Scale Vehicle Model Research Articles

Physics-guided diagnosis framework for bridge health monitoring using raw vehicle accelerations

Damage detection of bridges using vibrations from a passing vehicle has received a lot of interest recently. Though non-modal parameter-based methods (e.g., data-driven approaches) have shown promising results in this context, their advancement towards a comprehensive and rigorous monitoring system is hampered by their overreliance on machine learning techniques. On this background, this paper proposes a novel automatic physics-guided diagnosis framework for bridge health monitoring utilizing only raw vehicle accelerations. First, numerical studies are conducted to investigate the relationship between vehicle time-domain signals and bridge damage, based on which a new damage index is proposed. At the same time, it also explores the identification of damage locations and proposes a location index. Second, a damage diagnosis framework, which consists of a data processing method and a physics-guided model, is designed to overcome deficiencies from a drive-by measurement and to automate the damage detection process. The proposed framework was validated using datasets acquired from laboratory experiments employing a scale vehicle model and a steel beam. The results affirmed the method's efficacy in damage indication, quantification, and localization. Moreover, the superiority of the proposed damage index and the rationale for the proposed physics-guided approach were also demonstrated through comparisons with machine learning-based methods.

Primena prepoznavanja saobraćajnih znakova na skaliranom modelu vozila

The popularity of autonomous vehicles has grown in the past few years as autonomous systems are more and more present on vehicles. The most accessible way for students of mechanical and software engineers to learn about autonomous vehicles is by applying algorithms and systems necessary for autonomous driving on the scaled vehicle model. These models are, as in this case, and are equipped with all systems necessary for autonomous driving, such as a four-wheel drive powertrain, a suspension system, an electrically controlled steering system, a brain-computer and a camera. The goal of projects such as this one is to make the vehicle capable of autonomous driving on a designated track, obeying regular traffic rules and signs (for example, the vehicle has to perform a full stop when it approaches the stop sign). To make this possible, it is necessary for a vehicle to "know" which traffic sign is nearby, i.e., traffic sign recognition is required. For this purpose, traffic sign recognition is done by an artificial neural network. The training process of the proper artificial neural network will be shown in this paper.

自動車のフロントエンド形状とエンジン冷却風による空力特性

The purpose of this research is to experimentally investigate how increase of the air inlet area of the engine cooling air affects the aerodynamic characteristics depending on the shape of the front-end of the vehicle body. A simplified 1/5 scale vehicle model was used with reproduction of the engine compartment where FF and FR type engines could be installed. In past researches, we used a rectangular front-end model, and in this research we used a round front-end model with a shape closer to the actual vehicle. In the wind-tunnel experiments, the moving-belt ground board was used to capture ground effects, measuring drag force, lift force and body surface pressure. The experiments were conducted at a wind speed and a moving belt speed of 20 m/s. As a result, the reason for the increase in drag due to the increase in air inlet area was the damming effect caused by the interference between the scavenging air flow in the engine compartment and the underfloor flow. The drag force of the round model was lower than that of the rectangular model, but the lift force was not significantly reduced.

Reduction of Aerodynamically Undesirable Influences Due to Engine Cooling Flow in Road Vehicle

The purpose of this research is to clarify causes for the change in aerodynamic characteristics of a road vehicle model due to engine cooling flow in wind-tunnel experiments with the moving-belt ground board, in order to propose methods to reduce the drag and lift. With regard to engine cooling flow, the air-intake system was adjusted with variable opening area and position for the engine loading system of FF and FR with and without a radiator. A simplified 1/5 scale vehicle model was manufactured with transparent externals around the engine for flow visualization. The overall results show that with enlargement of the opening area, the drag and the front lift increased and the rear lift decreased. The flow visualization and the measurements of underfloor velocity and surface pressure indicated the cause of the characteristics changes. Enlargement of the opening area causes flow disturbance by merging of the scavenging flow and the underfloor flow, which has blockage effects for the upstream of each flow with keeping high pressure in the engine compartment and causes pressure loss under the floor behind the engine unit. The difference between the two engine loading systems lies indirection and location of the engine unit, which causes the differences of how the flow features affect the aerodynamic characteristics. The effect of the radiator is to reduce the range of changes in drag and lift. Finally, it is discussed that the principle of reducing drag and lift is to suppress interference of scavenging flow, and concrete methods are proposed.

