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SLAM (Simultaneous Localization and Mapping) plays a key role in autonomous driving. Recently, 4D Radar has attracted widespread attention because it breaks through the limitations of 3D millimeter wave radar and can simultaneously detect the distance, velocity, horizontal azimuth and elevation azimuth of the target with high resolution. However, there are few studies on 4D Radar in SLAM. In this paper, RI-FGO, a 4D Radar-Inertial SLAM method based on Factor Graph Optimization, is proposed. The RANSAC (Random Sample Consensus) method is used to eliminate the dynamic obstacle points from a single scan, and the ego-motion velocity is estimated from the static point cloud. A 4D Radar velocity factor is constructed in GTSAM to receive the estimated velocity in a single scan as a measurement and directly integrated into the factor graph. The 4D Radar point clouds of consecutive frames are matched as the odometry factor.

Positioning system is a key module of autonomous driving. As for LiDAR SLAM system, it faces great challenges in scenarios where there are repetitive and sparse features. Without loop closure or measurements from other sensors, odometry match errors or accumulated errors cannot be corrected. This paper proposes a construction method of LiDAR anchor constraints to improve the robustness of the SLAM system in the above challenging environment. We propose a robust anchor extraction method that adaptively extracts suitable cylindrical anchors in the environment, such as tree trunks, light poles, etc. Skewed tree trunks are detected by feature differences between laser lines. Boundary points on cylinders are removed to avoid misleading. After the appropriate anchors are detected, a factor graph-based anchor constraint construction method is designed. Where direct scans are made to anchor, direct constraints are constructed.

With increasing pressure from environment problem for reduction in CO2 emissions and stricter fuel targets from road vehicles, new transmission technologies are gaining more attention in different main market. To get suitable road load data for transmission durability development is becoming increasingly important and can shorten the development time of new transmission. This paper presents the procedure and methods of road load data development for durability design of transmission product and optimization based on the real road data measurement, statistical characteristics evaluation and fatigue damage equivalency. Apply this road load data method procedure on 3 type of vehicle which represent conventional vehicle, BEV and HEV.

To solve the problem of serious roller wear and improve the smoothness of the sliding door motion process, the rigid-flexible coupling multi-body model of the vehicle sliding door was built in ADAMS. Force boundary conditions of the model were determined to meet the speed requirement of monitoring point and time requirement of door opening-closing process according to the bench test specification. The results of dynamic simulation agreed well with that of test so the practicability and credibility of the model was verified. In the optimization of the ride comfort of the sliding door, two different schemes were proposed. The one was to optimize the position of hinge pivots and the other was to optimize the structural parameters of the middle guide. The impact load of lead roller on middle guide, the curvature of the motion trajectory and angular acceleration of the sliding door centroid were taken as optimization objectives.

Tire cavity noise of pure electric vehicles is particularly prominent due to the absence of engine noise, which are usually eliminated by adding Helmholtz resonators with arbitrary transversal section to the wheel rims. This paper provides theoretical basis for accurately predicting and effectively improving acoustic performance of wheel resonators. A hybrid finite element method is developed to extract the transversal wavenumbers and eigenvectors, and the mode-matching scheme is employed to determine the transmission loss of the Helmholtz resonator. Based on the accuracy validation of this method, the matching design of the wheel resonators and the optimization method of tire cavity noise are studied. The identification method of the tire cavity resonance frequency is developed through the acoustic modal test. A scientific transmission loss target curve and fitness function are defined according to the noise characteristics.

The backlash between engaging components in a driveline is unavoidable, especially when the gear runs freely and collides with the backlash, the impact torque generated increases the vibration amplitude. The power-split hybrid electric vehicle generates output torque only from the traction motor during the launching process. The nonlinear backlash can greatly influence the driveability of the driveline due to the rapid response of the traction motor and the lack of the traditional clutches and torsional shock absorbers in the powertrain. This paper focuses on the launch vibration of the power-split hybrid electric vehicle, establishes a nonlinear driveline model considering gear backlash, including an engine, two motors, a Ravigneaux planetary gear set, a reducer, a differential, a backlash assembly, half shafts, and wheels.

With the growing prosperity of the long-distance freight and urban logistics industry, the demand for cargo trucks is gradually increasing. The connecting bracket is the critical connecting part of the truck chassis, which bears the load transmitted by the road excitation and reduces the damage to the frame caused by the load. However, the occurrence of rough road conditions is inevitable in heavy-duty transportation. In this paper, road durability tests and fatigue life analysis are carried out on the original structure to ensure the safety of the vehicle. Based on the known boundary and load constraints, a lightweight and high-performance structure is obtained through size optimization, as the original structure cannot meet the performance requirements. Firstly, the road test was conducted on the truck where the original bracket structure is located.

