Patent Publication Number: US-2022227361-A1

Title: Vehicle control apparatus

Description:
BACKGROUND 
     Field 
     The invention relates to a vehicle control apparatus which is configured to execute a collision avoiding control. 
     Description of the Related Art 
     There is known a vehicle control apparatus which is configured to execute a collision avoiding control of avoiding collision of a vehicle with an obstacle (for example, see JP 2017-043262 A). For example, the collision avoiding control includes a steering control of changing steering angles of steered wheels of the vehicle and a braking force control of applying braking force to wheels of the vehicle. 
     When the vehicle control apparatus determines that the vehicle is going to collide with the obstacle, the vehicle control apparatus executes the steering control and the braking force control. Thereby, the vehicle is decelerated and passes by the obstacle. 
     For example, when the vehicle control apparatus terminates execution of the steering control and the braking force control simultaneously at a point of time when the collision of the vehicle with the obstacle has been avoided, deceleration of the vehicle is stopped at once. Thus, a driver of the vehicle may have a feel of strangeness. 
     For another example, when the driver carries out a driving maneuver, for example, of operating an accelerator pedal while the steering control and the braking force control are being executed, acceleration of the vehicle is restricted due to the braking force control being executed. Thus, the driving maneuver carried out by the driver is not reflected on the vehicle. Thus, the driver may have a feeling of strangeness. 
     SUMMARY 
     An object of the invention is to provide a vehicle control apparatus which changes processes to terminate the execution of the braking force control, depending on situations to prevent the driver from having a feeling of strangeness. 
     A vehicle control apparatus according to the invention comprises at least one sensor and an electronic control unit. The at least one sensor is configured to acquire object information on objects in a surrounding area around an own vehicle. The electronic control unit is configured to execute a collision avoiding control of avoiding collision of the own vehicle with the object when the electronic control unit determines, based on the object information, that a predetermined execution condition that the own vehicle is going to collide with the object, becomes satisfied. The collision avoiding control includes (i) a steering control of changing a steering angle of the own vehicle to move the own vehicle along a target route set to avoid collision of the own vehicle with the object and (ii) a braking force control of applying braking force to the own vehicle so as to realize a target deceleration. 
     The electronic control unit is configured to terminate executing the steering control and decrease the target deceleration at a first rate to terminate execution of the braking force control when a predetermined steering termination condition that the collision of the own vehicle with the object has been avoided by the steering control, becomes satisfied. In addition, the electronic control unit is configured to terminate executing the steering control and decrease the target deceleration at a second rate to terminate the execution of the braking force control when a predetermined cancelation condition that a driver of the own vehicle carries out a driving maneuver, becomes satisfied. Further, the second rate is greater than the first rate. 
     The vehicle control apparatus configured as described above can change the processes to terminate the execution of the braking force control, depending on the situations. In particular, when the predetermined steering termination condition becomes satisfied, the vehicle control apparatus decreases the target deceleration at the first rate to terminate the execution of the braking force control. Thereby, when the predetermined steering termination condition becomes satisfied, the target deceleration does not shortly become zero but gradually decreases. Thus, the driver is unlikely to have a feeling of strangeness. 
     On the other hand, when the predetermined cancelation condition becomes satisfied, the vehicle control apparatus decreases the target deceleration at the second rate to terminate the execution of the braking force control. The second rate is greater than the first rate. Thus, when the driver carries out the driving maneuver, the target deceleration is decreased at the greater rate, compared with when the predetermined steering termination condition becomes satisfied. In this case, the driving maneuver carried out by the driver is reflected on the own vehicle. Thus, the driver is unlikely to have a feeling of strangeness. 
     According to an aspect of the invention, the electronic control unit is configured to decrease the target deceleration at the second rate to terminate the execution of the braking force control when the predetermined cancelation condition becomes satisfied after the predetermined steering termination condition becomes satisfied. 
     With this aspect of the invention, when the driver carries out the driving maneuver after execution of the steering control is terminated, the execution of the braking force control is terminated shortly. In this case, the driving maneuver carried out by the driver is reflected on the vehicle. Thus, the driver is unlikely to have a feeling of strangeness. 
     According to another aspect of the invention, the electronic control unit is configured to determine that the predetermined steering termination condition becomes satisfied when (i) the own vehicle has passed by the object, and (ii) the steering angle continues to be smaller than or equal to a predetermined steering angle value for a predetermined duration time threshold or more. 
     According to further another aspect of the invention, the electronic control unit is configured to determine that the predetermined cancelation condition becomes satisfied when (i) a first condition that an operation amount of an accelerator pedal of the own vehicle is greater than or equal to a predetermined operation amount threshold, becomes satisfied, or (ii) a second condition that steering torque applied to a steering shaft of the own vehicle by maneuvering a steering wheel of the own vehicle by the driver is greater than or equal to a predetermined torque threshold, becomes satisfied. 
     According to one or more embodiments, the electronic control unit may be realized by a micro-processor which is programmed to execute one or more functions described in the specification. Further, according to one or more embodiments, the electronic control unit may be entirely or partially realized by hardware which is configured by one or more integrated circuits such as ASIC dedicated to one or more applications. 
     Elements of the invention are not limited to elements of embodiments and modified examples of the invention described with reference to the drawings. The other objects, features and accompanied advantages of the invention can be easily understood from the embodiments and the modified examples of the invention. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a general configuration view which shows a vehicle control apparatus according to one or more embodiments of the invention. 
         FIG. 2  is a view which describes object information acquired by surrounding sensors. 
         FIG. 3  is a plan view which describes a target route or an avoiding route. 
         FIG. 4  is a view which shows change of a control state. 
         FIG. 5  is a view which shows a situation that an own vehicle moves on a road on which there is an object (n). 
         FIG. 6  is a view which shows change of a moving speed Vs of the own vehicle and a target deceleration TG with time tin an operation example 1. 
         FIG. 7  is a view which shows the change of the moving speed Vs of the own vehicle and the target deceleration TG with time tin an operation example 2. 
         FIG. 8  is a view which shows the change of the moving speed Vs of the own vehicle and the target deceleration TG with time tin an operation example 3. 
         FIG. 9  is a view which shows a flowchart of a first routine executed by a collision avoiding ECU. 
         FIG. 10  is a view which shows a flowchart of a second routine executed by the collision avoiding ECU. 
