Showing papers on "Yaw published in 2004"

Simultaneous Optimal Distribution of Lateral and Longitudinal Tire Forces for the Model Following Control

Abstract: This paper presents a proposed optimum tire force distribution method in order to optimize tire usage and find out how the tires should share longitudinal and lateral forces to achieve a target vehicle response under the assumption that all four wheels can be independently steered, driven, and braked. The inputs to the optimization process are the driver's commands (steering wheel angle, accelerator pedal pressure, and foot brake pressure), while the outputs are lateral and longitudinal forces on all four wheels. Lateral and longitudinal tire forces cannot be chosen arbitrarily, they have to satisfy certain specified equality constraints. The equality constraints are related to the required total longitudinal force, total lateral force, and total yaw moment. The total lateral force and total moment required are introduced using the model responses of side-slip angle and yaw rate while the total longitudinal force is computed according to driver's command (traction or braking). A computer simulation of a closed-loop driver-vehicle system subjected to evasive lane change with braking is used to prove the significant effects of the proposed optimal tire force distribution method on improving the limit handling performance. The robustness of the vehicle motion with the proposed control against the coefficient of friction variation as well as the effect of steering wheel angle amplitude is discussed.

Attitude sensing system for an automotive vehicle relative to the road

Abstract: A system (18) for controlling a safety system (44) of an automotive vehicle (10) includes a longitudinal acceleration sensor (36), a vehicle speed sensor (20), a lateral acceleration sensor (32), a yaw rate sensor, and a controller (26). The controller (26) determines a reference pitch in response to the longitudinal acceleration signal and the vehicle speed signal and a reference roll angle in response to the yaw rate signal, the wheel speed signal and the lateral acceleration signal. The controller (26) determines a roll stability index and a pitch stability index. The controller (26) determines an adjusted pitch angle in response to the reference pitch angle and the pitch stability index and an adjusted roll angle in response to the reference roll angle and the roll stability index. The controller (26) controls the safety system (44) in response to the adjusted roll angle and the adjusted pitch angle.

Satellite based vehicle guidance control in straight and contour modes

Abstract: A method for steering an agricultural vehicle comprising: receiving global positioning system (GPS) data including position and velocity information corresponding to at least one of a position, velocity, and course of the vehicle; receiving a yaw rate signal; and computing a compensated heading, the compensated heading comprising a blend of the yaw rate signal with heading information based on the GPS data. For each desired swath comprising a plurality of desired positions and desired headings, the method also comprises: computing an actual track and a cross track error from the desired swath based on the compensated heading and the position; calculating a desired radius of curvature to arrive at the desired track with a desired heading; and generating a steering command based on the desired radius of curvature to a steering mechanism, the steering mechanism configured to direct the vehicle.

Road curvature estimation system

Abstract: A processor (26) using a first Kalman filter (52, 52.1) estimates a host vehicle state from speed (U) and yaw rate, the latter of which may be from a yaw rate sensor (16) if speed (U) is greater than a threshold, and, if less, from a steer angle sensor and speed (U). Road curvature parameters (C0, C1) are estimated from a curve fit of a host vehicle trajectory or from a second Kalman filter (54, 54.1) for which a state variable may be responsive to a plurality of host state variables (72, 74). Kalman filters (52, 52.1, 54, 54.1) may incorporate adaptive sliding windows. Curvature of a most likely road type is estimated with an interacting multiple model (IMM) algorithm (2400) using models of different road types. A road curvature fusion subsystem (96) provides for fusing road curvature estimates from a plurality of curvature estimators (42.1, 42.2, 42.N) using either host vehicle state, a map database (88) responsive to vehicle location (86), or measurements of a target vehicle (36) with a radar system (14).

