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On Prediction of Automotive Clutch Torsional Vibrations

Theofilos Gkinis PhD
Loughborough Univ-Homer Rahnejat
  • Technical Paper
  • 2020-01-1508
To be published on 2020-06-03 by SAE International in United States
Automotive clutches are prone to rigid body torsional vibrations during engagement, a phenomenon referred to as take-up judder. This is also accompanied by fore and aft vehicle motions. Aside from driver behaviour in sudden release of clutch pedal (resulting in loss of clamp load), and type and state of friction lining material, the interfacial slip speed and contact temperature can significantly affect the propensity of clutch to judder. The ability to accurately predict the judder phenomenon relies significantly on the determination of operational frictional characteristics of the clutch lining material. This is dependent upon contact pressure, temperature and interfacial slip speed. The current study investigates the ability to predict clutch judder vibration with the degree of complexity of the torsional dynamics model. For this purpose, the results from a four and nine degrees of freedom dynamics models are compared and discussed. Subsequently, the predictions are compared with the acquired data from an automotive driveline test rig. It is shown that the complexity of the dynamic model, intended for the study of a clutch system, can…
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Minimizing Disturbance Detection Time in Hydraulic Systems

General Motors LLC-Paul Otanez, Ramadityanand Bhogadi
  • Technical Paper
  • 2020-01-0263
To be published on 2020-04-14 by SAE International in United States
In a hydraulic system, parameter variation, contamination, and/or operating conditions can lead to instabilities in the pressure response. The resultant erratic pressure profile produces reduced performance that can lead to hardware damage. Specifically, in a transmission control system, the inability to track pressure commands can result in various types of slip and disturbances to the driveline. Therefore, it is advantageous to identify such pressure events and take remedial actions. The challenge is to detect the condition in the least amount of time while minimizing false alarms. In this study, cross and auto-correlation techniques are evaluated for the detection of pressure disturbances. The performance of the detectors is measured in terms of speed of detection and robustness to: 1) measurement noise, and 2) disturbance parameter uncertainty (frequency and amplitude). The implications in terms of computations and memory utilization of implementing the detectors in real-time embedded systems are also discussed. Both simulation and hardware examples are presented. The hardware experiment is performed in a hydraulic system with low damping composed of a solenoid and a regulator valve…
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A Smart Measuring System for Vehicle Dynamics Testing

Politecnico di Torino-Enrico Galvagno, Stefano Mauro, Stefano Pastorelli, Antonio Tota
  • Technical Paper
  • 2020-01-1066
To be published on 2020-04-14 by SAE International in United States
A fast measurement of the car handling performance is highly desirable to easily compare and assess different car setup, e.g. tires size and supplier, suspension settings, etc. Instead of the expensive professional equipment normally used by car manufacturers for vehicle testing, the authors propose a low cost solution that is nevertheless accurate enough for comparative evaluations. The paper presents a novel measuring system for vehicle dynamics analysis, which is based uniquely on the sensors embedded in a smartphone and completely independent on the signals available through vehicle CAN bus. Data from tri-axial accelerometer, gyroscope, GPS and camera are jointly used to compute the typical quantities analyzed in vehicle dynamics applications. In addition to signals like yaw rate, lateral and longitudinal acceleration, vehicle speed and trajectory, normally available when working with Inertial Measurement Units (IMU) equipped with GPS, in the present application also the steering wheel angle is measured by artificial vision algorithms that use the phone camera.. The latter signal, besides being important for identifying the maneuver imposed by the driver, it enables the usage…
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Analysis of the Dynamic Performance of an Engine Front End Accessory Drive System with an Asymmetric Damping Tensioner

