Search Results (94)

Sensor fusion in intelligent suspension systems constitutes a fundamental technology for optimizing vehicle dynamic stability, ride comfort, and occupant safety. By integrating data from multiple sensor modalities, this study proposes a hierarchical multi-sensor fusion framework for active suspension control, aiming to enhance control precision. Initially, a binocular vision system is employed for target detection, enabling the identification of lane curvature initiation points and speed bumps, with real-time distance measurements. Subsequently, the integration of Global Positioning System (GPS) and inertial measurement unit (IMU) data facilitates the extraction of road elevation profiles ahead of the vehicle. A BP-PID control strategy is implemented to formulate mode-switching rules for the active suspension under three distinct road conditions: flat road, curved road, and obstacle road. Additionally, an ant colony optimization algorithm is utilized to fine-tune four suspension parameters. Utilizing the hardware-in-the-loop (HIL) simulation platform, the observed reductions in vertical, pitch, and roll accelerations were 5.37%, 9.63%, and 11.58%, respectively, thereby substantiating the efficacy and robustness of this approach. Full article

Due to their self-adaptability, low friction, low loss, and high-speed stability, bump foil aerodynamic journal bearings are widely used in high-speed rotating equipment such as turbomachinery and flywheel energy storage. In the process of high-speed operation, the heat generated leads to changes in air parameters (such as viscosity, density, etc.), thus affecting the overall performance of air bearings. In this paper, combined with the compressible Reynolds equation, a fluid–solid coupling model was established to analyze the steady-state characteristics and key influencing factors of bearings. Through the energy equation, the air viscosity–temperature effect was considered, and different boundary conditions were set. The internal temperature distribution of the air bearing and the influence of the temperature on the bearing characteristics were systematically analyzed. It was found that the bearing capacity increased when the temperature was considered. In a certain range, with the increase in ambient temperature, the increase in bearing capacity is reduced. This paper provides a theoretical design basis for the design of high-stability bearings and promotes the design of next-generation air bearings with higher speed, lower loss, and stronger adaptability, which has very important theoretical and engineering significance. Full article

This paper proposes a multibody model calibration method for vehicle misuse testing. During misuse tests conducted at high driving speeds, the vehicle’s responses can become highly nonlinear due to certain key model parameters. Direct calibration using a complex multibody model is time-consuming and unstable, as it may fail or diverge due to improper settings of the model parameters. Therefore, a modified quarter-vehicle model is proposed for the analytical calibration of these nonlinear parameters by introducing an additional constraint on the sprung mass to recover the restoring force. The new model features only two degrees of freedom and incorporates key nonlinear parameters, including the suspension’s stiffness and the wheel’s center mass. It is suitable for misuse tests involving tire detachment at high driving speeds. The detailed analytical calibration procedure for the nonlinear parameters is deduced and subsequently validated through numerical simulation using these parameters. When the parameters are sufficiently close to the actual ones or linearly related to the responses, an optimization method such as the least squares method can be applied, along with simulations using complex models in commercial software. Full article

Surface roughness is a key factor influencing the safety, comfort, and overall quality of bicycle lanes, which are increasingly integrated into urban transportation systems worldwide. This study aims to assess and quantify the roughness of bicycle lanes in Sejong City, Republic of Korea, by utilizing accelerometer-based sensor technologies. Five study sections (A–E) were selected to represent a range of road surface conditions, from newly constructed roads to severely deteriorated surfaces. These sections were chosen based on bicycle traffic volume and prior reports of pavement degradation. The evaluation of road surface roughness was conducted using a smartphone-mounted accelerometer to measure the vertical, lateral, and longitudinal accelerations. The data collected were used to calculate the Bicycle Road Roughness Index (BRI) and Faulting Impact Index (FII), which provide a quantitative measure of road conditions and the impact of surface defects on cyclists. Field surveys, conducted in 2022, identified significant variation in roughness across the study sections, with values of BRI ranging from 0.2 to 0.8. Sections with a BRI greater than 0.5 were considered unsafe for cyclists. The FII showed a clear relationship between bump size and cycling speed, with higher bump sizes and faster cycling speeds leading to significantly increased impact forces on cyclists. These findings highlight the importance of using quantitative metrics to assess bicycle lane conditions and provide actionable data for maintenance planning. The results suggest that the proposed methodology could serve as a reliable tool for the evaluation and management of bicycle lane infrastructure, contributing to the improvement of cycling safety and comfort. Full article

