Car Roof Research Articles

Isolation enhancement of a capacitively-fed MIMO antenna using a quasi-fractal parasitic element and defected ground structure

Vehicular Internet of Things (IoT) is facilitated by efficient RF front ends with suppressed mutual coupling for enhanced spatial diversity and increased channel capacity. This paper presents a mutual coupling suppressed MIMO antenna with a hybrid decoupling technique for Vehicle-to-Everything (V2X) communications, enabling IoT in automotive systems. The single elements consist of a radiating patch with a cleaving circular slot to introduce a capacitive effect on the radiating structure. Afterwards, the single-unit design is further extrapolated to a 2 × 2 MIMO antenna. The mutual coupling is suppressed between antenna elements by introducing a quasi-fractal parasitic element and a defected ground structure (DGS). The MIMO antenna is designed to conform to the requirements posed by V2X systems in Dedicated Short-Range Communications (DSRC) and Intelligent transportation system (ITS) scenarios. The proposed MIMO antenna offers measured |S11| < −10 dB of 200 MHz, ranging from 5.77 GHz to 5.97 GHz, fully covering the spectrum guided by the IEEE 802.11p standard. A physical prototype is fabricated and placed on a car roof to assess the congruency between measured and simulated results. The MIMO antenna exhibits exceptional diversity properties, such as enhanced isolation (>28 dB) between its individual elements, a diversity gain (DG) close to the ideal value of 10 dB (9.99 dB), peak realized gain of 6.5 dBi, an ECC below 0.001, and a beam coverage area of 180° in azimuthal and elevation plane by dynamic port switching. Thus, the proposed MIMO antenna module is a considerable candidate for future V2X communication paradigms.

RFSoC Softwarisation of a 2.45 GHz Doppler Microwave Radar Motion Sensor

Microwave Doppler sensors are used extensively in motion detection as they are energy-efficient, small-size and relatively low-cost sensors. Common applications of microwave Doppler sensors are for detecting intrusion behind a car roof liner inside an automotive vehicle and to detect moving objects. These applications require a millisecond response from the target for effective detection. A Doppler microwave sensor is ideally suited to the task, as we are only interested in movement of a large water-based mass (i.e., a person) (FMCW Radar also detect static objects). Although microwave components at 2.45 GHz are now relatively cheap due to mass production of other Industrial Scientific and Medical application (ISM) devices, they do require tuning for temperature compensation, dielectric, and manufacturing variability. A digital solution would be ideal, as chip solutions are known to be more repeatable, but Application-Specific Integrated Circuits (ASICs) are expensive to initially prototype. This paper presents the first completely digital Doppler motion sensor solution at 2.45 GHz, implemented on the new RFSoC from Xilinx without the need to up/downconvert the frequency externally. Our proposed system uses a completely digital approach bringing the benefits of product repeatability, better overtemperature performance and softwarisation, without compromising any performance metric associated with a comparable analogue motion sensor. The RFSoC shows to give superior distance versus false detection, as the Signal-to-Noise Ratio (SNR) is better than a typical analogue system. This is mainly due to the high gain amplification requirement of an analogue system, making it susceptible to electrical noise appearing in the intermediate-frequency (IF) baseband. The proposed RFSoC-based Doppler sensor shows how digital technology can replace traditional analogue radio frequency (RF). A case study is presented showing how we can use a novel method of using multiple Doppler channels to provide range discrimination, which can be performed in both analogue and in a digital implementation (RFSoC).

