Electronic brake system
Disclosed herein is an electronic brake system. The electronic brake system includes a hydraulic pressure supply apparatus generating a hydraulic pressure by moving a piston forward or backward with a rotational force of a motor, and supplying the generated hydraulic pressure to wheel cylinders provided at wheels, respectively; a wheel speed sensor detecting speed of each of the wheels; a piston position detector detecting a position of the piston; and an ECU configured to calculate a piston displacement amount with respect to a vehicle speed change amount during an ABS operation; calculate an actual stroke of the piston; estimate a position of the piston at an entry time point of a preset low speed section; estimate a moving direction remaining stroke; and determine whether to change the moving direction of the piston in advance before entering the preset low speed section.
1. An electronic brake system, comprising:
a hydraulic pressure supply apparatus configured to generate a hydraulic pressure by moving a piston forward or backward with a rotational force of a motor, and supply the generated hydraulic pressure to wheel cylinders provided at wheels, respectively;
a wheel speed sensor configured to detect speed of each of the wheels;
a piston position detector configured to detect a position of the piston; and
an electronic control unit (ECU) configured to:
calculate a piston displacement amount with respect to a vehicle speed change amount during an anti-lock brake system (ABS) operation;
calculate an actual stroke of the piston by using the calculated piston displacement amount with respect to the vehicle speed change amount;
estimate a position of the piston at an entry time point of a preset low speed section based on the calculated actual stroke;
estimate a moving direction remaining stroke based on the estimated position of the piston and a moving direction of the piston; and
determine whether to change the moving direction of the piston in advance before entering the preset low speed section based on the estimated moving direction remaining stroke.
2. The electronic brake system of claim 1 ,
wherein the ECU compares the estimated moving direction remaining stroke at the entry time point of the preset low speed section with a preset moving direction minimum remaining stroke; and
when the estimated moving direction remaining stroke is greater than the preset moving direction minimum remaining stroke, maintains the moving direction of the piston without changing the moving direction of the piston in advance before entering the preset low speed section.
3. The electronic brake system of claim 1 ,
wherein the ECU compares the estimated moving direction remaining stroke at the entry time point of the preset low speed section with a preset moving direction minimum remaining stroke; and
when the estimated moving direction remaining stroke is smaller than the preset moving direction minimum remaining stroke, changes the moving direction of the piston in advance before entering the preset low speed section.
4. The electronic brake system of claim 3 ,
wherein the ECU estimates a virtual stroke of the piston by performing an inverse operation from a preset target position of the piston at the entry time point of the low speed section based on the calculated piston displacement amount with respect to the vehicle speed change amount and the preset target position of the piston; and
compares the calculated actual stroke with the estimated virtual stroke, and changes the moving direction of the piston in advance at a time point at which the calculated actual stroke and the estimated virtual stroke intersect such that the calculated actual stroke follows the estimated virtual stroke before entering the preset low speed section.
5. The electronic brake system of claim 1 ,
wherein the preset low speed section is an anti-lock brake system (ABS) fade-out section.
6. An electronic brake system, comprising:
a hydraulic pressure supply apparatus configured to generate a hydraulic pressure by moving a piston forward or backward with a rotational force of a motor, and supply the generated hydraulic pressure to wheel cylinders provided at wheels, respectively;
a wheel speed sensor configured to detect speed of each of the wheels;
a piston position detector configured to detect a position of the piston; and
an electronic control unit (ECU) configured to:
calculate a piston displacement amount with respect to a vehicle speed change amount during an anti-lock brake system (ABS) operation;
calculate an actual stroke of the piston by using the calculated piston displacement amount with respect to the vehicle speed change amount;
estimate a virtual stroke of the piston by performing an inverse operation from a preset target position of the piston at the entry time point of a low speed section based on the calculated piston displacement amount with respect to the vehicle speed change amount and the preset target position of the piston;
compare the calculated actual stroke with the estimated virtual stroke, and when the calculated actual stroke behaves differently from the estimated virtual stroke, changes the moving direction of the piston in advance at a time point at which the calculated actual stroke and the estimated virtual stroke intersect such that the calculated actual stroke follows the estimated virtual stroke before entering a preset low speed section.
7. An electronic brake system, comprising:
a hydraulic pressure supply apparatus configured to generate a hydraulic pressure by moving a piston forward or backward with a rotational force of a motor, and supply the generated hydraulic pressure to wheel cylinders provided at wheels, respectively;
a wheel speed sensor configured to detect speed of each of the wheels;
a piston position detector configured to detect a position of the piston; and
an electronic control unit (ECU) configured to:
calculate a piston displacement amount with respect to a vehicle speed change amount during an anti-lock brake system (ABS) operation;
calculate an actual stroke of the piston by using the calculated piston displacement amount with respect to the vehicle speed change amount;
estimate a virtual stroke of the piston by performing an inverse operation from a preset target position of the piston at the entry time point of a low speed section based on the calculated piston displacement amount with respect to the vehicle speed change amount and the preset target position of the piston;
determine whether a preset forward direction remaining stroke is secured at an entry time point of an ABS fade-out section based on the calculated actual stroke, and when the preset forward direction remaining stroke is not secured, change the moving direction of the piston in advance at a time point at which the calculated actual stroke and the estimated virtual stroke intersect such that the calculated actual stroke follows the estimated virtual stroke, and when the preset forward direction remaining stroke is secured, maintain the moving direction of the piston without changing the moving direction of the piston in advance.