         FIG. 11  is a view which shows a flowchart of a third routine executed by the collision avoiding ECU. 
     
    
    
     DESCRIPTION OF THE EMBODIMENTS 
     &lt;Configuration of Vehicle Control Apparatus&gt; 
     As shown in  FIG. 1 , a vehicle control apparatus according to one or more embodiments of the invention is applied to an own vehicle VA. The vehicle control apparatus includes a collision avoiding ECU  10 , an engine ECU  20 , a brake ECU  30 , a steering ECU  40 , and a meter ECU  50 . Some or all of the ECUs  10 ,  20 ,  30 ,  40 , and  50  may be integrated into one ECU. 
     Each of the ECUs  10  to  50  is an electronic control unit which includes a micro-computer as a main component. The ECUs  10  to  50  are electrically connected so as to send and receive information to and from each other via a CAN (Controller Area Network) not shown. 
     In this specification, the micro-computer includes a CPU, a ROM, a RAM, a non-volatile memory, and an interface I/F. For example, the collision avoiding ECU  10  includes the micro-computer which includes the CPU  101 , the ROM  102 , the RAM  103 , the non-volatile memory  104 , and the interface (I/F)  105 . The CPU  101  is configured or programmed to realize various functions by executing instructions or programs or routines stored in the ROM  102 . 
     The collision avoiding ECU  10  is electrically connected to sensors described below. The collision avoiding ECU  10  is configured or programmed to receive detection signals or output signals from the sensors. Some or all of the sensors may be electrically connected to any of the ECUs other than the collision avoiding ECU  10 . In this case, the collision avoiding ECU  10  receives the detection signals or the output signals of the sensors via the CAN from the ECUs which are electrically connected to the sensors. 
     An accelerator pedal operation amount sensor  11  detects operation amounts AP of an accelerator pedal  11   a  and outputs signals which represent the accelerator pedal operation amounts AP. A brake pedal operation amount sensor  12  detects operation amounts BP of a brake pedal  12   a  and outputs signals which represent the brake pedal operation amounts BP. 
     A vehicle moving speed sensor  13  detects moving speeds Vs of the own vehicle VA (vehicle moving speeds Vs) and outputs signals which represent the moving speeds Vs. A yaw rate sensor  14  detects yaw rates Yr of the own vehicle VA and outputs signals which represent the yaw rates Yr. 
     A steering torque sensor  15  detects steering torques Tra which are applied to a steering shaft US by steering maneuver applied to a steering wheel SW by a driver of the own vehicle VA and outputs signals which represent the steering torques Tra. The steering torque Tra takes a positive value when the steering wheel SW is rotated in a first direction or a counterclockwise direction. On the other hand, the steering torque Tra takes a negative value when the steering wheel SW is rotated in a second direction or a clockwise direction. 
     A steering angle sensor  16  detects steering angles θ of the own vehicle VA and outputs signals which represent the steering angles θ. The steering angle θ takes a positive value when the steering wheel SW is rotated from a predetermined reference position or a neutral position in the first direction or the counterclockwise direction. On the other hand, the steering angle θ takes a negative value when the steering wheel SW is rotated from the predetermined reference position or the neutral position in the second direction or the clockwise direction. When the steering wheel SW is positioned at the predetermined reference position, the steering angle θ is zero, and the own vehicle VA moves straight. 
     Hereinafter, “information on moving states of the own vehicle VA” output from the sensors  11  to  16  will be also referred to as “moving state information”. 
     Surrounding sensors  17  acquire information on a road around the own vehicle VA. The road around the own vehicle VA includes a moving lane on which the own vehicle VA moves. In addition, the surrounding sensors  17  acquire information on standing objects on the road. The standing objects are, for example, (i) moving objects such as four-wheeled vehicles and bicycles, and (ii) non-moving objects such as guard rails and fences. Hereinafter, the standing objects will be referred to as “objects”. 
     As shown in  FIG. 2 , the surrounding sensors acquire the object information on a two-dimension coordinate system. The two-dimension coordinate system is defined by an x-axis and a y-axis. An origin of the x-axis and the y-axis corresponds to a center position O of a front portion of the own vehicle VA in a width direction of the own vehicle VA. The x-axis extends through the center position O of the own vehicle VA in a longitudinal direction of the own vehicle VA. Values on the x-axis to the forward side of the center position O of the own vehicle VA are positive. The y-axis is perpendicular to the x-axis. Values on the y-axis to the left side of the center position O of the own vehicle VA are positive. 
     The object information includes longitudinal distances Dfx(n) of the objects (n), lateral positions Dfy(n) of the objects (n), orientations θp of the objects (n) with respect to the own vehicle VA, moving directions of the objects (n), relative speeds Vfx(n) of the objects (n), and types of the objects (n). 
     The longitudinal distance Dfx(n) is a distance between the object (n) and the origin O in an x-axis direction. The longitudinal distance Dfx(n) takes a positive or negative value. The lateral distance Dfy(n) is a distance between the object (n) and the origin O in a y-axis direction. The lateral distance Dfy(n) also takes a positive or negative value. The relative speed Vfx(n) is a difference between a moving speed Vn of the object (n) and the moving speed Vs of the own vehicle VA (Vfx(n)=Vn−Vs). The moving speed Vn of the object (n) is a moving speed of the object (n) in the x-axis direction. The type of the object (n) is information which the object (n) is, the moving object or the non-moving object. 
     Again, referring to  FIG. 1 , the surrounding sensors  17  include at least one radar sensor  18  and at least one camera sensor  19 . 
     For example, the radar sensor  18  transmits radio waves of a millimeter wave band (hereinafter, the radio waves of the millimeter wave band will be referred to as “millimeter waves”) at least to a surrounding area around the own vehicle VA. The surrounding area around the own vehicle VA includes a forward area ahead of the own vehicle VA. In addition, the radar sensor  18  receives reflected waves, i.e., the millimeter waves reflected by the objects in a millimeter-wave-transmitting area. Then, the radar sensor  18  detects the objects (n), based on reflected-wave information such as (i) phase differences between the respective transmitted millimeter waves and the respective received reflected waves, (ii) attenuated levels of the reflected waves, and (iii) time taken to receive the respective reflected waves from transmitting the respective millimeter waves. In addition, the radar sensor  18  acquires or calculates the object information on the objects (n), based on the reflected-wave information. 
