Browse Topic: Yaw

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Experimental Investigation into Modulated Aeroacoustic Cabin Noise arising from Unsteady Flow Conditions2025-01-002905/05/2023
The unsteady wind conditions experienced by a vehicle whilst driving on the road are different to those typically experienced in the steady-flow wind tunnel development environment, due to turbulence in the natural wind, moving through the unsteady wakes of other road vehicles and travelling through the stationary wakes generated by roadside obstacles. This paper presents the use of experimental approach using an SUV-shaped vehicle to assess the effect of unsteady wind on the modulated noise performance, commonly used to evaluate unsteady wind noise characteristics. The approach is extended to assess the pressure distribution on the front side glass of the vehicle, caused by the aerodynamic interactions of the turbulent inflow, to provide insight into the noise generation mechanisms and differences in behaviour between the two environments. The vehicle response to unsteady wind conditions was assessed using two approaches: a dynamic upstream unsteady flow the using active side wind
Jamaluddin, Nur Syafiqah, Oettle, Nicholas, Staron, Domenic
Parameters Optimization of a Double Gyroscope Concept for a Two-Wheel Vehicle15-15-02-000904/20/2022
Abstract The concept of making a two-wheeled self-stabilizing vehicle can be a possibility soon. These vehicles use control moment gyroscopes (CMGs) to provide enough torque for the vehicle to prevent it from rolling and falling to the ground. CMGs can be used with different numbers and configurations. In this article, the aim is to offer a design procedure for a double gyroscope system, which can be used for any two-wheel vehicle to be self-stabilized. The procedure is based on using optimization algorithms in reaching the optimum double gyroscope configuration for a certain two-wheel vehicle to reach a zero-degree roll angle in the least time possible, which is the novel part of the procedure. A design procedure for a double gyroscope with the yaw axis as a spinning axis for a two-wheel vehicle is offered. This procedure has been tested for both a small two-wheel robot and a two-wheel enclosed vehicle. The research method started with a presentation of motion equations, followed by a
Aboelsaoud, Mostafa, Taha, Ahmed Abdelsalam, Mabrouk, Mohamed Yasser, Aboelazm, Mohamed, Elgamal, Hassan
Parameters Optimization of a Double Gyroscope Concept for a Two-Wheel Vehicle15-15-02-0009-TEST-REC04/20/2022
Abstract The concept of making a two-wheeled self-stabilizing vehicle can be a possibility soon. These vehicles use control moment gyroscopes (CMGs) to provide enough torque for the vehicle to prevent it from rolling and falling to the ground. CMGs can be used with different numbers and configurations. In this article, the aim is to offer a design procedure for a double gyroscope system, which can be used for any two-wheel vehicle to be self-stabilized. The procedure is based on using optimization algorithms in reaching the optimum double gyroscope configuration for a certain two-wheel vehicle to reach a zero-degree roll angle in the least time possible, which is the novel part of the procedure. A design procedure for a double gyroscope with the yaw axis as a spinning axis for a two-wheel vehicle is offered. This procedure has been tested for both a small two-wheel robot and a two-wheel enclosed vehicle. The research method started with a presentation of motion equations, followed by a
Aboelsaoud, Mostafa, Taha, Ahmed Abdelsalam, Mabrouk, Mohamed Yasser, Aboelazm, Mohamed, Elgamal, Hassan
Hierarchical Vehicle Stability Control Strategy Based on Unscented Kalman Filter Estimation2022-01-034303/29/2022
High-speed vehicle is prone to instability under bad road conditions, causing many safety accidents such as tail-flicking and overturning. Stability control could assist vehicle to drive safely and stably by adjusting the additional yaw moment. However, most of the existing stability control strategies directly invoke the information of the sideslip angle of the centroid that is difficult to obtain on the vehicle, and carry out complex controller design, which deviates from the actual application. In order to achieve a complete set of stability control architecture oriented to practical applications, this paper designs a hierarchical vehicle stability control strategy based on differential braking and state estimation technology. Firstly, a model oriented to state estimation and controller design is built according to the vehicle's motion state; Secondly, the sideslip angle of the centroid is accurately estimated through the unscented Kalman filter algorithm; Subsequently, the sliding
Zhang, Jian, Jiang, Hongwei, Li, Linrun, Liu, Qiuzheng, Wang, Yu, Liu, Jinbo, Gao, Yuan, Chen, Zhicheng
Event-triggered Adaptive Robust Control for Lateral Stability of Steer-by-wire Vehicles with Abrupt Nonlinear Faults2022-01-111203/29/2022
Owing to the fact that autonomous vehicles equipped with active front steering (AFS) have the features of time-varying, uncertainties, high rate of fault and high burden on the in-vehicle networks, this article studies the adaptive robust control problem for improving steer-by-wire (SBW) vehicles lateral stability in the presence of abrupt nonlinear faults. Firstly, a robust H∞ controller, as an upper-level controller, is designed to obtain the corrected steering angle for driving both the yaw rate and the sideslip angle to achieve their desired values. Takagi-Sugeno (T-S) fuzzy modeling approach which has shown the extraordinary ability in coping with the issue of nonlinear is applied to deal with the challenge of the changing longitudinal velocity. The output of upper controller can be calculated by parallel-distribute-compensation (PDC) scheme. Then, an event triggered adaptive fault tolerant lower controller is proposed to track the desired front wheel steering angle offered by the
zheng, gong, Xie, Zhengchao, Zhao, Jing
Reconstructing Vehicle and Occupant Motion from EDR Data in High Yaw Velocity Crashes2021-01-089204/06/2021
Among the several data recorded by a typical motor vehicle’s event data recorder (EDR) prior to, during and after a crash event, are sampled time histories of longitudinal and lateral components of delta-v. The delta-v components are not measured directly but are calculated by numerically integrating the outputs of two perpendicular accelerometers contained within the EDR box. As currently designed and implemented a typical EDR does not measure yaw velocity or track vehicle heading during the impulse phase of a crash. Without this yaw information to orient the accelerometers relative to the fixed ground, the delta-v values calculated by the EDR through direct integration of its measured acceleration components should not be interpreted as representing absolute changes in vehicle velocity, especially in cases where the yaw velocity is high. EDR-calculated delta-v components must be adjusted to account for the yaw motion that occurred during acquisition of the data. With reasonable time
Smith, Gregory C.
