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Recent developments in intelligent robot systems, especially autonomous vehicles, put forward higher requirements for safety and comfort. Road conditions are crucial factors affecting the comprehensive performance of ground vehicles. Nonetheless, existing environment perception datasets for autonomous driving lack attention to road surface areas. In this paper, we introduce the road surface reconstruction dataset, providing multi-modal, high-resolution, and high-precision data collected by real-vehicle platform in diverse driving conditions. It covers common road types containing approximately 16,000 pairs of stereo images, point clouds, and ground-truth depth/disparity maps, with accurate data processing pipelines to ensure its quality. Preliminary evaluations reveal the effectiveness of our dataset and the challenge of the task, underscoring substantial opportunities of it as a valuable resource for advancing computer vision techniques. The reconstructed road structure and texture contribute to the analysis and prediction of vehicle responses for motion planning and control systems. [ABSTRACT FROM AUTHOR]

Purpose: The nonlinear transfer characteristics of the single/dual-chamber air suspension system without shock absorber damping are determined by using a high-fidelity quarter-car test bench. Such characteristics primarily describe the frequency and amplitude dependency of the air spring strut, which should be considered when designing, matching, and modeling. Methods: The general stiffness model of the rolling-lobe air spring is proposed, and the physical explanation of each part reveals the nonlinear dynamic behavior of the single/dual-chamber air suspension system. The model is simplified via equivalent damping and stiffness, and the parameter identification methods and amplitude-dependent nonlinear transfer function are also performed. Results: Test results show that the transfer characteristics of the single/dual air suspension system exhibit marked nonlinear resonance and low-pass filtering characteristics, verifying the correctness and accuracy of the proposed theory. The parameter influence and trends are also described by analyzing and guiding the forward design and dynamic matching of air springs. Conclusion: Both experiments and modeling demonstrate that the resonance frequency for the air spring-body system could shift 0.29 Hz (from 1.19 to 1.48 Hz), proving that the structural dependence nonlinearity must be considered. [ABSTRACT FROM AUTHOR]

As a smart material with controllable rheological properties, magnetorheological fluids (MRFs) have been increasingly used in various fields. The temperature of MRFs inevitably changes during operation, which markedly affects the rheological properties; thus, the modeling of temperature effects is critical for the control and design of magnetorheological devices. However, most studies only examine the temperature effects of MRFs in a narrow temperature range, which fails to effectively cover the operating temperature range of MRFs, and the viscosity-temperature models used have notable limitations. This paper proposes to use free volume theory, in the form of the universal Doolittle equation, to study the viscosity-temperature behavior of MRFs and their base oils over a wide temperature range. Compared with the existing Reynolds and Arrhenius equations, the Doolittle equation achieves an accuracy improvement of up to 17 times and eight times, respectively. It predicts the overall viscosity-temperature behavior of liquids based on four data points taken over a narrow temperature range, with a relative root-mean-square error (RMSE) of no more than 5%. Ignoring the limited effect of off-state yield stress, the Doolittle equation with strong expandability can be used to establish temperature-dependent MRF constitutive equations. It can even develop multiphysics models based on the highly similar viscosity-temperature characteristics between MRFs and their base oils, which will greatly facilitate the development and optimization of MRFs. [ABSTRACT FROM AUTHOR]

Cylindrical shells are widely used in engineering practice; in particular, one of the special applications is a tire, which can be modeled as a cylindrical shell on an elastic foundation (CSEF). To investigate influences of related parameters on the dynamic characteristics of the shell and help engineers to gain insights into the tire dynamics, a unified formulation for vibration analysis of the cylindrical shell with general boundaries has been developed; this unified formulation includes (i) formulations for CSEF governing equations based on the Donnell-Mushtari theory and Hamilton’s principle; (ii) a unified approach for the solutions of the characteristic equation; and (iii) a general treatment of the boundary conditions by adjusting the foundation spring coefficients. All nine sets of possible solutions of the characteristic equation are clarified and examined. Five case studies have been conducted to validate and verify the developed algorithm. The results based on the developed method generally have good agreement with those of the finite element method and experiment; missed solutions can be recovered. [ABSTRACT FROM AUTHOR]