A Fuzzy Logic Direct Yaw-Moment Control System for All-Wheel-Drive Electric Vehicles

Abstract: Summary In-wheel-motors are revolutionary new electric drive systems that can be housed in vehicle wheel assemblies. Such E-wheels permit packaging flexibility by eliminating the central drive motor and the associated transmission and driveline components, including the transmission, the differential, the universal joints and the drive shaft. Apart from many advantages of such a system, unequalled independent wheel control allows vehicle dynamic improvement to assist the driver in enhancing cornering and straight-line stability on slippery roads and in adverse ground conditions. In this paper a Fuzzy logic driver-assist stability system for all-wheel-drive electric vehicles based on a yaw reference DYC is introduced. The system assists the driver with path correction, thus enhancing cornering and straight-line stability and providing enhanced safety. A feed-forward neural network is employed to generate the required yaw rate reference. The neural net maps the vehicle speed and the steering angle to give t...

Vehicular steering device

Abstract: A first ECU 30 detects a steering torque applied to a steering system, estimates a self-aligning torque generated in a front wheel on the basis of the steering torque, and estimates a side force for the front wheel on the basis of lateral acceleration and a yaw rate. The first ECU 30 estimates a grip factor e for the front wheel on the basis of a change of the self-aligning torque to the side force. The first ECU 30 judges whether the grip factor is below a second OS (oversteer) start threshold value. A second ECU 40 controls the transfer ratio according to the vehicle state when the grip factor is less than the second OS start threshold value.

Hovering flight stabilization in wind gusts for ducted fan UAV

Abstract: This paper describes a control strategy to stabilize the position of a micro air vehicle in wind gusts despite unknown aerodynamic efforts. The proposed approach allows us to overcome the problem of gyroscopic coupling by taking advantage from both the structure of the thrust mechanism, which is made of two counter rotating propellers, and the control strategy which involves a decoupling of the yaw rate dynamics from the rest of the system dynamics. The controller is designed by means of backstepping techniques allowing the stabilization of the vehicle's position while on-line estimating the unknown aerodynamic efforts.

Control of a ground vehicle using quadratic programming based control allocation techniques

Abstract: This paper examines the use of control allocation techniques for the control of multiple inputs to a ground vehicle to track a desired yaw rate trajectory while minimizing vehicle sideslip. The proposed controller uses quadratic programming accompanied by linear quadratic regulator gains designed around a linear vehicle model to arrive at a combination of vehicle commands. Several failure scenarios are examined and the results for two different quadratic programming approaches are presented along with a discussion of the advantages each method has to offer.

Method and apparatus for detecting and correcting trailer induced yaw movements in a towing vehicle

Abstract: An apparatus and method for determining the presence of excessive yaw rate in a vehicle by calculating an instability index that is a function of the vehicle yaw rate and generating an excessive yaw rate signal when the instability index exceeds a yaw rate threshold.

Integrated Active Steering and Variable Torque Distribution Control for Improving Vehicle Handling and Stability

Abstract: This paper proposes an advanced control strategy to improve vehicle handling and directional stability by integrating either Active Front Steering (AFS) or Active Rear Steering (ARS) with Variable Torque Distribution (VTD) control. Both AFS and ARS serve as the steerability controller and are designed to achieve the improved yaw rate tracking in low to mid-range lateral acceleration using Sliding Mode Control (SMC); while VTD is used as the stability controller and employs differential driving torque between left and right wheels on the same axle to produce a relatively large stabilizing yaw moment when the vehicle states (sideslip angle and its angular velocity) exceed the reference stable region defined in the phase plane. Based on these stand-alone subsystems, an integrated control scheme which coordinates the control actions of both AFS/ARS and VTD is proposed. The functional difference between AFS and ARS when integrated with VTD is explained physically. The effect of the integrated control system on the vehicle handling characteristics and directional stability is studied through an open loop computer simulation of an eight degrees of freedom nonlinear vehicle model. Simulation results confirm the effectiveness of the proposed control system and the overall improvements in vehicle handling and directional stability.