SUV Kinematics during a Steer-Induced Rollover Resolved Using Consumer-Grade Video, Laser Scans and Match-Moving Techniques2020-01-064204/14/2020
Rollover crashes are complex events that generate motions in all six degrees of freedom (6DOF). Directly quantifying the angular rotations from video can be difficult and vehicle orientation as a function of time is often not reported for staged rollover crashes. Our goal was to evaluate the ability of using a match-moving technique and consumer-grade video cameras to quantify the roll, pitch and yaw angles and angular velocities of a rollover crash. We staged a steer-induced rollover of an SUV at 106 km/h. The vehicle was fitted with tri-axial accelerometers and angular rate sensors, and five consumer-grade video cameras (2 on tripods, 2 on drones, 1 handheld, ~30 fps) captured the event. Roll, pitch and yaw angles were determined from the video using specialized software. We then compared the vehicle orientation angles from the video data to the integrated angular rate data measured by onboard sensors, and also compared the angular rates from the differentiated video data to the
Young, Cole R., King, David J., Siegmund, Gunter P.
Alleviating the Magnetic Effects on Magnetometers Using Vehicle Kinematics for Yaw Estimation for Autonomous Ground Vehicles2020-01-102504/14/2020
Autonomous vehicle operation is dependent upon accurate position estimation and thus a major concern of implementing the autonomous navigation is obtaining robust and accurate data from sensors. This is especially true, in case of Inertial Measurement Unit (IMU) sensor data. The IMU consists of a 3-axis gyro, 3-axis accelerometer, and 3-axis magnetometer. The IMU provides vehicle orientation in 3D space in terms of yaw, roll and pitch. Out of which, yaw is a major parameter to control the ground vehicle’s lateral position during navigation. The accelerometer is responsible for attitude (roll-pitch) estimates and magnetometer is responsible for yaw estimates. However, the magnetometer is prone to environmental magnetic disturbances which induce errors in the measurement. The present work focuses on alleviating magnetic disturbances for ground vehicles by fusing the vehicle kinematics information with IMU senor in an Extended Kalman filter (EKF) with the vehicle orientation represented
Dudekula, Ahammad Basha, Naber, Jeffrey D.
Electronic Differential Control of Rear-Wheel Independent-Drive Electric Vehicle10-04-01-000412/02/2019
To track desired slip ratios and desired longitudinal speeds at the centers of driving wheels in the curve, this article proposes a hierarchical structured electronic differential control (EDC) of rear-wheel independent-drive electric vehicle (EV). In the high-level control, a fuzzy algorithm-based coefficient is computed according to the driver’s emotional intention of acceleration. The fuzzy algorithm-based coefficient is used to correct the desired driving torque of vehicle transmitting to the medium-level control. In the medium-level control, an optimization algorithm is developed to allocate the desired torques with requirement of as much accurate yaw moment as possible by the desired driving torque of the vehicle and yaw moment. And the desired longitudinal speeds at the centers of the rear left and right wheels are corrected twice, respectively, by Ackermann steering principle, considering the slip angle of the wheel and yaw moment. Based on the desired torques and desired
He, Ren, Yun, Hang
Speed Analysis of Yawing Passenger Vehicles Following a Tire Tread Detachment2019-01-041804/02/2019
This paper presents yaw testing of vehicles with tread removed from tires at various locations. A 2004 Chevrolet Malibu and a 2003 Ford Expedition were included in the test series. The vehicles were accelerated up to speed and a large steering input was made to induce yaw. Speed at the beginning of the tire mark evidence varied between 33 mph and 73 mph. Both vehicles were instrumented to record over the ground speed, steering angle, yaw angle and in some tests, wheel speeds. The tire marks on the roadway were surveyed and photographed. The Critical Speed Formula has long been used by accident reconstructionists for estimating a vehicle’s speed at the beginning of yaw tire marks. The method has been validated by previous researchers to calculate the speed of a vehicle with four intact tires. This research extends the Critical Speed Formula to include yawing vehicles following a tread detachment event. The Critical Speed Formula was found to produce results of acceptable and known
Beauchamp, Gray, Pentecost, David, Koch, Daniel, Bortles, William
Event Data Recorder Performance during High Speed Yaw Testing Subsequent to a Simulated Tire Tread Separation Event2019-01-063404/02/2019
This paper presents event data from the Sensing and Diagnostic Module (SDM) of a 2004 Chevrolet Malibu during high speed yaw testing. Yaw tests were performed using tires that were intact and tires that had the tread removed. The tires that had the tread removed were placed at various wheel positions on the vehicle (e.g. leading side - front, leading side -rear, trailing side - rear). This testing simulates the loss of control phase subsequent to a tread separation. Speeds up to 117 km/h (72.9 mph) were achieved. A simple electro-mechanical device was incorporated to the dynamic testing to simulate a low-severity non-deployment event that triggered the recording of pre-crash data by the SDM. The SDM data from the tests was imaged and compared to reference data from vehicle-mounted instrumentation recording wheel speed, steering angle, measured vehicle sideslip angle and GPS calculated over the ground speed. This paper examines the dynamic effect of high sideslip angles and changes to
Bortles, William, Koch, Daniel, Beauchamp, Gray, Pentecost, David, Rayburn, George, Hostetler, Ryan
Inter-Vehicular Sliding Friction and Crush Energy Losses in Impulse Momentum Planar Collision2019-01-042204/02/2019
New in this study is the mathematical formula for calculating energy dissipated due to sliding under the action of Coulomb kinetic friction in the context of Impulse Momentum Planar Collision (IMPC) with isotropic restitution. The surface sliding dissipated energy theorem established here is precisely consistent with the laws of physics underlying IMPC. A principal goal of distinguishing between surface sliding energy dissipation and energy dissipation due to vehicle crush is to improve the rational basis for use of crush energy analysis with IMPC. Also new in this study is a consistent interpretation of Newton's, Poisson's and Stronge's restitution hypotheses as they apply to IMPC with Coulomb kinetic friction. While this paper adds to the understanding of energy dissipation, the IMPC method presented here is not new. The IMPC method features a yaw velocity component and two translational velocity components referenced to the dynamic center of mass of each vehicle as well as an
Carpenter, Nicholas, Welcher, Judson
Uncertainty in Radius Determined by Multi-Point Curve Fits for Use in the Critical Curve Speed Formula2019-01-042804/02/2019
