Apparatus and method for determining a road wheel vibration of automotive vehicle, and apparatus and method for anti-skid control using the same

A method of determining a road-wheel vibration for an automotive vehicle having a plurality of road wheels comprising the operations of:

• (a) detecting a wheel speed of each of said plurality of road wheels;
• (b) calculating a wheel acceleration and a wheel deceleration of each of the road wheels, and in response to such calculation, calculating a maximum value of wheel acceleration;
• (c) calculating a wheel acceleration cycle of each of the road wheels;
• (d) calculating a wheel acceleration amplitude of each of the road wheels;
• (e) detecting the road wheel-vibration based on said calculated wheel acceleration cycle and said calculated wheel acceleration amplitude;
• and
• (f) determining whether the road-wheel vibration is caused by a bad road surface condition, or the road-wheel vibration is caused by a drive-train vibration, based on said calculated maximum value of the wheel acceleration.

A method of executing an anti-skid braking procedure for an automotive vehicle having a plurality of road wheels comprising the operations of:

• (a) detecting a wheel speed of each of said plurality of road wheels;
• (b) calculating a wheel acceleration and a wheel deceleration of each of the road wheels;
• (c) calculating a wheel acceleration cycle of each of the road wheels;
• (d) calculating a vehicle deceleration;
• (e) comparing said calculated wheel acceleration to a first predetermined value, and comparing said calculated wheel acceleration cycle to a second predetermined value, and in response to such comparisons, detecting a road-wheel vibration when said calculated wheel acceleration is larger than the first predetermined value, and when said calculated wheel acceleration cycle is smaller than the second predetermined value;
• (f) comparing said calculated vehicle deceleration to a third predetermined value, and in response to such comparison, determining that the road-wheel vibration is caused by a bad road surface condition when said calculated vehicle deceleration is larger than the third predetermined value, and that the road-wheel vibration is caused by a drive-train vibration when said calculated vehicle deceleration is smaller than the third predetermined value;
• (g) setting a pressure-reduction threshold to determine a timing of executing a pressure-reduction procedure depending on said operations (e) and (f), said operation (g) setting the pressure-reduction threshold at a lower value as compared to a normal road surface condition when the bad road surface condition is determined by said operation (f), and said operation (g) setting the pressure-reduction threshold at a higher value as compared to the normal road surface condition when the drive-train vibration is determined by said operation (f);
• and
• (h) executing a skid control by regulating each wheel-brake cylinder pressure, said operation (h) executing a pressure build-up procedure, the pressure-reduction procedure, and a pressure-hold procedure depending on the pressure-reduction threshold set by said operation (g).

A method of executing an anti-skid braking procedure for an automotive vehicle having a plurality of road wheels comprising the operations of:

• (a) detecting a wheel speed of each of said plurality of road wheels;
• (b) calculating a wheel acceleration and a wheel deceleration of each of the road wheels, and in response to such calculation, calculating a maximum value of the wheel acceleration;
• (c) calculating a wheel acceleration cycle of each of the road wheels;
• (d) calculating a wheel acceleration amplitude of each of the road wheels;
• (e) comparing said calculated wheel acceleration amplitude to a first predetermined value, and comparing said calculated wheel acceleration cycle to a second predetermined value, and in response to such comparisons, detecting a road-wheel vibration when said calculated wheel acceleration amplitude is larger than the first predetermined value, and when said calculated wheel acceleration cycle is smaller than the second predetermined value;
• (f) comparing said calculated maximum value of the wheel acceleration to a third predetermined value, and in response to such comparison, determining that the road-wheel vibration is caused by a bad road surface condition when said calculated maximum value of the wheel acceleration is smaller than the third predetermined value, and that the road-wheel vibration is caused by a drive-train vibration when said calculated maximum value of the wheel acceleration is larger than the third predetermined value;
• (g) setting a pressure-reduction threshold to determine a timing of executing a pressure-reduction procedure depending on said operations (e) and (f), said operation (g) setting the pressure-reduction threshold at a lower value as compared to a normal road surface condition when the bad road surface condition is determined by said operation (f), and said operation (g) setting the pressure-reduction threshold at a higher value as compared to the normal road surface condition when the drive-train vibration is determined by said operation (f);
• and (h) executing a skid control by regulating each wheel-brake cylinder pressure, said operation (h) executing a pressure build-up procedure, the pressure-reduction procedure, and a pressure-hold procedure depending on the pressure-reduction threshold set by said operation (g).

