Showing papers on "Yaw published in 1993"

Robust yaw damping of cars with front and rear wheel steering

Abstract: For a linear model of active car steering, a robust decoupling control law by feedback of the yaw rate to front wheel steering has previously been derived. This control law is extended by feedback of the yaw rate to rear wheel steering. A controller structure with one free damping parameter k/sub D/ is derived with the following properties: damping and natural frequency of the yaw mode are independent of speed; k/sub D/ can be adjusted to the desired damping level; and a variation of k/sub D/ has no influence on the natural frequency of the yaw mode and no influence on the steering transfer function by which the driver keeps the car-considered as a mass point at the front axle-on a planned path. Simulations with a nonlinear car steering model show significant safety advantages of the new control concept in situations when the driver of the conventional car has to stabilize unexpected yaw motions. >

Control system for a front and rear wheel steering vehicle

Abstract: In a control system for a front and rear wheel steering vehicle which steers the rear wheels so as to cancel a deviation of an actual yaw rate from a standard yaw rate which can be computed from the steering input, the vehicle speed and other parameters, there is provided a feature to automatically and manually cancel the yaw rate feedback control. If the actual yaw rate continues to exceed a threshold level for more than a certain time period, the yaw rate feedback is canceled gradually so as not to cause any abrupt change in the handling of the vehicle. Alternatively, if the vehicle operator wishes to operate the vehicle under extreme conditions, he may manually cancel the yaw rate feedback control so as to avoid undesirable interference or conflict between the manual steering effort and the yaw rate feedback control action. Thus, the maneuverability of the vehicle under extreme conditions can be improved without losing the benefits of the yaw rate feedback control.

The mean drift force and yaw moment on marine structures in waves and current

Abstract: The effect of the steady second-order velocities on the drift forces and moments acting on marine structures in waves and a (small) current is considered. The second-order velocities are found to arise due to first-order evanescent modes and linear body responses. Their contributions to the horizontal drift forces and yaw moment, obtained by pressure integration at the body, and to the yaw drift moment, obtained by integrating the angular momentum flux in the far field, are expressed entirely in terms of the linear first-order solution. The second-order velocities may considerably increase the forward speed part of the mean yaw moment on realistic marine structures, with the most important contribution occurring where the wave spectrum often has its maximal value. The contribution to the horizontal forces obtained by pressure integration is, however, always found to be small. The horizontal drift forces obtained by the linear momentum flux in the far field are independent of the second-order velocities, provided that there is no velocity circulation in the fluid.

Collision preventing device

Abstract: PURPOSE: To provide a collision preventing device capable of accurately judging the degree of risk that a vehicle collides with an obstacle. CONSTITUTION: This collision preventing device is provided with a yaw rate sensor detecting the yaw rate of a vehicle, a speed detecting device detecting the speed, and a radar device detecting the position and speed of a surrounding obstacle. The estimated travel locus (curve (a)) of the vehicle is obtained by the yaw rate sensor and the speed detecting device, the region at a distance on both sides of the estimated travel locus is set to the estimated travel area (curves (b), b'), and likewise the estimated travel locus (curve (d)) of an obstacle (black circle (c)) and the estimated travel area (curves (e), e') are obtained from the position and speed of the obstacle detected by the radar device. The collision point or proximity point of the vehicle and the obstacle is calculated from the estimated travel areas of them, the target and speed reducing acceleration and target deceleration speed are calculated to discriminate the degree of risk of collision. When the degree of risk of collision occurs, the speed of the vehicle is controlled in response to the target speed reducing acceleration and target deceleration speed. COPYRIGHT: (C)1995,JPO

Method for controlling motor vehicle stability

Abstract: A method for controlling vehicle stability comprises the steps of determining the rate of yaw and comparing it to a setpoint rate of yaw. The deviation is used to adjust a counter rate of yaw by means of a controller when the rate of yaw is too large. An optimal profile for a setpoint rate of yaw is determined, even when parameters such as the coefficient of friction of the road surface and the vehicle speed vary.

