Vehicle Structural Parameters Research Articles

Robust Frontal Vehicle Pose Estimation Based on Structural Parameter Optimization Using Reliable Edge Point Sequences

In order to enhance the stability of vehicle pose estimation within driving videos, a novel methodology for optimizing vehicle structural parameters is introduced. This approach hinges on evaluating the reliability of edge point sequences. Firstly, a multi−task and iterative convolutional neural network (MI−CNN) is constructed, enabling the simultaneous execution of four critical tasks: vehicle detection, yaw angle prediction, edge point location, and visibility assessment. Secondly, an imperative aspect of the methodology involves establishing a local tracking search area. This region is determined by modeling the limitations of vehicle displacement between successive frames. Vehicles are matched using a maximization approach that leverages point similarity. Finally, a reliable edge point sequence plays a pivotal role in resolving structural parameters robustly. The Gaussian mixture distribution of vehicle distance change ratios, derived from two measurement models, is employed to ascertain the reliability of the edge point sequence. The experimental results showed that the mean Average Precision (mAP) achieved by the MI−CNN network stands at 89.9%. A noteworthy observation is that the proportion of estimated parameters whose errors fall below the threshold of 0.8 m consistently surpasses the 85% mark. When the error threshold is set at less than 0.12 m, the proportion of estimated parameters meeting this criterion consistently exceeds 90%. Therefore, the proposed method has better application status and estimation precision.

Vehicle Braking Stability Analysis Considering Vehicle Structure Parameters Based on CarSim

Vehicle braking stability performance can improve the safety of vehicle driving during a braking. However, some parameters of vehicle structure impact on the vehicle braking stability, the characteristic law of the relevant parameters on vehicle braking stability is ignored. A simulation model of vehicle is established using the software of CarSim. The vehicle model is included in the driving system, suspension, steering mechanism, braking system. The impact of wheelbase, and the height of centre of vehicle mass on braking stability performance is analysed. The characteristic law of the relevant parameters on vehicle braking stability is concluded. Based on the characteristic law, the ideal vehicle braking stability is obtained by controlling the vehicle braking force of wheel and the steering angle during a braking.

Optimization of vehicle structural parameters considering stability improvement

The main structural parameters that affect vehicle bifurcation characteristics and the safe basin are obtained, with the goal of improving the stability. First, the distribution of the system equilibrium points in three-dimensional space is studied, and the bifurcation characteristics of the front steering angles are obtained. Second, the front steering angle range corresponding to the bifurcation point (FSAR-BP) and the safe basin of the system (SBS) are determined and used as optimization objective functions. Considering the influence of the structural parameters on the FSAR-BP and SBS, a sensitivity analysis of the parameters is performed to establish their importance ranking in terms of their influence on the FSAR-BP and SBS. Third, a non-dominated sorting genetic algorithm II (NSGA-II) is utilized to optimize the parameters, and the competitive Pareto parameter optimization solution sets are obtained. Finally, the three solution sets with better comprehensive performance are selected for comparison with the pre-optimized set in the FSAR-BP and SBS. The results indicate that the optimized FSAR-BP increased by 218.81%, 237.83%, and 267.88%, and the optimized SBS increased by 207.52%, 197.06%, and 173.93%, respectively.

Simulation Analysis of Vehicle Handling Stability Based on Trucksim

Based on the Trucksim simulation platform and referring to the parameters of the real vehicle, the vehicle body model, tire model, powertrain model, steering system model and braking system model was constructed. After the parametric modeling of the whole vehicle, the steering wheel angle step test was selected for simulation verification referring to the standards of automobile handling stability test in China. Besides, the vehicle handling stability was analyzed with changing part of the vehicle structure parameters. The research result shows that, although the response forms of vehicle motion parameters are different, they all indicate that the faster the vehicle speed is, the more obvious the vibration of vehicle parameter curve will be, and the vehicle handling stability performance will decrease accordingly. In the steering wheel angle step test, by changing the height of the vehicle’s center of mass and the front and rear wheelbases, it can be explained that reducing the height of the vehicle’s center of mass and increasing the wheelbase can improve the handling stability of the vehicle.

Research on Characteristics of Tracked Vehicle Steering on Slope

A special design is needed for an unmanned tracked vehicle (UTV) to meet the requirements of off-road environments and complex tasks. A loose surface is the main terrain for tracked vehicles in off-road driving. Slope steering is inevitable while driving in such conditions; hence, its performance is a major concern for tracked vehicles on loose terrain. This study investigates the slope steering performance of a tracked vehicle. An improved dynamic steering model is proposed when considering the shear stress-shear displacement relation of soil at the track-ground interface. The influence of ground characteristics on the slope steering performance of a tracked vehicle is illustrated. The track slip rate is adopted as an index to evaluate the influence of typical vehicle structure parameters on the slope steering performance of a tracked vehicle. This study provides technical support for the design and optimization of UTV.

