JP2017128167A - Vehicle control device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a vehicle control device that secures a maximum braking time and improve performance of avoiding a collision against an obstacle in front under control over prevention against a collision from an engine-stopped inertial travel time during automatic driving of a vehicle.SOLUTION: When a distance Ds from a self-vehicle to an object in front becomes less than a collision prevention control start distance Dc at a point T2 of time in an inertial travel control period in which a clutch is released and an engine is stopped (with fuel injection stopped), collision prevention control is started and the clutch changes from the released state to the fastened state. An engine rotating speed increases accordingly, and then braking is started at a point T3 of time. When the vehicle stops at a point T5 of time, the vehicle is put back under normal control from the inertial travel control, and the clutch changes from the fastened state to the released state. When a request to restart the engine is made at a point T6 of time, fuel injection is started and the engine is driven.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a vehicle control device that prevents a collision during automatic traveling without a driver's operation.

  When the automobile is stopped, a stopping method using friction in which a disc rotor provided on each wheel is sandwiched between brake pads is generally used. In addition, a technique for supplementing the braking force of the friction brake by using an engine brake for idling the engine while the clutch connecting the engine and the transmission is engaged is widely known.

  Also, in order to prevent automobile collision accidents, a function that detects obstacles in front of the vehicle with a camera or sensor and automatically performs a braking operation regardless of the driver's brake pedal operation to prevent contact accidents with the obstacles. Has been invented.

  Patent Document 1 describes a clutch engagement method during operation of a vehicle collision prevention apparatus. According to this clutch engagement method, when the collision prevention device operates, the clutch is opened to prevent further vehicle acceleration due to the driver's acceleration request or the acceleration request of an automatic speed control device such as a cruise control system. Thus, a method has been proposed in which the driving force is not transmitted to the driving wheels.

  Also, a method has been devised in which, in a scene where the braking force of the brake is insufficient after the clutch release control described above, the clutch is engaged and the braking force can be increased by the engine brake in a fuel cut state. And in order to prevent an engine stall when an engine speed falls, the device which can perform fuel injection recovery and can maintain idling is made.

  On the other hand, as a means for realizing exhaust gas reduction and fuel saving, an automobile having an idle stop function for stopping an engine in a scene that does not require engine output has been invented.

  Furthermore, for the purpose of higher exhaust gas reduction and fuel economy than those of the conventional technologies, the sailing technology to reduce the fuel injection amount by putting the engine in the idle state while driving, and the engine and the mission are disconnected during driving to stop the fuel. A coasting technique for reducing consumption has been invented.

  For example, in Patent Document 2, the engine and the transmission are separated by releasing the clutch during traveling, the fuel supply to the engine is stopped, the first inertia traveling by stopping the engine, and the fuel supply to the engine are performed. There has been proposed a control method for automatically switching the second inertial traveling in which the gear of the transmission is neutral with the clutch engaged, by the driver's brake pedal operation.

JP 2005-163936 A JP 2014-83999 A

  In the technique described in Patent Document 1, when an approach to the vehicle ahead is detected and there is a danger of a collision, no further acceleration is performed in response to an acceleration request from the driver or the automatic speed control device. Release the clutch to make it. When a braking operation is performed after the clutch release control, the clutch is engaged and braking using the engine brake is started.

  However, when inertial running is being performed by stopping the engine while the driver is not operating, it is desirable to give the highest priority to vehicle braking, and there has been a request for acceleration from the driver or the automatic speed control device. However, it is considered that engine braking operation by quick clutch engagement is desirable regardless of the requirement.

  Further, in a vehicle having an idle stop or coasting function, the engine is intentionally stopped when the vehicle is stopped. Therefore, it is necessary to maintain the idling engine speed unless the safety of the vehicle control is impaired. In the unlikely event of a collision, it is safer if the engine is stopped.

  Further, in the technique described in Patent Document 2, the coasting switching is performed by the driver's pedal operation, but when the driver performs the brake pedal operation after releasing the accelerator pedal. The first inertial traveling is canceled, but after the second inertial traveling, normal traveling control (neutral inertial traveling) is performed in the neutral state.

  However, when the collision prevention device works, it is advantageous in terms of time to quickly fasten the transmission and the engine in which the gear meshes with the forward gear other than neutral without going through neutral inertia traveling, Collision avoidance performance can be improved.

  In view of the above background art, the object of the present invention is to ensure the maximum brake braking time and improve the collision avoidance performance with the front obstacle in the collision prevention control from the engine stop inertia traveling in the automatic driving of the vehicle. It is to realize a vehicle control device that makes it possible.

  In order to achieve the above object, the present invention is configured as follows.

In the vehicle control device, a vehicle power source, a clutch mechanism for fastening or releasing the power source and the driving wheel of the vehicle, and an obstacle ahead of the vehicle are detected and a distance to the obstacle is measured. A distance measuring device, a wheel brake attached to each wheel of the vehicle, a vehicle speed sensor for measuring the traveling speed of the vehicle, and a distance between the vehicle and the obstacle ahead measured by the distance measuring device. A collision prevention control unit that determines that there is a possibility of collision between the vehicle and the obstacle ahead, and performs collision prevention control that automatically performs the operation of the wheel brake on behalf of the driver of the vehicle When,
An inertial traveling control unit that performs inertial traveling in which the vehicle travels with the power source and the driving wheel of the vehicle being released by the clutch mechanism, and the power source is stopped, and the inertial traveling When the collision prevention control unit determines that there is a possibility of collision between the vehicle and the front obstacle while the vehicle is performing the inertia running, the control unit is configured to perform the collision prevention control unit. Before the wheel brake is operated, the clutch mechanism starts the fastening operation of the power source and the driving wheel of the vehicle.