     The camera sensor  19  takes images of view ahead of the own vehicle VA and acquires image data. The camera sensor  19  recognizes a left lane marking LL and a right lane marking RL, based on the image data. The left lane marking LL and the right lane marking RL define the moving lane. Then, as shown in  FIG. 2 , the camera sensor  19  acquires position information on the left lane marking LL and position information on the right lane marking RL on the two-dimension coordinate system. The information acquired by the camera sensor  19  will be referred to as “lane information”. The camera sensor  19  may be configured to determine whether there are the objects and calculate the object information, based on the image data. 
     The surrounding sensors  17  output information on surrounding situation around the own vehicle VA to the collision avoiding ECU  10  as vehicle surrounding information. The vehicle surrounding information includes the object information and the lane information. 
     As shown in  FIG. 2 , the collision avoiding ECU  10  recognizes (i) a shape of the moving lane Ln 1  defined by the left lane marking LL and the right lane marking RL, (ii) positions of the own vehicle VA and the respective object (n) in the moving lane Ln 1 , and (iii) orientation of the own vehicle VA with respect to the moving lane Ln 1 , using the vehicle surrounding information. 
     Again, referring to  FIG. 1 , the engine ECU  20  is electrically connected to engine actuators  21 . The engine actuators  21  include a throttle valve actuator which changes an opening degree of a throttle valve of a spark-ignition gasoline-fuel-injection type of an internal combustion engine  22 . The engine ECU  20  can change torque which the internal combustion engine  22  generates by driving the engine actuators  21 . The torque generated by the internal combustion engine  22  is transmitted to driven wheels (not shown) of the own vehicle VA via a transmission (not shown). Thus, the engine ECU  20  can change an accelerated state or an acceleration of the own vehicle VA by controlling the engine actuators  21  to control driving force. 
     When the own vehicle VA is a hybrid vehicle, the engine ECU  20  can control the driving force generated by one or both of the internal combustion engine and at least one electric motor as vehicle driving sources. Further, when the own vehicle VA is an electric vehicle, the engine ECU  20  can control the driving force generated by at least one electric motor as the vehicle driving source. 
     The brake ECU  30  is electrically connected to brake actuators  31 . The brake actuators  31  include hydraulic circuits. The hydraulic circuits include (i) a master cylinder, (ii) hydraulic passages through which braking liquid flows, (iii) valves, (iv) at least one pump, and (v) at least one electric motor which drives the at least one pump. The brake ECU  30  adjusts hydraulic pressure applied to wheel cylinders installed in brake mechanisms  32  by controlling the brake actuators  31 . The wheel cylinders generate friction braking force to be applied to wheels of the own vehicle VA by the hydraulic pressure. Thus, the brake ECU  30  can change the accelerated state of the own vehicle VA, i.e., deceleration of the own vehicle VA, i.e., the negative acceleration of the own vehicle VA by controlling the brake actuators  31  to control the braking force. 
     The steering ECU  40  is a control unit of a known electric power steering system. The steering ECU  40  is electrically connected to an assist motor  41 . The assist motor  41  is installed in a steering mechanism of the own vehicle VA. The steering mechanism of the own vehicle VA includes the steering wheel SW, the steering shaft US, and a steering gear mechanism. The assist motor  41  can generate torque to apply steering assist torque and turn left and right steered wheels of the own vehicle VA. 
     The meter ECU  50  is electrically connected to a display  51  and a speaker  52 . The display  51  is a multi-information display provided in front of a driver&#39;s seat of the own vehicle VA. When the speaker  52  receives an announcement command from the collision avoiding ECU  10 , the speaker  52  generates announcement, depending on the received announcement command. 
     &lt;Collision Avoiding Control&gt; 
     Hereinafter, the collision avoiding ECU  10  will be simply referred to as “ECU  10 ”. The ECU  10  is configured or programmed to execute a collision avoiding control. The collision avoiding control is a control for avoiding collision of the own vehicle VA with an obstacle in the forward area ahead of the own vehicle VA. The collision avoiding control is known (for example, see JP 2017-043262 A and JP 2018-103645 A). Below, a flow of processes of the collision avoiding control will be described. 
     The ECU  10  detects the objects (n) in the surrounding area around the own vehicle VA, based on the object information included in the vehicle surrounding information. 
     Further, the ECU  10  calculates a first predicted path, based on the moving state information such as the moving speed Vs, the yaw rate Yr, and the steering angle θ. The first predicted path is a path predicted for the own vehicle VA to move. 
     Further, the ECU  10  determines which each object (n) is, the moving object or the non-moving object, based on the object information. When the object (n) is the moving object, the ECU  10  calculates a second predicted path, based on the object information such as the moving direction of the object (n) in question. The second predicted path is a path predicted for the object (n) in question to move. 
     When the object (n) is the non-moving object, the ECU  10  determines whether the own vehicle VA is going to collide with the object (n) in question, based on the first predicted path and the position of the object (n) in question. When the first predicted path passes through the position of the object (n) in question, the ECU  10  determines that the own vehicle VA is going to collide with the object (n) in question. 
     On the other hand, when the object (n) is the moving object, the ECU  10  determines whether the own vehicle VA is going to collide with the object (n) in question, based on the first predicted path and the second predicted path of the object (n) in question. When the first predicted path and the second predicted path cross each other, the ECU  10  determines that the own vehicle VA is going to collide with the object (n) in question. 
     When the ECU  10  determines that the own vehicle VA is going to collide with the object (n), the ECU  10  determines or sets the object (n) as the obstacle. 
     Next, the ECU  10  determines whether a predetermined execution condition is satisfied. The predetermined execution condition is a condition used to determine whether to execute the collision avoiding control or start executing the collision avoiding control. In particular, the ECU  10  calculates collision predicted time TTC (Time To Collision), based on (i) the longitudinal distance Dfx(n) between the own vehicle VA and the obstacle and (ii) the relative speed Vfx(n) between the own vehicle VA and the obstacle. The collision predicted time TTC is time presumably taken for the own vehicle VA to collide with the obstacle. The collision predicted time TTC can be calculated by dividing the longitudinal distance Dfx(n) by the relative speed Vfx(n). 