The transient impact load generated by door closing is used as the input of the closing condition, which is an important part of door system investigation. In this article, the basic theory of transfer path analysis (TPA) is introduced to handle the abnormal vibration of the front-left door with the glass down stall position of a certain vehicle during the closure. The transient impact loads are discretized under the closed door and obtained using the inverse matrix (IM) method in TPA. Vehicle test and bench test are conducted. The closed door is subjected to the transient impact loads of the sealing strip and the latch on the body side. In the vehicle test, acceleration sensors are pasted on the target point and the reference point on the door to obtain the acceleration vibration response upon the door closure.

X-in-the-loop (XiL) framework is a validation concept for vehicle product development, which integrates different virtual and physical components to improve the development efficiency. In order to develop and validate an extended validation method based on XiL, Tongji University in Shanghai, China and the Karlsruhe Institute of Technology (KIT) in Karlsruhe, Germany co- performed a feasibility study about an X-in-the-distance-loop demonstration platform. The X-in-the-distance-loop demonstration platform includes a MATLAB/Simulink software platform and geographically distributed equipment (driver simulator, driving electric motor and dynamometer test stand), which are used to conduct bidirectional experiments to test communication of powertrain data between China and Germany.

In view of the vibration and noise problem in the electric drive system, the vibration characteristics of its high-speed reducer are analyzed and studied. Through the vibration and noise bench test of the integrated electric drive system, the contribution of high-speed reducer gear meshing order vibration noise to the vibration noise of the electric drive system was studied. A rigid-flexible coupling dynamic model of high-speed reducer was established, and the accuracy of the model was verified. At the same time, based on the gear modification theory, the effects of different gear modification parameters on the peak-to-peak value of high-speed reducer gear transmission error, the amplitude of each order harmonic of the transmission error, and the vibration acceleration response of the high-speed reducer shell surface were studied. Genetic algorithm was used to optimize the gear modification parameters, and the optimization method was simulated and verified.

The frame of a low-speed electric vehicle was treated as the research object in the paper. The fatigue load of the frame was analyzed with multi-body dynamics method and the fatigue life of frame was analyzed with the nominal stress method. Firstly, the multi-body dynamics model of the vehicle was established and the multi-body dynamics simulation was carried out to simulate the condition where the vehicle used to travel. The fatigue load history of the frame was obtained from the simulation. Secondly, the amplitude-frequency characteristic of the fatigue load was analyzed. The frequency of the fatigue load mainly focused on 0~20HZ from the analysis. Thirdly, the modal of frame was analyzed. As the frequency of the fatigue load was less than the natural frequency of the frame, the quasi-static method was selected to calculate the stress history of the frame. Next, the fatigue life of the frame was analyzed based on S-N curve.

As a newly designed hybrid transmission, DHT (Dedicated Hybrid Transmission) owns the advantages of compact structure, multi-modes and excellent comprehensive performance. Compared with the traditional add-on hybrid transmission with one single motor, DHT uses one independent generator for engine starting and speed adjusting which can be largely improve the driving performance in the mode changing process. Based on the series-parallel DHT with wet clutch for power coupling, this paper firstly analyses the power coupling clutch device functionalities from the power flow viewpoint under normal and limp home condition. And for the changing process from series to parallel mode, a clutch coordination control strategy is designed by combining generator fast speed adjusting with clutch accurately pressure controlling to fulfill the fast driver intension response and clutch protection.

Nowadays, the design and development of the sliding door has been gained great attention for its easy egress and ingress. However, most studies on the kinematic and dynamic characteristics of sliding doors were based on the commercial code ADAMS, while the accuracy of flexibility in modal synthesis method and the ability of complex contact condition may not be guaranteed. Thus, a new dynamic analysis method by using the commercial code LS-Dyna was proposed in this paper to take into account the complex deformation and boundary conditions based on the finite element model. The impact force obtained from the Ls-dyna was compared with that from ADAMS when their monitoring points speed and closing time maintained the same during the sliding process. The impact force between the rollers and the guides was employed as evaluation criterion for different methods because of its effect on the roller wear and the moving smoothness in the sliding process.