Stress tolerance of lightweight glass-free PV modules for vehicle integration

Electric vehicles (EVs) currently dominate the sales in the automotive market. A big leap in this market can be made by developing a photovoltaic product that can be integrated to an EV, as it can boost the driving range of the EV while reducing the charging frequency. Such vehicle-integrated photovoltaic (VIPV) products are already successfully demonstrated, but they are usually made with glass as a front sheet – making them bulky and limiting their use to the car roofs due to safety reasons. The contemporary focus of the research in the field of VIPV is on developing a product that is lightweight (LW) and easily integrable into the complex shapes of an EV. Therefore, in this work, we present our initial findings on a novel architecture for LW VIPV modules employing polycarbonate (PC) as a front sheet. The mechanical behaviour of the LW module under bending is successfully simulated using finite elements (FE) modelling to predict the fracture of the solar cells, which can then be used as a predictive tool to check the maximal load on the PV body of an EV before cracking the c-Si solar cells. We demonstrate that a change in the temperature of the PC-based LW modules can modify the interspacing between the cells and thus create stress on the connectors. The dog-bone connectors are found to allow almost unconstrained movement of the cells in the module when subjected to variation of temperature. The cell movements may result in mechanical fatigue of the interconnection, which can ultimately result in disconnection of the cells. Initial performance of the dog-bone connectors is investigated by applying mechanical fatigue experiments, which demonstrate that the special geometry of the dog-bone connector could endure a greater number of thermal cycles than a simple prismatic shape would.

Classification of convertible car roofs and basics of their operation

This paper deals with cabrio type cars. The most interesting currently used solutions and groundbreaking designs from the last decades are presented. This paper contains collected knowledge on kinds of convertible roofs found in mass produced cabriolets. With the development of the automotive technology such constructions have evolved from simple mechanisms operated using the force of human muscles to highly complex mechatronic systems. The author introduces his own classification of car roofs with regard to their mechanical structure and the medium used to change the body status from closed to open and vice versa. In the second part of this publication the basics of the operation of car roof mechanisms are provided.

Health monitoring of composite car roof failure under effect of different impact velocity

Health monitoring of composite car roof failure under effect of different impact velocity

ОБОСНОВАНИЕ ПРОЧНОСТИ НЕСУЩЕЙ КОНСТРУКЦИИ КУЗОВА ВАГОНА С УЧЕТОМ КРИТИЧЕСКИХ НАПРЯЖЕНИЙ В ГОФРАХ

The issues are considered that are connected with substantiating the strength and stability of the metal structure of a double-deck passenger car body under the influence of both compressive loads and the effects of excessive solar radiation and other external factors. &#x0D; A computational and experimental method is proposed for assessing the stability of corrugated sections of the roof slopes of passenger car bodies. Five variants of the structural design of the double-deck car roof covering are proposed. The stability of the covering for the accepted variants was evaluated by an analytical method using a tabular and rod finite element model. Based on the results of the calculation, a rational variant of the structural design of the car roof was determined. &#x0D; The results of theoretical studies are confirmed by the data of full-scale bench tests of the metal structure of a new double-deck car body.

Experimental study of thermoelectric cooling system for a parked car with solar energy

Vehicles parked under the direct sun cause an increase in the cabin temperature drastically. The extreme increase in vehicles cabin temperature will increase air conditioning (AC) energy and fuel consumption, can damage interior equipment, and increases the health risk to passengers in the car. Therefore, this research aims to investigate the thermoelectric as a cooling system for a parked car integrated with solar energy. The solar panel on the car roof generates electricity as a cooling system energy source. The cooling system consists of 4 thermoelectric coolers equipped with heatsinks and axial fans on the hot and cold side of thermoelectric. The test was conducted on passenger cars during the day for 4 hours of parking. The result shows that the cabin car temperature decrease by 6,1°C or 13% compared to without cooling, which will increase passenger comfort and reduce energy consumption.

