Motor vehicle state detecting system

• US 7,412,318 B2
• Filed: 01/07/2005
• Issued: 08/12/2008
• Est. Priority Date: 05/23/2002
• Status: Active Grant

• Current Assignee: Mitsubishi Denki Kabushiki Kaisha (Mitsubishi Electric Corporation)
• Original Assignee: Mitsubishi Denki Kabushiki Kaisha (Mitsubishi Electric Corporation)
• Inventors: Tanaka, Hideyuki, Kurishige, Masahiko, Maeda, Takashi, Matsunaga, Takanori, Matsui, Toshinori, Fujioka, Hiroshi
• Primary Examiner(s): Tran; Khoi H.
• Assistant Examiner(s): Peche; Jorge O
• Application Number:
  US11/030,306
• Publication Number:
  US 20050119815A1
• Time in Patent Office: 1,313 Days
• Field of Search: 701 70- 76, 701/80, 701/36, 701/82, 701/90, 701/91, 701/92, 303/122.02, 303138-140, 303146-147, 303163-169, 303/175, 303/177
• US Class Current: 701/70
• CPC Class Codes: B60T 2230/02 Side slip angle, attitude angle, floating angle, drift angle
• CPC Class Codes: B60T 2260/02 Active Steering, Steer-by-Wire
• CPC Class Codes: B62D 6/005 treating sensor outputs to obtain the actual yaw rate
• CPC Class Codes: B62D 6/04 responsive only to forces disturbing the intended course of the vehicle, e.g. forces acting transversely to the direction of vehicle travel

Abstract

System for detecting stability/instability of behavior of a motor vehicle upon occurrence of tire slip or lock. State of the motor vehicle is determined on the basis of an alignment torque (Ta) applied from a road and a side slip angle (β). By taking advantage of such torque/slip-angle characteristic that although the alignment torque is proportional to a side slip angle when the latter is small, the alignment torque becomes smaller as the side slip angle increases, a normal value is determined from a straight line slope and the side slip angle in a region where the latter is small. Unstable behavior of the motor vehicle is determined when deviation of actual measured value from the normal value increases. Further, unstable state is determined when the slope of the alignment torque for the slip angle departs significantly from that of approximate straight line slope.

Claims

1. A motor vehicle state detecting system for detecting an unstable state of a motor vehicle or alternatively a prognostic sign thereof, comprising:

first detecting means for detecting an actual measured value of a first parameter corresponding to either a side slip angle or alternatively a steering angle of said motor vehicle;

second detecting means for detecting an actual measured value of a second parameter corresponding to either an alignment torque or alternatively a transverse acceleration which said motor vehicle is subjected to;

arithmetic means for arithmetically determining a third parameter relevant to a correlation which said first and second parameters bear to each other;

reference value setting means for setting in advance a comparison reference value for said third parameter;

motor vehicle behavior stability decision means for making decision that behavior of said motor vehicle is unstable when said third parameter departs from said comparison reference value; and

vehicle speed detecting means for detecting a running speed of said motor vehicle as a vehicle speed,

wherein said first detecting means is designed to detect an actual steering angle of said motor vehicle as an actual measured value of said first parameter,

wherein said second detecting means is designed to detect as an actual measured value of said second parameter an actual transverse acceleration applied to said motor vehicle in the course of running of said motor vehicle;

wherein said arithmetic means includes;

acceleration/steering-angle ratio setting means for setting in advance a ratio of said transverse acceleration to said steering angle of said motor vehicle as an acceleration/steering-angle ratio in dependence on said motor vehicle concerned and said vehicle speed;

normal value arithmetic means for arithmetically determining a normal transverse acceleration for said steering angle on the basis of said steering angle and said acceleration/steering-angle ratio, wherein said normal transverse acceleration is determined by multiplying said steering angle by said acceleration/steering-angle ratio; and

acceleration deviation arithmetic means for arithmetically determining an absolute value of a deviation of said actual transverse acceleration from said normal transverse acceleration as an acceleration deviation which serves as said third parameter,

wherein said reference value setting means is designed to set as said comparison reference value a predetermined deviation quantity for said acceleration deviation in dependence on said motor vehicle concerned and said vehicle speed, and

wherein said motor vehicle behavior stability decision means is designed to determine that behavior of said motor vehicle is unstable when said acceleration deviation is greater than or equal to said predetermined deviation quantity inclusive.