Integrated control apparatus for vehicle

Abstract: An electronic control unit calculates a target yaw rate in accordance with a vehicle speed and a steering angle and calculates the yaw rate difference on the basis of the target yaw rate and an actual yaw rate. The electronic control unit estimates the grip factor of a front wheel to road surface and sets a distribution ratio for distribution of a vehicle-control target value among actuators of a steering system, a brake system, and a drive system in accordance with the estimated grip factor. The electronic control unit controls the actuators of the three systems in accordance with control instruction values distributed on the basis of the vehicle-control target value and the distribution ratio.

Vehicle motion control device

Abstract: A transfer clutch control units operates a second transfer clutch torque corresponding to a yaw moment out of the transfer clutch torque to be output to a transfer clutch drive unit by a second transfer clutch torque operational unit. The second transfer clutch torque operational unit operates a reference lateral acceleration from a lateral acceleration to be operated based on a linear vehicle motion model from a vehicle driving state and a preset coefficient according to the vehicle driving state, in addition to the yaw moment sensing the yaw rate and the yaw moment sensing the steering wheel angle, and operate the yaw moment corresponding to the deviation between the reference lateral acceleration and the actual lateral acceleration as a corrected value of the yaw moment. Not only a high μ road but also a low μ road, even abrupt change of road surfaces or the like can be consistently and optimally coped with in excellent response.

Voice recognition system and moving body and vehicle having the system

Abstract: PROBLEM TO BE SOLVED: To provide a voice recognition system which more accurately performs voice recognition corresponding to actual environment and to provide a moving body and a vehicle which are provided with the system to improve convenience of a user. SOLUTION: A feature synthesis section 8 obtains the vehicle speed, the amount of air flow from an air-conditioner, the sound volume of audio signals, a yaw rate and in-vehicle brightness which indicate the in-vehicle conditions from a vehicle speed sensor 10, an air-conditioner ECU11, an audio ECU12, a yaw rate sensor 13 and a brightness sensor 14. Then, comparison is made between the values of the obtained vehicle speed, the amount of air flow from the air-conditioner, the sound volume of the audio, the yaw rate and in-vehicle brightness and respective threshold values of audio and an image which are determined for every object item indicating the vehicle conditions. Then, discrimination is made to determine whether the reliability of the featured values of the voice and the image of the user being inputted can be used for voice recognition or not. Then, the feature synthesis section 8 synthesizes the featured values of the voice and the image of the user using the weighting based on the reliability and outputs the values to a pattern recognition section 15. The pattern recognition section 15 conducts a recognition process of the voice. COPYRIGHT: (C)2006,JPO&NCIPI

Steering control apparatus and method for automotive vehicle

Abstract: In steering control apparatus and method for an automotive vehicle, a camera photographs a travel path in a traveling direction of a vehicle, a lateral displacement calculating circuit calculates a lateral displacement of the vehicle with respect to the travel path according to an image of the travel path photographed by the camera, a differentiator calculates a differential value of the lateral displacement, a vehicle speed sensor that detects a vehicle speed, a relative yaw rate calculating section calculates a relative yaw rate with respect to the travel path of the vehicle on the basis of the lateral displacement, the differential value of the lateral displacement, and the vehicle speed, an actuator provides an assistance force for the steering mechanism, and an actuator controlling section drivingly controls the actuator in a direction toward which the relative yaw rate is cancelled on the basis of the relative yaw rate.

Model-Based Road Friction Estimation

Abstract: The tire/road friction coefficient, μ, has a significant role in vehicle longitudinal and lateral control, and there has been associated efforts to measure or estimate the road surface condition to provide additional information for stability augmentation systems of automobiles. In this paper, a model based road friction estimation algorithm is proposed from easily measured signals such as yaw rate and wheel speed. For the development of the estimator, a low order vehicle model incorporated with simple but effective tire model. Field tests of the estimator using actual vehicle measurements show promising results.

