Anti-skid brake control system with capability of eliminating influence of noise in derivation of wheel acceleration data

An anti-skid brake control system for an automotive vehicle comprising:

• a fluid circuit including a fluid pressure source and a wheel cylinder for generating a braking force for decelerating a wheel;
• a pressure control valve means disposed in said fluid circuit for controlling braking pressure to be generated in said wheel cylinder, said pressure control valve means operating to increase said braking pressure in said wheel cylinder in a first mode position, to decrease said braking pressure in said wheel cylinder in a second mode position, and to hold said braking pressure in said wheel cylinder constant in a third mode position;
• a first sensor means for monitoring a rotation speed of said wheel for producing a wheel speed indicative signal;
• a second sensor means for monitoring a road friction indicative parameter for producing a friction indicative signal;
• first arithmetic means for deriving first wheel acceleration indicative data, said first arithmetic means being provided a first higher sensitivity with respect to variation of said wheel speed indicative signal value;
• second arithmetic means for deriving first wheel acceleration indicative data, said first arithmetic means being provided a second lower sensitivity with respect to variation of said wheel speed indicative signal value;
• third arithmetic means detecting the friction condition on the road surface to select one of said first and second wheel acceleration indicative data for outputting selected wheel acceleration indicative data;
• and
• fourth arithmetic means, receiving said wheel speed indicative data, said selected wheel acceleration indicative data and vehicle body speed representative data for processing the input data for selecting one of a first mode in which said pressure control valve means is operated in said first mode position, a second mode in which said pressure control valve means is operated in said second mode position and a third mode in which said pressure control valve is operated in said third mode position.

An anti-skid brake control system for an automotive vehicle comprising:

• a fluid circuit including a fluid pressure source and a wheel cylinder for generating a braking force for decelerating a wheel;
• at least first, second and third pressure control valve means disposed in said fluid circuit for controlling braking pressures generated in a respectively associated one of first, second and third wheel cylinders, each of said first, second and third pressure control valve means operating to increase said braking pressure in the associated one of said first, second and third wheel cylinders in a first mode, to decrease said braking pressure in said wheel cylinder in a second mode and to hold said braking pressure in said wheel cylinder at a constant value in a third mode;
• first sensor means for monitoring rotation speed of a first vehicular wheel with which said first wheel cylinder is associated to produce a first wheel speed indicative signal;
• second sensor means for monitoring rotation speed of a second vehicular wheel with which said second wheel cylinder is associated to produce a second wheel speed indicative signal;
• third sensor means for monitoring rotation speed of a third vehicular wheel with which said third wheel cylinder is associated to produce a third wheel speed indicative signal;
• fourth sensor means for monitoring a longitudinal acceleration exerted on a vehicle body for producing a longitudinal acceleration indicative signal;
• first arithmetic means for deriving first wheel acceleration indicative data with respect to a respective one of said first, second and third wheels on the basis of a respectively corresponding one of said first, second and third wheel speed indicative signals said first arithmetic means being provided a first higher sensitivity with respect to variation of a wheel speed indicative signal value;
• second arithmetic means for deriving second wheel acceleration indicative data with respect to a respective one of said first, second and third wheels on the basis of a respectively corresponding one of said first, second and third wheel speed indicative signals, said first arithmetic means being provided a second lower sensitivity with respect to variation of said wheel speed indicative signal value;
• third arithmetic means for selecting one of said first, second and third wheel speed indicative signals having the greatest value, integrating said longitudinal acceleration indicative signal values and deriving vehicle body speed representative data on the basis of said selected wheel speed indicative signal value and the integrated value;
• fourth arithmetic means processing said longitudinal acceleration indicative signal for detecting a friction condition on the road surface so as to select one of said first and second wheel acceleration indicative data for outputting selected wheel acceleration indicative data;
• and
• fifth arithmetic means, receiving said wheel speed indicative data, said selected wheel acceleration indicative data and said vehicle body speed representative data for processing the input data for selecting one of a first mode in which said pressure control valve means is operated in a first mode position, a second mode in which said pressure control valve means is operated in a second mode position and a third mode in which said pressure control valve is operated in a third mode position.