Vehicle Transmission Research Articles

A Lyapunov based robust control of the EV gearshift process

This paper presents a novel Lyapunov based robust control algorithm for gearshift system of automated manual transmission (AMT) in electric vehicle (EV). Gearshift process is analyzed and modeled considering a two-gear powertrain. Trajectory-tracking control is designed regarding the engagement rule of the shifting fork as the desired trajectory. Model uncertainties and external disturbance are lumped into a function with the assumed upper bound. The control algorithm consists of a PD feedback component and a piecewise function component, which is error-based and model-based inheriting from conventional PID control and robust control. Furthermore, this proposed control is based on Lyapunov approach, and is theoretical proved to render uniform boundedness and uniform ultimate boundedness. The proposed control can guarantee the deterministic performance of the gearshift system, and its effectiveness is illustrated by numerical simulations and sample vehicle test.

Fault Classification in Vehicle Power Transmission using Machine Learning

The work describes the application of machine learning (ML) to the categorization and diagnosis of vehicle faults in the power transmission system. For each failure characteristic condition, a machine learning algorithm may be employed to categorize their separate diagnostic elements. The use of acoustic sensors can be used to create a real-time detection approach for vehicle engines and transmission systems. Previously, it was contacting drivers or obscuring services based on vehicle maintenance and driving safety degree under internet of vehicle (IoV) needs. The car's variable acoustic signals are captured and categorised utilising fuzzy logic controllers through the data acquisition device (DAQ) in this manner (FLC). Further, the results are optimized using Particle Swarm Optimization (PSO) technique. While previous systems used 15 fault conditions, we have just used 8 conditions to obtain results.

A DSP-Controlled Permanent Magnet Synchronous Motor Control System for Hybrid Vehicles

Compared with other motors, the permanent magnet synchronous motor (PMSM) is small and occupies less space. At the same time, its weight is relatively light, so it is more in line with the development trend of hybrid electric vehicle (EV) drive motor lightweight miniaturization and has been widely used. This article studies a DSP-controlled PMSM control system for hybrid vehicles. Firstly, the motor drive control system is mainly controlled by DSP2812 chip. Then, a maximum torque current ratio control method was proposed to optimize the energy efficiency of hybrid vehicles based on PMSM. The longitudinal dynamic model of the moving hybrid vehicle was obtained by force analysis. Combined with the basic equation of PMSM and the transmission system of the hybrid vehicle, the mathematical model of PMSM-EV was established. The experimental results show that the maximum torque current ratio control method applied to hybrid vehicles can effectively reduce the loss, improve the efficiency and dynamic performance, and solve the endurance problem of hybrid vehicles to a certain extent. This advantage is significant in the dynamic acceleration and deceleration of hybrid vehicles.

Coordinated Receding-Horizon Control of Battery Electric Vehicle Speed and Gearshift Using Relaxed Mixed-Integer Nonlinear Programming

In this article, we investigate coordinated receding-horizon control of vehicle speed and transmission gearshift for energy-efficient operation of automated battery electric vehicles (BEVs). The introduction of multispeed transmissions in BEVs enables manipulation of electric motor operating point under given vehicle speed and acceleration command, thus creating the opportunity to further improve BEV energy efficiency. However, co-optimizing vehicle speed and transmission gearshift leads to a mixed-integer nonlinear programming (MINLP) problem, and it is well known that solving MINLP problems is computationally very challenging. To address this challenge, we propose a novel continuous relaxation technique that enables the computation of solutions to the speed and gearshift co-optimization problem using off-the-shelf nonlinear programming solvers. After analyzing theoretical properties of the proposed relaxation technique, we demonstrate its effectiveness through simulation-based case studies, where we show that co-optimizing vehicle speed and transmission gearshift can lead to considerably greater energy efficiency than optimizing them separately or sequentially and the proposed relaxation technique can reduce the computational cost of the co-optimization problem to a level that is comparable to the time budget available for onboard implementation.

