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Abstract A tandem axle suspension is an important system to the ride comfort and vehicle stability of and road damage experience from commercial vehicles. This article introduces an investigation into the use of a controlled active tandem axle suspension, which for the first time enables more effective control using two fuzzy logic controllers (FLC). The proposed controllers compute the actuator forces based on system outputs: displacements, velocities, and accelerations of movable parts of tandem axle suspension as inputs to the controllers, in order to achieve better ride comfort and vehicle stability and extend the lifetime of road surface than the conventional passive suspension. A mathematical model of a six-degree-of-freedom (6-DOF) tandem axle suspension system is derived and simulated using Matlab/Simulink software.

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Abstract An analysis method for the stability of combined braking system of tractor-semitrailer based on phase-plane is investigated. Based on a 9 degree of freedom model, considering longitudinal load transfer, nonlinear model of tire and other factors, the braking stability of tractor-semitrailer is analyzed graphically on the phase plane. The stability of both tractor and semitrailer with different retarder gear is validated with the energy plane, β plane, yaw angle plane and hinged angle plane. The result indicates that in the long downhill with curve condition, both tractor and semitrailer show good stability when retarder is working at 1st and 2nd gear, and when it is at 3rd gear, the tractor is close to be unstable while semitrailer is unstable already. Besides, tractor and semitrailer both lose stability when retarder is working at the 4th gear.

Abstract When commercial vehicles drive in a mountainous area, the complex road condition and long slopes cause frequent acceleration and braking, which will use 25% more fuel. And the brake temperature rises rapidly due to continuous braking on the long-distance downslopes, which will make the brake drum fail with the brake temperature exceeding 308°C [1]. Meanwhile, the kinetic energy is wasted during the driving progress on the slopes when the vehicle rolls up and down. Our laboratory built a model that could calculate the distance from the top of the slope, where the driver could release the accelerator pedal. Thus, on the slope, the vehicle uses less fuel when it rolls up and less brakes when down. What we do in this article is use this model in a real vehicle and measure how well it works.

Abstract Brake systems are one of the essential components of vehicles ensuring the safety of roads and passengers as well as accident prevention. Faulty brake systems, however, can cause inevitable accidents. Fatality analysis reporting system of NHTSA (National Highway Transport Safety Association) has reported that heavy and light trucks, which are obliged to be equipped with dual-circuit air brake system, were, respectively, involved in 8.8% and 38.0% of fatal crashes in the United States, during 2017. Number of heavy vehicle accidents due to complete failure of brake system is far less than accidents due to deficiencies such as worn out brake linings, out-of-adjustment push rod strokes, and leak in the circuits. Severe leakages due to ruptured air hoses or punctured reservoir are highly unlikely to be replenished by compressor and would be distinguished through pressure indicator.

Abstract Vehicle platooning reduces fuel consumption, improves traffic throughput, and achieves smaller intervehicle spacing which increases the probability of danger during platoon braking. This article presents a sliding mode control based on the safety spacing policy for longitudinal control of a connected truck platoon with a focus on the predecessor following interactions. In particular, the modified safety spacing policy considering the intervehicle braking information communication delay, the sluggish nature of the brake actuator, the road conditions on each vehicle as well as the vehicle motion state is proposed. On this basis, an acceleration sliding mode controller is proposed, which takes into consideration the spacing error and speed error of the intervehicle, and the control error is zero, so as to obtain the expected acceleration of each vehicle in the platoon.

Abstract The future of heavy trucking will require greater aerodynamic improvements and will involve active and automated systems that tailor varied parameters to optimize energy efficiency over a broad operational range. Continuous advancement of accuracy and precision is needed to realize these ever-smaller aerodynamic gains and to generate more detailed aerodynamic characterizations to feed these system-wide optimizations. To accomplish this, a comprehensive aerodynamic development approach is needed and should include computational fluid dynamics, operational testing, and wind tunnel testing. In 2016, a high-fidelity 1/3 scale wind tunnel model of a tractor-trailer heavy truck was developed for Reynolds equivalent wind tunnel testing with full coverage rolling road ground simulation. The model and support system were designed and built for use in the Windshear rolling road wind tunnel.

Abstract In order to reveal the temperature and stress change of wet brake under emergency working conditions, a wet multi-disc brake used in mining machinery was taken as the research object. The thermomechanical coupling simulation model of a wet brake was established, and the temperature and stress change of the friction disc under emergency working conditions were analyzed through a bench experiment. The temperature and stress change of the friction disc of the simulation model are compared to the experimental one to verify the correctness of the model. The results show that (1) There is a coupling relationship between the temperature field and stress field during emergency braking. In the process of braking, the variation trend and spatial distribution law of the temperature field and stress field are very similar. (2) When the brake is applied at 40 km/h, the temperature rise of the friction disc reaches 46.8°C during the process of emergency braking conditions.

Abstract This research develops a hierarchical control strategy to improve the stability of multi-axle electric vehicles with in-wheel motors while driving at high speed or on low adhesion-coefficient roads. The yaw rate and sideslip angle are chosen as the control parameters, and the direct yaw-moment control (DYC) method is employed to ensure the yaw stability of the vehicle. On the basis of this methodology, a hierarchical yaw stability control architecture that consists of a state reference layer, a desired moment calculation layer, a longitudinal force calculation layer, and a torque distribution layer is proposed. The ideal vehicle steering state is deduced by the state reference layer according to a linear two-degree-of-freedom (2-DOF) vehicle dynamics model.

