Imperial College London

Dr Min Yu

Faculty of EngineeringDepartment of Mechanical Engineering

Research Associate
 
 
 
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Contact

 

m.yu14

 
 
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Location

 

564City and Guilds BuildingSouth Kensington Campus

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Summary

 

Publications

Publication Type
Year
to

20 results found

Yu M, Reddyhoff T, Dini D, Holmes A, O'Sullivan Cet al., 2021, Using ultrasonic reflection resonance to probe stress wave velocity in assemblies of spherical particles, IEEE Sensors Journal, 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.

Journal article

Dou P, Wu T, Luo Z, Yang P, Peng Z, Yu M, Reddyhoff Tet al., 2021, A finite-element-aided ultrasonic method for measuring central oil film thickness in a roller-raceway tribo-pair, Friction, 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.

Journal article

Yu M, Cheng C, Evangelou S, Dini Det al., 2021, Series active variable geometry suspension: full-car prototyping and road testing, IEEE-ASME Transactions on Mechatronics, 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

Journal article

Yu M, Zhang J, Joedicke A, Reddyhoff Tet 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.

Journal article

Dou P, Wu T, Jia Y, Peng Z, Yu M, Reddyhoff Tet 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

Journal article

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)

Conference paper

Jia Y, Wu T, Dou P, Yu Met al., 2020, Temperature Compensation Strategy for Ultrasonic-based Measurement of Oil Film Thickness, Wear, ISSN: 0043-1648

Journal article

Yu M, Shen L, Mutasa T, Dou P, Wu T, Reddyhoff Tet 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.

Journal article

HONG H-C, ZHANG B, YU M, ZHONG Q, YANG H-Yet 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%.

Journal article

Yu M, Cheng C, Evangelou S, Dini Det 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.

Conference paper

Feng Z, Yu M, Cheng C, Evangelou S, Jaimoukha I, Dini Det al., 2020, Uncertainties Investigation and mu-Synthesis Control Design for a Full Car with Series Active Variable Geometry Suspension, International Federation of Automatic Control

Conference paper

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.

Journal article

Zhang B, Hong H, Yu M, Yang Het 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

Journal article

Yu M, Arana C, Evangelou S, Dini Det 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.

Journal article

Yu M, Arana C, Evangelou S, Dini D, Cleaver Get 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.

Journal article

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.

Conference paper

Yu M, Evangelou SIMOS, Dini DANIELE, 2018, Chassis Leveling Control with Parallel Active Link Suspension, 14th International Symposium on Advanced Vehicle Control

Conference paper

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.

Conference paper

Zhang B, Yu M, Yang H, 2015, Leakage analysis and ground tests of the O-type rubber ring seal applied in lunar sample return devices, PROCEEDINGS OF THE INSTITUTION OF MECHANICAL ENGINEERS PART G-JOURNAL OF AEROSPACE ENGINEERING, Vol: 229, Pages: 479-491, ISSN: 0954-4100

Journal article

Zhang B, Yu M, Yang H, Hong Het al., 2014, RESEARCH ON SEALING STRUCTURE AND GROUND TEST OF LUNAR SAMPLE RETURN DEVICES, ASME International Mechanical Engineering Congress and Exposition (IMECE2013), Publisher: AMER SOC MECHANICAL ENGINEERS

Conference paper

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