Some aspects of a realistic three-dimensional pursuit-evasion game

Abstract: A three-dimensio nal pursuit-evasion game between a realistic missile and an aircraft is studied employing point-mass models for both vehicles. Since a direct method to solve this complicated mini-max problem is too time-consuming, the study is conducted by carrying out massive simulations in the parameter space of initial conditions and guidance law parameters. The important role of information in the opponent's acceleration to the game and the effectiveness of the strategy in rotating the line-of-sight vector are shown. It is found that there exist very few cases where the aircraft can avoid the missile, among them typical air-combat maneuvers such as linear acceleration, high-£ barrel roll, split-S, and horizontal-S. Nomenclature flcmax = missile lateral acceleration command limit Ompjdmy = missile acceleration components measured in aircraft pitch and yaw axis, respectively ^p^y^pc^yc = missile-pitch and yaw-axis lateral accelerations and their command signals OpttOyt = aircraft-desir ed pitch and yaw acceleration components, respectively Otp9oty = aircraft acceleration components measured in missile pitch and yaw axis, respectively CD = drag coefficient CDO

Control of vehicle side slip using yaw rate

Abstract: A required yaw rate value is determined based on driver inputs such as steering angle, master cylinder pressure, and throttle butterfly angle. The required yaw rate is compared to a measured actual yaw rate value and the actual yaw moment acceleration is influenced based on the comparison.

Rear wheel steering angle controlling apparatus of four-wheel steering vehicle

Abstract: A control system robust with respect to a vehicle dynamic characteristic variation by a vehicle speed change by estimating an unknown characteristic term in a target yaw rate following system so as to reduce a side slip angle at a transmission time, wherein right and left rear wheels are directly steered using an electric motor controller, and an instruction signal to the motor controller is calculated with a simple calculation using a vehicle speed characteristic estimator with a control amount calculator so that a real yaw rate may follow a target yaw rate calculated by a target yaw rate calculator using respective sensor output values of a vehicle speed sensor, a yaw rate sensor, a steering wheel angle sensor, and a rear wheel steering sensor for each control period.

Optimal Control of Four Wheel Steering Vehicle

Abstract: SUMMARY This paper derives a method of controlling four wheel steering using optimal control theory. The purpose of control is to minimize the sideslip angle at the center of gravity. The control method feeds forward the steering wheel angle and feeds back the yaw velocity and the sideslip angle to the front and rear wheel angles. Theoretical studies show that the sideslip angle is reduced to zero even in the transient state, and that the understeer characteristic and frequency response can be changed regardless of the vehicle static margin. This Paper also examines various characteristics of the influence of the side force nonlinearities of tires and crosswinds.

Driving force distribution control device of automobile

Abstract: PURPOSE: To improve steering stability by further optimizing a control law to realize a target yaw rate. CONSTITUTION: Torque is transmitted from an engine 2 to left and right rear wheels 1RL, 1RR through left and right clutches 14L, 14R. Engaging force of the left and right clutches 14L, 14R is separately and independently controlled (control of a first control means) so as to realize a target yaw rate. A regulation unit 17 to separately and independently regulate braking force against the left and right rear wheels 1RL, 1RR is controlled to realize the target yaw rate (control of a second control means). A control ratio of clutch control and brake control is changed, for example, in accordance with car speed, acceleration in the longitudinal direction working on a car body, lateral acceleration, a rate of change of the car speed, or the magnitude distribution torque from the engine 2 to the rear wheels 1RL, 1RR and its rate of change. COPYRIGHT: (C)1995,JPO

System for controlling movement of a mobile body along a target path

Abstract: A mobile body such as an automobile is controlled to move substantially along a target path by a control system. The control system determines a target point on the target path, a control quantity such as a yaw rate to reach the target point to cause the mobile body to reach the target point from an optional position, the direction in which the mobile body moves at the target point based on the control quantity to reach the target point, the angular difference between the direction and the target path at the target point as a target point angular difference, and a target control quantity such as a target yaw rate for the mobile body by correcting the control quantity to reach the target point based on the target point angular difference. The mobile body is controlled based on the target control quantity.

