Apparatus for detecting road surface frictional coefficient

• US 5,229,955 A
• Filed: 03/08/1991
• Issued: 07/20/1993
• Est. Priority Date: 03/09/1990
• Status: Expired due to Fees

• Current Assignee: Toyota Jidosha Kabushiki Kaisha (Toyota Motor Corporation)
• Original Assignee: Toyota Jidosha Kabushiki Kaisha (Toyota Motor Corporation)
• Inventors: Nishiwaki, Masaaki, Kaneko, Hisanori, Harada, Hiroshi
• Primary Examiner(s): Chin, Gary
• Application Number:
  US07/665,957
• Time in Patent Office: 865 Days
• Field of Search: 364/424.05, 364/426.02, 364/426.04, 364/426.01, 364/550, 73/105, 180/197, 180/170, 180/249, 180/142, 280/707, 280/840
• US Class Current: 701/40
• CPC Class Codes: B60G 17/0182 involving parameter estimation, e.g. observer, Kalman filter
• CPC Class Codes: B60G 17/0195 characterised by the regulation being combined with other vehicle control systems conjoint control of vehicle sub-units including control of suspension systems B60W10/22
• CPC Class Codes: B60G 2400/00 Indexing codes relating to detected, measured or calculated conditions or factors
• CPC Class Codes: B60G 2400/10 Acceleration; Deceleration
• CPC Class Codes: B60G 2400/204 Vehicle speed
• CPC Class Codes: B60G 2400/208 of wheel rotation
• CPC Class Codes: B60G 2400/252 vertical
• CPC Class Codes: B60G 2400/41 Steering angle
• CPC Class Codes: B60G 2400/50 Pressure
• CPC Class Codes: B60G 2400/61 Load distribution
• CPC Class Codes: B60G 2400/82 Ground surface
• CPC Class Codes: B60G 2400/822 Road friction coefficient determination affecting wheel traction
• CPC Class Codes: B60G 2400/8422 of air
• CPC Class Codes: B60G 2400/843 Humidity; Rainfall
• CPC Class Codes: B60G 2500/30 Height or ground clearance
• CPC Class Codes: B60G 2600/1879 Fuzzy Logic Control
• CPC Class Codes: B60G 2800/012 Rolling condition
• CPC Class Codes: B60G 2800/014 Pitch; Nose dive
• CPC Class Codes: B60G 2800/21 Traction, slip, skid or slide control
• CPC Class Codes: B60G 2800/24 Steering, cornering
• CPC Class Codes: B60K 31/00 : Vehicle fittings, acting on a single sub-unit only, for automatically controlling vehicle speed, i.e. preventing speed from exceeding an arbitrarily established velocity or maintaining speed at a particular velocity, as selected by the vehicle operator fittings acting on two or more sub-units B60W30/14; speedometers G01P; systems or devices for controlling speed in general G05D13/00 ; in traffic anti-collision system for road vehicles G08G1/16
• CPC Class Codes: B60T 2210/122 : using fuzzy logic, neural computing
• CPC Class Codes: B60T 2260/022 : Rear-wheel steering; Four-wheel steering
• CPC Class Codes: B60T 8/172 : Determining control parameters used in the regulation, e.g. by calculations involving measured or detected parameters B60T8/17551 takes precedence
• CPC Class Codes: B60T 8/174 : characterised by using special control logic, e.g. fuzzy logic , neural computing
• CPC Class Codes: B62D 6/00 : Arrangements for automatically controlling steering depending on driving conditions sensed and responded to, e.g. control circuits means for initiating a change in direction B62D1/00; steering valves B62D5/06; combined with means for inclining the vehicle body or wheels on bends B62D9/00
• CPC Class Codes: B62D 7/159 : characterised by computing methods or stabilisation processes or systems, e.g. responding to yaw rate, lateral wind, load, road condition
• CPC Class Codes: Y10S 706/90 : Fuzzy logic

Abstract

A detecting apparatus for detecting a frictional coefficient of the road surface on which an automotive vehicle travels. In the detection apparatus, a plurality of condition amounts related to at least one of the vehicle in braking operation, turning operation and a weather condition during travel of the vehicle are detected. Fuzzy inference is carried out on the detected conditional amounts to determine the compatibility of road surface frictional coefficients corresponding with the detected condition amounts. The fuzzy inference outputs are used to calculate a road surface frictional coefficient.

Claims

1. A detection apparatus for detecting a frictional coefficient of a road surface on which an automotive vehicle travels, comprising:

detecting means for detecting conditional parameters, the conditional parameters being at least a hydraulic pressure applied to a power cylinder of a power assisted steering apparatus of the vehicle and a lateral acceleration acting on the vehicle;

fuzzy inference means for performing a fuzzy inference on the detected conditional parameters to determine a compatibility value corresponding to each detected conditional parameter, each compatibility value relating to a road surface frictional coefficient;

generating means for generating said road surface frictional coefficient based on the compatibility values.

2. The detection apparatus of claim 1, wherein the generating means includes means for logically summing the compatibility values and means for determining the road surface frictional coefficient based on the logical sum.

3. The detection apparatus of claim 1, wherein the detecting means includes means for detecting longitudinal acceleration of the vehicle as one of said conditional parameters.

4. The detection apparatus of claim 1, wherein the detecting means includes means for detecting torque acting on a steering shaft of the vehicle as one of said conditional parameters and means for detecting an axial force acting on a lateral bar in operative connection with a set of wheels of the vehicle as another one of said conditional parameters.

5. The detection apparatus of claim 4, wherein the detecting means includes ratio means for determining a ratio of the detected torque to a centrifugal force acting on the vehicle as one of said conditional parameters.

6. The detection apparatus of claim 5, wherein the detecting means includes means for detecting a traveling speed of the vehicle;

and the ratio means includes calculating means for calculating the centrifugal force based on said traveling speed of the vehicle and a steering angle of the steering shaft.

7. The detection apparatus of claim 3, wherein the detecting means includes means for detecting a yaw rate of the vehicle as one of said conditional parameters.

8. The detecting apparatus of claim 7, wherein the detecting means includes means for detecting front and rear wheel speeds of the vehicle;

and means for determining a difference between the detected front and rear wheels speeds as one of said conditional parameters.

9. The detection apparatus of claim 3, wherein the detecting means includes means for detecting front and rear wheel speeds of the vehicle;

and means for determining a difference between the detected front and rear wheels speeds as one of said conditional parameters.

10. The detecting apparatus of claim 9, wherein the detecting means includes means for determining a frequency of operation of an anti-skid control system of the vehicle as one of said conditional parameters.

11. The detecting means of claim 10, wherein the detecting means includes means for detecting a frequency of operation of a wiper of the vehicle, means for detecting humidity, and means for detecting ambient temperature as said conditional parameters.