Investigation on aerodynamic characteristics of tailing vehicle hood in a two-vehicle platoon

Experimental and numerical methods were performed to study the hood aerodynamics of a 1:18 scale vehicle model in a two-vehicle platoon under different fixed intra spacing and dynamic intra spacing at the Reynolds number of 4.9 × 105 and 4.08 × 105 in a 1:15 scale wind tunnel. Blockage ratio was calculated to be 5.6% for experiments. The averaged and fluctuating pressures of the hood of the tailing vehicle are much higher than that of single vehicle, and stronger fluctuation occurs at the front and rear edges of hood. Pressure fluctuation over the tailing vehicle hood increases as the intra spacing diminishes but sharply declines within intra spacing of 0.2 L. The energy of fluctuation is concentrated in frequency bands from 50 to 110 Hz at wind speed of 30 m/s and 40–90 Hz at wind speed of 25 m/s. Energy at the main frequency bands and peak frequencies take up nearly 25% of total energy, respectively. The results of proper orthogonal decomposition show that total energy proportion is 49.6% for the first 11 modes and 67.0% for the first 30 modes, respectively. Relative motion at low speed has no discernible effect on hood behavior and peak frequencies have inclination to decline during the process of vehicle approaching.

Crashworthiness of Aluminium Structures - An Illustration Through Scaled Model

The use of aluminium in aerospace structures is predominantly high for being one of the best candidates to achieve light weight with sufficient crashworthiness characteristics. This paper supports the study of aluminium-based vehicle crashworthiness through an aluminium space frame scaled model. Within the limitations of the availability of the extruded tubes, the current study reports about correlation of physical testing and simulation practice along with the visualisation of the crush behaviour of scaled model. An in-house Impact Testing Machine (ITM) is used for testing of the scaled vehicle model. The use ITM is justified using an extruded aluminium tube impact testing and its correlation with finite element simulation. With this confidence the same procedure was used for carrying impact test on scaled vehicle model. The results from physical test and simulation were correlated satisfactorily supporting the simulation procedure. The test results also helped in visualising the crush space behaviour of...

Study on detection of the early signs of derailment for railway vehicles

This paper proposes a technique for detecting the early signs of derailment of a railway vehicle. The proposed system detects abnormal vehicle signs before derailment using micro-electromechanical system acceleration sensors for automobiles. A derailment detection algorithm has been investigated using derailment simulations and experiments. A numerical analysis with a scaled vehicle model simulating wheelclimb derailment at low speeds has been examined. A scale model of a railway vehicle, including one carbody with two bogies, as well as an original device that can simulate various wheelclimb derailments for the selected wheel was designed and made. Based on a numerical analysis and scaled derailment experiments, an algorithm for detecting the signs of derailment beforehand has been proposed and verified. It is found that, using the peak threshold of the pitch angular rate and the integral threshold of the roll angular rate of the truck frame, it is possible to detect the signs of the derailment.

1108 脱線後にまくらぎ上を高速走行する車両の縮尺模型実験(OS2-2 鉄道,OS2 交通・物流システムのダイナミクス,オーガナイズド・セッション(OS))

To reduce secondary damage after the train is derailed by the earthquake vibration, it is important to know the behavior of the train set running at the high speed. When the derailed wheelsets run on a ballasted track, derailing wheels run on the sleepers and running resistance occurs to the vehicle because the wheels hit and bounce to the sleepers. To understand the running resistance and estimate the train set dynamic characteristics, we performed the experiment where 1/10 scaled vehicle model ran on steel sleepers at high speeds. We show the following results. (1) Equivalent running resistance coefficient was calculated from entrance and exit running speed of the test area. From the comparison between running on the flat plate and running on the sleepers, resistant coefficient on the sleepers was remarkably larger at 10〜70km/h speed than that on the flat plates. (2) There seems to be a relation between the size of the equivalent running resistance coefficient and the number of sleeper traces.