ИССЛЕДОВАНИЕ ВЛИЯНИЯ ИЗБЫТОЧНОЙ СОЛНЕЧНОЙ РАДИАЦИИ И БОКОВОЙ ВЕТРОВОЙ НАГРУЗКИ НА ОЦЕНКУ ПРОЧНОСТИ КУЗОВА ДВУХЭТАЖНОГО ВАГОНА

Approaches to the analysis of the load-bearing systems of the bodies of double-deck cars, as well as the experience of their operation on domestic railways are analyzed. It is found out that for modern load-bearing structures of bodies with minimum permissible safety margin and stability of elements, it is advisable to pay more attention to specific loads, such as wind and loads associated with excessive solar radiation.&#x0D; The method of studying the influence of these factors on the load-bearing capacity of the elements of car body pressure shell is proposed. The method provides for both experimental simulation of exposure of the double-deck car roof with excessive solar radiation in combination with subsequent exposure to repair loads, and carrying out a complex of calculations based on the application of the finite element method (FEM).&#x0D; The conducted studies indicate the need for a more precise account of the influence of lateral wind load and excessive solar radiation when assessing the strength of the load-bearing structures of the double-deck car bodies.&#x0D; It is shown that the proposed technique makes it possible to take into account these specific loads on the basis of mathematical modeling with confirmation of the results obtained by the data of field experiments.

Design of a Solar Powered Car (Electrical Car), Feasibility and Sustainability in Nigeria Using Imo State Polytechnics Umuagwo Site as a Case Study

The Design of a Solar Car was carried out, and its reality, feasibility, and workability in Nigeria were visualized. The sustainability was carried out by accessing and quantifying the optimal solar radiation in Nigeria using Imo State Polytechnic Umuagwo Ohaji, Imo State site as a case study. The Solar radiation on a horizontal plan and an inclined plan was calculated and quantified and their various values were compared and it was discovered that the radiation on an inclined plan was higher. The optimal mean monthly global radiation was calculated and adopted. &#x0D; Due to the constant dynamic nature of a car, the optimal mean monthly daily average tilt angle was calculated and adopted as 15.390. The optimal mean monthly average daily tilt angle was used in the design of the car roof, such that the solar panel mounted on it will be inclined at 15.390 to ensure the maximum hardness of the optimal solar radiation. The solar energy generated is connected to the batteries via the solar charging controller. The battery connects two 12v by 100Am batteries in series. The batteries generate electric current to the D.C motor connected to the car gear through a pulley system mechanism. The gear powers and controls the movement of the car to any location.

Estimating lighting device inventories with the LANcube v2 multiangular radiometer

This paper is a technical report describing the use of an open source instrument called LANcube v2 to estimate a lighting devices inventory. The LANcube v2 is and instrument having 5 color sensitive sensors, each on a face of a cube. The instrument can be mounted on a car roof in order to create a map of the artificial light at night while roaming the streets and roads. Based on the temporal variations of the detected signal on various cube’s faces, we developed a method of finding the approximate position in 3D of each source. The lamp spectral types can be determined relatively well thanks to the color balance of the raw Red (R), Green (G), Blue (B), and Clear (C) color bands. If one assumes a typical angular photometry of a source with respect to its location, it is possible to estimate roughly its current luminous flux. Such information allows us to build a lighting devices inventory of a territory. One advantage of that new method is that it can provide information about the private sources that are always excluded from public lighting inventories. We compared the inventory extracted with that new methodology with an in situ lamp inventory made for two villages in Canada. This comparison allow us to emphasize the strengths and limitations of the method by comparing to the ground truth. We actually found that we were able to detect 99% of the sources with flux higher than 1000 lumen and located within 15 meters from the road. We also found that we generally overestimate the height of the devices by 21 to 51% depending on the lamp photometry. This overestimate surely reflect in an overestimate of the fluxes. Finally, we found that the proposed method is very efficient to recognize the spectral type of the devices with 99% of success.

