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Semi-autonomous parking assist system (SA-PAS)

Hella India Automotive Private Limited-Ankit Dilip Yawale
  • Technical Paper
  • 2019-28-2529
Published 2019-11-21 by SAE International in United States
This paper describes the Semi-autonomous parking assist system (SA-PAS) developed using combination of high accuracy position sensing and electronic power steering. A real-time system that helps driver to identify the parking space and assist to perform maneuvers. Parking is often a difficult task, especially for inexperienced drivers. Starting with the problem of having to find a suitable parking spot, to then maneuvering in to it without colliding with anything or anyone, while trying avoiding disturbing the surrounding traffic. The numbers of vehicles are rapidly increasing as compared to the expansions of roads and parking spaces. Therefore, effective use of the existing spaces is needed (by making them narrower), which can cause inconvenience to many drivers. Semi-autonomous parking assist system searches for suitable space and steers the vehicle into it, while driver has to control the gear shifter, accelerator and brakes. If the driver presses the button to activate the park assist, a special sensor integrated into the side of the front bumper scans the side of the road as the vehicle drives past. The park…
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Compensation of Signal Offset, Amplitude Imbalance and Imperfect Quadrature in Rotor Position Sensor Signals for Motor Drives

Samiksha Meshram-Samiksha Meshram
  • Technical Paper
  • 2019-28-2524
Published 2019-11-21 by SAE International in United States
In recent years, the use of the electric motors in automotive applications such as electric power steering (EPS), hybrid and electric vehicles has increased. In these fields, rotor position information plays and important role in the field- oriented control concept. It performs a transformation from the stator reference frame to the rotor reference frame and vice versa. This is nothing but the Park and inverse Park transformation. They are typically used to provide accurate absolute rotor position in high-performance motor drive systems because their robustness and reliability make them particularly suited to Automotive Environment. Hence, greater accuracy of these sensor signals is required. However, in reality, the output signals include the position error in the sensor itself as well as error in the sensor signal conditioning circuits. The actual sensor signals have non ideal characteristics such as amplitude imbalance, imperfect quadrature, inductive harmonics, reference phase shift, excitation signal distortion, and disturbance signals. Due to the non-ideal characteristics of these signals, the position information of the Motor is considerably distorted. To solve this problem, the compensation…
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An Outer Loop of Trajectory and an Inner Loop of Steering Angle for Trajectory Tracking Control of Automatic Lane Change System

Tongji University-Yang Yang Wang, Yuan Xing Jiang, Zhi Guang Liu, Guang Da Chen
Published 2019-11-04 by SAE International in United States
Automatic Lane Change (ALC) function is an important step to promote the currently popular Advanced Driver Assistance Systems (ADAS) within a single lane. The key issue for ALC is accurate steering angle and trajectory tracking during the lane changing process. In this paper, an MPC controller with a receding horizon is designed to track the desired trajectory. During the tracking process, other objectives such as safety and smoothness are considered. Considering of the practical mechanism and parameter uncertainties, an SMC controller is designed to track the target steering angle. For validation, a Hardware-in-the-Loop (HIL) experiment platform is established, and experiments of different control algorithms under different conditions are carried out successively. Comparisons of the experiment results of MPC+SMC and PID+SMC schemes indicate that both the trajectory error and the steering angle error of the former combination are smaller. Specifically, the peak trajectory error in Y direction of MPC+SMC is by about 50% smaller under velocity from 60km/h to 80km/h, and lane change duration is also shorter than the PID+SMC scheme. And compared to the servo…
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Hydraulic Pump Airborne Noise Bench Test

Vehicle Performance Steering Committee
  • Ground Vehicle Standard
  • J2747_201909
  • Current
Published 2019-09-13 by SAE International in United States
Communicate the process of accurately measuring sound power levels of positive displacement hydraulic pumps commonly used in ground vehicle steering systems. This recommended practice defines the pump mounting (pulley, belt tension, isolation), operating conditions (fluid, speed, temperature, pressure), room acoustics, instrumentation, noise measurement technique and data acquisition setup to be used. Included are recommendations for test sample size, and format for data presentation/reporting.
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A Control Strategy to Reduce Torque Oscillation of the Electric Power Steering System

Concordia University Montreal-Subhash Rakheja
South China University of Technology-Duo Fu, Wen-Jun Yan, Wen-Bin Shangguan
Published 2019-06-05 by SAE International in United States
This paper proposes a new evaluation method of analyzing stability and design of a controller for an electric power steering (EPS) system. The main purpose of the EPS system’s control design is to ensure a comfortable driving experience of drivers, which mainly depends on the assist torque map. However, the high level of assist gain and its nonlinearity may cause oscillation, divergence and instability to the steering systems. Therefore, an EPS system needs to have an extra stability controller to eliminate the side effect of assist gain on system stability and attenuate the unpleasant vibration. In this paper, an accurate theoretical model is built and the method for evaluating system quality are suggested. The bench tests and vehicle experiments are carried out to verify the theoretical analysis. The evaluation method proposed in this paper can not only guide the design of controller parameters, but also evaluate the control effect while the performance of several controllers are all excellent.
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Robust NVH Engineering Using Experimental Methods - Source Characterization Techniques for Component Transfer Path Analysis and Virtual Acoustic Prototyping