Оптимізація інерційної маси гальмівного роликового стенда

The article deals with the issues of modeling conditions for obtaining diagnostic information when checking the braking properties of cars on a roller stand.As many studies show, roller stands of inertial type provide the most reliable information about the technical condition of the car. This concern, first of all, the parameters that determine the accuracy of simulation on the stand of real speed and thermal conditions. The accuracy of diagnosing the brake system of a car on an inertial test bench depends on many factors. One of the determining factors is the value of the reduced masses of rotating elements in the "car-stand" system: rollers, wheels and car transmission parts. The main design parameter of the inertial roller stand is the diameter of the roller. The reduced mass of the transmission can be determined by measuring the moments of inertia of its individual parts and bringing them to a given axis. But this is a laborious process and takes a lot of time. At the same time, the reduced mass of the transmission is also variable due to the wear of parts. Therefore, methods are required to determine the reduced mass of the transmission of a particular vehicle, regardless of the degree of wear of parts.To determine the reduced mass of the transmission, two modes of acceleration of the car on the stand are used: acceleration from the drive of the stand, while two wheels of the car rotate; acceleration from the stand drive, in which one wheel of the car rotates. The analysis of these modes is made and the equations for determination of the reduced mass of transmission are made.The analysis of changes in the moments of inertia of the wheel and rotating parts of the car, as well as the radius of the wheel is carried out. Based on this, the general variation of the reduced mass of the wheel and associated rotating parts of the vehicle is presented. This variation can have a significant impact on the accuracy of diagnosis. The optimal way to compensate for this uncertainty may be to increase the reduced mass of the stand so that the proportion of the reduced mass of the wheel and the associated rotating parts of the car is a small part and introduces an error no more than acceptable.

Stability analysis and development of gear shift patterns for an eight speed automatic transmission vehicle

The increasing stringency of exhaust emission regulations, as well as the rising index of carbon dioxide emissions from the road transport, has driven auto manufacturers and designers to develop solutions for even more efficient vehicles, with well-designed vehicle transmission and gear shift patterns among the alternative approaches used. The current article proposes a design method for developing an appropriate gear ratio set and gear shift patterns for an eight-speed automatic transmission. The BMW M4 Eight speed transmission model was developed using the MATLAB/Simulink platform, and the results were validated using experiment data. The effectiveness of the previously chosen gear ratio set and gear shift patterns was then assessed using a eight-speed transmission model based on the validated six speed transmission model. Based on a mathematical simulation approach, this article presents a novel microscopic model to illustrate the traffic phenomenon. The stability of the proposed model is investigated using the perturbation technique in order to analyze it and determine its stability conditions. The mathematical experimental tests were carried out, and the results reveal that the proposed model is valid. Patterns for sport mode, eco mode, and an accomplished by two modes were analyzed and the results.

Coefficient of friction behavior of gear oils and significance for the meshing process of spur gears

The mechanical properties of oils are determined using test methods. There are standardized test methods for determining viscosity and density. The characterization of transmission oil based on its dynamic viscosity alone is not sufficient for the physical explanation of different levels of noise emissions in vehicle transmissions. For this reason, the test procedure for determining the coefficient of friction is used in the following to enable a further differentiation between the oils according to mechanical properties.In gear transmissions with involute gear teeth, rolling friction occurs in the gear pair meshing along the line of action due to the variation in the equivalent curvature radii throughout the meshing cycle. This is rolling friction on which a sliding friction component, so-called slip, is superimposed. Pure rolling friction only occurs in the pitch point. From the pitch point to the start and end of the meshing, there is a superimposed sliding friction component that increases with increasing distance from the pitch point. Slip values occur in the range of 5–50% depending on tooth geometry.These friction conditions during tooth flank lubrication can be assessed using the Stribeck curve. The Stribeck curve represents the coefficient of friction as a function of the speed. A mini traction machine from PCS Instruments with a ball/plate measurement setup was used to determine the coefficient of friction behavior of gear oils. This allows the coefficient of friction of an oil to be assessed at low speeds in the range from boundary and mixed friction to elastohydrodynamic fluid friction at high speeds.The investigations show that the coefficient of friction behavior of a gear oil depends on the oil viscosity and above all on the chemical composition. The lower the coefficient of friction, the less energy is required to shear the lubricating film and the lower the power transmission through the fluid. The coefficient of friction is a property that is dominated by the type of base oil and the type of VI improver in the area of mixed and fluid friction, especially with additional sliding in contact.It will be shown in the paper that the use of a gear oil that has been optimized with regard to the coefficient of friction curve can reduce the entry impacts of meshing gear pairs under vibration excitation and the gear transmission thus generates lower noise emissions.