A road-wheel vibration determining system for an automotive vehicle having a plurality of road wheels, comprising:

• a plurality of wheel-speed sensors, each for detecting the wheel speed of each of the road wheels;
• and
• a control unit being configured to be electrically connected to said wheel-speed sensors for processing a wheel-speed data signal detected from each of the wheel-speed sensors, said control unit comprising:
• a wheel acceleration calculating section for calculating a wheel acceleration and a wheel deceleration of each of the road wheels based on the wheel-speed data signal;
• a wheel acceleration cycle calculating section for calculating a wheel acceleration cycle of each of the road wheels;
• a vehicle deceleration calculating section for calculating a vehicle deceleration;
• a vibration detecting section for detecting a road-wheel vibration of the road wheel based on at least the wheel acceleration cycle;
• and
• a vibration determining section for determining whether the road-wheel vibration is caused by a bad road surface condition, or the road-wheel vibration is caused by a drive-train vibration of the automotive vehicle, based on the vehicle deceleration.

A road-wheel vibration determining system for an automotive vehicle having a plurality of road wheels, comprising:

• a plurality of wheel-speed sensors, each for detecting the wheel speed of each of the road wheels;
• and
• a control unit being configured to be electrically connected to said wheel-speed sensors for processing a wheel-speed data signal detected from each of the wheel-speed sensors, said control unit comprising:
• a wheel acceleration calculating section for calculating a wheel acceleration and a wheel deceleration of each of the road wheels based on the wheel-speed data signal;
• a wheel acceleration cycle calculating section for calculating a wheel acceleration cycle of each of the road wheels;
• a wheel acceleration amplitude calculating section for calculating a wheel acceleration amplitude of each of the road wheels;
• a vibration detecting section for detecting a road-wheel vibration of the road wheel based on the wheel acceleration cycle and the wheel acceleration amplitude;
• and
• a vibration determining section for determining whether the road-wheel vibration is caused by a bad road surface condition, or the road-wheel vibration is caused by a drive-train vibration of the automotive vehicle, based on a maximum value of the wheel acceleration calculated by said wheel acceleration calculating section.

An anti-skid braking system for an automotive vehicle having a plurality of road wheels, comprising:

• a plurality of wheel-speed sensors, each for detecting the wheel speed of each of the road wheels;
• a hydraulic brake unit for regulating wheel-brake cylinder pressure of wheel-brake cylinders mounted to each of the road wheels, said hydraulic brake unit being capable of forming a pressure build-up mode, a pressure-reduction mode, and a pressure-hold mode of each of the wheel-brake cylinders;
• and
• a control unit being configured to be electrically connected to said wheel-speed sensors for processing a wheel-speed data signal detected from each of the wheel-speed sensors, said control unit comprising:
• a wheel acceleration calculating section for calculating a wheel acceleration and a wheel deceleration of each of the road wheels based on the wheel-speed data signal;
• a wheel acceleration cycle calculating section for calculating a wheel acceleration cycle of each of the road wheels;
• a vehicle deceleration calculating section for calculating a vehicle deceleration;
• a vibration detecting section for detecting a road-wheel vibration of the road wheel based on the wheel acceleration and the wheel acceleration cycle, said vibration detecting section detecting the road-wheel vibration when the wheel acceleration is larger than a first predetermined value, and when the wheel acceleration cycle is smaller than a second predetermined value;
• a vibration determining section for determining whether the road-wheel vibration is caused by a bad road surface condition, or the road-wheel vibration is caused by a drive-train vibration of the automotive vehicle, said vibration determining section determining that the road-wheel vibration is caused by the bad road surface condition when the vehicle deceleration is larger than a third predetermined value, and that the road-wheel vibration is caused by the drive-train vibration when the vehicle deceleration is smaller than the third predetermined value;
• a pressure-reduction threshold setting section for setting a pressure-reduction threshold to determine a timing of executing a pressure-reduction procedure depending on the road-wheel vibration detected and determined by said vibration detecting section and said vibration determining section, said pressure-reduction threshold setting section setting the pressure-reduction threshold at a lower value as compared to a normal road surface condition when the bad road surface condition is determined by the vibration determining section, said pressure-reduction threshold setting section setting the pressure-reduction threshold at a higher value as compared to the normal road surface condition when the drive-train vibration is determined by said vibration determining section;
• and
• a skid control section for preventing a skid of each of the road wheels by regulating each wheel-brake cylinder pressure, said skid control section executing a pressure build-up procedure, the pressure-reduction procedure, and a pressure-hold procedure depending on the pressure-reduction threshold set by said pressure-reduction threshold setting section.