Computer Vision Implementation in Scratch Inspection and Color Detection on The Car Roof Surface

The automotive industry in Indonesia is one of the important pillars in the manufacturing sector. High speed productivity and high-level quality of their products are required for increasing the company value. The car roof inspection is still in low speed and inadequate quality control method for most of the car company’s manufacturing production line. This inspection process is highly dependent to human expertise and skill of the assembly operators. This study purposes to increase the productivity in the inspection line by eliminate human error using computer vision. This research aims to find an automatic and accurate method for visual inspection of the color quality and scratch defect on car roof surfaces, using the data generated from the standardized database QR Code. The proposed solution uses MobileNet-SSD method of computer vision in recognizing scratch defects, while color detection of the roof is attained through hue saturation method. The study employs data capture from a camera and compares the amount of object inspected in real time. The scratch inspection with 70 image samples and 4000 training steps results in a 3.33% error with color detection and inspection success rate of 80%.

Numerical investigation of thermal buckling and post-buckling behavior of an EN AW 6016-T4 car roof assembled in a steel body-in-white

The automotive industry is undergoing significant changes driven by factors such as reducing carbon dioxide emissions, advancing technology, evolving regulations, and the emergence of new energy sources. Lightweight materials, particularly aluminum alloys, are being extensively researched and integrated into vehicles to reduce weight and improve performance. However, the heating process during vehicle production can cause thermal buckling in thin aluminum alloy structures, affecting their appearance and quality. While thermal buckling has been studied in other industries, research in the automotive sector, particularly for non-structural parts like car roofs, is limited. This study uses numerical simulation to predict thermal buckling and post-buckling behavior of a EN AW 6016-T4 alloy car roof assembled in a predominantly steel body-in-white. The research findings indicate that roof buckling occurs at a relatively low temperature difference of approximately 60 °C, which is lower than the maximum temperatures experienced during the painting phases in the automotive industry. Consequently, undulations in the roof's shape become apparent, underscoring the importance of design modifications to ensure visual conformity. Validation through physical testing confirms the model's accuracy, providing valuable insights for designing lightweight structures with improved performance and aesthetics.

Loading Research of Load-Bearing Structure of Hopper Car with Composite Roof

Purpose. The work is aimed to investigate the loading of load-bearing structure with composite material roof. This will allow reducing the dead weight of the hopper car and will contribute to the possibility of increasing its carrying capacity. Methodology. Investigations were performed using the example of hoper car for grain transporting, model 19-6869, manufactured by Karpaty Experimental Mechanical Plant. It is important to say that the use of composite material reduces the roof weight by up to 40% in comparison with the metal design. That is why mathematical modeling of dynamic loading of the hopper car with composite roof was carried out. Differential equations were solved by Runge-Kutta method in MathCad software package. Initial conditions were assumed to be zero. During the calculations, the spring suspension parameters of the 18-100 bogie models were taken into account. The obtained results of calculations were used when determining the main indicators of the roof strength. The spatial model of the hopper car roof was created in SolidWorks software complex. Calculation was performed by the finite element method, which is implemented in the SolidWorks Simulation (CosmosWorks) software complex. When constructing the finite element model of the hopper car, the isoparametric tetrahedra were used. The optimum number of the model elements was determined by the grapho-analytical method. Findings. The basic indices of load-bearing structure dynamics of hopper car with composite roof were obtained. Acceleration of the body in the mass center was 5,0 m/s2. Coefficient of vertical dynamics is equal to 0.67. It was found that the maximum equivalent stresses in the roof for all the considered loading schemes do not exceed the admissible values, that is, the roof strength is ensured. Originality. The mathematical modeling of dynamic loading of the load-bearing structure of the hopper car with composite roof was carried out. The acceleration values as the components of dynamic loading acting on it during operation as well as vertical dynamics coefficient were determined. The strength indicators of the composite roof under the main operational loading modes have been found out. Practical value. The conducted research will contribute to the creation of guidelines for the design of innovative structures of the rolling stock, as well as increase the efficiency of its operation.

