Method to control the operation of wheels of a vehicle to prevent slipping or skidding, and brake locking

US4794538A · kind A · utility

Assignee

• Robert Bosch GmbH · DE

Inventors

• Chi-Thuan Cao · Ditzingen, DE
• Helmut Janetzke · Hemmingen, DE
• Alfred Schulz · Oberriexingen, DE
• Harald Michi · Heilbronn, DE

Key dates

• Filing date: Oct 6, 1986
• Grant date: Dec 27, 1988
• Expiry date: Oct 6, 2006

Classification

• Technology area (CPC B): Performing Operations; Transporting
• CPC primary: B60T2210/12
• WIPO field: Transport
• WIPO sector: Mechanical engineering

Abstract

Wheel speed (V.sub.R) and braking pressure (P.sub.B) applied to a wheel are continuously measured and utilized to estimated values from a mathematical system model, to obtain the physical values: coefficient of friction (.mu.), vehicle speed (V.sub.F), slope of a slip curve (d.mu./dS), slip (S), and coefficient of friction of a stationary-rotary brake couple structure. At least one of the physical values so obtained, and preferably the coefficient of friction (.mu.), vehicle speed, and slope of wheel slip curve are used to control braking pressure being applied to the wheel. Braking pressure can be controlled for example for braking in accordance with coefficient of friction and slope of the friction-slip curve, for example to operate the wheel just before the coefficient of friction drops as the wheel begins to slip. Spinning of a wheel can be avoided by controlling the braking pressure to be below slippage value.