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Vehicle wheel traction forces play an important role in vehicle performance, especially for four-wheel-drive vehicles, where a transfer case clutch is used to distribute torque between front and rear wheels. Due to lack of production ready low-cost torque sensor, the transfer case clutch torque is not measured and needs to be estimated accurately to optimize vehicle traction performance. This article proposes to estimate the transfer case clutch torque by forming an estimation problem with unknown system input(s). Specifically, a unified clutch torque estimation model is developed for different clutch conditions, where overtaken-clutch case is treated as a special case of slip-clutch condition with slip-speed equals to zero. Note that under overtaken condition, the associated system model with only one known input is different from that under slip condition with two known inputs. A real-time implementable recursive solution for unknown input(s) is obtained by utilizing an unknown input observer based on the extended Kalman filter (EKF-UIO) algorithm. Comparing with the existing direct estimation method and experimental measured data, it is found that the proposed EKF-UIO algorithm is able to reduce both absolute mean square error and relative-mean-square error significantly with respect to the measured clutch torque under both slip and overtaken conditions. In summary, the EKF-UIO estimation algorithm based on the unified clutch torque model is able to estimate clutch torque accurately.

This article suggests a model-based controller for an all-wheel drive (AWD) vehicle using a novel vehicle dynamics model. Recently, an active type of AWD system that automatically controls the clutch engagement force of the transfer case has become popular. However, its performance has been limited by its rule-based controller, which necessitates the development of a model-based controller. Although the bicycle model has been most widely adopted for upper level controller of vehicle control systems, it is not appropriate for AWD controllers because the model does not have a direct relationship between the states and control inputs. In this sense, this study adopted a tire force-based full car model for the AWD controller. The clutch engagement force limit, which varies depending on the current engagement state, was calculated systematically by considering changeable dynamic behavior that is inherent in AWD vehicle and was used as a valid value for input limit in linear quadratic regulator (LQR) control algorithm. For the real-time application of the designed controller, only data obtained from the controller area network (CAN) of production vehicles were used. Then, the performance of the proposed controller was validated through vehicle experiments that included scenarios of both longitudinal and lateral movements.

This research investigates the discrete-time adaptive backstepping control to track the reference clutch torque and estimate the clutch touchpoint displacement simultaneously for a transfer case clutch. Note that the clutch touchpoint changes due to the clutch wear, temperature variation, and other factors. As a result, it needs to be estimated in real time for accurate clutch torque control. Instead of using a separate algorithm to estimate touchpoints, this brief proposes to utilize an integrated scheme for both tracking reference torque and estimating varying touchpoints. More specifically, the deadbeat-based control law is designed based on a systematic non-Lyapunov-function-based backstepping scheme. The stability of the closed-loop system is guaranteed, and all closed-loop states are bounded. In addition, due to the deadbeat design, the tracking and estimation convergence rates are faster than or equal to any other backstepping designs. Furthermore, the closed-loop system performance is robust to external disturbances. Finally, the proposed method is validated through simulation studies using experimental data.

The clutch touchpoint of an automotive transfer case is a key parameter for accurate clutch torque control, which varies over time due to clutch wear, clutch plate temperature change, and clutch actuation system part-to-part variation. Typically, the touchpoint displacement is unknown and needs to be estimated online. This article, based on the clutch actuation system model, proposes an adaptive scheme using normalized gradient method to estimate the clutch touchpoint in real time. The proposed algorithm uses only the motor control voltage of the clutch actuator and measured cam position while the clutch is engaged. Simulation studies reveal that clutch actuation system friction plays an important role, leading to the investigation of multiple friction models. Among the Coulomb friction, Stribeck friction and proposed modified general kinetic friction (MGKF) models, the MGKF is proved to be the best in describing the friction in the clutch actuation system. Multiple experimental datasets from proving ground and general driving cycle tests are used to validate the effectiveness of the proposed scheme with the MGKF model. In addition, the proposed adaptive estimation results are compared with that of existing direct-detection method (based on the sudden change in clutch torque or wheel speed), showing improved accuracy and robustness.