     The predetermined execution condition is satisfied when the collision predicted time TTC is shorter than or equal to a predetermined time threshold Tath. When the collision predicted time TTC is shorter than or equal to the predetermined time threshold Tath, it means that the own vehicle VA is going to collide with the obstacle. Thus, the ECU  10  executes the collision avoiding control for the obstacle. 
     In this embodiment, the collision avoiding control at least includes a braking force control and a steering control. The steering control is a control of changing steering angles of the steered wheels of the own vehicle VA to move the own vehicle VA along a target route TP or an avoiding route set to avoid the collision of the own vehicle VA with the obstacle. The braking force control is a control of applying the braking force to the own vehicle VA, in particular, the wheels of the own vehicle VA, to realize a target deceleration TG. Below, the braking force control and the steering control will be described. 
     &lt;Steering Control&gt; 
     As shown in  FIG. 3 , the ECU  10  calculates the target route TP. The target route TP is a route along which the center position O of the own vehicle VA (i.e., the center position of the front portion of the own vehicle VA in the width direction of the own vehicle VA) moves. The target route TP is set such that (i) a distance ds in a road-width direction between the own vehicle VA and the object (n) is maintained longer than or equal to a predetermined distance threshold dth, and (ii) the own vehicle VA is prevented from departing from the moving lane Ln 1 . In addition, the target route TP is set such that the moving direction of the own vehicle VA finally corresponds to a direction dr 1  in which the moving lane Ln 1  extends. Thereby, the moving direction of the own vehicle VA finally becomes parallel to the left lane marking LL and the right lane marking RL. Thus, when the driver of the own vehicle VA does not maneuver the steering wheel SW, the own vehicle VA is prevented from departing from the moving lane Ln 1 . 
     Then, the ECU  10  calculates a target steering torque Atr, based on the target route TP. The target steering torque Atr corresponds to a control amount to move the own vehicle VA along the target route TP. The target steering torque Atr will be also referred to as “steering control amount”. Then, the ECU  10  sends steering command signals to the steering ECU  40 . The steering command signal includes the target steering torque Atr. When the steering ECU  40  receives the steering command signal from the ECU  10 , the steering ECU  40  drives the assist motor  41 , based on the target steering torque Atr. 
     After the ECU  10  starts executing the steering control, the ECU  10  determines whether a predetermined steering termination condition is satisfied. The predetermined steering termination condition becomes satisfied when the collision of the own vehicle VA with the obstacle (the object (n)) has been avoided by the steering control. 
     In particular, the predetermined steering termination condition becomes satisfied when (i) the own vehicle VA has passed by the object (n), and (ii) a magnitude or an absolute value of the steering angle θ of the own vehicle VA continues to be smaller than or equal to a predetermined steering angle value θn (for example, a value near zero) for a predetermined duration time threshold Tdth or more. It means that the own vehicle VA has passed by the object (n), and the moving direction of the own vehicle VA becomes parallel to the left lane marking LL and the right lane marking RL. Thus, the own vehicle VA does not collide with the object (n), and the own vehicle VA does not depart from the moving lane Ln 1 . When the predetermined steering termination condition becomes satisfied, the ECU  10  terminates executing the steering control. In addition, as described later, after the ECU  10  terminates executing the steering control, the ECU  10  terminates executing the braking force control. As such, the ECU  10  terminates executing the steering control and the braking force control at different timings. 
     In addition, after the ECU  10  starts executing the collision avoiding control, the ECU  10  determines whether a predetermined cancelation condition is satisfied. The predetermined cancelation condition is a condition for stopping or cancelling the execution of the collision avoiding control. The predetermined cancelation condition becomes satisfied when the driver of the own vehicle VA carries out a predetermined driving maneuver. 
     In particular, the predetermined cancelation condition becomes satisfied when at least one of conditions A1 and A2 becomes satisfied. 
     Condition A1: The accelerator pedal operation amount AP is greater than or equal to a predetermined operation amount threshold APth. 
     Condition A2: A magnitude or an absolute value of the steering torque Tra is greater than or equal to a predetermined torque threshold Trth. 
     A situation that the predetermined cancelation condition becomes satisfied, is any of a situation (a) and a situation (b) described below. 
     Situation (a): The predetermined cancelation condition becomes satisfied before the predetermined steering termination condition becomes satisfied. It means that the driver carries out the driving maneuver, i.e., an operation of operating the accelerator pedal  11   a  and/or an operation of operating the steering wheel SW for avoiding the collision of the own vehicle VA with the object (n) before the own vehicle VA has passed by the object (n). 
     Situation (b): The predetermined cancelation condition becomes satisfied after the predetermined steering termination condition becomes satisfied. It means that the driver starts the driving maneuver, i.e., the operation of operating the accelerator pedal  11   a  and/or the operation of operating the steering wheel SW after the own vehicle VA has passed by the object (n). 
     In the situation (a), the ECU  10  terminates executing the steering control and then, terminates executing the braking force control. 
     In the situation (b), execution of the steering control has been already terminated. Thus, the ECU  10  terminates executing the braking force control. 
     &lt;Braking Force Control&gt; 
     The ECU  10  sets the target deceleration TG. Then, the ECU  10  sends braking command signals to the brake ECU  30 . The braking command signal includes information on the target deceleration TG. When the brake ECU  30  receives the braking command signal from the ECU  10 , the brake ECU  30  controls the brake actuators to apply the braking force to the wheels of the own vehicle VA so as to control the actual acceleration of the own vehicle VA to the target deceleration TG. 
     In this embodiment, the braking force control includes a first decelerating control, a second decelerating control, and a third decelerating control. The ECU  10  executes any of the first decelerating control, the second decelerating control, and the third decelerating control in accordance with a state transition of a control state shown in  FIG. 4 . 
     As shown in  FIG. 4 , the control state includes a first state  401 , a second state  402 , and a third state  403 . After the ECU  10  starts executing the braking force control, the ECU  10  repeatedly determines which the control state is, the first state  401 , the second state  402 , or the third state  403 . 
     As shown in  FIG. 4 , when the predetermined execution condition becomes satisfied, that is, when the ECU  10  starts executing the braking force control, the ECU  10  determines that the control state is the first state  401 . The first state  401  is a state that the predetermined steering termination condition and the predetermined cancelation condition are not satisfied. When the control state is the first state  401 , the ECU  10  executes the first decelerating control. The first decelerating control is a control of setting the target deceleration TG to a deceleration da 1  and decelerating the own vehicle VA. The deceleration da 1  is a negative acceleration. 