To reduce the power consumption of rotary tillage and enhance the operational quality of rotary tillage, a rotary blade that imitates the surface of a pufferfish was designed through reverse engineering. The bump structure on the pufferfish surface was employed to decrease the power consumption when the blades till the soil. The performance of the bionic blade was investigated. A single-factor soil bin test was conducted, with the forward speed of the rotary tiller and the rotation speed of the blade shaft serving as the test factors, and the power consumption of the rotary tiller and the ground surface flatness as the evaluation indexes. The test results revealed that the power consumption of the rotary tiller initially decreases, then increases, and finally decreases with the increase in the forward speed of the rotary tiller. It is positively correlated with the rotation speed of the blade shaft. The ground surface flatness is positively correlated with the forward speed of the rotary tiller but negatively correlated with the rotation speed of the blade shaft. Compared with the rotary tiller with standard IT225 blades, the rotary tiller with bionic blades achieves a 9.4% reduction in power consumption and a 6.5% improvement in ground surface flatness. This study has demonstrated that the bump structure of the pufferfish surface can effectively reduce the power consumption of the blades and enhance ground surface quality, thus offering novel insights for the development of energy-saving tillage tools. Full article

The electrification trend characterizing the current automotive industry creates opportunities for the implementation of innovative functionalities, enhancing aspects of energy efficiency and vehicle dynamics. Active vehicle suspensions are an important subsystem in this process. To enable proper suspension control, vehicle sensors can be used to measure the system’s response and, in some cases, preview the road conditions and the presence of possible obstacles. When assessing the performance of a suspension system, the speed bump crossing represents a challenging maneuver. A suitable trade-off between comfort and road holding must be found through different phases of the profile. The proposed work uses a fixed-gain observer obtained from Kalman filtering to identify road unevenness and adapt the control strategy when the vehicle travels through a bump. To this end, the obstacle is identified through the use of affordable sensors available in high-end vehicles: accelerometers, inertial measurement units, and stroke sensors. The proposed technique is also affordable from the computational point of view, thus enabling its use in common microprocessors tailored for the automotive field. The bump identification technique is validated through experimental data captured in a vehicle demonstrator. Subsequently, numerical results show that the proposed technique is able to enhance comfort while keeping road holding and attenuating the transient after taking the bump. Full article

Road safety systems are critical engineering solutions designed to minimize the effects of traffic accidents and increase the safety of transportation infrastructures. Traditional road safety structures are generally manufactured using steel, concrete and polymer materials. However, manufacturing processes with these materials are high-cost, limited in terms of design flexibility and can lead to material waste. In recent years, rapidly developing additive manufacturing (AM) technologies stand out as an important alternative in the production of road safety systems. AM enables the production of complex geometries and enables the development of lightweight and high-strength structures that can absorb impact energy more effectively. This study focuses on the use of AM methods in road safety systems, examining the performance and applicability of polymer, metal and composite materials. The advantages of AM-produced road safety barriers, traffic signs, speed bumps and shock absorbing structures, depending on the material type, are evaluated. In addition, the advantages offered by AM, such as design flexibility, sustainable production processes and material efficiency, are discussed, and technical challenges and applicability limitations are also discussed. This review evaluates the current and potential applications of AM for road safety systems, providing insights into how this technology can be used more effectively in the future. The findings of the study provide significant contributions towards improving the integration of AM technologies into road safety systems from both academic and industrial perspectives. The findings of the study provide important contributions to the development of the integration of AM technologies into road safety systems from both academic and industrial perspectives. Future research can further enhance the innovative potential of AM in road safety systems, with a particular focus on sustainable material use, design optimization and energy efficiency in manufacturing processes. However, overcoming technical challenges in large-scale applications and compliance with regulatory standards are critical research areas for the widespread adoption of this technology. Full article

