System for detecting frictional state of running road surface

• US 5,758,305 A
• Filed: 10/20/1995
• Issued: 05/26/1998
• Est. Priority Date: 10/25/1994
• Status: Expired due to Fees

• Current Assignee: Toyota Jidosha Kabushiki Kaisha (Toyota Motor Corporation)
• Original Assignee: Toyota Jidosha Kabushiki Kaisha (Toyota Motor Corporation)
• Inventors: Otsubo, Hideaki, Nakawaki, Yasunori
• Primary Examiner(s): Zanelli, Michael
• Application Number:
  US08/546,159
• Time in Patent Office: 949 Days
• Field of Search: 364/424.045, 364/426.01, 364/426.015, 364/426.017, 364/426.025, 180/197, 303/149, 303/150
• US Class Current: 701/71
• 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 order to correctly detect the frictional state of a running road surface, the running road surface is determined as a low-friction road surface, when tire lock is detected by tire lock detection device, and besides a state in which vehicle deceleration obtained by vehicle deceleration detection means is greater than a predetermined value, is shorter than a predetermined time in a period extending from the start of braking until the tire lock.

Claims

1. A system for detecting a frictional state of a running road surface, having means for detecting vehicle deceleration from a rotational speed of a rotating member included in a power transmission path, wherein whether or not the running road surface is a low-friction road surface is detected on the basis of the vehicle deceleration during braking, comprising:

a braking detector;

means for detecting tire lock;

means for detecting-a state in which said vehicle deceleration during braking is greater than a predetermined value, and means for determining whether said detected state lasts for shorter than a predetermined time during a period extending from start of said braking until the detection of the tire lock; and

low-friction road determination means for determining said running road surface as the low-friction road surface when said tire lock is detected and said state is determined to have lasted for shorter than the predetermined time during said period.

2. A system for detecting a frictional state of a running road surface, having means for detecting vehicle deceleration from a rotational speed of a rotating member included in a power transmission path, wherein whether or not the running road surface is a high-friction road surface is detected on the basis of the vehicle deceleration during braking, comprising:

a braking detector;

means for detecting tire lock;

means for detecting a first state in which said vehicle deceleration during the braking is greater than a first predetermined value, and means for determining whether said detected first state lasts for shorter than a first predetermined time during a period extending from start of said braking until the detection of the tire lock;

low-friction road determination means for determining said running road surface as the low-friction road surface when said tire lock is detected said first state is determined to have lasted for shorter than the first predetermined time during said period;

means for detecting a second state in which said vehicle deceleration during the braking is greater than a second predetermined value, and means for determining whether or not said detected second state continues for longer than a second predetermined time; and

high-friction road determination means for determining said running road surface as the high-friction road surface when the second state is determined to have continued for longer than the second predetermined time.

3. A system for detecting a frictional state of a running road surface, having means for detecting vehicle deceleration from a rotational speed of a rotating member included in a power transmission path, wherein whether or not the running road surface is a low-friction road surface is detected on the basis of the vehicle deceleration during braking, comprising:

a braking detector;

means for detecting tire lock;

means for detecting a first state in which said vehicle deceleration during the braking is greater than a first predetermined value, and means for determining whether said detected first state lasts for shorter than a first predetermined time during a period extending from start of said braking until the detection of the tire lock;

low-friction road determination means for determining said running road surface as the low-friction road surface when said tire lock is detected and said first state is determined to have lasted for shorter than the first predetermined time during said period;

means for detecting a second state in which said vehicle deceleration during the braking is greater than a second predetermined value, and means for determining whether or not said detected second state continues for longer than a second predetermined time; and

high-friction road determination means for determining said running road surface as the high-friction road surface when the second state is determined to have continued for longer than the second predetermined time wherein;

in the case where both low-friction road detecting condition and high-friction road detecting condition are not satisfied, the preceding determination of the frictional state of the running road surface is maintained as a newly determined frictional state of the running road surface.