The critical curve speed formula used for estimating vehicle speed from yaw marks depends on the tire-to-road friction and the mark’s radius of curvature. This paper quantifies uncertainty in the radius when it is determined by fitting a circular arc to three or more points. A Monte Carlo analysis was used to generate points on a circular arc given three parameters: number of points n, arc angle θ, and point measurement error σ. For each iteration, circular fits were performed using three techniques. The results show that uncertainty in radius is reduced for increasing arc length, decreasing point measurement error, and increasing number of points used in the curve fit. Radius uncertainty is linear if the ratio of the standard deviation in point measurement error (σ) to the curve’s middle ordinate (m) is less than 0.1. The ratio σ/m should be less than 0.018 for a radius found using a 3-point circular fit to be within 5% of the actual value 95% of the time. Increasing the number of
Heinrichs, Bradley, Mithrush, Troy
Accuracy and Sensitivity of Yaw Speed Analysis to Available Data2019-01-041704/02/2019
Accident reconstructionists rarely have complete data with which to determine vehicle speed, and so the true value must be bracketed within a range. Previous work has shown the effect of friction uncertainty in determining speed from tire marks left by a vehicle in yaw. The goal of the current study was to assess improvements in the accuracy of vehicle speed estimated from yaw marks using progressively more scene and vehicle information. Data for this analysis came from staged S-turn maneuvers that in some cases led to rollover of sport utility vehicles. Initial speeds were first calculated using the critical curve speed (CCS) formula on the yaw marks from the first portion of the S-maneuver. Then computer simulations were performed with progressively more input data: i) the complete tire marks from the whole S-maneuver, ii) measured vehicle mass, iii) measured suspension stiffness and damping, and iv) measured steering history. Simulations based on the complete tire marks reduced the
Heinrichs, Bradley, Lee, Janice, Young, Cole
Heavy-Duty Aerodynamic Testing for CO 2 Certification: A Methodology Comparison2019-01-064904/02/2019
Aerodynamic drag testing is a key component of the CO2 certification schemes for heavy-duty vehicles around the world. This paper presents and compares the regulatory approaches for measuring the drag coefficient of heavy-duty vehicles in Europe, which uses a constant-speed test, and in the United States and Canada, which use a coastdown test. Two European trucks and one North American truck were tested using the constant-speed and coastdown methods. When corrected to zero yaw angle, a difference of up to 12% was observed in the measured drag coefficients from the US coastdown procedure and the EU constant-speed test. The differences in the measured drag coefficient can be attributed, among others, to the assumptions in the speed-dependence of the tire rolling resistance and axle spin losses, the data post-processing required by each methodology, unaccounted frictional losses in the transmission, the behavior of the automated manual transmission during the coastdown run, and the yaw
Rodriguez, J. Felipe, Delgado, Oscar, Demirgok, Berk, Baki, Cem, Besch, Marc, Thiruvengadam, Arvind, Rexeis, Martin, Röck, Martin
Flow around a Heavy Vehicle in a Side Wind2019-01-501903/21/2019
Driving stability can be an issue for heavy vehicles. In a side wind, a side force and rolling moment will develop, and they both affect driving stability, from which the vehicle may overturn. It is important to understand the flow structure in order to prevent a truck from rolling over. The main purpose of this study is to investigate the flow around a heavy vehicle that causes it to overturn. A 1/8 scaled, simplified tractor/trailer configuration called the Ground Transportation System (GTS) with Reynolds number (based on the GTS width) equal to 1.6 × 106 was used for this study. A side wind was modeled by turning the GTS model with respect to its moment reference point. A triangular mesh was used for the truck and the computational domain surfaces, while hybrid meshes filled the computational domain volume. The Ansys® CFX code based on the k-ω shear stress transport (SST) turbulence model was used to solve the governing equations numerically for an incompressible fluid. All results
Levin, Jeffrey, Chen, Shih-Hsiung
Comparison of Active Front Wheel Steering and Differential Braking for Yaw/Roll Stability Enhancement of a Coach2018-01-082004/03/2018
Both active front wheel steering (AFS) and differential braking control (DBC) can improve the vehicle handling and stability. In this article, an AFS strategy and a DBC strategy are proposed and compared. The strategies are as follows: A yaw instability judging module and a rollover instability judging module are put forward to determine whether the coach is in a linear state and whether the additional torque/angle module should be actuated. The additional torque module based on linear quadratic regulator (LQR) and the additional steering wheel angle module based on adaptive proportion integral differential (PID) fuzzy controller are designed to make the actual yaw rate and sideslip angle track the reference yaw rate and sideslip angle. Under some typical driving conditions such as sinusoidal, J-turning, crosswind, and straight-line brake maneuver on the μ-split road, simulation tests are carried out for the coach with no control, DBC strategy, and AFS control, respectively. The
Zheng, Hongyu, yangyang, miao, Wang, Linlin, Zhang, Jiaxu
Active Crosswind Generation and Its Effect on the Unsteady Aerodynamic Vehicle Properties Determined in an Open Jet Wind Tunnel2018-01-072204/03/2018
In this article the unsteady aerodynamic properties of a 25% scale DrivAer notchback model as well as the influence of the wind tunnel environment on the resulting unsteady aerodynamic forces and moments under crosswind excitation are investigated using experimental and corresponding numerical methods. Research Institute of Automotive Engineering and Vehicle Engines Stuttgart (FKFS) swing® (side wind generator) is used to reproduce the essential properties of natural stochastic crosswind in the open jet test section of the Institute for Internal Combustion Engines and Automotive Engineering (IVK) model scale wind tunnel (MWK). The results show that the test environment of an open jet wind tunnel alters the amplitudes of side force and yaw moment under crosswind excitation when compared to an ideal environment neglecting wind tunnel interference effects. The presented approach for the quantification of the unsteady behavior of the flow field provides a basic understanding of the
Stoll, Daniel, Wiedemann, Jochen
2021-12-29.TEST Steering Control Based on the Yaw Rate and Projected Steering Wheel Angle in Evasion Maneuvers2018-01-003004/03/2018