Bump foil gas bearings (BFGBs) play an important role in high-speed turbomachinery. However, most studies on the dynamic characteristics of BFGBs focus on a one-pad structure composed of a bump foil and a top foil. This paper considers the multi-pad foil structure in BFGBs by developing the finite element model of bump and top foils and introducing nonlinear contact constraints between bearing components. In addition, a transient dynamic model of a rotor and multi-pad bump foil gas bearing (MP-BFGB) system is established through sufficient considerations of coupling effects among rotor, gas film, and foil structures. Nonlinear rotor dynamic responses, including stability and vibration characteristics, are obtained through integrating the transient state variables in the time domain. The results show that the rotor stability can be enhanced by increasing the number of top foil pads, which, however, tends to reduce the bearing load capacity and gas film stiffness. In addition, rotor sub-synchronous vibrations are more prone to appear under greater gas film stiffness. Full article

This paper presents an analysis of the dynamic characteristics observed and studied during the startup process of a gas foil radial bearing. It utilizes a comparison of both experimental data and three-dimensional fluid–solid interaction computational fluid dynamics simulations to investigate a gas foil bearing with three bump-type pads. The analytical model employs the fluid–structure interaction finite element method to examine the relationship between the components and the thin working fluid film within the bearing. This analysis was conducted under various operational conditions, including ambient pressure and temperature, shaft rotational speed, and the load applied to the shaft within the bearing. The foil structure of the bearing was modeled by representing the top and bump foils as a series of linear springs that are interconnected with the rigid housing. Meanwhile, the hydrodynamic pressure distribution acting on the top foil was modeled as a gas film operating under steady-state lubrication conditions. The comprehensive three-dimensional multi-physics model was developed using a commercial computer-aided engineering package, enabling independent finite element calculations for both fluid and solid domains. Following these calculations, the model exchanged analysis results across the interface between domains, allowing simulations to continue until the system achieved a quasi-steady state. An in-house experimental system was designed to evaluate the performance of the gas foil bearing under different working conditions, including the load applied to the shaft and the rotational speed. The experiment investigated the operational state of a gas foil radial bearing under ambient pressure (1 bar), ambient temperature (303 K), rotational speeds ranging from 1.5 to 9.5 krpm, and a load of 0.5602 kgw. Some operational conditions of the bearing were defined as boundary condition inputs for the simulation model. The model’s results, notably the predicted lift-off rotational speed of the bearing, show strong alignment with results from in-house experiments. Full article

Weigh-in-motion (WIM) systems aim to estimate a vehicle’s weight by measuring static wheel loads as it passes at highway speed over roadway-embedded sensors. Vehicle oscillations and the resulting dynamic load components are critical factors affecting measurements and limiting accuracy. As of now, a satisfactory solution has yet to be found. This paper discusses a novel correction approach that fuses WIM sensor data with wheel oscillation captured by cameras. In an experiment, a hard plastic speed bump was placed ahead of a piezoelectric WIM sensor to induce oscillation in trucks crossing the WIM sensor. Three high-speed cameras captured the motion of the wheels. The results show that the proposed method improved the accuracy of the measured gross weight for significant wheel oscillations, while no improvement is observed for smaller oscillation amplitudes. Full article

Currently, the high-speed performance of thin-film lithium niobate electro-optic modulator chips is evolving rapidly. Nevertheless, due to the inherent technical limitations imposed by the packaging design and material architecture, the intrinsic electro-optic bandwidth of thin-film lithium niobate electro-optic modulator chips often exceeds the bandwidth of their packaging interfaces, which can constrain the realization of modulation performance. Bump bonding emerges as a high-bandwidth EO interconnection technology, outperforming wire bonding for faster optical communication. In this paper, we present a high-speed thin-film lithium niobate modulator chip tailored for concave–convex bonding, alongside an analysis and design of the chip’s flip-chip bonding packaging. By exploiting the superior electrical characteristics of concave–convex bonding, we effectively mitigate the radio frequency losses of modulator chip and packaging. The simulated half-wave voltage (Vπ) of 3.5 V and E-O modulation bandwidth greater than 150 GHz is obtained for a 0.5 cm long modulator after flip-chip bonding packaging. Full article