System and method for determining a wheel departure angle for a rollover control system with respect to road roll rate and loading misalignment

Abstract: A control system (18) and method for an automotive vehicle includes a roll rate sensor (34) generating a roll rate signal, a lateral acceleration sensor (32) generating a lateral acceleration signal, a pitch rate sensor (37) generating a pitch rate signal, a yaw rate sensor (28) generating a yaw rate signal and a controller (26). The controller (26) is coupled to the roll rate sensor (34), the lateral acceleration sensor, the yaw rate sensor and the pitch rate sensor. The controller (26) determines a roll velocity total from the roll rate signal, the yaw rate signal and the pitch rate signal. The controller (26) also determines a relative roll angle from the roll rate signal and the lateral acceleration signal. The controller (26) determines a wheel departure angle from the total roll velocity. The controller (26) determines a calculated roll signal from the wheel departure angle and the relative roll angle signal.

Vehicle state estimation using steering torque

Abstract: This work presents a new approach to estimating vehicle sideslip using steering torque information. This method is especially suited to vehicles equipped with steer-by-wire systems since the steering torque can easily be determined from the current applied to the steering motor. By combining a linear vehicle model with the steering system model, a simple observer may be devised to estimate sideslip when yaw rate and steering angle are measured. The observer is validated on a test vehicle equipped with a steer-by-wire system.

Horizontal axis wind turbine and method for controlling horizontal axis wind turbine

Abstract: A horizontal axis wind turbine includes: a yaw sensor; a rotor rotating around a rotor axis extending in a substantially horizontal direction, the rotor axis rotating in a substantially horizontal plane depending on wind direction; a plate-like member disposed on a rotational central portion of the rotor and extending in a parallel direction to the rotor axis and in a vertical direction; two anemometers disposed at positions which are across the plate-like member; and a controller for yaw control based on a difference or a ratio between wind speeds measured by the two anemometers.

Multi-objective H ∞ optimal control for four-wheel steering vehicle based on yaw rate tracking

Abstract: In this paper, a lateral controller is designed for four-wheel steering (4WS) vehicles. The linear lateral dynamics of 4WS vehicles are deduced and then analysed, aided with three-dimensional graphs. To improve vehicle handling and stability at high speed, a multiobjective H ∞ optimal control algorithm is presented, while yaw rate is the only feedback signal. Simulation shows that the sideslip angle, yaw rate, and lateral acceleration of the 4WS vehicle follow and maintain preferable characteristics. The 4WS vehicle is agile and consistent with the steering input and does not understeer excessively.

Reference signal generator for an integrated sensing system

Abstract: A vehicle control system includes a sensor cluster within a housing generating a plurality of signals including a roll rate signal, a pitch rate signal, a yaw rate signal, a longitudinal acceleration signal, a lateral acceleration signal, and a vertical acceleration signal. An integrated controller includes a reference signal generator generating a reference lateral velocity signal as a function of a kinematics road constraint condition, a dynamic road constraint condition, and singularity removal logic, all of which are responsive to sensor cluster signals. A dynamic system controller receives the reference lateral velocity signal and generates a dynamic control signal in response thereto. A vehicle safety system controller receives the dynamic control signal and further generates a vehicle safety device activation signal in response thereto.

System and method for determining desired yaw rate and lateral velocity for use in a vehicle dynamic control system

Abstract: A control system ( 18 ) and method for an automotive vehicle ( 10 ) includes a lateral acceleration sensor ( 32 ) for generating a lateral acceleration signal, a yaw rate sensor ( 28 ) for generating a yaw rate signal, and a safety system. The safety system ( 44 ) and the sensors are coupled to a controller ( 26 ). The controller ( 26 ) determines a front lateral tire force and a rear lateral tire force from the vehicle yaw rate signal and the vehicle lateral acceleration signal; determines a calculated lateral velocity from the front lateral tire force, the rear lateral tire force, and a bank angle; determines a calculated yaw rate from the front lateral tire force and the rear lateral tire force; and controls the safety system in response to the calculated lateral velocity and the calculated yaw rate.