     When the predetermined steering termination condition becomes satisfied while the control state is the first state  401 , the ECU  10  changes the control state from the first state  401  to the second state  402 . In the second state  402 , the collision of the own vehicle VA with the obstacle has been avoided, and the driver has not started the driving maneuver, i.e., the operation of operating the accelerator pedal  11   a  and the operation of operating the steering wheel SW yet. If deceleration of the own vehicle VA is shortly terminated in the second state  402 , the driver may have a feeling of strangeness. Thus, when the control state is the second state  402 , the ECU  10  executes the second decelerating control. The second decelerating control is a control of decelerating the own vehicle VA with decreasing the magnitude or the absolute value of the target deceleration TG at a first rate. In particular, a change amount of the magnitude of the target deceleration TG per unit time dT in the second decelerating control is a first change amount ΔG1 (&gt;0). Thereby, the magnitude of the target deceleration TG is gradually decreased. Thus, the driver is unlikely to have a feeling of strangeness. In addition, the driver can be provided with enough time to start the driving maneuver. 
     When the predetermined cancelation condition becomes satisfied while the control state is the first state  401  or the second state  402 , the ECU  10  changes the control state to the third state  403 . In the third state  403 , the driver is carrying out the driving maneuver, i.e., the operation of operating the accelerator pedal  11   a  and/or the operation of operating the steering wheel SW. Thus, if acceleration of the own vehicle VA is restricted due to the braking force control, the driver may have a feeling of strangeness. Thus, when the control state is the third state  403 , the ECU  10  executes the third decelerating control. The third decelerating control is a control of decelerating the own vehicle VA with decreasing the magnitude or the absolute value of the target deceleration TG at a second rate. The second rate is greater than the first rate. In particular, the change amount of the magnitude of the target deceleration TG per unit time dT in the third decelerating control is a second change amount ΔG2 (&gt;0). The second change amount ΔG2 is greater than the first change amount ΔG1. 
     After the ECU  10  starts executing the braking force control, the ECU  10  determines whether a predetermined braking termination condition is satisfied. The predetermined braking termination condition becomes satisfied when one of conditions B1 and B2 described below becomes satisfied. When the predetermined braking termination condition becomes satisfied, the ECU  10  terminates executing the braking force control. 
     Condition B1: The target deceleration TG is zero. 
     Condition B2: The moving speed Vs of the own vehicle VA is zero. 
     Operation Example 1 
     With reference to  FIG. 5  and  FIG. 6 , an operation example 1 of the vehicle control apparatus will be described. In an example shown in  FIG. 5 , the own vehicle VA moves on the road RD. The road RD is a road which has two lanes in each direction. The road RD includes a first moving lane Ln 1  and a second moving lane Ln 2 . A substantial part of the second moving lane Ln 2  is omitted. The moving lane Ln 1  is defined by the left lane marking LL and the right lane marking RL. The own vehicle VA moves in the moving lane Ln 1 . 
     &lt;Point of Time t 0 &gt; 
     At a point of time t 0 , the center position O of the own vehicle VA is at a position P 0  (see  FIG. 5 ). The ECU  10  detects the object (n) in the forward area ahead of the own vehicle VA, based on the object information. The ECU  10  determines that the own vehicle VA is going to collide with the object (n) and determines or sets the object (n) as the obstacle. 
     &lt;Point of Time t 1 &gt; 
     At a point of time t 1 , the center position O of the own vehicle VA reaches a position P 1  (see  FIG. 5 ). At this point of time, the collision predicted time TTC becomes shorter than or equal to the predetermined time threshold Tath. Thus, the predetermined execution condition becomes satisfied. Thus, the ECU  10  starts executing the collision avoiding control. The ECU  10  calculates the target route TP and starts executing the steering control. In addition, the ECU  10  starts executing the braking force control. In this case, the ECU  10  sets the control state to the first state  401  and executes the first decelerating control. As shown in  FIG. 6 , the ECU  10  sets the target deceleration TG to the deceleration da 1  which is a negative acceleration. Then, the ECU  10  decelerates the own vehicle VA. Thus, after the point of time t 1 , the moving speed Vs of the own vehicle VA is gradually decreased. 
     &lt;Point of Time t 2 &gt; 
     At a point of time t 2 , the center position O of the own vehicle VA reaches a position P 2  (see  FIG. 5 ). At this point of time, the predetermined steering termination condition becomes satisfied. Thus, the ECU  10  terminates executing the steering control. After the ECU  10  terminates executing the steering control, the ECU  10  continues executing the braking force control as described below. In particular, as shown in  FIG. 4 , the ECU  10  changes the control state from the first state  401  to the second state  402 . Thus, the ECU  10  executes the second decelerating control in place of the first decelerating control. That is, the ECU  10  changes the braking force control from the first decelerating control to the second decelerating control. After the point of time t 2 , the ECU  10  calculates the target deceleration TG in accordance with an expression (1) described below each time a time dT elapses. 
         TG=TG+ΔG 1  (1)
 
     Thus, after the point of time t 2 , the magnitude of the target deceleration TG is decreased at the first rate. 
     &lt;Point of Time t 3 &gt; 
     At a point of time t 3 , the center position O of the own vehicle VA reaches a position P 3  (see  FIG. 5 ). As shown in  FIG. 6 , at this point of time, the moving speed Vs is not zero. On the other hand, the target deceleration TG is zero. Thus, the predetermined braking termination condition becomes satisfied. Thus, the ECU  10  terminates executing the braking force control. In this example, the ECU  10  terminates executing the second decelerating control. 
     Thereby, when the predetermined steering termination condition becomes satisfied, the ECU  10  terminates executing the steering control and decreases the magnitude of the target deceleration TG at the first rate to terminate execution of the braking force control. Thus, after the execution of the steering control is terminated, the magnitude of the target deceleration TG does not shortly become zero but is gradually decreased. Thus, the driver is unlikely to have a feeling of strangeness. 
     Operation Example 2 
     With reference to  FIG. 5  and  FIG. 7 , an operation example 2 of the vehicle control apparatus will be described. The operation example 2 corresponds to the situation (a) described above. It should be noted that processes of the operation example 2 executed until the point of time t 1  are the same as the processes of the operation example 1. Thus, description of the processes of the operation example 2 executed until the point of time t 1  will be omitted. Processes of the operation example 2 executed after the point of time t 1  will be described. 