This paper suggests a novel model-based control scheme for an all-wheel drive (AWD) vehicle. Using transfer case, AWD system is able to transfer the engine torque to all the wheels mechanically, helping the vehicle to maintain traction on a slippery road or to climb a hill. Recently, an active type AWD system that is able to control the torque transmitted through transfer case continuously by the aid of electronic clutch actuator has become popular. In order to realize preemptive operation which is necessary property for AWD system while simultaneously considering states and input constraints which is originated from mechanical and physical characteristics, this paper adopted model predictive control (MPC) concept. The proposed MPC-based controller was designed by using planar full-car model that is based on tire force and motion states, which represents the direct relationship between these states and control input. Therefore, the planar full-car model contributed the suggested controller to follow standard MPC design process. The target states of longitudinal wheel slip and yaw rate, which have commonly been adopted in previous studies, were selected for practical concerns. The advantages of the suggested MPC-based controller that is designed especially for an AWD system were validated by conducting simulations through a SimulinkCarSim-based AWD vehicle model.

Generally the transmission can be considered as a mechanical system formed by a set of rigid links, the position and speed of which are determined by the problem of the law of motion of the engine crankshaft. The transmission of the car consists of a large number of flywheels which are interconnected by shafts, clutches and other elastic elements with different angular stiffness. These assembly units form a rather complex torsional oscillatory system with scattered parameters. Loads acting on the transmission of the car are due to environmental influences (macro- and micro-profile of the bearing surface, physical and mechanical properties of the soil, etc.) and fluctuations of the car itself, and are random.To determine the actual loads in its elements and the degree of non-uniformity of their motion, as well as finding the laws of this motion, it is necessary to take into account their elasticity and the impact of these processes on fuel consumption.The method of determining losses in the transmission of the car on the basis of the energy approach taking into account the operating conditions of armored vehicles of the NGU is proposed. The method should be based on a mathematical model of fuel consumption as the main source of energy, which takes into account the variety of operating conditions and follows from the theory of the car. Mechanical losses in the engine can be expressed through the magnitude of the piston stroke and crankshaft speed. The average effective pressure is determined by the force lost in the transmission and the force applied to the wheels of the car. The total moment of resistance of transmission given to driving wheels is presented in the form of two components: the moment caused by friction losses in knots transferring loadings (gearboxes, a transfer case, reducers of leading axles, cardan transfers), and the moment taking into account expenses energy for oil spraying in units (hydraulic losses). The total transmission losses consist of two main components: idling losses and torque transmission losses. Losses in transmission separately on units are defined by means of the special stands equipped with braking and loading devices. An important advantage of the method is the ability to obtain the equation of engine power balance and determine the efficiency of the transmission as a system with distributed parameters. Further research should be aimed at improving the mathematical model of fuel consumption, taking into account the calculated values of the transmission efficiency depending on the operating conditions of armored vehicles of the NGU., Пропонується метод визначення втрат у трансмісії автомобілів на основі енергетичного підходу з урахуванням умов експлуатації автобронетанкової техніки НГУ. Основою методу є математична модель витрати пального як основного джерела енергії, що враховує різноманіття умов експлуатації і випливає з теорії автомобіля. Важливою перевагою методу є можливість отримання рівняння балансу потужності двигуна та визначення коефіцієнта корисної дії трансмісії як системи з розподіленими параметрами.

This paper describes a yaw stability control algorithm of 4WD vehicles based on model predictive torque vectoring with physical constraints. A vehicle planar model based predictive rear and all-wheel torque vectoring algorithms were developed for 4WD vehicles by considering predictive states and driver’s steering wheel angle. The physical constraints applied to the model predictive control consist of three types: limitation on magnitude of tire force, change rate of tire force, and output torque of transfer case. Two types of torque vectoring algorithms, rear-wheel and all-wheel, were constructed for comparative analysis. The steady state yaw rate was derived and applied as a desired value for yaw stability of the vehicle. The algorithm was constructed in a MATLAB/Simulink environment and the performance evaluation was conducted under various test scenarios, such as step steering and double lane change, using the CarSim software. The evaluation results of the predictive torque vectoring showed sound performance based on the prediction of states and driver’s steering angle.