Stabilization Control for Hunting Motion of Railway Vehicle by Gyroscopic Damper (Experimental Analysis Using 1/10 Scale Vehicle Model)

Stabilization Control for Hunting Motion of Railway Vehicle by Gyroscopic Damper (Experimental Analysis Using 1/10 Scale Vehicle Model)

2213 ジャイロを用いた鉄道車両に生じる蛇行動現象の安定化 : 1/10スケール車両を用いた実験的検討(シミュレーション技術,OS3 交通・物流システムのダイナミクスと制御)

2213 ジャイロを用いた鉄道車両に生じる蛇行動現象の安定化 : 1/10スケール車両を用いた実験的検討(シミュレーション技術,OS3 交通・物流システムのダイナミクスと制御)

Steering control for advanced guideway bus system with all-wheel steering system

This article proposes a steering control strategy for articulated buses equipped with an all-wheel steering system to eliminate off-tracking. In this system, the center of each axle passes through the same locus, which is similar to the operation of trains. This control system was validated by means of a numerical simulation, using a vehicle dynamics model and some experiments with a scaled vehicle model. The proposed control system was confirmed to be effective in eliminating off-tracking for articulated buses.

VIRTUAL PROTOTYPING FOR VEHICLE DYNAMIC MODELLING

The purpose of this paper is to provide an overview of the research that was conducted in the development of a virtual prototype of a real vehicle. For that purpose the ADAMS/CAR software was chosen because it is a sophisticated mechanical dynamic modelling tool typically used by some of the main car manufacturers. The main motivation of this virtual prototyping was to test different control techniques in an active suspension of a full scale vehicle model. This is a preliminary approach to the virtual prototyping process and how it can be used to solve forward and reverse engineering problems.

Automatic Geometry Based FE Model Generation for Optimization and Robust Design for Passive Safety of Passenger Vehicles

AbstractIn this paper the optimization of large scale vehicle structures is addressed. A process strategy based on Latin Hypercube sampling, genetic algorithm optimization, and sensitivity analysis is discussed. This process was implemented on a dedicated Linux Cluster, utilizing various free and commercially available software tools, including SFE Concept, Perl, Matlab, and Radioss. The viability of the method is demonstrated for a large scale vehicle model in an offset deformable barrier crash test at 64 kph impact velocity. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

UNSTEADYWAKE OF A PASSENGER CAR MOOEL

How around an automobile is usually considered as steady phenomenon. Aerodynamic coefficients, the most imponant of which is the drag coefficient, are regarded as constants because of the steady flow around the vehicle body. Them is a thought however, the flow separations and the vortical motions around the body me unsteady and the constant drag coefficient can be obtained as a time averaged value of unsteady forces. The present study has been carried out horn this view point The unsteady wake structure up to 300 Hz of a scale vehicle model was measured using 252 total pressure probes. The measuring system is based on ESP (Electronically Scanned Pressure) sensors, which is very popular in the wind engineering field. The results show the wake of the vehicle model has unsteady structure.

The reduction of accident risk for high sided road vehicles in cross winds

Wind tunnel tests have been performed to investigate methods of reducing the accident risk (the number of hours a year that the accident wind speed is exceeded) for high sided road vehicles in high winds. Measurements were made of the aerodynamic forces acting on a 1/50th scale vehicle model in a turbulent flow behind wind fences of various geometry and with the upper corners of the trailer rounded to various radii. Extreme forces were also measured for the model behind a wind fence. The results showed the drastic reduction in the accident risk achieved by the use of wind fences due to the large reductions of the aerodynamic forces acting on the vehicle. However, only a modest reduction resulted from the rounding of trailer corners due to the strong Reynolds number dependency of the force coefficients.

Sensitivity analysis for structural frequency response characteristics. (First report. Proposition of new frequency response sensitivity analyses and comparison between some different methods).

Frequency response characteristics of a vehicle's structure affect the vehicle's sound and vibration, such as booming noise, road noise, riding comfort and handling stability. Therefore, a reliable analysis technique to determine the proper means of effectively controlling these factors, is desired. Sensitivity analysis, in the broad sense, is effective to accomplish this purpose, as it shows the change in response when parts of the structure are varied. Sensitivity analysis must be accurate and time-efficient. There are no studies comparing the merits and demerits, of major methods of frequency response sensitivity analysis from these two aspects. In this paper we introduce two new modal frequency response sensitivity analysis methods, and compare them with conventional methods by using the FEM bar model. We define relative advantages of these methods. In addition we clarify the important points when applying the sensitivity analysis to optimize a frequency response of a large scale vehicle model.