mechatronic system, with two AC rotary servo motors driving the single links (in the SAVGS) at two front corners, respectively.A robust control scheme, with an outer-loop H-infinity control and an inner-loop actuator velocity tracking control, is synthesized to enhance the vehicle ride comfort and road holding performance. Numerical simulations of the full-car prototype, withthetypical road events of a 2 Hz harmonic road, and a speed humptested, are performed. Nonlinear simulation results provide the potential suspension performance improvement contributed by the SAVGS and the power usage in the batteries, which will be compared in the future with the upcoming experimental testing results of the prototype on-road driving.
Feng Z, Yu M, Cheng C, et al., 2020, Uncertainties Investigation and mu-Synthesis Control Design for a Full Car with Series Active Variable Geometry Suspension, International Federation of Automatic Control
Yu M, Evangelou S, Dini D, 2019, Position control of parallel active link suspension with backlash, IEEE Transactions on Industrial Electronics, Vol: 67, Pages: 4741-4751, ISSN: 0278-0046
In this paper, a position control scheme for the novel Parallel Active Link Suspension (PALS) with backlash is developed to enhance the vehicle ride comfort and road holding. A PALS-retrofitted quarter car test rig is adopted, with the torque flow and backlash effect on the suspension performance analyzed. An elastic linear equivalent model of the PALS-retrofitted quarter car, which bridges the actuator position and the equivalent force between the sprung and unsprung masses, is proposed and mathematically derived, with both the geometry and backlash nonlinearities compensated. A position control scheme is then synthesized, with an outer-loop H∞ control for ride comfort and road holding enhancement and an inner-loop cascaded proportional-integral control for the reference position tracking. Experiments with the PALS-retrofitted quarter car test rig are performed over road cases of a harmonic road, a smoothed bump and frequency swept road excitation. As compared to a conventional torque control scheme, the newly proposed position control maintains the performance enhancement by the PALS, while it notably attenuates the overshoot in the actuator’s speed variation, and thereby it benefits the PALS with less power demand and less suspension deflection increment.
Zhang B, Hong H, Yu M, et al., 2019, Leakage analysis and ground tests of knife edge indium seal to lunar sample return devices, Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering, Vol: 233, Pages: 2010-2022, ISSN: 0954-4100
Yu M, Arana C, Evangelou S, et al., 2019, Quarter-car experimental study for series active variable geometry suspension, IEEE Transactions on Control Systems Technology, Vol: 27, Pages: 743-759, ISSN: 1063-6536
In this paper, the recently introduced series active variable geometry suspension (SAVGS) for road vehicles is experimentally studied. A realistic quarter-car test rig equipped with double-wishbone suspension is designed and built to mimic an actual grand tourer real axle, with a single-link variant of the SAVGS and a road excitation mechanism implemented. A linear equivalent modeling method is adopted to synthesize an H-infinity control scheme for the SAVGS, with the geometric nonlinearity compensated. Simulations with a theoretical nonlinear quarter-car indicate the SAVGS potential to enhance suspension performance, in terms of ride comfort and road holding. Practical features in the test rig are further considered and included in the nonlinear model to compensate the difference between the theoretical and testing behaviors. Experiments with a sinusoidal road, a smoothed bump and hole, and a random road are performed to evaluate the SAVGS practical feasibility and performance improvement, the accuracy of the model, and the robustness of the control schemes. Compared with the conventional passive suspension, ride comfort improvements of up to 41% without any deterioration of the suspension deflection are demonstrated, while the SAVGS actuator power is kept very low, at levels below 500 W.
