Vehicle speed control system

• US 5,315,295 A
• Filed: 01/21/1992
• Issued: 05/24/1994
• Est. Priority Date: 01/18/1991
• Status: Expired due to Term

• Current Assignee: Mazda Motor Corporation
• Original Assignee: Mazda Motor Corporation
• Inventors: Fujii, Yutaka
• Primary Examiner(s): Peng, John K.
• Assistant Examiner(s): TONG, NINA C
• Application Number:
  US07/822,285
• Time in Patent Office: 854 Days
• Field of Search: 340/936, 340/905, 340/995, 340/990, 340/988, 340/435
• US Class Current: 340/936
• CPC Class Codes: B60K 31/0058 responsive to externally generated signalling
• CPC Class Codes: B60K 31/0066 responsive to vehicle path curvature
• CPC Class Codes: B60W 2530/16 Driving resistance
• CPC Class Codes: B60W 2552/20 Road profile, i.e. the change in elevation or curvature of a plurality of continuous road segments
• CPC Class Codes: B60W 2552/30 Road curve radius
• CPC Class Codes: B60W 2552/40 Coefficient of friction
• CPC Class Codes: B60W 2555/20 Ambient conditions, e.g. wind or rain
• CPC Class Codes: B60W 2556/50 of positioning data, e.g. GPS [Global Positioning System] data
• CPC Class Codes: B60W 2710/0605 Throttle position
• CPC Class Codes: F02D 2200/701 Information about vehicle position, e.g. from navigation system or GPS signal
• CPC Class Codes: G01C 21/26 specially adapted for navigation in a road network
• CPC Class Codes: G01C 21/3697 Output of additional, non-guidance related information, e.g. low fuel level G01C21/3679 takes precedence
• CPC Class Codes: G08G 1/096827 where the route is computed onboard
• CPC Class Codes: G08G 1/096872 where instructions are given per voice
• CPC Class Codes: G08G 1/166 for active traffic, e.g. moving vehicles, pedestrians, bikes

Abstract

A vehicle speed control system for a vehicle is used, with a vehicle navigation system, for indicating a location of the vehicle on a road map as the vehicle travels and for providing information related to the road, including curves of the road. The vehicle speed control system receives information related to curves of a road on which the vehicle travels, such as the radius of curvature, when the vehicle navigation system indicates that the vehicle location is before the curve. The system calculates a limit vehicle speed, at which the vehicle can negotiate and pass safely through the curve, based on the vehicle speed and the radius of curvature of the curve. When the vehicle speed is higher than the limit vehicle speed, the vehicle speed control system provides a warning and/or automatically brakes the vehicle, or automatically closes a throttle of the vehicle, so as to lower cause the vehicle speed to fall below the limit vehicle speed.

Claims

1. A vehicle speed control system for a vehicle for use with a vehicle navigation system which indicates a location of the vehicle on a road map displayed on a screen as the vehicle travels and provides road information relating to curves, said vehicle speed control system comprising:

speed detecting means for detecting a speed of the vehicle;

vehicle speed control means for receiving information related to a curve in a road including at least the radius of curvature on which the vehicle is traveling when the vehicle navigation system indicates the vehicle is located at a predetermined location in front of said curve, calculating a limit vehicle speed, at which the vehicle can negotiate and pass safely through the curve, based on said speed of the vehicle detected by the speed detecting means and information related to said curve, comparing said speed of the vehicle with said limit vehicle speed, and responsive thereto causing at least one of a warning and deceleration of the vehicle to occur when said speed of the vehicle is higher than said limit vehicle speed.

2. A vehicle speed control system as recited in claim 1, wherein said vehicle speed control means automatically brakes the vehicle when said speed of the vehicle is higher than said limit vehicle speed.

3. A vehicle speed control system as recited in claim 1, wherein said vehicle speed control means automatically closes a throttle of the vehicle when said speed of the vehicle is higher than said limit vehicle speed.

4. A vehicle speed control system as recited in claim 1, wherein said information related to the curve in the road further includes frictional drag of said curve.

5. A vehicle speed control system as recited in claim 4, wherein said limit vehicle speed (VB) is calculated from the following equation:

##EQU3## wherein g is the gravitational acceleration;

R is the radius of curvature; and

F is the frictional drag of the road.

6. A vehicle speed control system as recited in claim 5, and further comprising road condition detecting means for detecting a wetness and a temperature of the road.

7. A vehicle speed control system as recited in claim 6, wherein said frictional drag of the road is determined based on a frictional drag, a temperature and a wetness of said curve.

8. A vehicle speed control system as recited in claim 1, wherein said vehicle has a vehicle location detector for receiving radio waves from a global positioning satellite so as to detect a present location of the vehicle.

9. A vehicle speed control system as recited in claim 1, wherein said vehicle has a vehicle location detector for detecting terrestrial magnetism of a place at which the vehicle is presently located and responsive thereto determining a present location of the vehicle.

10. A vehicle speed control system as recited in claim 1, wherein said vehicle has information receiving means for receiving road information from a tele-terminal of an automobile traffic information communication system in an area in which the vehicle is presently traveling and responsive thereto determining present location of the vehicle.

11. A vehicle speed control system as recited in claim 1, wherein said vehicle speed control means includes road condition detecting means for detecting road conditions which are taken into account in determining the limit vehicle speed.

12. A vehicle speed control system as recited in claim 11, wherein the road condition detecting means includes a temperature detector and a road wetness detector.