Method and device for automatic speed adjustment in a vehicle

• US 6,626,257 B2
• Filed: 05/08/2002
• Issued: 09/30/2003
• Est. Priority Date: 08/03/2000
• Status: Expired due to Fees

• Current Assignee: Daimler AG (Mercedes-Benz Group AG)
• Original Assignee: Daimler Chrysler Company LLC (Stellantis NV)
• Inventors: Röhrig-Gericke, Thomas, Schöb, Reinhold, Tröster, Harry, Kurz, Gerhard, Multhaupt, Hans-Dieter
• Primary Examiner(s): LERNER, AVRAHAM H
• Application Number:
  US10/129,556
• Publication Number:
  US 20020179355A1
• Time in Patent Office: 510 Days
• Field of Search: 180/169, 180/170, 180/168, 180/167, 180/178, 180/179, 701/96, 701/119, 701/301
• US Class Current: 180/169
• CPC Class Codes: B60K 28/16 responsive to, or preventing, skidding of wheels brake control systems for vehicle drive stability B60T8/1755; arrangements responsive to a speed condition for adjusting wheel braking force B60T8/32; control of vehicle driving stability otherwise than by controlling the propulsion unit only B60W30/02; preventing wheel slippage by reducing power in rail vehicles B61C15/00
• CPC Class Codes: B60K 31/0008 including means for detecting potential obstacles in vehicle path
• CPC Class Codes: B60T 7/22 initiated by contact of vehicle, e.g. bumper, with an external object, e.g. another vehicle , or by means of contactless obstacle detectors mounted on the vehicle
• CPC Class Codes: B60W 2520/28 Wheel speed
• CPC Class Codes: B60W 2554/00 Input parameters relating to objects
• CPC Class Codes: B60W 2554/802 Longitudinal distance
• CPC Class Codes: B60W 2554/804 Relative longitudinal speed
• CPC Class Codes: B60W 30/146 Speed limiting

Abstract

A method and apparatus for automatically setting the speed in a vehicle, with the distance and relative speed between the vehicle and an obstacle determined and used as the basis for the calculation of a braking torque and drive torque which are to be generated independently of the driver in order to approximate the vehicle actual speed to a calculated setpoint speed. The speed of the vehicle is adapted to the speed of the obstacle, in which respect a maximum permissible limiting speed must not be exceeded.

Claims

1. A method for automatically setting the speed in a vehicle, comprising the steps of:

sensing a first distance and a relative speed between the vehicle and an obstacle;

calculating, as a function of said first distance and said relative speed, one of a braking torque and a drive torque;

generating said one of a braking torque and a drive torque independent of a driver of said vehicle in order to automatically approximate an actual speed of said vehicle with a vehicle setpoint speed;

predetermining a maximum permissible limiting speed;

setting the vehicle setpoint speed to a speed of the obstacle but limited to a maximum value of said predetermined maximum limiting speed whenever said obstacle is moving away from said vehicle.

2. The method according to claim 1, including the step of maintaining the automatic setting of the speed only as long as a distance (Δ

s) between the vehicle and the obstacle is below a proximity limit (s_NG).

3. The method according to claim 2, wherein the automatic setting of the speed is maintained only as long as the distance (Δ

s) between the vehicle (1) and obstacle exceeds a stopping limit (s_SG), the stopping limit (s_SG) being smaller than the proximity limit (s_NG).

4. The method according to one claim 1, wherein the automatic setting of the speed is used exclusively in the low speed range and a crawling speed (v_Kr) is predefined as the limiting speed.

5. The method according to claim 1, wherein, when a stopping limit (s_SG) between the vehicle and obstacle is undershot, the vehicle is automatically braked to a standstill.

6. The method according to claim 1, wherein the idling mode is automatically set when a vehicle with an automatic gearbox is stationary.

7. The method according to claim 1, wherein the automatic setting of the speed is switched off if the vehicle actual speed which exceeds the vehicle setpoint speed is set by the driver.

8. The method according to claim 1, wherein, when the automatic setting of the speed is activated, a minimum braking torque (M_Br) is generated at least in acceleration and braking phases.

9. The method according to claim 8, wherein, when the automatic setting of the speed is switched off, the braking torque (M_Br) is reduced in accordance with a predefined characteristic curve.

10. The method according to claim 8, wherein the braking torque (M_Br) is reduced if the distance (Δ

s) exceeds a distance threshold (s_WG).

11. The method according to claim 8, wherein the engine torque (M_M) is increased above the value of the braking torque (M_Br) if the distance (Δ

s) exceeds a distance threshold (s_WG).

12. The method according to claims 8, wherein, even when the vehicle actual speed (v) is constant, a braking torque (M_Br) is generated which is however smaller than the drive torque (M_M).

13. A system for automatically setting a speed in a vehicle, comprising:

a measuring device for determining a distance and a relative speed between the vehicle and an obstacle;

a control unit for providing actuating signals to actuating elements in the vehicle in order to automatically set an actual speed of the vehicle to be equal to a vehicle setpoint speed wherein said actuation signals are generated as a function of measurement signals output from said measuring device and wherein said actuating signals from said control unit determine that the vehicle setpoint speed is restricted to a speed of the obstacle limited by a maximum value of a permissible limiting speed whenever the obstacle is moving away from the vehicle.