Stability factor learning method and apparatus for a vehicle and control apparatus for a vehicle

Abstract: The invention provides a technique for learning a stability factor of a vehicle by which the stability factor of the vehicle can be calculated in response to a state of the vehicle. To this end, a state of the vehicle during traveling is detected, and it is decided based on the detection information whether or not the current traveling state of the vehicle is a stable turning state. If it is decided that the current traveling state of the vehicle is a stable turning state, then the stability factor of the vehicle is calculated in accordance with a predetermined arithmetic operation expression based on a vehicle speed, a steering angle and a yaw rate detected during traveling, and the calculated value is determined as a learned value of the stability factor of the vehicle thereby to determine the stability factor in the current state of the vehicle.

Yaw rate control of electric vehicle using steer-by-wire system

Abstract: Recently electric power steering system has been developed. Steer-by-wire system has big advantages of packaging flexibility, advanced vehicle control system, and superior performance. Steer-by-wire system has no mechanical linkage between the steering gear and the steering column. It is possible to control the steering wheel and the front-wheels steering independently. The active steering which reduce the difference between actual and estimated vehicle yaw rate can be realized. Since the information from the steering wheel is important for the driver to know the road condition, tire force should be fed back to the steering wheel. But unexpected disturbance is better suppressed without affecting to the steering wheel. Based on estimating the vehicle side slip angle from the internal sensor response, the tire self-aligning torque can be estimated. This torque is fed back to the steering wheel so that the driver can know the road condition. In this paper, we propose the method to control the vehicle yaw rate using steer-by-wire system, also disturbance applied to the front tires is suppressed by disturbance observer without affecting to the steering wheel. Numerical simulations are carried out to show the validity of the proposed method.

Drive force control device of wheel independently driven type electric vehicle

Abstract: PROBLEM TO BE SOLVED: To make the protection of a motor compatible with the stability of traveling, by preventing the traveling from being unstable due to a change of the yaw rate behavior of a vehicle, when correcting an output of the motor to a reduction side that is estimated, such that a seizure-preventing temperature of the motor exceeded an allowable temperature range, in an electric vehicle of a wheel independently driven type, whose wheels are driven by the individual motors. SOLUTION: A controller 5 reads motor temperature, detected by using signals of temperature sensors 6FL, 6FR, 6RL and 6RR installed at the driving motors 3FL, 3FR, 3RL and 3RR, and estimates the motor temperature after the detection. When the controller estimates that the left-side motor 3FL in the vehicle width direction is out of the allowable temperature range, the controller narrows down an output of the motor 3FL, and corrects the target driving force of a wheel 2FL to decrease by an amount -α. The controller then simultaneously increase an output of the remaining motor 3RL, corrects the target driving force of a wheel 2RL to increase by an amount +α, makes the total of drive forces at the left side in the vehicle width direction same as the one before the correction, and makes the sum of the drive forces of the wheels 2FL, 2FR, 2RL and 2RR the same as the one before the correction. COPYRIGHT: (C)2005,JPO&NCIPI

Robust adaptive control of sawyer motors without current measurements

Abstract: We address nonlinear robust adaptive dynamic output feedback of voltage-fed dual-axis linear stepper (Sawyer) motors using a detailed motor model with electrical dynamics and significant uncertainties and disturbances. A coordinate transformation is proposed to decouple the model into three third-order subsystems along with an appended fifth-order subsystem. The controller utilizes only position and velocity measurements in each axis and achieves practical stabilization of position tracking errors. Adaptations are utilized so as not to require any knowledge of electromechanical system parameters. The controller is robust to load torques, friction, cogging forces, and other disturbances satisfying certain bounds. The controller corrects for the yaw rotation to achieve synchrony of motor and platen teeth.

