System for computing a road surface frictional coefficient

• US 6,662,097 B2
• Filed: 09/16/2002
• Issued: 12/09/2003
• Est. Priority Date: 10/11/2001
• Status: Expired due to Fees

• Current Assignee: Honda Giken Kogyo Kabushiki Kaisha (Honda Motor Company)
• Original Assignee: Honda Giken Kogyo Kabushiki Kaisha (Honda Motor Company)
• Inventors: Urabe, Hiroyuki, Yano, Osamu, Kin, Keiyu
• Primary Examiner(s): Chin, Gary
• Application Number:
  US10/244,322
• Publication Number:
  US 20030074127A1
• Time in Patent Office: 449 Days
• Field of Search: 701/70, 701/80, 731/04, 731/05, 731/46
• US Class Current: 701/80
• CPC Class Codes: B60T 2210/12 Friction
• CPC Class Codes: B60T 2270/86 Optimizing braking by using ESP vehicle or tire model
• 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

Abstract

In a system for computing a road surface frictional coefficient for controlling a motion of a vehicle, the road surface frictional coefficient is estimated according to the deviation of the estimated vehicle body fore-and-aft/lateral acceleration from the actually detected vehicle body fore-and-aft/lateral acceleration, instead of estimating it directly from the tire slip ratio so that the road surface frictional coefficient is prevented from being estimated substantially higher than it actually is. In particular, by judging a sudden change in the road surface frictional coefficient only when a change in the road surface frictional coefficient, in particular an increase in the frictional coefficient, has persisted for more than a prescribed time period, an error in the estimation of the road surface frictional coefficient can be minimized, and a favorable vehicle motion control based on the estimated road surface frictional coefficient can be ensured under all conditions.

Claims

1. A system for computing a road surface frictional coefficient for controlling a motion of a vehicle, comprising:

a vehicle body fore-and-aft acceleration sensor for detecting a vehicle body fore-and-aft acceleration;

a vehicle body lateral acceleration sensor for detecting a vehicle body lateral acceleration;

a wheel speed sensor for detecting a road wheel speed;

a vehicle body speed estimating unit for computing a vehicle body speed according to the wheel speed;

a tire slip ratio computing unit for computing a tire slip ratio according to the vehicle body speed and wheel speed;

a tire model defining unit for defining a dynamic tire model;

a tire fore-and-aft force computing unit for computing tire fore-and-aft force according to the tire slip ratio and tire model;

an estimated vehicle body fore-and-aft acceleration computing unit for estimating the vehicle body fore-and-aft acceleration according to the tire fore-and-aft force;

a tire lateral force computing unit for computing a tire lateral force according to the tire slip ratio and tire model;

an estimated vehicle body lateral acceleration computing unit for estimating the vehicle body lateral acceleration according to the tire lateral force; and

a road surface frictional coefficient computing unit for computing a road surface frictional coefficient according to at least one of a result of comparison between the detected vehicle body fore-and-aft acceleration and estimated vehicle body fore-and-aft acceleration, and a result of comparison between the detected vehicle body lateral acceleration and estimated vehicle body lateral acceleration.

2. A system for computing a road surface frictional coefficient according to claim 1, further comprising means for determining a sudden change in the road surface frictional coefficient.