Yu M, 2018, Development of experimental techniques and control strategies for two novel road vehicle mechatronic suspensions
Two novel active mechatronic suspensions for road vehicles are studied in this thesis, including the Series Active Variable Geometry Suspension (SAVGS) and the Parallel Active Link Suspension (PALS). Compared to existing active suspension solutions, both the SAVGS and the PALS are capable of low-frequency chassis attitude control and high-frequency ride comfort and road holding enhancement, with the main features of 1) negligible unsprung mass increment, 2) small sprung mass increment, 3) mature technology employment of rotary-electromechanical-actuation, and 4) inherent fail-safe characteristics. On the other hand, the SAVGS and the PALS complement each other in the application range of vehicle categories (from light high performance vehicles to heavy SUV vehicles), depending on the sprung mass and the passive suspension stiffness. In order to evaluate the practical feasibility of these two novel active suspensions, a quarter car test rig is developed for experimental study, with the SAVGS and PALS mechanisms integrated separately. Multi-body nonlinear models of the SAVGS/PALS-retrofitted test rig are built to explore the novel suspensions’ potential in performance improvement and power demand. Practical features existing in the rig (e.g. the backlash in actuation transmission) are further taken into account to compensate simulation and testing behaviours. Linear equivalent models of the SAVGS/PALS-retrofitted quarter car are derived, with geometry nonlinearity compensated. Robust control schemes with an outer-loop H-infinity control and an inner-loop actuator reference signal tracking control are then synthesized to enhance the quarter car suspension performance, in terms of the ride comfort and the road holding. A set of road cases, including a sinusoidal road, a speed bump and hole, and a frequency swept road profile are tested respectively to validate the accuracy of the model assumptions, the robustness of the synthesized controllers and the feasibility
Yu M, Arana C, Evangelou S, et al., 2018, Parallel active link suspension: a quarter-car experimental study, IEEE-ASME Transactions on Mechatronics, Vol: 23, Pages: 2066-2077, ISSN: 1083-4435
In this paper, a novel electro-mechanical active suspension for cars, the Parallel Active Link Suspension (PALS), is proposed and then experimentally studied. PALS involves the introduction of a rotary-actuator-driven rocker-pushrod mechanism in parallel with the conventional passive suspension assembly, to exert an additional controlled force between the chassis and the wheel. The PALS geometric arrangement is designed and optimized to maximize the rocker torque propagation onto the tire load increment. A quarter car test rig with double wishbone suspension is utilized for the PALS physical implementation. Based on a linear equivalent model of the PALS quarter car, a conservative and an aggressive robust H∞ control schemes are synthesized separately to improve the ride comfort and the road holding, with different levels of control effort allowed in each of the control schemes. Simulations with a theoretical nonlinear model of the PALS quarter car are performed to evaluate the potential in suspension performance enhancement and power demand in the rocker actuator. Experiments with a harmonic road, a smoothed bump and hole, and swept frequency are conducted with the quarter car test rig to validate the practical feasibility of the novel PALS, the ride comfort enhancement, as well as the accuracy of the theoretical model and of a further nonlinear model in which practical features existing in the test rig are identified and included.
Yu M, Evangelou S, Dini D, 2018, Control design for a quarter car test rig with parallel active linkSuspension, 2018 Annual American Control Conference (ACC), ISSN: 2378-5861
In this paper, a recently proposed novel vehicle suspension of Parallel Active Link Suspension (PALS) is adapted on a quarter car test rig. Control strategies with the PALS are studied and synthesized for ride comfort and road holding performance enhancement. A linear equivalent model of the PALS-retrofitted quarter car is derived, with geometric nonlinearity compensated. A linear control scheme is then synthesized, with an outer-loop H-infinity control and an inner-loop actuator torque tracking. Nonlinear simulations with the model of the PALS-retrofitted quarter car test rig are performed over typical road profiles, including 2 Hz harmonic road, smoothed bump and hole, and ISO random road. Results are discussed to evaluate the potential of the PALS-retrofitted quarter car test rig in ride comfort and road holding performance enhancement, as well as the power consumption in the actuator.
Yu M, Evangelou SIMOS, Dini DANIELE, 2018, Chassis Leveling Control with Parallel Active Link Suspension, 14th International Symposium on Advanced Vehicle Control
Yu M, Evangelou SA, Dini D, 2017, Model Identification and Control for a Quarter Car Test Rig of Series Active Variable Geometry Suspension, 20th IFAC World Congress, Publisher: Elsevier, Pages: 3376-3381, ISSN: 1474-6670
In this paper, a quarter car test rig is utilized to perform an experimental study of the singlelinkvariant of the Series Active Variable Geometry Suspension (SAVGS). A nonlinear model of the testrig is identified with the use of a theoretical quarter car model and the rig’s experimental frequencyresponse. A linear equivalent modeling method that compensates the geometric nonlinearity is alsoadopted to synthesize an H-infinity control scheme. The controller actively adjusts the single-linkvelocity in the SAVGS to improve the suspension performance. Experiments are performed to evaluatethe SAVGS practical feasibility, the performance improvement, the accuracy of the nonlinear model andthe controller’s robustness.
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