Static Concentrator Photovoltaics Module for Electric Vehicle Applications Based on Compound Parabolic Concentrator

Electric vehicles (EVs) and photovoltaics (PVs) are new technologies that will play an important role in the transportation industry over the next decade. Using solar panels on the roofs of cars is one of the simplest ways to reduce fuel costs and increase the mobility of electric vehicles. Solar electric cars can be charged anywhere under the Sun without additional infrastructure, but the problem is the size of the solar panel is limited on the roof and the electricity conversion efficiency of the panel is only 15% to 20%. This means they will not provide significant electricity to EVs. An effective way to increase efficiency is to utilize multi-junction solar cells with concentrator photovoltaic (CPV) technology. The challenge is that the moving sun-tracking mechanism will reduce the stability of the vehicle structure. To solve this issue, in this research, we present a static concentrator photovoltaic system for electric vehicles. This structure is more stable and simpler than CPV systems using sun-tracking mechanisms and thus suitable for car roof application. The CPV system includes solid compound parabolic concentrators (CPCs), three-junction solar cells, and a crystalline Si cell panel. This structure allows for the manufacture of a static CPV with a geometrical concentration ratio of 4× for three-junction cells. The simulation results showed that the module can achieve 25% annual efficiency. Moreover, it can be flexible to meet the requirements of car roof application.

Potential of Bamboo as Car Roof Material

An effort to achieve SDGs 12# responsible for consumption and production is by optimizing the application of natural recycled materials, such as bamboo, in the automotive industry. Bamboo is a potential insulating material because it has low thermal conductivity. This study used Gigantochloa Atroviolacea as a thermal insulator projected as a car roof. Experiments were performed to identify the effective thermal conductivity. There were two shapes tested: slab and box. The first specimen is a laminated bamboo slab, and the second is a combined slab of laminated bamboo, glass wool, and aluminum foil. Based on the heat transfer calculation, the effective thermal conductivity is 0.21 W/mK and 0.14 W/mK for the laminated bamboo slab and combined slab, respectively. The thermal flow characteristic was analyzed in two box models with different material arrangements. The first box is laminated bamboo and fiber, and the second is laminated bamboo and glass wool. The results show that the first box can insulate heat better than the second. It was concluded that laminated bamboo and bamboo fiber can be used as a substitute for glass wool material. The bending test of laminated bamboo with three different layers was performed according to ASTM D 790. The maximum load was 616 kg for five layers. The bending test showed that laminated bamboo is insufficient as a car roof. Steel plates are still necessary to comply with the requirements of the FMVSS 216 standard.

An Algorithm for Painting Large Objects Based on a Nine-Axis UR5 Robotic Manipulator

An algorithm for automatically planning trajectories designed for painting large objects is proposed in this paper to eliminate the difficulty of painting large objects and ensure their surface quality. The algorithm was divided into three phases, comprising the target point acquisition phase, the trajectory planning phase, and the UR5 robot inverse solution acquisition phase. In the target point acquisition phase, the standard triangle language (STL) file, algorithm of principal component analyses (PCA), and k-dimensional tree (k-d tree) were employed to obtain the point cloud model of the car roof to be painted. Simultaneously, the point cloud data were compressed as per the requirements of the painting process. In the trajectory planning phase, combined with the maximum operating space of the UR5 robot, the painting trajectory of the target points was converted into multiple traveling salesman problem (TSP) models, and each TSP model was created with a genetic algorithm (GA). In the last phase, in conformity with the singularities of the UR5 robot’s motion space, the painting trajectory was divided into a recommended area trajectory and a non-recommended area trajectory and created by the analytical method and sequential quadratic programming (SQP). Finally, the proposed algorithm for painting large objects was deployed in a simulation experiment. Simulation results showed that the accuracy of the algorithm could meet the requirements of painting technology, and it has promising engineering practicability.