Many industrial products are made of cord-rubber composite materials. Their mechanical behavior not only depends on rubber but also depends on cord. Nylon 66 cord is one of the most important reinforcement in these products. This paper research the mechanical behavior of nylon 66 cord under various load cases. A series of experiments were carried out to obtaining stress-strain curves under different load cases. Complex changes of the modulus and Mullins effect can be found in monotonic and cyclic tension, respectively. Mechanism of these behaviors has been analyzed considering both the twisted structure and material. A phenomenological constitutive model, accounting for different loading conditions, has been firstly proposed base on strain energy density function and damage mechanics method. The proposed model has been verified by comparing the predicted results with experimental data. It has been found that the proposed model predicted the stress-strain curves that were consistent with the experimental data. The proposed model can be implemented in finite element software for engineering design and application. [ABSTRACT FROM AUTHOR]

Drive wheel systems combined with the in-wheel permanent magnet synchronous motor (I-PMSM) and the tire are highly electromechanical-coupled. However, the deformation dynamics of this system, which may influence the system performance, is neglected in most existing literatures. For this reason, a deformable tire and a detailed I-PMSM are modeled using Matlab/Simulink. Furthermore, the influence of tire/road contact interface is accurately described by the non-linear relaxation length-based model and magic formula pragmatic model. The drive wheel model used in this paper is closer to that of a real tire in contrast to the rigid tire model which is widely used. Based on the near-precise model mentioned above, the sensitivity of the dynamic tire and I-PMSM parameters to the relative error of slip ratio estimation is analyzed. Additionally, the torsional and longitudinal vibrations of the drive wheel are presented both in time and frequency domains when a quarter vehicle is started under conditions of a specific torque curve, which includes an abrupt torque change from 30 N · m to 200 N · m. The parameters sensitivity on drive wheel vibrations is also studied, and the parameters include the mass distribution ratio of tire, the tire torsional stiffness, the tire damping coefficient, and the hysteresis band of the PMSM current control algorithm. Finally, different target torque curves are compared in the simulation, which shows that the estimation error of the slip ratio gets violent, and the longitudinal force includes more fluctuation components with the increasing change rate of the torque. This paper analyzes the influence of the drive wheel deformation on the vehicle dynamic control, and provides useful information regarding the electric vehicle traction control. [ABSTRACT FROM AUTHOR]

The independent driving wheel system, which is composed of in-wheel permanent magnet synchronous motor(I-PMSM) and tire, is more convenient to estimate the slip ratio because the rotary speed of the rotor can be accurately measured. However, the ring speed of the tire ring doesn't equal to the rotor speed considering the tire deformation. For this reason, a deformable tire and a detailed I-PMSM are modeled by using Matlab/Simulink. Moreover, the tire/road contact interface(a slippery road) is accurately described by the non-linear relaxation length-based model and the Magic Formula pragmatic model. Based on the relatively accurate model, the error of slip ratio estimated by the rotor rotary speed is analyzed in both time and frequency domains when a quarter car is started by the I-PMSM with a definite target torque input curve. In addition, the natural frequencies(NFs) of the driving wheel system with variable parameters are illustrated to present the relationship between the slip ratio estimation error and the NF. According to this relationship, a low-pass filter, whose cut-off frequency corresponds to the NF, is proposed to eliminate the error in the estimated slip ratio. The analysis, concerning the effect of the driving wheel parameters and road conditions on slip ratio estimation, shows that the peak estimation error can be reduced up to 75% when the LPF is adopted. The robustness and effectiveness of the LPF are therefore validated. This paper builds up the deformable tire model and the detailed I-PMSM models, and analyzes the effect of the driving wheel parameters and road conditions on slip ratio estimation. [ABSTRACT FROM AUTHOR]

This paper presents a comparative analysis of contact algorithms used for solving contact shape optimization problems. Specifically, a nonlinear, feasible direction interior point method (FDIPM) for the frictional contact analysis of hyperelastic materials has been implemented in which the friction is introduced using the return mapping approach. This comparative investigation aims to find the cause of instability in sensitivity of the contact pressure nonuniformity (CPN). The results obtained by the FDIPM are found to be comparable with those by the penalty methods (PM) and the augmented Lagrange multiplier methods (ALMM); however, the FDIPM possesses advantages, including good convergence and convenience in modeling. Furthermore, the basic cause of the unstable sensitivity is revealed to be the discretization of the finite element method, which causes the discontinuous increase of contact area with respect to the continuous increase of contact load. To improve the stability of the CPN, an adaptive post-processing technique is proposed. [ABSTRACT FROM AUTHOR]