Optimization method of vehicle handling stability based on response surface model with D-optimal test design

In order to improve the handling stability of a vehicle, an optimization method of vehicle handling stability based on D-optimal test design was proposed in this paper. The multibody dynamic model was established and verified by experiments. On this basis, a response surface model was established based on D-optimal test design. An improved genetic-particle swarm algorithm was used to optimize the vehicle handling stability. The general evaluation score of vehicle handling stability was taken as the optimization objective. The vehicle structural parameters, tire and spring characteristics were regarded as design variables. The results showed that the multi-body dynamic model was accurate. After optimization, the general evaluation score of vehicle handling stability increased by 8.98 %; the score of the steering returnability and steady static circular test was increased by 20.43 % and 27.31 %, respectively. Then from the sensitivity of the optimization variables to the stability of the vehicle's handling, the rear wheel lateral stiffness has the greatest impact on it, with a sensitivity of 86.9 %; the wheelbase has the smallest impact on it, with a sensitivity of -3.39 %, which can be reduced in future optimization variable to improve design efficiency.

Research on the influence of electric vehicle driven system on vehicle shimmy based on numerical calculation

A 6 degrees of freedom shimmy model for four in-wheel motors independent drive electric vehicle with independent front suspension is established, and numerical analysis and simulation are used to study the dynamic response of vehicle shimmy. The influence of electric vehicle driving system on shimmy is studied by comparing with fuelengined vehicle, and the influence of vehicle structural parameters such as the caster angle, the inclination angle of front suspensions and the centre of gravity of vehicle on shimmy are studied too. It shows that as the in-wheel motor in drive system increases the weight of wheel, the amplitude of each degree of freedom in electric vehicle are larger than in fuel-engined vehicle when vehicle shimmies. The influence of the caster angle and the centre of gravity of vehicle on vehicle shimmy is obvious, but the inclination angle of front suspension have little influence.

Parameter matching and sensitivity analysis for the powertrain system of micro-electric vehicle

Parameter matching for power system with micro-electric vehicle is carried out based on the prototype. The performance of micro-electric vehicle is verified in the ADVISOR software. The mathematical model and calculation method of sensitivity analysis for the complete vehicle curb mass to maximum acceleration of evaluating indicator are established as the example. The maximum acceleration and SOC are selected as the evaluation indexes of the micro-electric vehicle performance, the typical vehicle structural parameters are selected as the influence factors based on many simulation comparisons and comprehensive analysis. The non-parametric statistical method is proposed to analyse the sensitivity of typical structural factors affecting its performance by drawing on one-at-a-time sensitivity measures. Analysis of the results shows that the windward area, the air resistance coefficient, and the centroid height are the most important factors affecting the two evaluation indexes. The final conclusion is significant for the design and application of micro-electric vehicles.

Study on Directional Stability of B-Double Vehicle Combination

B-double is one kind of vehicle combinations with three vehicle units structurally and widely applied in cargo transport, so its directional stability analysis is crucial but more complex than a car. Directional stability was related with vehicle operating conditions and structure parameters. A basic linear dynamic model with four degrees of freedom for B-double was developed with a special method for simplification in a calculation process. The method was verified from the simulation results with MATLAB. The step input is tractor’s steering wheel angle, so the steady-state yaw rate gains with understeer gradient for three vehicle units were solved. Steady-state relative gain was also derived and has an impact on directional stability, which could be influenced by the structure parameters, such as body mass (cargo weight), tire cornering stiffness of rear axle, location of mass center, wheelbase, and location of articulated point. The results indicate that increasing body mass and tire cornering stiffness of rear axle appropriately, moving backward mass center, and moving forward articulated points could increase the understeer gradient, which results in the improvement of directional stability. It is theoretical basis for the stability tests and structure design of B-double.

Roll Stability Model of Lateral Load Transfer of Passenger Vehicle

In order to research the influence of lateral load transfer on the roll stability of passenger vehicle, the dynamics simulation model is established. Pass through simulation, the influence of the passenger vehicle structural parameters and speed on its roll stability is analyzed. The research result shows that, the passenger vehicle rear wheel drive axle is risky for roll stability; it will first lift off when the speed is too high or the front wheel angle is too big. The roll stability of passenger vehicle can be effectively improved by increasing the wheel spread and wheelbase, lowering sprung mass center height, and improving the passenger vehicle suspension roll stiffness.

Study on one Kind of Test Method of Simplified Side Impact Using Sled Test

Frontal sled test is an important platform that widely employed to predict and assess changes in overall safety performance as vehicle structural and occupant restraint parameters are varied. In this paper, a characteristic door intrusion velocity pulse in side impact was analyzed and a set of side test jig was designed, which realized one kind of simplified side impact sled test method. Then we compared the injury values of the side impact dummy, the result showed that there existed good correlation between sled test and full-vehicle test.