Magnetic-marker-based lane keeping: a robustness experimental study

Abstract: Experimental results on an automatic lane keeping control study are presented in this paper. A magnetic reference system was used to provide the vehicle lateral tracking error as well as future road curvature information and vehicle speed measurement to the vehicle steering controller. The front wheels of the vehicle are steered according to vehicle lateral displacement, future road curvature, vehicle yaw rate and lateral acceleration, and vehicle speed. The control algorithm used to design the feedback and feedforward controllers is known as the Frequency-Shaped-Linear-Quadratic Preview (FSLQ-preview) optimal control design method. The clossed loop response of the vehicle was examined under a wide variety of test conditions, including low tire pressure, measurement noise, perturbed reference system, hard braking, and snowy road.

Automatic design of fuzzy systems using genetic algorithms and its application to lateral vehicle guidance

Abstract: A method of tuning a fuzzy logic controller (FLC) by a genetic algorithm (GA) is proposed for lane following maneuvers in an automated highway system. The GA simultaneously determines the shape of membership functions, number of rules, and consequent parameters of the FLC. The GA approach operates on binary representations of FLCs and uses an expression for a fitness score to be maximized, which takes into account the tracking error, yaw rate error, lateral acceleration error, rate of lateral acceleration, front wheel steering angle, and rate of front wheel steering angle, to find an optimal controller. Apriori knowledge about both the physical application and FLCs is incorporated into the design method to increase the performance of the design method and the resulting controller. The controllers designed by this method are compared in simulation to a conventional PID controller, a frequency shaped linear quadratic controller, and previously designed FLCs tuned manually.

Steering control device for vehicle

Abstract: PURPOSE:To prevent driving difficulty by providing a control means wherein assist steering control is performed by changing a vehicle model so as to decrease a yaw rate gain while holding phase delay of a yaw rate to almost a fixed value despite darkness when the outside is changed dark in a predetermined value or more, based on an output of a detecting means. CONSTITUTION:In a control means 17, wherein at least one of front or rear wheel steering angle is controlled by assist steering 18 based on a vehicle model of setting a predesired yaw rate characteristic of a vehicle, a yaw rate gain is decreased in accordance with darkness in the case that the outside is changed dark in a predetermined value or more based on an output of a detecting means 20 of detecting darkness of the outside, and in order to control phase delay of a yaw rate to be held almost constant despite the darkness, the vehicle model of setting the desired yaw rate characteristic is changed. In this way, only a steady gain of the yaw rate can be decreased when the outside is dark without worsening the phase delay of the yaw rate, and responsiveness of yaw is properly decreased to increase stability.

Comparison of Feedforward and Feedback Control for 4WS

Abstract: SUMMARY A system incorporating feedforward plus feedback control was configured such that it would follow the target yaw rate found by calculation. Selection of optimum values for the control system constants made it possible to separate control of the steering input response characteristic from control of vehicle stability against external disturbances. The former is controlled by the feedforward control function and the latter by the feedback control function; the values of the two functions can be set independently.

Braking force control device

Abstract: PURPOSE: To stabilize the braking by suppressing the control at the area where the behabior of a vehicle is made unstable (a condition of spinning tendency and the like) by this control, in a braking force control system by means of a braking force difference generated between the left side and the right side. CONSTITUTION: In case of a yaw rate F/B system, a controller determines an object differential pressure ΔP (S) between the left side and the right side by finding a yaw rate difference value Δ (d/dt) ϕ of the difference between an object yaw rate (d/dt) ϕref, and an actual yaw rate (d/dt) ϕ (S 113 and 114). The object value (d/dt) ϕref can be set based on a steering angle δ and a car speed V (S110 to 112). Object wheel cylinder pressures of the left side and the right side wheels are set depending on the object differential pressure ΔP (S), but prior to the setting, the ΔP(S) is corrected according to the actual yaw rate (d/dt) ϕ, for example, and an object W/C pressure is determined by the corrected ΔP(S) (S115 and 116). In this correction, when an excessive yaw such an over steering of the steering in the condition that the yaw rate is large and a side slide is generated, for example, the controller executes a correction to reduce the difference between the left side and the right side. COPYRIGHT: (C)1993,JPO&Japio