When automobiles are at the threat of collisions, steering usually needs shorter longitudinal distance than braking for collision avoidance, especially under the condition of high speed or low adhesion. Thus, more collision accidents can be avoided in the same situation. The steering assistance is in need since the operation is hard for drivers. And considering the dynamic characteristics of vehicles in those maneuvers, the real-time and the accuracy of the assisted algorithms is essential. In view of the above problems, this paper first takes lateral acceleration of the vehicle as the constraint, aiming at the collision avoidance situation of the straight lane and the stable driving inside the curve, and trajectory of the collision avoidance is derived by a quintic polynomial. Based on the control of the steering wheel angle by the optimal preview control algorithm, the differential braking control is carried out by using the feedbacks of yaw rate and the projected steering wheel
Ye, Yifan, Zhao, Jian, Wu, Jian, Zhu, Bing, Zhao, Yang, Deng, Weiwen
Parametric Study of Asymmetric Side Tapering in Constant Cross Wind Conditions2018-01-071804/03/2018
Sports Utility Vehicles (SUVs) often have blunt rear end geometries for design and practicality, which is not typically aerodynamic. Drag can be reduced with a number of passive and active methods, which are generally prioritised at zero yaw, which is not entirely representative of the “on road” environment. As such, to combine a visually square geometry (at rest) with optimal drag reductions at non-zero yaw, an adaptive system that applies vertical side edge tapers independently is tested statically. A parametric study has been undertaken in Loughborough University’s Large Wind Tunnel with the ¼ scale Windsor Model. The aerodynamic effect of implementing asymmetric side tapering has been assessed for a range of yaw angles (0°, ±2.5°, ±5° and ±10°) on the force and moment coefficients. This adaptive system reduced drag at every non-zero yaw angle tested, from the simplest geometry (full body taper without wheels) to the most complex geometry (upper body taper with wheels) with varying
Varney, Max, Passmore, Martin, Gaylard, Adrian
Optimal Torque Allocation for Distributed Drive Electric Skid-Steered Vehicles Based on Energy Efficiency2018-01-057904/03/2018
Steering of skid-steered vehicles without steering mechanism is realized by differential drive/brake torque generated from in-wheel motors at left and right sides. Compared to traditional Ackerman-steered vehicles, skid-steered vehicles consume much more energy while steering due to greater steering resistance. Torque allocation is critical to the distributed drive skid-steered vehicles, since it influences not only steering performance, but also energy efficiency. In this paper, the dynamic characteristics of six-wheeled skid-steered vehicles were analyzed, and a 2-DOF vehicle model was established, which is important for both motion tracking control and torque allocation. Furthermore, a hierarchical controller was proposed. Considering tire force characteristics and tire slip, the upper layer calculates the generalized force and desired yaw moment based on anti-windup PI (proportion-integral) control method. On the fundamental of dynamic characteristics of skid-steered vehicles and
GAO, Letian, Xiong, Lu, Gao, Xiang, Yu, Zhuoping
Handling Improvement for Distributed Drive Electric Vehicle Based on Motion Tracking Control2018-01-056404/03/2018
The integrated control system which combines the differential drive assisted steering (DDAS) and the direct yaw moment control (DYC) for the distributed drive electric vehicle (DDEV) is studied. A handling improvement algorithm for the normal cornering maneuvers is proposed based on motion tracking control. Considering the ideal assistant power character curves at different velocities, an open-loop DDAS control strategy is developed to respond the driver’s demand of steering wheel torque. The DYC strategy contains the steering angle feedforward and the yaw rate feedback. The steering angle feedforward control strategy is employed to improve yaw rate steady gain of vehicle. The maximum feedforward coefficients at different velocities are obtained from the constraint of the motor external characteristic, final feedforward coefficients are calculated according to the ideal assistant power character curve of the DDAS. Meanwhile, an integral anti-windup PI control is proposed to track
Yang, Xing, Xiong, Lu, Leng, Bo, Li, Yue
Aerodynamics Development for a New EV Hatchback Considering Crosswind Sensitivity2018-01-071504/03/2018
An electric vehicle (EV) has less powertrain energy loss than an internal combustion engine vehicle (ICE), so its aerodynamic accounts have a larger portion of drag contribution of the total energy loss. This means that EV aerodynamic performance has a larger impact on the all-electric range (AER). Therefore, the target set for the aerodynamics development for a new EV hatchback was to improving AER for the customer’s benefit. To achieve lower aerodynamic drag than the previous model’s good aerodynamic performance, an ideal airflow wake structure was initially defined for the new EV hatchback that has a flat underbody with no exhaust system. Several important parameters were specified and proper numerical values for the ideal airflow were defined for them. As a result, the new EV hatchback achieves a 4% reduction in drag coefficient (CD) from the previous model. A wind tunnel with a 0 degree yaw angle is generally used in new vehicle development, but this condition is different from
Iinuma, Yusuke, Taniguchi, Keiichi, Oshima, Munehiko
Use of Active Rear Steering to Achieve Desired Vehicle Transient Lateral Dynamics2018-01-056504/03/2018
This paper studies the use of active rear steering (4-wheel steering) to change the transient lateral dynamics and body motion of passenger cars in the stable or linear region of the tires. Rear steering systems have been used for several decades to improve low speed turning maneuverability and high speed stability, and various control strategies have been previously published. With a model-based, feed-forward rear steer control strategy, the lateral transient can be influenced separately from the steady-state steering gain. This lateral transient is influenced by many vehicle parameters, but we will look at the influence of active rear steer and various tire types such as all-season, snow, and summer. This study will explore the ability for a rear steering system to change the lateral transient to a step steer input, compared to the effect of changing tire types. While the yaw rate response to a steering input can be dramatically influenced by rear steering, the effect in a dynamic
Bredthauer, Lance, Lynch, David
Design of an Integrated Yaw-Roll Moment and Active Front Steering Controller using Fuzzy Logic Control2017-01-156903/28/2017