An anti-skid braking system for an automotive vehicle having a plurality of road wheels, comprising:

• a plurality of wheel-speed sensors, each for detecting the wheel speed of each of the road wheels;
• a hydraulic brake unit for regulating wheel-brake cylinder pressure of wheel-brake cylinders mounted to each of the road wheels, said hydraulic brake unit being capable of forming a pressure build-up mode, a pressure-reduction mode, and a pressure-hold mode of each of the wheel-brake cylinders;
• and
• a control unit being configured to be electrically connected to said wheel-speed sensors for processing a wheel-speed data signal detected from each of the wheel-speed sensors, said control unit comprising:
• a wheel acceleration calculating section for calculating a wheel acceleration and a wheel deceleration of each of the road wheels based on the wheel-speed data signal;
• a wheel acceleration cycle calculating section for calculating a wheel acceleration cycle of each of the road wheels;
• a wheel acceleration amplitude calculating section for calculating a wheel acceleration amplitude of each of the road wheels;
• a vibration detecting section for detecting a road-wheel vibration of the road wheel based on the wheel acceleration cycle and the wheel acceleration amplitude, said vibration detecting section detecting the road-wheel vibration when the wheel acceleration amplitude is larger than a first predetermined value, and when the wheel acceleration cycle is smaller than a second predetermined value;
• a vibration determining section for determining whether the road-wheel vibration is caused by a bad road surface condition, or the road wheel vibration is caused by a drive-train vibration of the automotive vehicle, based on a maximum value of the wheel acceleration calculated by said wheel acceleration calculating section, said vibration determining section determining that the road-wheel vibration is caused by the drive-train vibration when the maximum value of the wheel acceleration is larger than a third predetermined value, and that the road-wheel vibration is caused by the bad road surface condition when the maximum value of the wheel acceleration is smaller than the third predetermined value;
• a pressure-reduction threshold setting section for setting a pressure-reduction threshold to determine a timing of executing a pressure-reduction procedure depending on the road-wheel vibration detected and determined by said vibration detecting section and said vibration determining section, said pressure-reduction threshold setting section setting the pressure-reduction threshold at a lower value as compared to a normal road surface condition when the bad road surface condition is determined by the vibration determining section, said pressure-reduction threshold setting section setting the pressure-reduction threshold at a higher value as compared to the normal road surface condition when the drive-train vibration is determined by said vibration determining section;
• and
• a skid control section for preventing a skid of each of the road wheels by regulating each wheel-brake cylinder pressure, said skid control section executing a pressure build-up procedure, the pressure-reduction procedure, and a pressure-hold procedure depending on the pressure-reduction threshold set by said pressure-reduction threshold setting section.