Robust design of gain matrix of body slip angle observer for Electric Vehicles and its experimental demonstration

Abstract: Electric Vehicles (EVs) are inherently suitable for 2-dimension control. To utilize EV's advantages, body slip angle /spl beta/ and yaw rate /spl gamma/ play an important role. However as sensors to measure /spl beta/ are very expensive, we need to estimate /spl beta/ from only variables to be measurable. In this paper, an improved estimation method for body slip angle /spl beta/ for EVs is proposed. This method is based on a linear observer from side acceleration a/sub y/ and /spl gamma/ sensors. We especially considered the design of gain matrix and we achieved succeeded in exact and robust estimation. We performed experiments by UOT MarchII. This experimental vehicle was made for study of advanced control of EV to be driven by four in-wheel motors. Some experimental results are shown to verify the effectiveness of the proposed method.

Control of the aircraft-on-ground lateral motion during low speed roll and manoeuvers

Abstract: The aim of this paper is to present the study of a yaw rate control of the aircraft-on-ground. Such a control law can ease ground handling and turn it safer. It helps to stabilize the aircraft trajectory and guarantee a predictable behavior. Due to the high non-linearities of the model, the control design methodology is based on feedback linearizing. This technique aims to design a non-linear controller that constrains the system outputs to follow a linear reference behavior. However, it supposes that the reference model perfectly corresponds to the real system. This assumption is not verified in this application (neglected dynamics, presence of saturations and high uncertainties). Nevertheless, as this article shows, maneuverability requirements can be assured in every case by slightly adapting and properly tuning the control law.

Adaptive compensation of rear-wheel steering control using vehicle dynamics parameter estimation

Abstract: An active rear-wheel vehicle steering control system that employs both open-loop and closed-loop control, where the open-loop and closed-loop control include adaptive compensation sub-systems that compensate for changes in vehicle dynamic parameters. The control system includes a dynamic parameter estimation sub-system that provides an estimated front-wheel cornering compliance and rear-wheel cornering compliance based on a front-wheel steering angle signal, a rear-wheel steering angle signal, a vehicle lateral acceleration signal, a vehicle yaw rate signal and a vehicle speed signal. The closed-loop control includes active gain for each of vehicle yaw rate, vehicle yaw rate acceleration, side-slip velocity and side-slip velocity rate, all based on the vehicle speed and vehicle dynamic parameter changes.

Independent control of all-wheel-drive torque distribution

Abstract: The sophistication of all-wheel-drive (AWD) technology is approaching the point where the drive torque to each wheel can be independently controlled. This potentially offers vehicle handling enhancements similar to those provided by dynamic stability control, but without the inevitable reduction in vehicle acceleration. Independent control of AWD torque distribution would therefore be especially beneficial under acceleration close to the limit of stability. A vehicle model of a typical sports sedan was developed in Simulink, with fully independent control of torque distribution. Box–Behnken experimental design was employed to determine which torque distribution parameters have the greatest impact on the vehicle course and acceleration. A proportional-integral control strategy was implemented, applying yaw rate feedback to vary the front–rear torque distribution and lateral acceleration feedback to adjust the left–right distribution. The resulting system shows a significant improvement over conventional dr...

Method for Identifying Vehicle Movements for Analysis of Field Operational Test Data

Abstract: The independent evaluation of a roadway-departure crash-warning system will involve identifying and classifying conflicts and near-collisions from a vast quantity of field data. The classification of these events includes identifying vehicle movements such as negotiating a curve, making a turn, changing lanes, and merging. A unified algorithm that relies solely on vehicle kinematic data is developed for identifying such movements. The method works reliably for various types of road surfaces, road types, speeds, and conditions. The algorithm relies on metrics such as heading angle, lateral position, radius of curvature, and peak yaw rate—calculated from yaw rate and vehicle speed data—to classify vehicle-movement events from a large file of vehicle data. Tuning parameters for the algorithm, set both analytically and empirically, are provided. The results of the tests show that the algorithm makes correct identifications of vehicle movement about 80% of the time. The highest success is for turns, followed b...