Regenerative braking system using reference deceleration during vehicle coasting drive and method thereof

A regenerative braking system of a vehicle, comprising:

• a preceding vehicle recognition module installed in a vehicle, the preceding vehicle recognition module configured to determine whether a preceding vehicle is present and measure information on a relative distance and a relative velocity to the preceding vehicle;
• a vehicle sensor installed in the vehicle;
• and
• a controller configured to:
• receive information generated from the preceding vehicle recognition module and a sensor signal generated form the vehicle sensor;
• generate a reference deceleration (a_ref) to maintain a distance from the preceding vehicle within a safety distance, wherein the reference deceleration (a_ref) is generated based on a constant acceleration model acceleration value (a_ca);
• generate a driving torque command for outputting regenerative braking torque for following the generated reference deceleration;
• and
• transfer the generated driving torque command to a vehicular driving system;
• wherein the vehicular driving system is configured to receive the driving torque command and to apply regenerative braking torque to a motor of a vehicle according to the driving torque command;
• wherein the controller further comprises,
• a deceleration requirement determining unit configured to:
• determine whether regenerative braking actuation is required according to a sensor signal input from the vehicle sensor;
• and
• when it is determined that the regenerative braking actuation is required, determine whether deceleration of the vehicle is required according to information of the preceding vehicle input from the preceding vehicle recognition module;
• a reference deceleration generating unit configured to:
• when it is determined that the deceleration of the vehicle is required, generate the reference deceleration (a_ref) depending on a driving situation of the vehicle by using the information of the preceding vehicle input from the preceding vehicle recognition module and the sensor signal input from the vehicle sensor;
• and
• a driving torque amount generating unit configured to:
• generate a driving torque command to allow the vehicle to follow the reference deceleration (a_ref) generated by the reference deceleration generating unit;
• and
• transfer the generated driving torque command to the vehicular driving system;
• wherein the reference deceleration generating unit is further configured to:
• generate the reference deceleration (a_ref) depending on a driving situation of the user vehicle according to the information of the relative distance and the relative velocity between the user vehicle and the preceding vehicle, and velocities and acceleration sensor signals of the user vehicle and the preceding vehicle, respectively;
• and
• calculate the constant acceleration model acceleration value (a_ca) by using a constant acceleration (CA) model based on the information of the relative distance and the relative speed, and the sensor signals of the speed and the acceleration;
• and
• calculate a CTG policy model acceleration value (a_ctg) by using a constant time gap (CTG) policy model based on the information of the relative distance and the relative speed, and the sensor signals of the speed and the acceleration.