PROSPECTS FOR THE DEVELOPMENT OF HYBRID CONTINUOUSLY VARIABLE HYDROSTATIC-MECHANICAL TRANSMISSION OF VEHICLES

The paper considers ways to increase the efficiency of two-stream hydrovolume-mechanical transmissions (GOMT) of vehicles through the rational choice of transmission mode and the introduction into the design of the recovery system of circulating parasitic power of the closed circuit. The proposed direction of development of two-stream GOMT type with differential "output" aims to expand the range of operating speeds where the transmission efficiency is high, in particular in the area of ​​low "creeping" speeds. Global trends to increase the efficiency of transmissions and reduce emissions of harmful substances into the atmosphere have led to the creation of hybrid and fully electric power plants. Hybrid transmissions, which include electric machines and internal combustion engines, are the most attractive from the point of view of operation, as they do not limit the distance of movement. In case of discharge of batteries, when there is no charging station, they will be powered by a standard engine. One of the ways to increase the technical and economic performance of wheeled and tracked agricultural tractors equipped with HOMT with an differential "output" is to coordinate the optimal modes of transmission with the main technological speeds at the design stage

Automatic Transmission Fluids in Electrified Transmissions: Compatibility with Elastomers

The location of the electric motor (EM) inside the transmission in an electric vehicle requires the compatibility of the automatic transmission fluids (ATFs) with the materials of the EM and the transmission. This work studies the compatibility of four conventional ATFs with three elastomers: fluoroelastomer (FKM), ethylene-propylene-diene monomer (EPDM), and vinyl-methyl silicone rubber (silicone). Changes in volume, hardness, tensile strength, and elongation at break of the elastomers after aging in the ATFs were measured, and additional Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), and thermogravimetric and derivative thermogravimetric (TGA and DTGA) tests were performed. The four ATFs showed high or medium compatibility with FKM and silicone, and low compatibility with EPDM. This low compatibility was related to changes in the composition and crystalline structure of the elastomer. The non-compatibility of the EPDM with the oils from Group III was also proven.

Influence of a New Type of Two-Speed Planetary Gear Automatic Transmission on the Performance of Battery Electric Vehicles

This paper introduces a new two-speed planetary gear automatic transmission using an electronically controlled wedge clutch. In order to verify the feasibility of using this transmission in pure electric vehicles, the influencing factors of the two-speed transmission due to the increase in mass and the reduction in transmission efficiency are introduced. The vehicle simulation model was established on the MATLAB/Simulink platform, and the dynamic programming method was used to optimize the transmission ratio and shifting law. The simulation results show that the use of a two-speed automatic transmission can effectively improve the economic performance and dynamic performance of battery electric vehicles.

Multi-Objective Optimization of Gear Ratios of a Seamless Three-Speed Automated Manual Transmission for Electric Vehicles Considering Shift Performance

Multi-speed transmission can greatly improve the power and economic performance of electric vehicles (EVs) compared with single-speed transmission. Gear ratio is the key design parameter of multi-speed transmission. Optimizing gear ratios can further improve vehicle performance. Most of the existing optimization methods of gear ratios take the power and economy of vehicles in gear as the optimization objectives, but rarely consider the shift performance of the transmission, such as shift time, friction, and shift jerk. Considering the shift performance in the process of gear ratio optimization can not only optimize the vehicle performance in gear, but also improve the shift performance of the transmission. Therefore, this paper proposes a multi-objective optimization method of gear ratios considering the shift performance. Firstly, a seamless three-speed automated manual transmission (AMT) of EVs is selected as the research object, the structure and the shift process without power interruption of the three-speed AMT are introduced, and the detailed EV simulation model is established. Then, the multi-objective optimization method of gear ratios considering shifting performance is described. Specifically, the acceleration time, energy consumption, and jerk of the vehicle in gear are taken as the objective functions, and the shift time, clutch friction, and the shift jerk are added to the corresponding objective functions, respectively. Finally, the multi-objective optimization algorithm is used to solve the gear ratio optimization problem. The simulation results show optimization of the gear ratios significantly improves the power, economy, and comfort of the vehicle compared with the original. More importantly, compared with the optimization method without shift performance, gear ratios optimized by the proposed optimization method has better shift performance, and the feasibility of the proposed method is verified by simulations.

Performance analysis of cognitive radio‐assisted clustering car‐following V2X communication system

SummaryIn this paper, we study high spectrum efficiency transmission in vehicle to everything (V2X) system to allow the roadside unit (RSU) broadcasts its safety information to vehicles which belong to a dedicated group. However, low latency and high reliability are tightly required in related applications of V2X; we explore advantages of cognitive radio (CR) and non‐orthogonal multiple access (NOMA) to form system, namely, CR NOMA‐V2X. Such considered system provides transmissions from the RSU to vehicles with respect to lower access latency and to enhance the packet reception probability. In the proposed scheme, the vehicles need channel state information (CSI) for signal decoding order, but we face with imperfect CSI occurs in practical scenarios. To evaluate such degraded system performance of the involved CR NOMA‐V2X, we introduce the approximate closed‐form expressions of outage probability. Numerical results indicate the validness of our derivations.