The vehicle transfer case clutch plays an important role for four-wheel drive (4WD) vehicles since the torque transmitted through the clutch determines the amount of traction torque on tires, which is important for vehicle performance. However, the clutch torque measurement is usually unavailable on production vehicles and needs to be estimated accurately to improve vehicle performance. This paper proposes a unified scheme to model clutch output torque under all three conditions: open (no torque output), slipping, and overtaken. Specifically, the clutch torque model under clutch overtaken condition is first investigated using the vehicle longitudinal and tire dynamics. It was found that effective radius of front tires, powered by the transfer case clutch torque, cannot be assumed as constant and should be compensated by vehicle acceleration, while the effective radius of rear tires connected directly to the propulsion system does not need to be compensated. In addition, it was found that torque model under clutch overtaken condition cannot be used under slip condition. As a result, a general clutch torque model is developed for both slip and overtaken conditions with a clutch slip speed compensation, resulting a root-mean-square error percentage (RMSE%) of 6.8% comparing with the experimental measurement data. Note that overtaken torque model is a special case of the general torque model by setting slip speed equal to zero. The general clutch torque model is able to calculate clutch output torque accurately under both slip and overtaken conditions.

Lyophilization modeling is well documented in academic circles but has not yet been widely adopted by pharmaceutical manufacturing companies. To facilitate wider adoption and implementation, an accessible ExcelTM-based tool is provided, presenting several fresh examples as a practical introduction to the process of modeling the primary drying phase. Case studies are presented of the tool's application during process development and scale up which highlight business benefits that have been realized by using the model. The authors and contributors are members of the BioPhorum's Lyophilization Workstream and represent several pharmaceutical companies. The current manuscript is intended to serve as a pathway to not only share the collective knowledge on the topic but also accelerate its adoption in the industry.

This research applies the discrete-time adaptive backstepping control scheme to a transfer case clutch actuation system for tracking the reference clutch torque and estimating the clutch touchpoint simultaneously. Note that due to the clutch wear and temperature variation, the transfer case clutch touchpoint is typically unknown and needs to be estimated. Instead of using a seperated algorithm for estimating the touchpoint, the proposed approach utilizes one control scheme for tracking the reference torque and estimating the varying touchpoint at the same time. The deadbeat control law is designed based on a systematic non-Lyapunov-Function-based backstepping control scheme, and the stability of the closed-loop system are guaranteed, where all the closed-loop states are bounded. In addition, due to the deadbeat design, the tracking and estimation convergence rates are quite fast, and as a result, the closed-loop system performance is robust to the external disturbance. The proposed method is validated through simulation study.

The lubrication performance and lubricant volume are of great significance in the design and operating processes for closed mechanical assemblies. A transfer case was taken as the research object, and simulations of flow fields under different working scenarios based on computational fluid dynamics and optimization of lubricant volume were performed. First, a model was proposed based on the volume of fluid method, and the model was validated when good agreement was achieved between simulation and experimental results. Next, the lubrication performances under different lubricant volumes and gear rotation speeds were predicted, and they showed that too much or too little volume of lubricant is undesirable and harmful. Consequently, the optimization of lubrication volume was designed by means of a response surface methodology, and an optimal lubricant volume was configured under a gear speed of 5260 rpm and immersion depth of 2.6 mm, accounting for 66.69% of the total volume.

Due to demands for active control systems that can enhance driving performance, active-type all-wheel drive (AWD) systems have drawn interest recently. Equipped with an electronically actuated motor to control a wet clutch in a transfer case, the active-type AWD facilitates the variable distribution of torque from the main driveshaft to the subdriveshaft. The conventional approaches to the estimation of tire force, developed to implement chassis control, have only focused on the two-wheel drive vehicle dynamics model. In this paper, an individual tire force estimation algorithm that is particularly designed for AWD vehicles is proposed. Using the interacting multiple model filter method, the suggested algorithm can help avoid the chattering response caused by immediately switching between vehicle dynamic models. Data obtained from the controller area network of production vehicles were used for the real-time application of the proposed estimator to chassis control. Then, the proposed estimator was validated using an AWD vehicle in various driving scenarios.

Recent developments in control design, system architecture and control module communication have significantly improved traction control systems for vehicles with single axle drive. No such results are available for the four-wheel drive case, using an electronic transfer case, yet. In this work, we therefore extend these developments and propose a coupled input-output linearization controller for vehicles with four-wheel drive, while taking into account the torsional dynamics of the crankshaft. Global, parameter independent stability is shown for the resulting zero dynamics, which has not been considered by previous work. Experiments in a test vehicle are used to evaluate the proposed control system. It is shown that the approach successfully solves the task of traction control for vehicles with on-demand four-wheel drive torque bias systems and is able to outperform classical techniques.