     &lt;Point of Time t 1   a&gt;   
     At a point of time t 1   a , the center position O of the own vehicle VA reaches a position P 1   a  (see  FIG. 5 ). At this point of time, the driver tries to move the own vehicle VA from the first moving lane Ln 1  to the second moving lane Ln 2  for avoiding the collision of the own vehicle VA with the object (n). That is, the driver carries out the driving maneuver for moving the own vehicle VA in a direction shown by an arrow Ar 1 . In particular, the driver presses the accelerator pedal  11   a  with holding the steering wheel SW. Thereby, the accelerator pedal operation amount AP becomes greater than or equal to the predetermined operation amount threshold APth, and the magnitude of the steering torque Tra becomes greater than or equal to the predetermined torque threshold Trth. Thus, the predetermined cancelation condition becomes satisfied. Thus, the ECU  10  terminates executing the steering control. On the other hand, after the ECU  10  terminates executing the steering control, the ECU  10  continues executing the braking force control as described below. In particular, as shown in  FIG. 4 , the ECU  10  changes the control state from the first state  401  to the third state  403 . Thus, the ECU  10  executes the third decelerating control in place of the first decelerating control. That is, the ECU  10  changes the braking force control from the first decelerating control to the third decelerating control. The ECU  10  calculates the target deceleration TG in accordance with an expression (2) described below each time the time dT elapses. 
         TG=TG+ΔG 2  (2)
 
     Thus, as shown in  FIG. 7 , after the point of time t 1   a , the magnitude of the target deceleration TG is decreased at the second rate. 
     &lt;Point of Time t 1   b&gt;   
     At a point of time t 1   b , the center position O of the own vehicle VA reaches a position P 1   b  (see  FIG. 5 ). As shown in  FIG. 7 , at this point of time, the target deceleration TG is zero. Thus, the predetermined braking termination condition becomes satisfied. Thus, the ECU  10  terminates executing the braking force control. In this example, the ECU  10  terminates executing the third decelerating control. Thus, after the point of time t 1   b , the driving maneuver carried out by the driver is reflected on the own vehicle VA, and the own vehicle VA is accelerated. 
     Thereby, when the predetermined cancelation condition becomes satisfied, the ECU  10  terminates executing the steering control and decreases the magnitude of the target deceleration TG at the second rate to terminate the execution of the braking force control. Thus, when the driver carries out the driving maneuver, the magnitude of the target deceleration TG relatively shortly becomes zero. That is, the execution of the braking control is shortly terminated. Thereby, the driving maneuver carried out by the driver is reflected on the own vehicle VA. Thus, the driver is unlikely to have a feeling of strangeness. 
     Operation Example 3 
     With reference to  FIG. 5  and  FIG. 8 , an operation example 3 of the vehicle control apparatus will be described. The operation example 3 corresponds to the situation (b) described above. Processes of the operation example 3 executed until the point of time t 2  are the same as the processes of the operation example 1. Thus, description of the processes of the operation example 3 executed until the point of time t 2  will be omitted. Processes of the operation example 3 executed after the point of time t 2  will be described. 
     &lt;Point of Time t 2   a&gt;   
     At a point of time t 2   a , the center position O of the own vehicle VA reaches a position P 2   a  (see  FIG. 5 ). At this point of time, the driver presses the accelerator pedal  11   a . Thereby, the accelerator pedal operation amount AP becomes greater than or equal to the predetermined operation amount threshold APth. Thus, the predetermined cancelation condition becomes satisfied. Thus, as shown in  FIG. 4 , the ECU  10  changes the control state from the second state  402  to the third state  403 . Thus, the ECU  10  executes the third decelerating control in place of the second decelerating control. That is, the ECU  10  changes the braking force control from the second decelerating control to the third decelerating control. After the point of time t 2   a , the ECU  10  calculates the target deceleration TG in accordance with the expression (2) each time the time dT elapses. 
     Thus, as shown in  FIG. 8 , after the point of time t 2   a , the magnitude of the target deceleration TG is decreased at the second rate. 
     &lt;Point of Time t 2   b&gt;   
     At a point of time t 2   b , the center position O of the own vehicle VA reaches a position P 2   b  (see  FIG. 5 ). As shown in  FIG. 8 , at this point of time, the target deceleration TG is zero. Thus, the predetermined braking termination condition becomes satisfied. Thus, the ECU  10  terminates executing the braking force control. In this example, the ECU  10  terminates executing the third decelerating control. Thus, after the point of time t 2   b , the driving maneuver (i.t., operating the accelerator pedal  11   a ) carried out by the driver is reflected on the own vehicle VA, and the own vehicle VA is accelerated. 
     Thereby, when the predetermined cancelation condition becomes satisfied after the predetermined steering termination condition becomes satisfied, the ECU  10  decreases the magnitude of the target deceleration TG at the second rate to terminate the execution of the braking force control. Thus, when the driver carries out the driving maneuver after the execution of the steering control is terminated, the execution of the braking control is terminated shortly, compared with the operation example 1. Thereby, the driving maneuver carried out by the driver is reflected on the own vehicle VA. Thus, the driver is unlikely to have a feeling of strangeness. 
     &lt;Operations&gt; 
     The CPU  101  (hereinafter, the CPU  101  will be simply referred to as “CPU”) of the ECU  10  is configured or programmed to execute routines shown in  FIG. 9  to  FIG. 11  each time the time dT elapses. 
     In addition, the CPU acquires the moving state information from the sensors  11  to  16  and the vehicle surrounding information from the surrounding sensors  17  and memorizes the acquired information in the RAM  103 . 
     It should be noted that the CPU sets values of various flags (i.e., flags XA 1 , XA 2 , XB 1 , and XB 2  described later) to “0”, respectively in an initializing routine which the CPU executes when an ignition switch not shown is changed from an OFF state to an ON state. 
     At a predetermined timing, the CPU starts a process from a step  900  of the routine shown in  FIG. 9  and proceeds with the process to a step  901  to determine whether there are one or more objects in the surrounding area around the own vehicle VA. When there are no objects in the surrounding area around the own vehicle VA, the CPU determines “No” at the step  901  and proceeds with the process directly to a step  995  to terminate executing the process of this routine once. 