This paper presents an advanced control system, which integrates three fuzzy logic controllers namely; Direct Yaw-moment Control (DYC), Active Roll-moment Control (ARC) and Active Front Steering (AFS) to enhance vehicle cornering and overturning stability. Based on a well-developed and validated fourteen degree of freedom (DOF) full vehicle model with non-linear tire characteristics, a reference 3-DOF yaw-roll plane vehicle model is introduced to control yaw rate, sideslip angle, and roll angle of the vehicle body. The control actions of both direct yaw and active roll moments are performed by generating differential braking moments across the front wheels, while the control action of the active steering is performed by modifying the steering wheel angle. Different standard cornering tests are conducted in MATLAB / Simulink environment such as J-turn, fishhook and lane change maneuvers. The simulation results show a substantial improvement in vehicle stability by employing the proposed
Elhefnawy, Amro, sharaf, Alhossein, Ragheb, Hossam, Hegazy, Shawky
Yaw Stability Enhancement of Articulated Commercial Vehicles via Gain-Scheduling Optimal Control Approach2017-01-043703/28/2017
In this paper, a gain-scheduling optimal control approach is proposed to enhance yaw stability of articulated commercial vehicles through active braking of the proper wheel(s). For this purpose, an optimal feedback control is used to design a family of yaw moment controllers considering a broad range of vehicle velocities. The yaw moment controller is designed such that the instantaneous tractor yaw rate and articulation angle responses are forced to track the target values at each specific vehicle velocity. A gain scheduling mechanism is subsequently constructed via interpolations among the controllers. Furthermore, yaw moments derived from the proposed controller are realized by braking torque distribution among the appropriate wheels. The effectiveness of the proposed yaw stability control scheme is evaluated through software-in-the-loop (SIL) co-simulations involving Matlab/Simulink and TruckSim under lane change maneuvers. Simulation results demonstrate that the proposed gain
Li, Bin, Rakheja, Subhash
Accurate Fuel Economy Prediction via a Realistic Wind Averaged Drag Coefficient2017-01-153503/28/2017
The ultimate goal for vehicle aerodynamicists is to develop vehicles that perform well on the road under real-world conditions. One of the most important metrics to evaluate vehicle performance is the drag coefficient. However, vehicle development today is performed mostly under controlled settings using wind tunnels and computational fluid dynamics (CFD) with artificially uniform upstream conditions, neglecting real-world effects due to road turbulence from wind and other vehicles. Thus, the drag coefficients computed with these methods might not be representative of the real performance of the car on the road. This might ultimately lead engineers to develop design solutions and aerodynamic devices which, while performing well in idealized conditions, do not perform well on the road. For this reason, it is important to assess the vehicle’s drag as seen in real-world environments. An effort in this direction is represented by using the wind-averaged drag. The wind-averaged drag
Dalessio, Luca, Duncan, Bradley, Chang, Chinwei, Gargoloff, Joaquin Ivan, Tate, Ed
Bifurcation Analysis of a Car Model Running on an Even Surface - A Fundamental Study for Addressing Automomous Vehicle Dynamics2017-01-158903/28/2017
The paper deals with the bifurcation analysis of a simple mathematical model describing an automobile running on an even surface. Bifurcation analysis is adopted as the proper procedure for an in-depth understanding of the stability of steady-state motion of cars (either cornering or running straight ahead). The aim of the paper is providing the fundamental information for inspiring further studies on vehicle dynamics with or without a human driver. The considered mechanical model of the car has two degrees of freedom, nonlinear tire characteristics are included. A simple driver model is introduced. Experimental validations of the model are produced. As a first step, bifurcation analysis is performed without driver (fixed control). Ten different combinations of front and rear tire characteristics (featuring understeer or oversteer automobiles) are considered. Steering angle and speed are varied. Many different dynamical behaviors of the model are found. Homoclinic bifurcations, stable
Mastinu, Giampiero, Della Rossa, Fabio, Gobbi, Massimiliano, Previati, Giorgio
The Effect of Passive Base Ventilation on the Aerodynamic Drag of a Generic SUV Vehicle2017-01-154803/28/2017
Sports Utility Vehicles (SUVs) typically have a blunt rear end shape (for design and practicality), however this is not beneficial for aerodynamic drag. Drag can be reduced by a number of passive and active methods such as tapering and blowing into the base. In an effort to combine these effects and to reduce the drag of a visually square geometry slots have been introduced in the upper side and roof trailing edges of a squareback geometry, to take air from the freestream and passively injects it into the base of the vehicle to effectively create a tapered body. This investigation has been conducted in the Loughborough University’s Large Wind Tunnel with the ¼ scale generic SUV model. The basic aerodynamic effect of a range of body tapers and straight slots have been assessed for 0° yaw. This includes force and pressure measurements for most configurations. The slots generate useful, but small, drag reductions with the best configurations giving reductions in drag coefficient (Cd) of
Varney, Max, Passmore, Martin, Gaylard, Adrian
The Effect of a Sheared Crosswind Flow on Car Aerodynamics2017-01-153603/28/2017
In the wind tunnel the effect of a wind input on the aerodynamic characteristics of any road vehicle is simulated by yawing the vehicle. This represents a wind input where the wind velocity is constant with height above the ground. In reality the natural wind is a boundary layer flow and is sheared so that the wind velocity will vary with height. A CFD simulation has been conducted to compare the aerodynamic characteristics of a DrivAer model, in fastback and squareback form, subject to a crosswind flow, with and without shear. The yaw simulation has been carried out at a yaw angle of 10° and with one shear flow exponent. It is shown that the car experiences almost identical forces and moments in the two cases when the mass flow in the crosswind over the height of the car is similar. Load distributions are presented for the two cases. The implications for wind averaged drag are discussed.
Howell, Jeff, Forbes, David, Passmore, Martin, Page, Gary
An Advanced Yaw Stability Control System2017-01-155603/28/2017
This paper presents an advanced yaw stability control system that uses a sensor set including an inertial measurement unit to sense the 6 degrees-of-freedom motions of a vehicle. The full degree of the inertial measurement unit improves and enhances the vehicle motion state estimation over the one in the traditional electronic stability controls. The addition of vehicle state estimation leads to the performance refinement of vehicle stability control that can improve performance in certain situations. The paper provides both detailed system description and test results showing the effectiveness of the system.