A new MATLAB based graphical user interface integrating several multivariate calibration transfer approaches is presented. Several methods for standard-based and standard-free calibration transfer are integrated. A demonstration of the toolbox and functionalities of different approaches was judged using a calibration transfer case of the corn dataset. All methods were tested on the corn dataset and the results showed that the toolbox is ready to be used. The best feature of the toolbox is that it is a push-button toolbox that even non-expert can use to achieve complex calibration transfer tasks. The CT-GUI toolbox is available at https://tinyurl.com/PMishra .

With automated driving, new challenges for vehicle longitudinal motion control arise. The precise control of speed and acceleration requires knowledge of the torques acting at the wheels. In this work we present an observer that estimates the shaft torques of an all-wheel-drive vehicle and pay attention to the especially challenging use case of driving over large obstacles like curb stones. The performance of our observer is compared with two other approaches and verified using realworld measurement data. The results show that the observer provides good estimates and cooperates well with the switching system. The all-wheel-drive specific, fundamental reallocation of drive torque due to the differential lock in the transfer case is also covered.

Chains play an important role in modern drive trains. Following the successful introduction of the LuK articulated chain for high torque applications in powerful CVT transmissions, this expertise is now being transferred to chains in the transfer case.

This work in progress paper presents initial results on the development and testing of a novel assessment tool utilizing an ethics transfer case methodology targeted at measuring the ethical reasoning ability of engineering students employing reflexive principlism. This work evaluates the reliability and transferability of a rubric-based assessment of students' responses to a transfer case study employed at Purdue University in the Spring of 2014. The scoring rubric was developed to assess students' ability to apply the reasoning components of reflexive principlism including: (a) identification, (b) specification, (c) empathie perspective-taking, (d) justification, and (e) reflectivity. To determine reliability of the scoring rubric, two raters independently scored 19 students' pre-course responses through 3 iterations of the rubric's development, until 85% overall inter-rater agreement was reached. Two additional scorers, normed on the coding framework, then provided feedback on wording and applied the rubric to the same 19 student responses. Initial results from this analysis and discussion of the assessment tool are presented.

Research target: There are exists many principle types of limited slip differential. If simplify limited slip differential model to open differential, vehicle handling and stability simulation results will be uncorrected. So the paper’s target is to build several principle differentials, prove that: different differential have different effects to handling and stability, different transfer case and drive style have the same effects additionally. Research method: Build several limited slip differential models and vehicle dynamic models, respectively; then, simulate different drive style vehicle with different differential or transfer case on the Steady State Cornering and steering wheel angle step input maneuver; compared the simulation results to prove the conclusion of the paper. Research production: Through research and analyses, build up several principle limited slip differential and transfer case models rightly, and connected with vehicle model perfectly. Innovation: Through vehicle dynamic simulation, it is easy for us to find effects of limited slip differential to handling and stability. Other papers in the field have not cover limited slip differential, transfer case model and vehicle drive style, comprehensively, this paper has researched all of those models, getting some general conclusion at last. Insufficiency: This paper shows different differential models how to affect handling and stability, but lacking of correlation of the corresponding differential and vehicle test. Conclusion: The compared simulation analysis of vehicle with different forms of differential and drive type shows that: limited slip differential in the low friction coefficient road affects more obviously, and have more effects to front-drive vehicle, different differential models will have a significant impact to handling and stability. Remark: The work was completed with the assistance of National 863 plan (serial number is 2012AA111801).

This paper discusses a practical approach to predict low range planetary gear noise in an automotive transfer case using commercial numerical codes. Dynamic responses of the planetary gear set are calculated using a 2D finite element/contact mechanics model. These responses are used as boundary conditions to calculate surface velocities on the transfer case housing using model frequency response analysis. Subsequently, the surface velocities are used in a vibro‐acoustic model to predict acoustic responses of the transfer case. The predicted acoustic responses are compared to experimental measurements conducted in a hemianechoic chamber. It is shown that the predictions are in reasonable agreement with the experiments and the approach enables designers to obtain required information on acoustic responses of the transfer case in a timely and cost‐efficient manner.