Automatic dosing controller of bulldozer

Abstract: PURPOSE:To automatically discriminate start and end positions of excavation and also a course so as to carry out a restricted unmanned operation. CONSTITUTION:A laser beam sensor 40B is set on a bulldozer 1 and laser projectors 48S, 48E rotating around the horizontal axis are installed on the ground corresponding to start and end positions S, E of excavation. When a bulldozer 1 reaches the start position S, the transmission is changed over to the forward position and when it reaches the end position E, the transmission is changed over to the backward position. The traveling direction of the bulldozer 1 is detected by a yaw rate gyroscope. When the deviation from an objective traveling direction is detected, a steering wheel or a blade tilt cylinder is driven to correct the proceeding direction.

Engine efficiency improvement system

Abstract: A multiple-cylinder combustion engine includes a counter rotating system eliminating any vibratory pitch, yaw, and roll torques. The net angular momentum of all rotating parts in the engine is equal to zero. The multiple-cylinder combustion engine activates or deactivates the number of the cylinders without any additional pitch, yaw, and roll torques.

Suspension control device

Abstract: PURPOSE:To prevent giving a feeling of nonconformity regarding the behavior of a vehicle body under roll rigidity control while the vehicle makes a turn CONSTITUTION:A suspension is provided with a variable damping force shock absorber, and a target yaw rate YO is calculated (step S32) according to a detected value V of vehicle velocity and a detected value 63 of steering angle, and when the target yaw rate is not more than a set value YOS, front and rear wheel side damping-force control gains FF and FR are reset to '0', thus performing skyhook control for the variable damping force shock absorber according to pitch speed and relative speed When the target yaw rate exceeds the set value YOS, front and rear wheel side delay time DELTAT1 and DELTAT2 are calculated according to the detected value V of vehicle velocity and the detected value thetaS of steering angle, and a yaw-rate correction YT is calculated according to a yaw-rate feedback control gain (step S39-S40), and front and rear wheel side delay time tF and tR by which high damping forces are applied to front and rear turning outer wheels are calculated (step S42) according to the delay time DELTAT1 and DELTAT2 and the correction YT, and the damping force is witched accordingly

Road surface friction coefficient detection device

Abstract: PURPOSE:To enable detecting road surface beforehand of falling in grip limit of wheels based on the relation of wheel receovery moment and cornering force by using a device detecting road surface based on the cornering characteristics of wheels. CONSTITUTION:There is a fact that the increase slope of recovery moment to cornering force is different for road surface mu fairly prior to the step wheels fall in grip limit. By making use of this fact, the road surface mu is detected. Further in detail, for 4 wheel vehicles with power steering device, the receovery moment SAM around the king pin of front wheels is calculated (S3) based on the left and right pressure PL, PR of the power cylinder and steering torque TH (S2), the cornering force CF of the front wheels is calculated (S4) based on time differentiated value of vehicle body yaw rate and horizontal acceleration CY at the vehicle gravity center, and from the relative relation of the calculated values, the road surface mu is detected.

Automatic steering device for vehicle

Abstract: PURPOSE:To surely recognize the traveling vehicle line even in the obstacle avoiding operation CONSTITUTION:A standard yaw rate calculating means 5 calculaties the standard yaw rate necessary for following the traveling vehicle line on the basis of the road shape information supplied from a road shape recognizing means 1 through the image recognition and the traveling speed detected by an own vehicle speed detecting means When an obstacle exists on the traveling vehicle line, a line passage determining means 9 determines an avoiding passage for avoiding the obstacle, from the signal supplied from an obstacle detecting means and the road shape information A front/rear wheel steering angle calculating means 11 sets the generated yaw rate only as the reference yaw rate necessary for the turning along the traveling vehicle line at present, and each steering angle for the front and rear wheels is calculated so that the obstacle is avoided through the lateral shift for the traveling vehicle line, and the steering angle is outputted to a front/rear wheel steering angle control means 13 Since the change in the yaw direction is not generated, the change of the position of the featured point on the image reduces, and the security in the tracking of the featured point in the image recognizing processing is improved