Lu, Jianbo, Xu, Li, Eisele, Daniel, Samuel, Stephen, Rupp, Matthew, Tellis, Levasseur
A Nonlinear Dynamic Control Design with Conditional Integrators Applied to Unmanned Skid-steering Vehicle2017-01-158503/28/2017
A dynamic controller is designed for unmanned skid-steering vehicle. The vehicle speed is controlled through driving torque of engine to achieve the desired vehicle speed and the steering is controlled through hydraulic braking on each side of the vehicle to achieve the desired yaw rate. Contrary to the common approaches by considering non-holonomic constraints, tire slip and saturation of actuators torque influencing the driving and braking are considered, based on the analysis of vehicle dynamic model and nonlinear tire model. Hence, with conditional integrators, the dynamic controller overcoming integral saturation is designed to ensure the accurate tracking for desired signals under influence of tire forces and constraint of actuators. In addition, the exponential kind filter is utilized to enhance the ability of smoothing noise of wheel speed. To perform small radius cornering maneuvers, a dynamic control strategy for steering when vehicle speed is zero is also designed. In the
Zhang, Renxie, Xiong, Lu, Yu, Zhuoping, Liu, Wei
Investigation of Rollover Prevention with Coupling from Driver Yaw Control Using a Scaled Vehicle2017-01-157903/28/2017
The development of an integrated controller for a 4WS/4WD electric bus is investigated. The front wheel steering angle is assumed to be controlled by the human driver. The vehicle is controlled by the rear wheel steering and the yaw moment that can be generated by the differential torque/brake control on each wheel. The high speed cornering is used as the testing scenario to validate the designed controller. Due to the highly nonlinear and the multiple-input and multiple-output nature, the control design is separated into different stages using the hierarchical layer control concept. The longitudinal speed is controlled using a PI controller together with a rule-based speed modification. The other two control inputs, namely the rear wheel steering and the DYC moment, are then designed using the state-dependent Riccati equation method. The designed controllers are evaluated using computer simulations first, and the simulations showed promising results. A scaled electric bus is being
Chen, Liang-kuang, Chen, Chien-An
The Application of a One-Way Coupled Aerodynamic and Multi-Body Dynamics Simulation Process to Predict Vehicle Response during a Severe Crosswind Event2017-01-151503/28/2017
Industry trends towards lighter, more aerodynamically efficient road vehicles have the potential to degrade a vehicle’s response to crosswinds. In this paper, a methodology is outlined that indirectly couples a computational fluid dynamics (CFD) simulation of the vehicle’s aerodynamic characteristics with a multi-body dynamics simulation (MBD) to determine yaw, roll and pitch response characteristics during a severe crosswind event. This one-way coupling approach mimics physical test conditions outlined in open loop test procedure ISO 12021:2010 that forms part of the vehicle sign-off criterion at Ford Motor Company. The methodology uses an overset mesh CFD method to drive the vehicle through a prescribed crosswind event, providing unfiltered predictions of vehicle force and moment responses that are used as applied forces in the MBD model. The method does not account for changes in vehicle attitude due to applied aerodynamic forces and moments. Traditionally, a vehicle’s crosswind
Lewington, Neil, Ohra-aho, Lauri, Lange, Olav, Rudnik, Klaus
Vehicle Stability Criterion Research Based on Phase Plane Method2017-01-156003/28/2017
In this paper, a novel method is proposed to establish the vehicle yaw stability criterion based on the sideslip angle-yaw rate (β-r) phase plane method. First, nonlinear two degrees of freedom vehicle analysis model is established by adopting the Magic Formula of nonlinear tire model. Then, according to the model in the Matlab/Simulink environment, the β-r phase plane is gained. Emphatically, the effects of different driving conditions (front wheels steering angle, road adhesion coefficient and speed) on the stability boundaries of the phase plane are analyzed. Through a large number of simulation analysis, results show that there are two types of phase plane: curve stability region and diamond stability region, and the judgment method of the vehicle stability domain type under different driving conditions is solved. Finally, different conditions of stability boundary plane database look-up tables are set up, besides, the effects of different conditions on the stability boundary’s
Liu, Wei, Xiong, Lu, Leng, Bo, Meng, Haolan, Zhang, Renxie
Aerodynamic Drag of a Vehicle and Trailer Combination in Yaw2017-01-154003/28/2017
Typical production vehicle development includes road testing of a vehicle towing a trailer to evaluate powertrain thermal performance. In order to correlate tests with simulations, the aerodynamic effects of pulling a trailer behind a vehicle must be estimated. During real world operation a vehicle often encounters cross winds. Therefore, the effects of cross winds on the drag of a vehicle–trailer combination should be taken into account. Improving the accuracy of aerodynamic load prediction for a vehicle-trailer combination should in turn lead to improved simulations and better thermal performance. In order to best simulate conditions for real world trailer towing, a study was performed using reduced scale models of a Sport Utility Vehicle (SUV) and a Pickup Truck (PT) towing a medium size cargo trailer. The scale model vehicle and trailer combinations were tested in a full scale wind tunnel. Utilizing a full scale wind tunnel allowed for very low blockage conditions and testing at
Lopes, Yuri M., Taylor, Maxwell R., Lounsberry, Todd H., Fadler, Gregory J.