To overcome some drawbacks of using UHSS (Ultra High Strength Steel) in vehicle weight reduction, like spot weld HAZ (Heat Affected Zone) softening, hard machining and brittleness, a new solution of ultra-high stress strengthening was proposed and applied to the ridgelines of thin-walled structures in this paper. Firstly, stress distribution characteristics, the laws of stress variation and the compressed plate buckling process of the rectangular thin-walled beam under compressive and bending load were analyzed in elastic plastic stage by theory and Finite Element (FE) simulation. Secondly, based on elastic plastic buckling theory of the compressed plate and stress distribution similarity of the buckling process of the thin-walled box structure, three factors influencing the ultimate resistance enhancement of thin-walled hat section beam were found, and the rationality and accuracy of cross section ultimate resistance prediction formulas were also verified by FE simulation.

Carbon fiber reinforced plastic (CFRP) composites have gained particular interests due to their high specific modulus, high strength, lightweight and resistance to environment. In the automotive industry, numerous studies have been ongoing to replace the metal components with CFRP for the purpose of weight saving. One of the significant benefits of CFRP laminates is the ability of tailoring fiber orientation and ply thickness to meet the acceptable level of structural performance with little waste of material capability. This study focused on the concurrent optimization of ply orientation and thickness for CFRP laminated engine hood, which was based on the gradient-based discrete material and thickness optimization (DMTO) method. Two manufactural constraints, namely contiguity and intermediate void constraints, were taken into account in the optimization problem to reduce the potential risk of cracking matrix of CFRP.

A new range-extension hybrid powertrain concept, namely the Tongji Extended-range Hybrid Technology (TJEHT) was developed and demonstrated in this study. This hybrid system is composed of a direct-injection gasoline engine, a traction motor, an Integrated Starter-Generator (ISG) motor, and a transmission. In addition, an electronically controlled clutch between the ISG motor and engine, and an electronically controlled synchronizer between the ISG motor and transmission are also employed in the transmission case. Hence, this system can provide six basic operating modes including the single-motor driving, dual-motor driving, serial driving, parallel driving, engine-only driving and regeneration mode depending on the engagement status of the clutch and synchronizer. Importantly, the unique dual-motor operation mode can improve vehicle acceleration performance and the overall operating efficiency.

To overcome some drawbacks of using AHSS (Advanced High Strength Steel) in vehicle weight reduction, like brittleness, spot weld HAZ (Heat Affected Zone) softening and high cost, a new ridgeline strengthening technology was introduced and applied to the thin-walled structure in this paper. The energy absorption mechanism of thin-walled box structure with selective strengthened ridgelines under axial compressing load was discussed in first section. After this, the formulas of mean crushing force and corresponding energy absorption for square tube were theoretically discussed. To demonstrate prediction capabilities of formulas, a set of FE simulations of square tubes were conducted. Simulation results show that energy absorption capacity of square tube under quasi-static axial crushing load is dramatically improved by selectively strengthening their ridgelines.

Optimization design of hard point parameters for hinge mechanism has been paid more attention in recent years, attributable to their significant improvement in dynamic performance. In this paper, the experimental analysis and dynamic optimization design of hinge mechanism is performed. The acceleration measurement experiments are carried out at different arrangement points and under different working conditions. Furthermore, the accuracy of established multi-body dynamics model is verified by three-axis accelerometer measurement experiment. In addition, sensitivity analysis for electric strut and gas strut coordinates is performed and shows that the Y coordinate of the lower end point of the electric strut is the design variable that has the greatest impact on the responses.

This paper reports an experimental investigation of the wake flow behind a 1/12 scale notchback MIRA model at Re = UL/ν = 6.9×105 (where U is free-stream velocity, L the length of the model and ν viscosity). Focus is placed on the flow asymmetry over the backlight and decklid. Forty pressure taps are used to map the surface pressure distribution on the backlight and decklid, while the wake topology is investigated by means of 2D Particle Image Velocimetry. The analysis of the instantaneous pressure signals over the notch configuration clearly shows that the pressure presents a bi-stable behavior in the spanwise direction, characterized by the switches between two preferred values, which is not found in the vertical direction.

In order to research the vibration and noise reduction in pure electric vehicle power-train, a comprehensive work is to simulate the power-train incentive of a high-speed pure electric vehicle, and indicates significant impact of gear mesh system on the power-train NVH performance. Therefore, it is necessary to further study the impact of meshing gear system on electric vehicle power-train vibration and noise performance and seek reasonable methods to reduce the vibration and noise. In this paper, a typical pure electric vehicle's powertrain was used to conduct vibration and noise dynamic simulation. Firstly, the power train model was established considering the gear meshing stiffness, transmission errors, bearing factors and shell flexible, then the vibration and sound radiation dynamic response of power-train was simulated. Based on the accuracy of prediction model, a gear tooth modification was carried out for vibration and noise optimization.