Control device for vehicle

Abstract: PURPOSE:To detect accurately and speedily that a yaw rate detecting means runs into trouble without causing misjudgment. CONSTITUTION:A control device for a vehicle has a yaw rate sensor 28 to detect a yaw rate of a vehicle and a behavior changing means to change behavior of the vehicle according to the detecting value, and has a traveling condition detecting means such as a steering angle sensor 25 and a wheel speed sensor 26 and a yaw rate estimating means 31 to estimate the yaw rate according to the detecting value, and has a trouble judging means 32 to judge that the yaw rate sensor 28 runs into trouble when a difference between a detecting value of the yaw rate detected by the yaw rate sensor 28 and an estimation value of the yaw rate estimated by the yaw rate estimating means 31 becomes a reference value or more and a reference value setting means 35 to set a reference value according to a detecting value of the traveling condition detecting means.

Collision discriminating device for vehicle

Abstract: PURPOSE:To improve the driving feeling of a vehicle by changing a colliding possibility discriminating criterion in accordance with the awakening state of the driver or running state of the vehicle, such as high-speed running, etc CONSTITUTION:An its-own-vehicle calculating section 43 calculates the vector of its own vehicle from the speed of the vehicle and a yaw rate detected by a yaw rate sensor 36 and outputs the vector to four its-own-vehicle position calculating sections 44-47 which calculate the position of its own vehicle at every set time from braking starting time A switching section 48 outputs the output of the section 44 to a discriminating section 40 when the output of an awakening-degree detector 37 is low or the output of the section 45 to the section 40 when the output of the detector 37 is high A switching section 49 outputs the output of the section 46 to a discriminating section 41 when the output of an awakening-degree detector 37 is low on the output of the section 47 to the section 41 when the output of the detector 37 is high On the other hand, a relative velocity vector calculating section 53 calculates the relative velocity vector against an objective obstacle based on a signal from a distance measuring unit 32, outputs the vector to obstacle position calculating sections 54-57, and outputs the output of either one of the sections 54 and 55 to the section 40 and the output of either one of the sections 56 and 57 to the section 41 in accordance with the output of the detector 37

Automatic driving controller for vehicle

Abstract: PURPOSE:To accurately run a vehicle on a target course even in the case of the difference between the running condition (the wet state on the road surface or the like) for teaching operation and that for automatic running operation. CONSTITUTION:At the time of teaching operation, a vehicle position (x), a vehicle velocity v, a transverse deviation DELTA1, a yaw angle DELTAtheta, a yaw rate omega, and an extent F of steering are stored in maps 141 and 143. The radius of turning is detected by the vehicle velocity V and the yaw rate omega, and correspondence relations between the extent of steering and the radius of turning (correspondence relations between the extent of steering and the curvature of turning) are calculated as an ideal model. At the time of actual automatic running operation, the taught extent F of steering is corrected by a forecasted error DELTAl-L.DELTAtheta (DELTAl is the transverse deviation error and DELTAtheta is the yaw angle error) at the position Lm ahead to obtain an extent delta of steering, and a gain K is so adjusted by an adjuster 144 that an error (e) between a curvature rho0 of turning and an actual curvature rho of turning in the ideal model of this extent delta of steering is dissolved, and it is outputted.