Optimization Design Based on I-GA and Simulation Test Verification of 5-Stage Hydraulic Mechanical Continuously Variable Transmission Used for Tractor

To improve the characteristics of a tractor power transmission system, make the transmission system not only meet the geometric principle but also meet the working speed requirements of the tractor, realize the continuous adjustment of the speed ratio, and solve the power interruption caused by the change of speed ratio. This paper not only proposes a new type of five-stage hydraulic mechanical continuously variable transmission (HMCVT), but also proposes a geometric design method based on I-GA. In this paper, the intersection position of each working section is introduced in the optimization design process, and six wet clutches, one brake and two planetary rows are used to achieve a flexible geometric design. The results show that the HMCVT proposed in this paper can effectively match the required speed of the tractor. After optimization, the transmission ratio characteristics are consistent with the target characteristics (the average error is about 3.27% and the common ratio is about 1.81); the simulation results based on Simulation X are highly consistent with the theoretical design values (the MAPE of 36 simulation experiments is about 0.72%); and the maximum speed of the tractor is 41.62 km/h. The proposed HMCVT design scheme and optimization design method provide a direct basis for the research and development of the composite power transmission system of tractors or other vehicles and agricultural machinery.

Design, Control, and Validation of Two-Speed Clutchless Automatic Transmission for Electric Vehicle

Two-speed or multiple-speed automatic transmissions can obviously improve the overall manipulating performance in terms of shifting quality and energy efficiency when equipped in electric vehicles (EVs). This study details the design of a two-speed clutch-less automatic transmission (2AT) for EVs and the motor controlled shifting mechanism. Firstly, a novel two-speed clutch automatic transmission is devised with a motor-controlled shifting mechanism, which enables the shift motions and the speed control of the driving motor for synchronization during shifts. Secondly, a coordinated control strategy of the driving motor and controlling motor for shifting is detailed during different shifting processes to achieve fast and smooth shifting. The torque trajectory optimization during synchronizing process is attained by applying the Pontryagin's minimum principle. The simulation and experimental results verify the shifting mechanism design and the shift control algorithm in terms of shift response and smoothness for the designed 2AT.

Gear downshift control of inverse-automatic mechanical transmission of electric vehicle

In order to improve the driving dynamics and riding comfort of pure electric vehicles, taking a two-speed I-AMT (Inverse-Automatic Mechanical Transmission) with rear friction clutch as the research object, a gear shift strategy, which consists of the open-loop control of the clutch position control and the closed-loop control of the drive motor speed control, is proposed. Considering the inherent time-delay and external disturbances within the motor speed adjustment system, a two DOF (degree-of-freedom) Smith predictor with feedforward input is designed to track the target speed of the drive motor. The feedforward input is used to eliminate the influence of clutch sliding friction on the motor speed control, while the feedback speed tracking controller is applied to realize the speed tracking performance with the existence of time-delay and the external disturbance. In order to verify the effectiveness of the gear shift control strategy and the accuracy of the two DOF Smith controller with feedforward control, simulation results comparison is firstly carried out to illustrate the effectiveness of the control scheme. Then, a light pure electric vehicle equipped with I-AMT was used for downshift experiments under large throttle, which is the most difficult working scenario to control the transmission. The experimental results show that the two DOF Smith controller can eliminate the influence of time-delay on the closed-loop control, and the proposed whole gear shift control strategy can limit the clutch slippage time within 1.5 s, resulting in a smaller shift jerk, thus guarantee the driving dynamics and riding comfort simultaneously.

FSAQoS

To ensure a successful transfer of messages in Vehicular Ad hoc Networks (VANETs), data communication channels between vehicles must meet specific standards. As a result, determining the Quality of Service (QoS) of the communication links established among vehicles is a critical task. In this paper, we present a Fuzzy System for Assessment of Quality of Service (FSAQoS), in which we consider two models (FSAQoS1 and FSAQoS2) to assess QoS in Software-Defined VANETs (SDN-VANETs). FSAQoS1 takes into consideration the latency of message transmission between neighboring vehicles, the reliability of data exchange, as well as the beacon signals disseminated across the network that inform vehicles about the state and location of their neighbors. In addition to these parameters, FSAQoS2 considers the interference of the concurrent transmission of nearby vehicles. We evaluate the proposed system by computer simulations. From the evaluation results, we see that FSAQoS2 shows better results than FSAQoS1, although its complexity is higher.