     On the other hand, when the CPU detects at least one object (n), the CPU determines “Yes” at the step  901  and proceeds with the process to a step  902 . At the step  902 , the CPU determines whether the own vehicle VA is going to collide with the detected object (n). When the own vehicle VA is not going to collide with the object (n), the CPU determines “No” at the step  902  and proceeds with the process directly to the step  995  to terminate executing the process of this routine once. 
     On the other hand, when the own vehicle VA is going to collide with the object (n), the CPU determines “Yes” at the step  902  and proceeds with the process to a step  903 . At the step  903 , the CPU determines whether the predetermined execution condition is satisfied. In particular, the CPU determines that the collision predicted time TTC is shorter than or equal to the predetermined time threshold Tath. When the predetermined execution condition is not satisfied, the CPU determines “No” at the step  903  and proceeds with the process directly to the step  995  to terminate executing the process of this routine once. 
     On the other hand, when the predetermined execution condition is satisfied, the CPU determines “Yes” at the step  903  and proceeds with the process to a step  904 . At the step  904 , the CPU sets a value of a flag XA 1  to “1” and a value of a flag XB 1  to “1”. Then, the CPU proceeds with the process to the step  995  to terminate executing the process of this routine once. When the value of the flag XA 1  is “1”, the flag XA 1  represents that the routine shown in  FIG. 10  described later is executed. When the value of the flag XB 1  is “1”, the flag XB 1  represents that the routine shown in  FIG. 11  described later is executed. 
     Further, at a predetermined timing, the CPU executes the routine shown in  FIG. 10 . The CPU starts a process from a step  1000  of the routine shown in  FIG. 10  and proceeds with the process to a step  1001  to determine whether the value of the flag XA 1  is “1”. When the value of the flag XA 1  is not “1”, the CPU determines “No” at the step  1001  and proceeds with the process directly to a step  1095  to terminate executing the process of this routine once. 
     When the value of the flag XA 1  has been set to “1” at the step  904  of the routine shown in  FIG. 9 , the CPU determines “Yes” at the step  1001  and proceeds with the process to a step  1002  to determine whether the value of the flag XA 2  is “0”. When the value of the flag XA 2  is “0”, the flag XA 2  represents that the steering control is not executed. On the other hand, when the value of the flag XA 2  is “1”, the flag XA 2  represents that the steering control is being executed. 
     When the value of the flag XA 2  is “0”, the CPU determines “Yes” at the step  1002  and sequentially executes processes of steps  1003  to  1005  described below. Then, the CPU proceeds with the process to the step  1095  to terminate executing the process of this routine once. 
     Step  1003 : The CPU calculates the target route TP as described above. 
     Step  1004 : The CPU sets the value of the flag XA 2  to “1”. 
     Step  1005 : The CPU executes the steering control, based on the target route TP. The CPU calculates the target steering torque Atr, based on the target route TP and sends the steering command signal including the calculated target steering torque Atr to the steering ECU  40 . The steering ECU  40  drives the assist motor  41 , based on the target steering torque Atr. 
     Thereafter, when the CPU starts the process of the routine shown in  FIG. 10  from the step  1000  and proceeds with the process to the step  1002 , the CPU determines “No” and proceeds with the process to a step  1006 . At the step  1006 , the CPU determines whether the predetermined cancelation condition is satisfied. When the predetermined cancelation condition is not satisfied, the CPU determines “No” at the step  1006  and proceeds with the process to a step  1007  to determine whether the predetermined steering termination condition is satisfied. When the predetermined steering termination condition is not satisfied, the CPU determines “No” at the step  1007  and proceeds with the process to the step  1005  to execute the steering control. As such, when the predetermined cancelation condition and the predetermined steering termination condition are not satisfied, the CPU continues executing the steering control. 
     When the predetermined cancelation condition becomes satisfied while the CPU repeatedly executes the routine shown in  FIG. 10 , the CPU determines “Yes” at the step  1006  and proceeds with the process to a step  1008 . 
     In addition, when the predetermined steering termination condition becomes satisfied while the CPU repeatedly executes the routine shown in  FIG. 10 , the CPU determines “Yes” at the step  1007  and proceeds with the process to the step  1008 . 
     At the step  1008 , the CPU sets the value of the flag XA 1  to “0” and the value of the flag XA 2  to “0”. Thereby, the CPU determines “No” at the step  1001 . Thus, the execution of the steering control is terminated. 
     Further, at a predetermined timing, the CPU executes the routine shown in  FIG. 11 . The CPU starts a process from a step  1100  and proceeds with the process to a step  1101  to determine whether the value of the flag XB 1  is “1”. When the value of the flag XB 1  is not “1”, the CPU determines “No” at the step  1110  and proceeds with the process directly to a step  1195  to terminate executing the process of this routine once. 
     When the value of the flag XB 1  has been set to “1” at the step  904  of the routine shown in  FIG. 9 , the CPU determines “Yes” at the step  1101  and proceeds with the process to a step  1102  to determine whether a value of a flag XB 2  is “0”. When the value of the flag XB 2  is “0”, the flag XB 2  represents that the braking force control is not executed. On the other hand, when the value of the flag XB 2  is “1”, the flag XB 2  represents that the braking force control is being executed. 
     When the value of the flag XB 2  is “0”, the CPU determines “Yes” at the step  1102  and sequentially executes processes of steps  1103  and  1104  described below. Then, the CPU proceeds with the process to a step  1105 . 
     Step  1103 : The CPU sets the control state to the first state  401  since the CPU will start executing the braking force control. 
     Step  1104 : The CPU sets the value of the flag XB 2  to “1”. 
     At the step  1105 , the CPU determines which the current control state is, the first state  401 , the second state  402 , or the third state  403 . 
     When the control state is the first state  401 , the CPU sequentially executes processes of steps  1106  and  1109  described below. That is, the CPU executes the first decelerating control. Then, the CPU proceeds with the process to the step  1195  to terminate executing the process of this routine once. 
     Step  1106 : The CPU sets the target deceleration TG to the deceleration da 1 . 
     Step  1109 : The CPU sends the braking command signal including the target deceleration TG to the brake ECU  30 . The brake ECU  30  controls the brake actuators  31 , based on the target deceleration TG. 