Pre-impact fall detection during e-scooter riding is essential for rider safety. Both threshold-based and deep learning algorithms (supervised and unsupervised models) were developed in this study. Twenty participants performed normal driving maneuvers such as straight driving, speed bumps, clockwise roundabouts, and counterclockwise roundabouts, along with falls (abnormal driving maneuvers). A 6-axis IMU sensor (Xsens DOT, The Netherlands) was positioned at the T7 location to record data at 60 Hz. The approaches included threshold-based, supervised learning, and unsupervised learning models The threshold-based approach yielded an accuracy of 98.86% with an F1 score of 0.99, while the supervised model had a slightly lower performance, reaching 86.29% accuracy and an F1 score of 0.56. The unsupervised knowledge distillation model achieved 98.86% accuracy, an F1 score of 0.99, and a memory size of only 46 kB. All models demonstrated lead times of more than 250 ms, sufficient for airbag deployment. Full article

In this work, the development and implementation of a dynamic characteristics model for a specific multi-foil aerodynamic journal bearing with bump-backing foils (MFJB) is considered. Based on the previously established static characteristics model, the elastohydrodynamic influence is carefully considered, and the perturbation method is adopted, as this model is more effective and computationally efficient. The effects of the operational, structural, and geometric parameters on stiffness and damping coefficients are emphasized. The results show that the eccentricity ratio effects are more intensive when the bearing speed is at a moderately high level, which is no more than approximately 30,000 rpm. The foil thickness has obvious effects on dynamic characteristics, whereas the influence of the elastic modulus is limited. Within the research scope, the eight-foils bearing exhibits a better performance than the four-foils. This paper is designed to provide effective methods and supply theoretical guidance for improving the engineering design and operational stability of bearings. Full article

Accurately predicting the performance of gas foil bearings (GFBs) is important. This paper presents a new fully coupled elastic–aerodynamic model for analyzing the static performance of gas foil journal bearings (GFJBs). The gas compressible lubrication model was solved in MATLAB to obtain the gas pressure. The foil structure deformation was solved in COMSOL by considering the Coulomb friction and allowing the contact surfaces to be separated from each other. Under given load and rotational speed conditions, the calculated minimum gas film thickness and attitude angle match well with the literature data, validating the accuracy of the developed model. Based on the model developed, a comprehensive and systematic analysis of the effects of the structural parameters on the static performance was performed. The results showed that as the bump height, top foil thickness, and bump foil thickness increased, the load capacity could be improved to different degrees. The bump foil thickness had the greatest effect on the load capacity. These results provide theoretical guidance for the structural design and practical applications of GFJBs. Full article

Effects of the road, such as speed bumps, can significantly affect a car’s stability. This study focuses on how a quarter-car model is affected by a basic harmonic speed hump and how Cubic Negative Velocity Control (CNVC) is used to control the amplitude of disturbances. This study differs from earlier research in considering various control and force kinds that impact the system. The external forces in this context are a component of a non-linear dynamic system. Two-degree-of-freedom (2DOF) differential coupled equations describe the system’s equation. Numerous numerical experiments have been conducted, including proportional derivative (PD), negative derivative feedback (NDF), positive position feedback (PPF), linear negative velocity control (LNVC), and CNVC; the results show that when the hump is represented as a simple harmonic hump, CNVC has the best effect and can regulate vibrations more precisely than the other approaches on this system. Subsequently, the vibration value of the system was numerically analyzed both before and after the control was implemented. Using the frequency response equation and phase plane approaches in conjunction with the Runge–Kutta fourth order method (RK-4) in the context of resonance situation analysis, the stability of the numerical solution has been evaluated. Full article