An anti-skid braking system for an automotive vehicle having a plurality of road wheels, comprising:

• a plurality of wheel-speed sensors, each for detecting the wheel speed of each of the road wheels;
• a hydraulic brake unit for regulating wheel-brake cylinder pressure of wheel-brake cylinders mounted to each of the road wheels, said hydraulic brake unit being capable of forming a pressure build-up mode, a pressure-reduction mode, and a pressure-hold mode of each of the wheel-brake cylinders;
• and
• a control unit being configured to be electrically connected to said wheel-speed sensors for processing a wheel-speed data signal detected from each of the wheel-speed sensors, said control unit comprising:
• a wheel acceleration calculating section for calculating a wheel acceleration and a wheel deceleration of each of the road wheels based on the wheel-speed data signal;
• a wheel acceleration cycle calculating section for calculating a wheel acceleration cycle of each of the road wheels;
• a vehicle deceleration calculating section for calculating a vehicle deceleration;
• a vibration detecting section for detecting a road-wheel vibration of the road wheel based on the wheel acceleration and the wheel acceleration cycle, said vibration detecting section detecting the road-wheel vibration when the wheel acceleration is larger than a first predetermined value, and when the wheel acceleration cycle is smaller than a second predetermined value;
• a vibration determining section for determining whether the road-wheel vibration is caused by a bad road surface condition, or the road-wheel vibration is caused by a drive-train vibration of the automotive vehicle, said vibration determining section determining that the road-wheel vibration is caused by the bad road surface condition when the vehicle deceleration is larger than a third predetermined value, and that the road-wheel vibration is caused by the drive-train vibration when the vehicle deceleration is smaller than the third predetermined value;
• a pressure-reduction threshold setting section for setting a pressure-reduction threshold to determine a timing of executing a pressure-reduction procedure depending on the road-wheel vibration detected and determined by said vibration detecting section and said vibration determining section, said pressure-reduction threshold setting section setting the pressure-reduction threshold at a lower value as compared to a normal road surface condition when the bad road surface condition is determined by the vibration determining section, said pressure-reduction threshold setting section setting the pressure-reduction threshold at a higher value as compared to the normal road surface condition when the drive-train vibration is determined by said vibration determining section;
• and
• a skid control section for preventing a skid of each of the road wheels by regulating each wheel-brake cylinder pressure, said skid control section executing a pressure build-up procedure, the pressure-reduction procedure, and a pressure-hold procedure depending on the pressure-reduction threshold set by said pressure-reduction threshold setting section, said skid control section prohibiting the pressure build-up procedure within a predetermined period at least right after an initial pressure-reduction procedure is executed, when the drive-train vibration is determined by said vibration determining section, and said skid control section comprising:
• a pressure build-up procedure control section for controlling the pressure build-up procedure, said pressure build-up procedure control section executing a gradual pressure build-up procedure after an initial pressure build-up procedure is executed, when said skid control section determines a further pressure build-up procedure is needed;
• a pressure-rising volume changing section for changing a pressure-rising volume depending on the road-wheel vibration detected and determined by said vibration detecting section and said vibration determining section, said pressure-rising volume changing section changing the pressure-rising volume at a higher value as compared to the normal road surface condition when the bad road surface condition is determined by said vibration determining section, said pressure-rising volume changing section changing the pressure-rising volume at a lower value as compared to the normal road surface condition when the drive-train vibration is determined by said vibration determining section, said pressure-rising volume changing section changing the pressure-rising volume at least when said pressure build-up procedure control section executes the initial pressure build-up procedure, said pressure-rising volume changing section changing a pressure-rising period at a shorter value as compared to a normal pressure-rising period executed in the normal road surface condition when said pressure-rising volume changing section changes the pressure-rising volume at the higher value, said pressure-rising volume changing section changing the pressure-rising period at a longer value as compared to the normal pressure-rising period when said pressure-rising volume changing section changes the pressure-rising volume at the lower value;
• and
• a pressure-reduction volume changing section for changing a pressure-reduction volume depending on the road-wheel vibration detected and determined by said vibration detecting section and said vibration determining section, said pressure-reduction volume changing section changing the pressure-reduction volume at a lower value as compared to the normal road surface condition when the bad road surface condition is determined by the vibration determining section.