Ningbo Fengmao Far-East Rubber Co., Ltd.-Weijun Zhao
South China University of Technology-Bo Zhou, Wen-Bin Shangguan, Shangbin Long, Yi Sun
  • Technical Paper
  • 2020-01-0409
To be published on 2020-04-14 by SAE International in United States
The automatic tensioner is an important component of the engine front end accessory drive system (EFEADS). It maintains the tension of the belt steadily and reduces the slip of pulley, which is benefit for improving the life of V-ribbed belt. In this paper, an EFEADS model is established which is considering with the hysteretic behavior and the asymmetry of friction damping of a tensioner. A four-pulley EFEADS is taken as a study subject. The dynamic responses of system, such as the oscillation angle of each pulley, the slip factor of pulley, the oscillation of tensioner arm and the dynamic belt tension are analyzed with symmetric damping and asymmetric damping tensioner. Meanwhile, the influence of asymmetric damping factors of tensioner on the dynamic response of EFEADS is also investigated. The experimental results show that tensioner with an asymmetric damping can effectively reduce the oscillation angle of each pulley and the oscillation of tensioner arm, and the fluctuation of dynamic belt tension.
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An investigation into the Traction and Anti-Lock Braking System Control Design

Ford Motor Company-Ming Kuang, Rajit Johri, Jose Velazquez Alcantar
University of California Davis-Louis Filipozzi, Francis Assadian
  • Technical Paper
  • 2020-01-0997
To be published on 2020-04-14 by SAE International in United States
Wheel slip control is crucial to active safety control systems such as Traction Control System (TCS) and Anti-lock Braking System (ABS) that ensure the vehicle safety by maintaining the wheel slip in a stable region. For this reason, a wide variety of control methods has been implemented by both researchers and in the industry. Moreover, the use of new electro-hydraulic, electro-mechanical brakes and in-wheel electric motors allow for a finer control of the slip, which should further improve the vehicle dynamics and safety. In this paper, we compare two methods for wheel slip control: a loop-shaping Youla parametrization method, and a sliding mode control method. Each controller is designed based on a simple single wheel system. The benefits and drawbacks of both methods are adressed. Finally, the controller performance and stability robustness are then compared based on several metrics in a simulation using a high-fidelity vehicle model with several driving scenarios.
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Testing of a wet plate clutch system for anti-shudder performance

Afton Chemical Corp.-Philippe Ezanno
BorgWarner Automotive-Jason Bares
  • Technical Paper
  • 2020-01-0560
To be published on 2020-04-14 by SAE International in United States
The wet clutch system ( WCS ) is a complex combination of friction plates, separator plates and lubricant. The basic function of the WCS is to transfer torque under various operating conditions such as slipping, shifting, start/launch and/or torque converter clutch operation. During these conditions the slope of the coefficient of friction versus slip speed ( µ-V ) curve must be positive to prevent shudder of the WCS. A test procedure is needed to evaluate the WCS over a durability duty cycle to monitor the µ-V curve slope and shudder potential. The clutch plates and fluid must be tested together and remain together during the test to evaluate as a WCS. The objective of this paper is to describe this new test procedure which builds on the basics of the SAE J2964 - Low Speed Continuous Slip µ-PVT test procedure but a duty cycle is added to age the WCS. The test includes measurement of the µ-V slope at several intervals during the test ( before break in, after break in, and after each 12…
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Minimization of Electric Heating of the Traction Induction Machine Rotor

South Ural State University-Elena Nikiforova, Victor Smolin
University of Michigan-Sergey Gladyshev
  • Technical Paper
  • 2020-01-0562
To be published on 2020-04-14 by SAE International in United States
The article solves the problem of reducing electric power losses of the traction induction machine rotor to prevent its overheating in nominal and high-load modes. Electric losses of the rotor power are optimized by the stabilization of the main magnetic flow of the electric machine at a nominal level with the amplitude-frequency control in a wide range of speeds and increased loads. The quasi-independent excitation of the induction machine allows us to increase the rigidity of mechanical characteristics, decrease the rotor slip at nominal loads and overloads and significantly decrease electrical losses in the rotor as compared to other control methods. The article considers the technology of converting the power of individual phases into a single energy flow using a three-phase electric machine equivalent circuit and obtaining an energy model in the form of equations of instantaneous active and reactive power balance. The quasi-independent excitation of the induction machine is performed according to the model by stabilizing the current of the magnetizing branch using the algorithms to control the voltage amplitude, synchronous frequency and electromagnetic…
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A Prediction Method of Tire Combined Slip Characteristics from Pure Slip Test Data