     Thereafter, when the CPU starts the process of the routine shown in  FIG. 11  from the step  1100  and proceeds with the process to the step  1102 , the CPU determines “No” and proceeds with the process to a step  1110 . At the step  1110 , the CPU determines whether the predetermined braking termination condition is satisfied. 
     When the predetermined braking termination condition is not satisfied, the CPU determines “No” at the step  1110  and proceeds with the process to a step  1111 . At the step  1111 , the CPU determines the current control state. In particular, the CPU determines whether the predetermined steering termination condition or the predetermined cancelation condition is satisfied and changes the control state as shown in  FIG. 4 . When the predetermined steering termination condition is satisfied, the CPU changes the control state to the second state  402 . Then, the CPU proceeds with the process to the step  1105 . When the control state is the second state  402 , the CPU sequentially executes a process of a step  1107  and the process of the step  1109  as described below. That is, the CPU executes the second decelerating control. Then, the CPU proceeds with the process to the step  1195  to terminate executing the process of this routine once. 
     Step  1107 : The CPU calculates the target deceleration TG in accordance with the expression (1). 
     Step  1109 : The CPU sends the braking command signal including the target deceleration TG to the brake ECU  30 . The brake ECU  30  controls the brake actuators  31 , based on the target deceleration TG. 
     On the other hand, when the predetermined cancelation condition is satisfied, the CPU changes the control state to the third state  403  at the step  1111 . Then, the CPU proceeds with the process to the step  1105 . When the control state is the third state  403 , the CPU sequentially executes a process of a step  1108  and the process of the step  1109  described below. That is, the CPU executes the third decelerating control. Then, the CPU proceeds with the process to the step  1195  to terminate executing the process of this routine once. 
     Step  1108 : The CPU calculates the target deceleration TG in accordance with the expression (2). 
     Step  1109 : The CPU sends the braking command signal including the target deceleration TG to the brake ECU  30 . The brake ECU  30  controls the brake actuators  31 , based on the target deceleration TG. 
     When the predetermined braking termination condition becomes satisfied while the CPU repeatedly executes the routine shown in  FIG. 11 , the CPU determines “Yes” at the step  1110  and proceeds with the process to a step  1112 . At the step  1112 , the CPU sets the value of the flag XB 1  to “0” and the value of the flag XB 2  to “0”. Thereby, the CPU determines “No” at the step  1101 . Thus, the execution of the braking force control is terminated. 
     The vehicle control apparatus configured as described above, can change the termination processes to terminate the execution of the braking force control, depending on the situations. When the predetermined steering termination condition becomes satisfied, the vehicle control apparatus decreases the target deceleration TG at the first rate to terminate the execution of the braking force control. On the other hand, when the predetermined cancelation condition becomes satisfied, the vehicle control apparatus decreases the target deceleration TG at the second rate to terminate the execution of the braking force control. As described above, the second rate is greater than the first rate. Thereby, when the predetermined steering termination condition becomes satisfied, the magnitude of the target deceleration TG is gradually, not shortly decreased. Thus, the driver is unlikely to have a feeling of strangeness. Further, when the predetermined cancelation condition becomes satisfied, that is, when the driver carries out the driving maneuver, the magnitude of the target deceleration TG becomes zero in shorter time than when the predetermined steering termination condition becomes satisfied. The driving maneuver carried out by the driver is reflected on the own vehicle VA. Thus, the driver is unlikely to have a feeling of strangeness. 
     Furthermore, also when the predetermined cancelation condition becomes satisfied after the predetermined steering termination condition becomes satisfied, the vehicle control apparatus decreases the target deceleration TG at the second rate to terminate the execution of the braking force control. When the driver carries out the driving maneuver after the execution of the steering control is terminated, the execution of the braking force control is shortly terminated. Thus, the driving maneuver carried out by the driver is reflected on the own vehicle VA. Thus, the driver is unlikely to have a feeling of strangeness. 
     It should be noted that the invention is not limited to the aforementioned embodiments, and various modifications can be employed within the scope of the invention. 
     Modified Example 1 
     The predetermined execution condition is not limited to one described above. The predetermined execution condition may be other conditions. For example, the predetermined execution condition may additionally include a condition which relates to a moving distance Lx until the own vehicle VA stops. 
     In particular, the ECU  10  may be configured to calculate the moving distance Lx assuming that the own vehicle VA is decelerated at the deceleration da 1 . The moving distance Lx is also referred to as “braking distance”. The moving distance Lx can be calculated by one of known techniques. For example, the ECU  10  may calculate the moving distance Lx, based on the current moving speed Vs and the deceleration da 1 . 
     The ECU  10  may be configured to determine whether an expression (3) described below is satisfied. As shown in  FIG. 3 , the longitudinal distance Dfx(n) is a longitudinal distance to the obstacle or the object (n). β is a predetermined distance. 
         Lx &gt;( Dfx ( n )−β)  (3)
 
     When the expression (3) is satisfied, it means the own vehicle VA cannot stop a position away from the object (n) by the distance β (see  FIG. 3 ). Thus, probability that the own vehicle VA collides with the object (n), is high. Thus, the ECU  10  may be configured to determine that the predetermined execution condition is satisfied when the condition relating to the moving distance Lx and the condition relating to the collision predicted time TTC are satisfied. 
     Modified Example 2 
     The collision avoiding control may include an alerting control of alerting the driver. In particular, when the predetermined execution condition becomes satisfied, the ECU  10  may send an alerting command signal to the meter ECU  50 . When the meter ECU  50  receives the alerting command signal from the ECU  10 , the meter ECU  50  displays an alerting mark on the display  51  and outputs an alerting sound from the speaker  52 . 
     Modified Example 3 
     The predetermined steering termination condition is not limited to one described above. The predetermined steering termination condition may be other conditions as far as the predetermined steering termination condition is a condition which allows to determine a fact that the own vehicle VA has avoided the collision with the object (n). Also, the predetermined cancelation condition is not limited to one described above. The predetermined cancelation condition may be other conditions as far as the predetermined cancelation condition is a condition which allows to determine the driving maneuver carried out by the driver. 
     Modified Example 4 
     The CPU may be configured to calculate a target steering angle θt which is a target value of the steering angle θ of the own vehicle VA. In this case, the CPU sends the steering command signal including the target steering angle θt to the steering ECU  40 . In this case, the steering ECU  40  drives the assist motor  41 , based on the target steering angle θt.