Yaw Rate Based Trailer Hitch Angle Estimation for Trailer Backup Assist2017-01-002703/28/2017
In the current Ford Pro-Trailer Backup Assist (TBA) system, trailer hitch angle is determined utilizing the reverse camera of the vehicle. In addition to being sensitive to environmental factors such as lighting conditions and occlusion, the vision-based approach is difficult to be applied to gooseneck or fifth wheel trailers. In this paper, a yaw rate based hitch angle observer is proposed as an alternative sensing solution for TBA. Based on the kinematic model of the vehicle-trailer, an instantaneous hitch angle is first derived by utilizing vehicle yaw rate, trailer yaw rate, vehicle velocity and vehicle/trailer parameters provided by the TBA system. Due to signal errors and parameter uncertainties, this instantaneous hitch angle may be noisy, especially at lower vehicle speed. To improve the estimation accuracy, a Kalman filter (or an extended Kalman filter) which is based on the vehicle-trailer kinematic model is then formulated to obtain the optimal estimate, with the
Xu, Li, Tseng, Eric, Pilutti, Thomas, Schondorf, Steven
Model Predictive Control for Feasible Region of Active Collision Avoidance2017-01-004503/28/2017
Vehicle active collision avoidance includes collision avoidance by braking and by steering. However, both of these two methods have their limitations. Therefore, it is significant to establish the feasible region of active collision avoidance to choose the optimal way to avoid traffic accidents. This paper focuses on the steering control of an autonomous vehicle to track the planned trajectory and to perform an emergency collision avoidance maneuver. Meanwhile, the collision avoidance effect of steering control is compared with that of braking control. The path tracking controller is designed by hierarchical control structure. The upper controller includes model predictive control allocation and speed controller, and the lower is designed by weighted least-squares control allocation for torque allocation. Besides, seven order polynomial is used for path planning. In this paper, two kinds of steering collision avoidance measures are compared, including steering without yaw moment and
Zhuo, Guirong, Wu, Cheng, Zhang, Fengbo
Yaw Effects on the Narrowband Spectra Above a Delta Wing in Turbulent Flow2016-01-205609/20/2016
Combat aircraft maneuvering at high angles of attack or in landing approach are likely to encounter conditions where the flow over the swept wings is yawed. This paper examines the effect of yaw on the spectra of turbulence above and aft of the wing, in the region where fins and control surfaces are located. Prior work has shown the occurrence of narrowband velocity fluctuations in this region for most combat aircraft models, including those with twin fins. Fin vibration and damage has been traced to excitation by such narrowband fluctuations. The narrowband fluctuations themselves have been traced to the wing surface. The issue in this paper is the effect of yaw on these fluctuations, as well as on the aerodynamic loads on a wing, without including the perturbations due to the airframe. A 42 degree delta wing with rounded leading edges, roughly equivalent to a 1/20 scale of existing combat aircraft, is used in a 2.74 m low speed wind tunnel in the angle of attack range 18 to 35
Thorell, Nikolaus, Kumar, Vaibhav, Komerath, Narayanan
Elimination of Yaw Component of Gyroscope Propagation Error During Arm Activity in MSLTBMG-2532409/01/2016
When updating attitude during arm motion, gyroscope propagation error soon becomes greater than the tilt being monitored. The solution is to add an accelerometer-only mode that can update attitude without using gyroscopes, and to add the ability to monitor pitch and roll separately. Accelerometer-only mode is used only when it is safe to assume that any vehicle shifting in yaw would also be accompanied by shifting in pitch and/or roll. For surface contact operations, it is important to monitor change in tilt of the vehicle resulting from arm motion.
Development of Integrated Chassis Control for Limit Handling2016-01-163804/05/2016
This paper presents the integrated chassis control(ICC) of four-wheel drive(4WD), electronic stability control(ESC), electronic control suspension(ECS), and active roll stabilizer(ARS) for limit handling. The ICC consists of three layers: 1) a supervisor determines target vehicle states; 2) upper level controller calculates generalized forces; 3) lower level controller, which is contributed in this paper, optimally allocates the generalized force to chassis modules. The lower level controller consists of two integrated parts, 1) longitudinal force control part (4WD/ESC) and 2) vertical force control part (ECS/ARS). The principal concept of both algorithms is optimally utilizing the capability of the each tire by monitoring tire saturation, with tire combined slip. By monitoring tire saturation, 4WD/ESC integrated system minimizes the sum of the tire saturation, and ECS/ARS integrated system minimizes the variance of the tire saturation. However, with only minimizing the sum of tire
Joa, Eunhyek, Yi, Kyongsu, Kim, Kilsoo
An Experimental Study on Truck Side-Skirt Flow2016-01-159304/05/2016
The underbody of a truck is responsible for an appreciable portion of the vehicle’s aerodynamic drag, and thus its fuel consumption. This paper investigates experimentally the flow around side-skirts, a common underbody aerodynamic device which is known to be effective at reducing vehicle drag. A full, 1/10 scale European truck model is used. The chassis of the model is designed to represent one that would be found on a typical trailer, and is fully reconfigurable. Testing is carried out in a water towing tank, which allows the correct establishment of the ground flow and rotating wheels. Optical access into the underbody is possible through the clear working section of the facility. Stereoscopic and planar Particle Image Velocimetry (PIV) set-ups are used to provide both qualitative images of and quantitative information on the flow field. The planar PIV set-up employs novel techniques developed in-house, including the use of two laser sheets to reduce shadow regions, and frame
Stephens, R.G., Babinsky, H.
A Fully Coupled, 6 Degree-of-Freedom, Aerodynamic and Vehicle Handling Crosswind Simulation using the DrivAer Model2016-01-160104/05/2016
In a real-world environment, a vehicle on the road is subjected to a range of flow yaw angles, the most severe of which can impact handling and stability. A fully coupled, six degrees-of-freedom CFD and vehicle handling simulation has modelled the complete closed loop system. Varying flow yaw angles are introduced via time dependent boundary conditions and aerodynamic loads predicted, whilst a handling model running simultaneously calculates the resulting vehicle response. Updates to the vehicle position and orientation within the CFD simulation are achieved using the overset grid method. Using this approach, a crosswind simulation that follows the parameters of ISO 12021:2010 (Sensitivity to lateral wind - Open-loop test method using wind generator input), was performed using the fastback variant of the DrivAer model. Fully coupled aerodynamic and vehicle response was compared to that obtained using the simplified quasi-steady and unsteady, one way coupled method. Between the quasi
Forbes, David C., Page, Gary J., Passmore, Martin A., Gaylard, Adrian P.
