System for driving stability control

• US 5,774,821 A
• Filed: 06/07/1995
• Issued: 06/30/1998
• Est. Priority Date: 11/25/1994
• Status: Expired due to Term

• Current Assignee: ITT Automotive Europe GmbH
• Original Assignee: ITT Automotive Europe GmbH
• Inventors: Eckert, Alfred
• Primary Examiner(s): ZANELLI, MICHAEL J
• Application Number:
  US08/475,389
• Time in Patent Office: 1,119 Days
• Field of Search: 364/426.01, 364/426.02, 364/426.03, 364/426.023, 364/426.028, 364/426.016, 303/139, 303/140, 303/146, 303/147, 303/148, 303/150, 303/155, 303/167, 303/186, 303/189, 180/197, 701/78, 701/83, 701/72, 701/70
• US Class Current: 701/78
• CPC Class Codes: B60G 2400/1042 using at least two sensors
• CPC Class Codes: B60T 2210/12 Friction
• CPC Class Codes: B60T 2230/02 Side slip angle, attitude angle, floating angle, drift angle
• CPC Class Codes: B60T 2270/313 with less than three sensors (yaw rate, steering angle, lateral acceleration)
• CPC Class Codes: B60T 8/1755 Brake regulation specially adapted to control the stability of the vehicle, e.g. taking into account yaw rate or transverse acceleration in a curve road vehicle drive control systems for control of driving stability otherwise than by controlling a particular sub-unit B60W30/02
• CPC Class Codes: B60W 10/184 with wheel brakes
• CPC Class Codes: B60W 2422/95 Measuring the same parameter at multiple locations of the vehicle
• CPC Class Codes: B60W 2520/125 Lateral acceleration
• CPC Class Codes: B60W 2520/14 Yaw
• CPC Class Codes: B60W 2520/20 Sideslip angle
• CPC Class Codes: B60W 2720/14 Yaw
• CPC Class Codes: B60W 2720/30 Wheel torque
• CPC Class Codes: B60W 30/02 Control of vehicle driving stability
• CPC Class Codes: B60W 40/064 Degree of grip

Abstract

Apparatus for improving the driving behavior of a vehicle is provided. The vehicle has front and rear axles, each having a plurality of wheels. Each wheel has a brake. Sensor are provided for measuring the rotational speed of each wheel, the vehicle yaw rate and the vehicle lateral acceleration. An anti-lock braking system provides first preset pressure values for controlling each brake, to prevent the wheels from locking during braking. A traction slip control system provides second preset pressure values for controlling each brake, to prevent the wheels from slipping during acceleration. A brake effort proportioning system provides third preset pressure values for distributing braking pressure between the wheels of the front axle and the wheels of the rear axle. A yawing moment controller provides fourth preset pressure values used to control each brake during cornering, to avoid application to the vehicle of an unbalanced moment which would cause the vehicle to understeer or oversteer. The antilock braking system, traction slip control system, brake effort proportioning means and yawing moment control system all operate independently of one another. A prioritizing mechanism applies criteria to determine a desired brake pressure that is applied to each wheel, based on the outputs of the antilock braking, traction slip control, brake effort proportioning, and yawing moment control systems.

Claims

1. Control circuit for controlling the driving stability of a vehicle, in which variables entered for setting the velocity of travel and the steering wheel angle are sent to a vehicle model circuit, said vehicle model circuit determining a desired value for the yaw rate on the basis of a vehicle model, wherein said vehicle model is in the vehicle model circuit and simulates the properties of the vehicle, and in which the yaw rate is compared with a measured value of the yaw rate, in a comparison unit, wherein an additional moment is calculated in a yawing moment controller, and this additional yawing moment is used to set pressure variables, which generate, via the wheel brakes of the vehicle, an additional yawing moment, which brings the yaw rate towards the calculated rate, wherein said vehicle model circuit includes:

a first vehicle model used to calculate the desired value of the controlled variable; and

a second vehicle model that replaces the first vehicle model as a function of the measured velocity of travel.

2. Control circuit in accordance with claim 1, wherein a model of stationary circular travel is used as the first model at low speeds, and a model of dynamic single-track travel is used as the second vehicle model at high speeds.

3. Control circuit in accordance with claim 2, wherein said vehicle model circuit calculates at least some of the values using the previously applicable vehicle model to form a calculated variable for the new vehicle model at the time of the changeover from the previous vehicle model to a new vehicle model.

4. Control circuit in accordance with claim 2, wherein said vehicle model circuit changes the model from the stationary circular travel model to the dynamic single-track travel model at the time of the change from a first velocity to a second velocity, and said vehicle model circuit changes the model from the dynamic single-track model to the static model of circular travel at the time of a change from a third velocity to a fourth velocity, and the second velocity is higher than the first velocity and the third velocity is higher than the fourth velocity, and the first velocity is higher than the third velocity, and the first velocity is higher than the fourth velocity.

5. Control circuit in accordance with claim 4, wherein said vehicle model circuit changes the vehicle model at a velocity between 30 and 50 km/hr., and said vehicle model circuit performs the changeover at lower velocities in the case of smaller vehicles than in the case of large vehicles.

6. Control circuit in accordance with claim 4, wherein said vehicle model circuit uses the values calculated last via the circular travel model to form the initial values of the single-track model at the time of the changeover from the circular travel model to the single-track model.

7. A control system for controlling driving stability of a vehicle which has a velocity, a steering angle, a measured yaw rate, and a plurality of brakes to which respective braking pressures are applied, individually, comprising:

means for receiving first signals representing the velocity, second signals representing the steering angle and third signals representing the measured yaw rate;

vehicle model means responsive to the first and second signals for providing one of a first desired yaw rate and a second desired yaw rate, including;

(1) first modeling means for determining the first desired yaw rate while the velocity is within a first predetermined range of values, and

(2) second modeling means for determining the second desired yaw rate while the velocity is within a second predetermined range of values, said first predetermined range including velocity values lower than said second predetermined range;

means coupled to the receiving means and the vehicle model means for comparing the measured yaw rate to the one of the first and second desired yaw rates provided by the vehicle model means, to calculate a difference therebetween;

yawing moment control means responsive to the difference for determining a moment that is applied to the vehicle, so that the measured yaw rate is adjusted towards the desired yaw rate; and

means responsive to the yawing moment control means for determining pressure adjustments that are applied to each brake, individually, to generate the moment.

8. A control system according to claim 7, wherein:

the first modeling means include means for determining the first desired yaw rate based on a stationary circular travel model of the vehicle, and

the second modeling means include means for determining the second desired yaw rate based on a dynamic single track travel model of the vehicle.

9. A control system according to claim 7, wherein:

the first modeling means generate a plurality of output values, and

the second modeling means determine the second desired yaw rate based on the plurality of output values when the velocity of the vehicle passes from the first predetermined range to the second predetermined range.

10. A control system according to claim 7, wherein the second modeling means generate a set of output values, further comprising:

means for generating a plurality of correction factors based on the set of output values,

wherein the first modeling means determine the first desired yaw rate based on the correction factors when the velocity of the vehicle passes from the second predetermined range to the first predetermined range.

11. A control system according to claim 7, wherein:

the vehicle model means provide the first desired yaw rate when the velocity of the vehicle is less than 30 kilometers per hour (km/hr),

the vehicle model means provide the second desired yaw rate when the velocity of the vehicle is greater than 50 km/hr, and

the vehicle model means switch between providing the first desired rate and the second desired rate while the velocity of the vehicle is between 30 and 50 km/hr.