An anti-skid braking system for an automotive vehicle having a plurality of road wheels, comprising:

• a plurality of wheel-speed sensors, each for detecting the wheel speed of each of the road wheels;
• a hydraulic brake unit for regulating wheel-brake cylinder pressure of wheel-brake cylinders mounted to each of the road wheels, said hydraulic brake unit being capable of forming a pressure build-up mode, a pressure-reduction mode, and a pressure-hold mode of each of the wheel-brake cylinders;
• and
• a control unit being configured to be electrically connected to said wheel-speed sensors for processing a wheel-speed data signal detected from each of the wheel-speed sensors, said control unit comprising:
• a wheel acceleration calculating section for calculating a wheel acceleration and a wheel deceleration of each of the road wheels based on the wheel-speed data signal;
• a wheel acceleration cycle calculating section for calculating a wheel acceleration cycle of each of the road wheels;
• a wheel acceleration amplitude calculating section for calculating a wheel acceleration amplitude of each of the road wheels;
• a vibration detecting section for detecting a road-wheel vibration of the road wheel based on the wheel acceleration cycle and the wheel acceleration amplitude, said vibration detecting section detecting the road-wheel vibration when the wheel acceleration amplitude is larger than a first predetermined value, and when the wheel acceleration cycle is smaller than a second predetermined value;
• a vibration determining section for determining whether the road-wheel vibration is caused by a bad road surface condition, or the road-wheel vibration is caused by a drive-train vibration of the automotive vehicle, based on a maximum value of the wheel acceleration calculated by said wheel acceleration calculating section, said vibration determining section determining that the road-wheel vibration is caused by the drive-train vibration when the maximum value of the wheel acceleration is larger than a third predetermined value, and that the road-wheel vibration is caused by the bad road surface condition when the maximum value of the wheel acceleration is smaller than the third predetermined value;
• a pressure-reduction threshold setting section for setting a pressure-reduction threshold to determine a timing of executing a pressure-reduction procedure depending on the road-wheel vibration detected and determined by said vibration detecting section and said vibration determining section, said pressure-reduction threshold setting section setting the pressure-reduction threshold at a lower value as compared to a normal road surface condition when the bad road surface condition is determined by the vibration determining section, said pressure-reduction threshold setting section setting the pressure-reduction threshold at a higher value as compared to the normal road surface condition when the drive-train vibration is determined by said vibration determining section;
• and
• a skid control section for preventing a skid of each of the road wheels by regulating each wheel-brake cylinder pressure, said skid control section executing a pressure build-up procedure, the pressure-reduction procedure, and a pressure-hold procedure depending on the pressure-reduction threshold set by said pressure-reduction threshold setting section, said skid control section prohibiting the pressure build-up procedure within a predetermined period at least right after an initial pressure-reduction procedure is executed, when the drive-train vibration is determined by said vibration determining section, and said skid control section comprising:
• a pressure build-up procedure control section for controlling the pressure build-up procedure, said pressure build-up procedure control section executes a gradual pressure build-up procedure after an initial pressure build-up procedure is executed, when said skid control section determines a further pressure build-up procedure is needed;
• a pressure-rising volume changing section for changing a pressure-rising volume depending on the road-wheel vibration detected and determined by said vibration detecting section and said vibration determining section, said pressure-rising volume changing section changing the pressure-rising volume at a higher value as compared to the normal road surface condition when the bad road surface condition is determined by said vibration determining section, said pressure-rising volume changing section changing the pressure-rising volume at a lower value as compared to the normal road surface condition when the drive-train vibration is determined by said vibration determining section, said pressure-rising volume changing section changing the pressure-rising volume at least when said pressure build-up procedure control section executes the initial pressure build-up procedure, said pressure-rising volume changing section changing a pressure-rising period at a shorter value as compared to a normal pressure-rising period executed in the normal road surface condition when said pressure-rising volume changing section changes the pressure-rising volume at the higher value, said pressure-rising volume changing section changing the pressure-rising period at a longer value as compared to the normal pressure-rising period when said pressure-rising volume changing section changes the pressure-rising volume at the lower value;
• and
• a pressure-reduction volume changing section for changing a pressure-reduction volume depending on the road-wheel vibration detected and determined by said vibration detecting section and said vibration determining section, said pressure-reduction volume changing section changing the pressure-reduction volume at a lower value as compared to the normal road surface condition when the bad road surface condition is determined by the vibration determining section.