Development of a Parameter Identification Method for MF-Tyre/MF-Swift Applied to Parking and Low Speed Manoeuvres2016-01-164504/05/2016
A vehicle parking manoeuvre is characterized by low or zero speed, small turning radius and large yaw velocity of the steered wheels. To predict the forces and moments generated by a wheel under these conditions, the Pacejka Magic Formula model has been extended to incorporate the effect of spin (turn slip model) in the past years. The extensions have been further developed and incorporated in the MFTyre/MF-Swift 6.2 model. This paper describes the development of a method for the identification of the turn slip parameters. Based on the operating conditions of a typical parking manoeuvre, the dominant parameters of the turn slip model are firstly defined. At an indoor test facility, the response of a tyre under the identified operating conditions is measured. An algorithm is developed to identify the dominant turn slip parameters from the measured responses. Wherever possible, the algorithm is based on direct analytical relationships between the turn slip model parameters and the
Lugaro, Carlo, Schmeitz, Antoine, Ogawa, Toshiya, Murakami, Tetsuya, Huisman, Sonny
Investigation of Aerodynamic Drag in Turbulent Flow Conditions2016-01-160504/05/2016
In this paper the influence of different turbulent flow conditions on the aerodynamic drag of a quarter scale model with notchback and estate back rear ends is investigated. FKFS swing® (Side Wind Generator) is used to generate a turbulent flow field in the test section of the IVK model scale wind tunnel. In order to investigate the increase in drag with increasing yaw, a steady state yaw sweep is performed for both vehicle models. The shape of the drag curves vary for each vehicle model. The notchback model shows a more pronounced drag minimum at 0° yaw angle and experiences a more severe increase in drag at increasing yaw when compared to the estate back model. Unsteady time averaged aerodynamic drag values are obtained at two flow situations with different turbulent length scales, turbulence intensities, and yaw angle amplitudes. While the first one is representing light wind, the second one is recreating the presence of strong gusty wind. The results are compared to a quasi-steady
Stoll, Daniel, Schoenleber, Christoph, Wittmeier, Felix, Kuthada, Timo, Wiedemann, Jochen
Modeling of Transient Aerodynamic Forces based on Crosswind Test2016-01-157704/05/2016
The aerodynamic stability of energy-saving, lightweight, and low-drag vehicles is reduced by crosswind disturbances. In particular, crosswinds cause unsteady motion in vehicles with low-drag body shapes due to aerodynamic yaw moment. To verify fluctuations in the unsteady aerodynamic forces of a vehicle, a direct measurement method of these forces in a crosswind test was established using inertial force and tire load data. The former uses an inertia sensor comprised of a gyro, acceleration sensor, and GPS sensor, and the latter uses a wheel force sensor. Noise in the measurement data caused by the natural frequency of the tires was reduced using a spectral subtraction method. It was confirmed that aerodynamic data measured in the crosswind test corresponded to wind tunnel test data. Numerical expressions were defined to model the unsteady aerodynamic forces in a crosswind. Crosswind tests were conducted under various conditions consisting of different wind patterns and test vehicle
Fukagawa, Tateru, Shimokawa, Shinnosuke, Itakura, Eiji, Nakatani, Hiroyuki, Kitahama, Kenichi
Lateral Control System for Autonomous Lane Change System on Highways2016-01-164104/05/2016
In this paper, we propose a vision based lateral control scheme for autonomous lane change system on highways. Three main techniques are proposed, to improve the lane keeping/lane change performance, and to reduce the ripple in the yaw rate on highways. First, we propose a model based lane prediction method to cope with the momentary failure of lane detection. Second, we innovate an approach to steering wheel angle control based on torque overlay for the EPS of the lateral control. Finally, the multi-rate lane-keeping control scheme is proposed to improve the lateral control performance and to reduce the ripple in the yaw rate. The performance of the proposed method was experimentally evaluated via test vehicle
Kang, Chang Mook, Sung Gu, Yi, Jeon, Soo Jung, Son, Young Seop, Kim, Wonhee, Lee, Seung-Hi, Chung, Chung Choo
Aerodynamic Side Forces on Passenger Cars at Yaw2016-01-162004/05/2016
Side force has an influence on the behaviour of passenger cars in windy conditions. It increases approximately linearly with yaw angle over a significant range of yaw for almost all cars and the side force derivative, (the gradient of side force coefficient with yaw angle), is similar for vehicles of a given category and size. The shape factors and components which affect side force for different vehicle types are discussed. The dominant influence on side force, for most cars, however, is shown to be the vehicle height which is consistent with slender wing theory if the car and its mirror image are considered. This simple theory is shown to apply to 1-box and 2- box shapes, covering most MPVs, hatchbacks and SUVs, but does not adequately represent the side forces on notchback and fastback car shapes. Data from simple bodies is used to develop a modification to the basic theory, which is applied to these vehicle types.
Howell, Jeff, Panigrahi, Sumit
Aerodynamics Evaluation of Road Vehicles in Dynamic Maneuvering2016-01-161804/05/2016
A road vehicle’s cornering motion is known to be a compound motion composed mainly of forward, sideslip and yaw motions. But little is known about the aerodynamics of cornering because little study has been conducted in this field. By clarifying and understanding a vehicle’s aerodynamic characteristics during cornering, a vehicle’s maneuvering stability during high-speed driving can be aerodynamically improved. Therefore, in this study, the aerodynamic characteristics of a vehicle’s cornering motion, i.e. the compound motion of forward, sideslip and yaw motions, were investigated. We also considered proposing an aerodynamics evaluation method for vehicles in dynamic maneuvering. Firstly, we decomposed cornering motion into yaw and sideslip motions. Then, we assumed that the aerodynamic side force and yaw moment of a cornering motion could be expressed by superposing linear expressions of yaw motion parameters and those of sideslip motion parameters, respectively. Next, we conducted CFD
Okada, Yoshihiro, Nakashima, Takuji, Tsubokura, Makoto, Morikawa, Yousuke, Kouno, Ryousuke, Okamoto, Satoshi, Matsuhiro, Tanaka, Nouzawa, Takahide
Combination of Front Steering and Differential Braking Control for the Path Tracking of Autonomous Vehicle2016-01-162704/05/2016
In order to improve the robustness and stability of autonomous vehicle at high speed, a path tracking approach which combines front steering and differential braking is investigated in this paper. A bicycle model with 3-DOFs is established and a linear time-varying predictive model using front steering as its control input can be derived. Based on model predictive theory, the path tracking issue using linear time-varying model predictive control can be transformed into an online quadratic programming problem with constraints. The expected front steering angle can be obtained from online moving optimization. Then the direct yawing control is adopted to treat two types of differential braking control. The first one investigates steady-state gain of yaw rate in linear 2-DOFs vehicle model, and designs a stable differential braking controller which is based on reference yaw rate. The other one is based on the research of stable area of side-slip angle phase portrait, and corresponding
Zhang, Liangxiu, Wu, Guangqiang
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