Jilin University-Danhua Xia, Dang Lu
Zhongce Rubber Group Co., Ltd.-Yang Tong
  • Technical Paper
  • 2020-01-0896
To be published on 2020-04-14 by SAE International in United States
A high-precision steady state tire model is critical in the tire and vehicle matching research. For the moment, the popular Magic Formula model is an empirical model, which requires the pure and combined test data to identify the model parameters. Although MTS Flat-trac is an efficient tire test rig, the long test period and high test cost of a complete tire model tests for handling are yet to be solved. Therefore, it is necessary to explore a high accuracy method for predicting tire complex mechanical properties with as few test data as possible. In this study, a method for predicting tire combined slip characteristics from pure cornering and pure longitudinal test data has been investigated, and verified by comparing with the test data. Firstly, the prediction theory of UniTire model is introduced, and the formula for predicting combined slip characteristics based on constant friction coefficient is derived. Secondly, three different sizes of tires were tested for force and moment, and then the combined slip characteristics were predicted through the proposed method, and the prediction accuracy…
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Development of Active Rear Axles Steering Controller For 8X8 Combat Vehicle

OntarioTech University-Moataz Ahmed, Moustafa El-Gindy, Haoxiang Lang, Mohamed Omar
  • Technical Paper
  • 2020-01-0174
To be published on 2020-04-14 by SAE International in United States
Lateral dynamic control considered to be crucial to enhance the handling characteristics and stabilization of a vehicle as a safety demand. In this paper, an active rear axles steering control system will be developed using optimal quadratic regulator (LQR) control methodology. The controller aims to minimize the vehicle sideslip and consequently increase its handling stability and transient state performance. The controller design has been utilized the independent steering of the vehicle`s 3rd and 4th axles as control inputs. Furthermore, the developed controller will be combined with feedforward zero sideslip (ZSS) controller based on the steady state model of the vehicle and satisfying the Ackermann steering condition. In addition, the steady state handling performance will be evaluated using Skid Pad test. The transient state performance will be assessed at low coefficient of friction (COF) surface using FMVSS 126 Electronic Stability Control (ESC) system test speed, while Open Loop Step Slalom Test will be used for assessing the controller at high COF. The controllers will be implemented using MATLAB Simulink and will be simulated in a co-software…
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Research on Yaw Stability Control of Unmanned Vehicle Based on Integrated Electromechanical Brake Booster

Jilin University-Dexing Lao, Jian Wu, Rui He, Bing Zhu, Jian Zhao, Zhicheng Chen
  • Technical Paper
  • 2020-01-0212
To be published on 2020-04-14 by SAE International in United States
The Electromechanical Brake Booster(EMBB) integrates active braking and energy recovery and becomes a novel brake-by-wire solution that substitutes the vacuum booster. While the intelligent unmanned vehicle is in unstable state, the Electromechanical Brake Booster can improve the vehicle yaw stability more quickly and safely. In this paper, a new type of intgarted EMBB has been designed, which mainly includes two parts: servo motor unit and hydraulic control unit. Aiming at the dynamics instability problem of intelligent unmanned vehicle, a three-layer vehicle yaw stability control structure including decision layer, distribution layer and execution layer is proposed based on integrated EMBB. Firstly, the decision layer calculates the ideal yaw rate and the side slip angle of the vehicle with the classic 2DOF vehicle dynamics model. The boundary of the stable region is determined by the phase plane method and the additional yaw moment is determined by the feedback PI control algorithm. Secondly, the distribution layer optimally selects the wheel with the highest differential braking efficiency and assigns the brake pressure to the corresponding wheel based on the…