CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority from Japanese Patent Application No. 2020-003411 filed on Jan. 14, 2020, the entire contents of which are hereby incorporated by reference.

BACKGROUND

The disclosure relates to a braking control device that controls a braking device, or a brake device, of a vehicle such as an automobile.

Vehicles such as automobiles include brake devices. Brake devices make an ABS (Antilock Braking System) control. The ABS control includes preventing wheels locking. Wheels locking is caused by excessive braking power with respect to friction force generated between tires and a road surface. With wheels locking, vehicle steering does not work, causing lowered operation stability such as occurrence of a side slip.

In the ABS control, a revolution speed of each of the wheels is monitored. In a case of detection of wheels locking or a symptom of wheels locking, braking power of relevant ones of the wheels are periodically increased and decreased, to restore revolutions of the wheels.

For example, Japanese Unexamined Patent Application Publication (JP-A) No. 2013-20293 describes one of existing techniques to reduce side slips on vehicle travel and provide vehicle operation stability. In JP-A No. 2013-20293, during passage over a metal structure on a road surface on accelerated travel or on turning travel, an engine torque control, a throttle valve control, and a brake control are carried out to control an acceleration rate of an own vehicle and to prevent a slip or a spin.

SUMMARY

An aspect of the technology provides a braking control device including a target vehicle speed setting unit, a braking power control unit, and a low friction coefficient region recognition unit. The target vehicle speed setting unit is configured to set a target position ahead of an own vehicle, and set a target vehicle speed at arrival of the own vehicle at the target position. The braking power control unit is configured to make a braking power control of a braking device, to bring a vehicle speed of the own vehicle to the target vehicle speed at the arrival of the own vehicle at the target position. The low friction coefficient region recognition unit is configured to recognize a low friction coefficient region of a road surface between a current position of the own vehicle and the target position. The low friction coefficient region has a friction coefficient locally lower than a friction coefficient of a surrounding region of the road surface. The braking power control unit is configured to estimate a maximum deceleration rate assuming braking to be started after passage through the low friction coefficient region to cause deceleration to the target vehicle speed at the target position. On the condition that the maximum deceleration rate is smaller than a predetermined upper limit on a deceleration rate, the braking power control unit is configured to cause a start of generation of braking power after the passage through the low friction coefficient region.

An aspect of the technology provides a braking control device including a target vehicle speed setting unit, a braking power control unit, and a low friction coefficient region recognition unit. The target vehicle speed setting unit is configured to set a target position ahead of an own vehicle, and set a target vehicle speed at arrival of the own vehicle at the target position. The braking power control unit is configured to make a braking power control of a braking device, to bring a vehicle speed of the own vehicle to the target vehicle speed at the arrival of the own vehicle at the target position. The low friction coefficient region recognition unit is configured to recognize a low friction coefficient region of a road surface. The low friction coefficient region is expected to be passed through by the own vehicle during the braking power control, and has a friction coefficient locally lower than a friction coefficient of a surrounding region of the road surface. On the condition that the low friction coefficient region recognition unit recognizes the low friction coefficient region, the braking power control unit is configured to change a position of a start of generation of braking power, in front of the low friction coefficient region, in a direction more away from the target position than without the low friction coefficient region recognized, and reduce a maximum deceleration rate during deceleration, to a smaller value than without the low friction coefficient region recognized.

An aspect of the technology provides a braking control device including a target vehicle speed setting unit, a braking power control unit, and a low friction coefficient region recognition unit. The target vehicle speed setting unit is configured to set a target position ahead of an own vehicle, and set a target vehicle speed at arrival of the own vehicle at the target position. The braking power control unit is configured to make a braking power control of a braking device, to bring a vehicle speed of the own vehicle to the target vehicle speed at the arrival of the own vehicle at the target position. The low friction coefficient region recognition unit is configured to recognize a low friction coefficient region of a road surface. The low friction coefficient region is expected to be passed through by the own vehicle during the braking power control, and has a friction coefficient locally lower than a friction coefficient of a surrounding region of the road surface. On the condition that the low friction coefficient region recognition unit recognizes the low friction coefficient region, the braking power control unit is configured to reduce a deceleration rate before passage through the low friction coefficient region, and raise the deceleration rate after the passage through the low friction coefficient region.