Facile fabrication of PEI/BN/PDA hierarchical structure for boosting tribological performances of carbon fiber/resin composites matched with copper dual disk

Copper dual disks applied in the braking and transmission of vehicles and aircraft, were susceptible to the damage of shear force and friction heat, seriously affecting friction stability and service life. In this study, enhanced building blocks including polyethyleneimine (PEI), boron nitride (BN) and polydopamine (PDA) were employed to construct a hierarchical interfacial structure for boosting tribological performances of carbon fiber/resin composites paired with copper dual disk. Furthermore, this flexible/rigid/flexible reinforcement contributed to the formation of friction films and high-efficiency thermal conduction network, significantly reducing wear damage to dual disks. The drop in the wear rate of PEI/BN/PDA-modified composite reached 85.07%. Moreover, the wear rate of copper dual disk decreased from 1.63 × 10−8 cm3J−1 to 0.80 × 10−8 cm3J−1, showing a 50.92% decline.

Response Sensitivity of Centrifugal Pendulum Vibration Absorbers to Symmetry-Breaking Absorber Imperfections

This paper details an analytical investigation on free and forced vibration response sensitivity of centrifugal pendulum vibration absorbers (CPVA) to symmetry-breaking absorber imperfections. Minor variations in the absorbers’ design due to manufacturing tolerances, errors as well as operational wear and tear tend to break cyclic-symmetry and lead to asynchronous absorber oscillations, unbalanced rotor translations and thus significant vibration amplification. Therefore, an in-depth understanding on the sensitivity of CPVA's vibration response to absorber imperfections is needed to devise an improved absorber tuning strategy for robust vibration and noise reduction from realistic vehicle transmissions and drivelines. In this paper, free and forced vibration response sensitivity of generalized CPVA systems are analytically derived for absorber spacing and mass variations using the perturbation-based eigensensitivity technique in conjunction with modal superposition. The methodology applied in this study is realized through a linearized planar dynamic model, which includes both torsional and translational motions of the rotor along with oscillations of N equally-spaced baseline identical absorbers. Distinct mode distortions and degenerate mode splitting from the known baseline modal structure (with translational, rotational and absorber modes) are investigated for systems with asymmetric absorber spacing and absorber mass variations. The baseline modal structure is modified differently due to having unequal absorber masses or absorber spacing errors, and these differences are analytically derived and demonstrated. Moreover, it was identified that CPVA systems do not exhibit mode splitting with the absorber mass and spacing deviations. Response alterations and localized response patterns due to asymmetric absorber spacing and mass variations are identified and visualized through a case study. Results define a new parametric lower limit for the overtuning of absorbers to avoid localized absorber response and vibration amplification due to absorber imperfections. Additionally, the outcomes are used to locate unique excitation orders, which would help distinguish the alterations in system response due to absorber spacing and mass from each other and serve as a diagnostic tool.

Power Parametric Optimization of an Electro-Hydraulic Integrated Drive System for Power-Carrying Vehicles Based on the Taguchi Method

Focused on the troubles and defects introduced by the traditional single form of electric vehicle transmission, this paper proposes an electro-hydraulic power coupled electric vehicle based on the working principle of an electro-hydraulic power integrated drive system for light-duty cargo vehicles. The integration of the planetary row into the drive system allows the interconversion of mechanical, electrical, and hydraulic energy. By describing the system structure and composition, several working conditions during automobile driving are proposed, and the working principle of every circumstance is introduced. Simultaneously, the article determines the preliminary optimal ratio with the battery’s state of charge (SOC) as the constraint. Then, the orthogonal test matrix of electro-hydraulic ratios and speed thresholds for each operating condition is established according to Taguchi’s method. The impact of each optimized parameter on the motor torque and hydraulic torque as well as the SOC and the proportion of the effect is evaluated by the simulation to obtain the optimal solution. The simulation consequences show that the motor torque and hydraulic torque are reduced, and thus, the vehicle’s acceleration performance and energy recovery efficiency are improved.

Study on the improvement of gearshift performance in commercial vehicle based on ergonomics

Due to the more demanding quality requirements for the vehicle manipulating comfort imposed by the market in recent years, the driver's feeling during gear shifting has become very important in the design stage of the shifting systems. This paper combines the ergonomics theory with the vehicle shifting device, and expounds the application and practice of the ergonomics in the innovative design of the vehicle shifting device. Firstly, GSA analysis system is used to pre-evaluate the static and dynamic shifting performance of the whole vehicle, and analyzes the shifting device of the vehicle transmission according to ergonomics theory. And then the corresponding improvement measures are put forward for the existing defects in the shifting device. Finally, the post-test analysis is carried out to verify the effectiveness in improving the driving experience of the whole vehicle, and ultimately enhance the competitiveness of the studied shifting device in the vehicle industry.