Random Vibration Fatigue Analysis of Car Roof Luggage Carrier

In this paper, random vibration analysis was applied to predict the car roof luggage carrier's fatigue life. Ansys Workbench 19.2 program was used in this study for finite element analysis. The car roof luggage carrier geometry has meshed with 325,536 nodes and 105,682 elements. Random vibration analysis was applied by defining a 75kg load on the car roof luggage carrier applied according to the vibration and PSD data obtained according to the engine, wind, and road conditions of the vehicle, and it was estimated that no fatigue damage would occur for a minimum of 154564 hours using the Steinberg method.

A Multiwideband Compact Antenna Design for Vehicular Sub-6 GHz 5G Wireless Systems

This article presents a multiwideband monopole antenna for automotive application in the long-term evolution (LTE) and 5G systems that covers the frequency range from 617 MHz to 5 GHz with reasonable rejection on the L1/L2/L5 GNSS bands. The antenna is suitable for placement on a car roof within a shark-fin radome due to its physical dimensions and performance. The antenna is simulated using software and then fabricated and measured on a 1 m ground plane and a vehicle roof. The measurement results of the fabricated prototype are presented and plotted in terms of reflection coefficient, radiation patterns, antenna efficiency, and linear average gain (LAG). The proposed antenna shows very good properties that make it suitable for the automotive industry.

Numerical and Non-Destructive Analysis of an Aluminum-CFRP Hybrid 3D Structure

Advanced materials are widely used in many industries. They play an important role especially in the aeronautic and automotive sectors where weight reduction is required in order to reduce fuel consumption. Composite materials have a high strength to weight ratio and are applied in airplane construction. Nevertheless, sometimes it is not viable to replace all metal parts by composite ones due to the cost factor. In this sense, hybrid structures are highly welcome. In order to ensure the safety of these hybrid components during their entire life cycle, non-destructive testing evaluation (NDT&amp;E) methods are used and sometimes they are the only option. In this study, we use infrared thermography (IRT) to inspect an aluminum-composite hybrid structure with a 3D shape. The sample has a composite part with a small metal inlay (EN AW-6082) overmolded with a thermoplastic layer. The inlay is bended to reach the desired 3D geometry. This sample was design to be used for the connection between an A- or B-pillar and a car roof made of carbon fiber reinforced polymer (CFRP). A dual-band infrared camera is used in order to capture images in two different spectral ranges. In addition, two data processing techniques for infrared images are applied to enhance the images: principal component thermography (PCT) and partial least squares thermography (PLST). Then, a signal-to-noise ratio analysis is performed with three randomly chosen previous known defects to assess the quality of the images and detected defects. Results showed that principal component thermography has a slight advantage over partial least squares thermography in our specific experiments. Specifically, for the long-wave infrared band, PCT presented, among the defects analyzed, PCT presented a mean value 12.5% higher while the standard deviation was almost three times lower than PLST. In parallel to the non-detructive analysis, a numerical finite element model was formulated in ANSYS® to analyze the total deformations to which the metal-composite-hybrid structure is subjected during a possible use. Results obtained with the numerical model indicate that the interface region between composite and metal parts is where the highest degree of deformation occur, which indicates possible regions where defects and failures may occur in real use cases.

Simulation study on effects of purifier positions on formaldehyde removal under the condition of vehicle air supply

In order to further improve the interior air quality and comfort of the vehicle, CFD method is used to simulate the different airflow distribution caused by car-mounted air purifiers at different positions. Combined with the change of formaldehyde concentration field in car, the influence of car-mounted air purifiers on the formaldehyde dilution and removal under the condition of air conditioning air supply is analyzed. The simulation results are verified by actual measurement, and the trend of the simulation results is basically consistent with the measured results. When the car air purifier placed in the middle of the car roof, it can effectively dilute and purify the formaldehyde gas in the car, and reduce the concentration of formaldehyde in the breathing area of the driver and passengers. The adsorption and degradation of formaldehyde by the purifier, together with the dilution of formaldehyde by air supply, can improve the air quality in cars more effectively than using only one of the air purification methods.