Controller of vehicle

Abstract: PURPOSE: To enhance running stability by avoiding the interference of control between a yaw rate feedback controller and a differential limiting device. CONSTITUTION: A differential limiting means 62 which limits the differential function of an inter-wheel differential gear on the basis of the difference in rotation between right and left wheels, and a driving force control means 61 which sets a desired yaw rate on the basis of a two-wheel model and controls driving forces for right and left driving wheels so that the actual yaw rate detected by a yaw rate sensor coincides with the desired yaw rate, are provided. A control adjustment means 63, which prefers the control of the driving force control means 61 to the operation of the differential limiting means 62 when the deviation between the actual and desired yaw rates is at or greater than a predetermined value, is provided. The control adjustment means 63 prefers the control of the driving force control means 61 to the operation of the differential limiting means 62 by decreasing the control gain G of the differential limiting means 62 and increasing the dead zone width L of control. COPYRIGHT: (C)1995,JPO

Steering reaction force control device of vehicle

Abstract: PURPOSE:To improve steering stability of a vehicle by detecting conditions of road surface precisely with simple constitution, and by controlling steering reaction force exactly in accordance with the results of the detection. CONSTITUTION:A microcomputer 34 assumes the yaw rate of a vehicle based on the wheel speeds of non-driven wheels RW1 and RW2 which are detected by wheel speed sensors 31 and 32, and also detects road surface conditions in accordance with deviation of the assumed yaw rate from a yaw rate detected by a yaw rate sensor 33. The micro-computer 34 controls an amount of electric current in an electromagnetic solenoid 17a in accordance with the detected road surface conditions, so that reaction force by a control valve 17 provided with a reaction force mechanism can be large when the vehicle runs on a bad road, such as uneven road, puddly road, and snowy road.

Control system for ride characteristics of motor vehicle - corrects estimated characteristic index in accordance with control signal dependent on ride, movement and route evaluations.

Abstract: The state of ride is identified by detectors of steering wheel position (33), vehicular acceleration (34) in terms of throttle flap position, and brake pedal pressure (35). The conditions of motion are assessed from yaw rate (31) and road speed (32). A microprocessor (37) operates on these inputs and other from a decimal keyboard (38a) and changeover switch (38b) used for entry of learning data and renewal of combination coeffts. and threshold values in a parameter memory (37e). A driver circuit (39) operates an electric control (21) of the rear wheel steering. USE/ADVANTAGE - In a vehicle equipped with four-wheel steering, a neural net affords precise control of ride.

Vehicle motion controller

Abstract: PURPOSE:To provide a power steering device which correctly detects the variation speed of the lateral slip angle of a vehicle center of gravity point independently of the fact that the relation between the lateral slip angle of a tire and the cornering force is in a linear region or nonlinear region and varies the steering torque according to the variation speed. CONSTITUTION:The lateral accelerating speed Gy, car body speed and the yaw rate gamma are read from a variety of sensors, and the standard speed Dbeta0 is read from a ROM (S1). Then, the lateral slip angle variation speed Dbeta is calculated by subtracting gamma from the value which is obtained by dividing Gy by V (S2), and if the variation speed is not over Dbeta0, it is judged that a vehicle does not reach a turning limit, and the limit judgement flag is turned OFF (S3, S4). If the variation speed is over Dbeta0, it is judged that the vehicle reaches the turning limit, and the limit judgement flag is turned ON (S3, S5). If the limit judgement flag is turned ON, the steering torque is varied so that the heavy steering feeling is obtained.

Travel controller at braking

Abstract: PURPOSE:To control both symmetrical wheels so as to make them brakeable at the shortest distance independently even in a split road surface as well as to prevent any unwilling yaw moment in a vehicle from occurring too CONSTITUTION:A vehicle is provided with a target yaw rate operational means 90 calculating a target yaw rate for doing an optimum behavior in the vehicle, from a steering angle and a car speed, a real yaw rate measuring means measuring a real yaw rate of the vehicle, a yaw rate deviation operational means operating a deviation between the target yaw rate and the real yaw rate, two wheel steering gears 100, 21 regulating the steering angle of a wheel (a front wheel or rear wheel) so as to bring this yaw rate deviation into zero, and two antiskid devices 70, 40 regulating the braking force of each wheel of both symmetrical ones in an independent manner