Robert Bosch Automotive Steering LLC-Kevin Wienen, Michael Sturm
University of Salford-Andy Moorhouse, Joshua Meggitt
Published 2019-06-05 by SAE International in United States
A major challenge in automotive NVH engineering is to approach complex structure-borne sound and vibration problems with sufficient accuracy but reasonable experimental effort. Typical issues encountered are poor correlation between objective component performance criteria tested for during bench validation and corresponding subjective targets evaluated during system validation in the actual vehicle. Additional challenges arise from the need to impose assumptions on sophisticated physical vibration problems to reduce the complexity to a level feasible for conventional experimental test methods. This paper addresses all mentioned issues by elaborating on a system NVH engineering approach employing Virtual Acoustic Prototyping (VAP) (related to what is now often called component Transfer Path Analysis) to synthesize time domain sound and vibration responses of vibrating machinery operated in a virtual vehicle environment. One crucial step of VAP is to characterize the strength of vibrating machinery by independent quantities at the significant coupling degrees of freedom (DoF). This study puts special focus on the measurement of free velocity, suitable for machinery operated when resiliently mounted as per ISO 9611, and the in-situ measurement…
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Development of Evaluation Methods for Steering Loss of Assist

General Motors-Ibrahim A. Badiru, Valarie Boatman, Steve Gornick, Brian Latouf, Peter Shear, Richard Krentz
Published 2019-04-02 by SAE International in United States
Loss of power steering assist (LoA) is viewed as a potential hazard in certain vehicle operational scenarios. Despite the importance of this steering failure mode, few published test protocols for the objective or subjective evaluation of vehicle performance in a loss of assist situation exist.The first part of this paper examines five of the key steering failure modes that can result in LoA and discusses why LoA persists as a key industry challenge. The second part analyzes the situational dynamics affecting vehicle controllability during a LoA event and proposes a subjective evaluation driving course that facilitates evaluations in various LoA scenarios. A corresponding objective test procedure and metric is also proposed. These evaluation methods support consistent performance evaluation of physical vehicles while also enabling the prediction of vehicle characteristics early in the vehicle development process (VDP). The final section of this paper gives an overview of a steering system design method aimed at first classifying the level of risk associated with any LoA induced hazard (Automotive Safety Integrity Level - ASIL) and then taking appropriate…
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A Drive-by-Wire Conversion of an FMVSS-500 Vehicle for Autonomous Driving Applications

University of Detroit- Mercy-Viken Yeranosian, Nayan Patel, Joseph Vega, Utayba Mohammad, Mark Paulik, Michael Santora
Published 2019-04-02 by SAE International in United States
Autonomous driving has witnessed many developments in the past decade. Most automotive manufacturers and technology companies have been investing in the software and platform development of these vehicles, and long strides have been made in this domain. Nonetheless, academia has been partially isolated from the practical efforts of these developments, due to the cost involved in converting a standard vehicle into a drive-by-wire platform suitable for self-driving vehicular research. In this paper, a low-cost autonomous vehicle platform is developed and the process for converting a Polaris Gem e2 FMVSS-500 vehicle to brake-by-wire, throttle-by-wire, and steer-by-wire is elaborated. The tools and the procedures followed here were all conducted by students, in house, and can be easily duplicated for other FMVSS-500 compatible vehicles. Discussions include the interface of an embedded controller for an electric power steering system, electronic control of hydraulic brake pressure, and modulation of vehicle velocity and acceleration. Complete system operation via remote control is demonstrated.
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A Development of the Model Based Torque Feedback Control with Disturbance Observer for Electric Power Steering System

Hyundai Motor Company-Deukpyo Lee, Yun Gab Lo, Minwoo Han, Kyuwon Kim, Chulhee Kim
Published 2019-04-02 by SAE International in United States
Electric Power Steering (EPS) needs to meet both functional and stability requirements, it plays significant role in controlling vehicle motion. In the meantime, customers emphasizes natural steering feel which can reflect vehicle motion and road surface information while isolate unwanted external disturbances. In general, conventional EPS control algorithms exert assist torque according to driver torque measured from torque sensor, while maintaining stability using stabilizing compensator. However, there exist significant trade-off between steering feel and stability, because the performances of assist torque control and stabilizing compensator are strongly coupled. In this paper a torque feedback control algorithm for EPS system is proposed in order to overcome the trade-off, and to achieve more natural, robust steering feel. The torque feedback algorithm consists of two main components; target torque generator, target torque following controller which can decouple steering feel and stability control performances. Target torque generator defines desired driver torque based on estimated road reaction torque; the road reaction torque estimation is carried out using EPS system dynamics model. Target torque following controller based on lead-lag compensator controls…
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Development of Compensation Logic for EPS in Limit Cornering Condition

Hyundai & Kia Corporation-Hanseung Lee, Jae Kil Lee
Published 2019-03-25 by SAE International in United States
This paper proposes steering compensation logic of Electric Power Steering (EPS) system in limit cornering condition. Steering wheel torque is decided by relationships between internal forces and external forces. The internal forces are steering frictions and assist force. The external forces are transferred from tire forces through kingpin axis and steering system. Kingpin moments are analyzed by using vector analysis and tire model. Relations of these forces are defined and used to explain steering disturbance by comparing simulation results and measurement data. Using these relationships, the proposed compensation logic is designed. This logic is verified by simulation models and validated in proto type vehicle.
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