Abstract This article proposes a new multi-axle steering vehicle (MSV) kinematics model to improve the tire wear of multi-axle heavy commercial vehicles while ensuring driving safety. The MSV kinematics model is based on the Ackerman steering geometry, which properly distributes the tire steering angles of each axle to cause the tractor unit and the trailer unit of the multi-axle heavy commercial vehicle to steer around the same steering center. In order to compensate for the influence of the factors such as the slip angle of each tire, the adjustment parameter K is introduced to reasonably adjust the relationship between the steering wheel angle input and the tire steering angles of each axle of the trailer unit. The adjustment parameter K makes the trajectory of the trailer unit of the MSV accurately follow the trajectory of the tractor unit of the MSV without changing the trajectory of the tractor unit.

Abstract A combination of machine learning (ML) and optimal fuzzy control (OFC) is proposed for the semi-active air suspensions of heavy trucks to further improve ride comfort and road friendliness. To obtain the study aim, a vehicle dynamics model with 10 degrees-of-freedom (10-DOF) is established in the MATLAB/Simulink environment to simulate and calculate the objective functions of the root-mean-square (RMS) acceleration responses of the vertical driver’s seat and pitching cab angle and the dynamic load coefficient (DLC) on the wheel axles under various working conditions. Based on the OFC with its control rules optimized by the genetic algorithm (GA) and the data map of the random road surfaces, an ML method of the Adaptive Network-based Fuzzy Inference System (ANFIS) in MATLAB is developed and applied to control the semi-active air suspensions.

Abstract In view of the traditional constant spacing policy (CSP) can’t maximize the fuel saving rate of the truck platoon when choosing the smaller desired vehicle spacing as the control target, a new control strategy is proposed in this article. This strategy dramatically reduces the fuel consumption of the truck platoon from the start to the formation of a stable platoon, thus greatly increasing the fuel saving rate of the platoon. To prove the effectiveness of the strategy, this article carried out the longitudinal dynamics modeling of the truck and the modeling of the fuel consumption model of engine first. Longitudinal dynamics modeling establishes the dynamic equations for truck braking and nonbraking. The fuel consumption model of engine is built using a three-dimensional map. Second, the design of the controller is described. The controller calculates the desired acceleration of the following vehicle based on the speed error and the following distance error.

Abstract This study proposes a control strategy to improve the energy recovery during the regenerative braking process of a pure electric bus and to ensure brake safety and maximum braking efficiency. By considering the battery state of charge (SOC) value and the motor speed, this strategy aims to distribute the friction braking force among the front and rear wheels according to a fixed ratio; the difference between the I curve and the β line shows the regenerative braking force. This strategy is embedded into the “ADvanced VehIcle SimulatOR” (ADVISOR) simulation platform and uses the New European Driving Cycle (CYC_NEDC) for simulation. The simulation results show that the proposed control strategy achieves braking energy recovery rate of 17.4%, which suggests effective recovery of energy.

Abstract The response time of the air braking system is the main parameter affecting the longitudinal braking distance of vehicles. In this article, in order to predict and control the response time of the braking system of semitrailers, an AMESim model of the semitrailer braking system involving the relay emergency valve (REV) and chambers was established on the basis of analyzing systematically the working characteristics of the braking system in different braking stages: feedback braking, relay braking, and emergency braking. A semitrailer braking test bench including the brake test circuit and data acquisition system was built to verify the model with typical maneuver. For further evaluating the semitrailer braking response time, an experiment under different control pressures was carried out. Experimental results revealed the necessity of controlling the response time.

Abstract Vehicle-to-everything (V2X) technology has played an important role in improving the active safety of autonomous vehicles. In order to improve the stability of the autonomous vehicle on the curved road, this article presents a pre-emptive braking control method based on V2X technology. Instead of using the active safety system to try to stabilize the vehicle in case of danger, the pre-emptive braking action is proposed to reduce the vehicle speed in advance to a level that allows safe navigation of the turn to avoid danger. It is assumed that the friction and curvature of the curved road ahead can be obtained through V2X technology. Combined with a linear two degrees of freedom (2-DOF) bicycle model, an optimal control method is adopted to calculate the front and rear wheel steering angles to track the centerline of the curve lane. A more complex vehicle dynamics model established earlier is selected for simulation analysis to verify the proposed control method.

Abstract The ongoing electrification and data-intelligence trends in logistics industries enable efficient powertrain design and operation. In this work, the commercial package delivery vehicle powertrain design space is revisited with a specific combination of optimization and control techniques that promise accurate results with relatively fast computational time. The specific application that is explored here is a Class 6 pickup and delivery truck. A statistical learning approach is used to refine the search for the most optimal designs. Five hybrid powertrain architectures, namely, two-speed e-axle, three-speed and four-speed automated manual transmission (AMT) with electric motor (EM), direct-drive, and dual-motor options are explored, and a set of Pareto-optimal designs are found for a specific driving mission that represents the variations in a hypothetical operational scenario. The modeling and optimization processes are performed on the MATLAB™-Simulink platform.

Abstract This article aims at the calibration of an onboard sensor and actuator parameters as well as the identification of the open-loop transfer function of the steering and traction control systems of tripod electric vehicles (EVs). Tripod EVs are commonly used as forklifts and automatic guided vehicles in a factory or wheelchairs in a hospital. A test procedure called the circular, linear, and cornering motions (CLCM) test is introduced in this article for making the corrections which are caused by many factors including the potentiometer of the steering angle error, hall sensor error of the traction speed, the backlash of the steering system, and the tire slip angle that can lead the tripod EV to deviate from the path. The CLCM test is subdivided into circular, linear, and cornering motion subtasks for each individual identification and calibration purposes.