  According to the present invention, there is provided a vehicle control device capable of ensuring the maximum brake braking time and improving the collision avoidance performance with a front obstacle in the collision prevention control from the engine stop inertia running in the automatic driving of the vehicle. Can be realized.

1 is a schematic configuration diagram of an automobile to which the present invention is applied. It is a flowchart of the control in the automatic brake from the inertia running by the Example of this invention. It is the timing chart which showed the vehicle state in the operational control of one execution example of this invention.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

<Device configuration>
FIG. 1 is a schematic configuration diagram of an automobile to which the present invention is applied.

  In FIG. 1, an automobile a100 includes a vehicle control unit a101 that receives a driver's input and an input from each sensor, determines a driving force and a gear ratio, opens and closes a clutch that connects a power source and a transmission, and determines brake braking. Prepare. An accelerator pedal a102, a brake pedal a103, a shift lever a104, and a cruise control switch a105 that detect a driver's operation are connected to the vehicle control unit a101.

  The vehicle control unit a101 performs control to drive or stop the engine a106 (vehicle power source) by the operation of these drivers. The clutch mechanism a107 transmits or interrupts the driving force of the engine a106 to the automatic transmission a108.

  Further, the vehicle control unit a101 instructs the automatic transmission a108 to specify an appropriate gear position based on the driver's request, and rotates the propeller shaft a109. The rotation of the propeller shaft a109 is transmitted to the differential gear a110, the drive shaft a111 is rotated, and this rotation is transmitted to each wheel.

  Each wheel is provided with a wheel brake a112 to brake the vehicle in conjunction with the driver's braking operation.

  In addition, the automobile a100 is equipped with a camera sensor a113 (distance measuring device) that measures the distance to the obstacle ahead and a vehicle speed sensor a114 that measures the vehicle speed (traveling speed) of the vehicle based on the rotation speed of the wheels. To do. The camera sensor a113 always transmits distance information to the front obstacle to the vehicle control unit a101, and the vehicle control unit a101 stores the distance to the front obstacle at regular intervals, and the stored past distance information and the vehicle speed sensor. Based on the vehicle speed information transmitted from a114, the approach to the obstacle and the possibility of collision are determined.

  The vehicle control unit a101 includes an ECU (Engine Control Unit) a1011 that mainly performs engine control, an ATCU (Automatic Transmission Control Unit) a1012 that mainly performs shift control and clutch control of an automatic transmission, and a BCU that mainly performs brake control. (Brake Control Unit) a1013 and ADAS (Advanced Driver Assistance System) a1014 (automatic driving control unit) that performs automatic driving control mainly by recognition of the outside world, and each control unit performs communication and performs cooperative control .

  The BCUa 1013 (brake control unit) and the ECU a1011 (engine control unit) determine that the vehicle a100 may collide with an obstacle ahead, and operate the wheel brake a112 on behalf of the driver of the vehicle a100. A collision prevention control unit that automatically performs collision prevention control is configured.

  Further, the ATCUa 1012 (clutch control unit) and the ECU a 1011 release the engine (power source) a106 and the driving wheels of the vehicle a100 by the clutch mechanism a107, and the vehicle a100 is in a state where the engine (power source) a106 is stopped. An inertia traveling control unit that performs inertia traveling is configured.

The ECU a 1011 is also a fuel injection control unit that performs combustion injection control.
<Inertia running>
Next, inertial running will be described.

  The vehicle control unit a101 can perform traveling control by automatic driving that does not require the driver's operation of the accelerator pedal a102 or the brake pedal a103, and performs inertial traveling by stopping the engine and releasing the clutch under a predetermined condition. The start of the traveling control by the automatic driving is performed by an input from the driver such as the cruise control switch a105. However, the driving control is not limited to the cruise control switch a105, and another switch input or activation means such as a remote control operation may be used. .

  During inertial running by this automatic driving, the vehicle control unit a101 performs release control of the clutch mechanism a107, and the engine a106 is stopped (the fuel injection amount is set to 0). Immediately before the clutch release control is started, the automatic transmission a108 is in a state other than the neutral meshed with one of the forward gears in order to maintain the vehicle in an acceleration or constant speed running state. The gear position may be held during control, or may be replaced with another forward gear.

  FIG. 2 is a flowchart of control in automatic braking from inertia running according to an embodiment of the present invention.

The operation shown in this flowchart is periodically executed by one unit or a plurality of units in the vehicle control unit a101 of FIG.
<Collision prevention 1: Start of collision prevention control>
Next, the start of collision prevention control in one embodiment of the present invention will be described.

  While the host vehicle is carrying out the inertia running, the collision prevention control start distance Dc is calculated in step S201 in FIG. The collision prevention control start distance Dc is simply calculated based on the vehicle speed. For example, the braking distance of a vehicle traveling at 100 km / h is 80 m to 90 m for a general vehicle, and when the current vehicle speed of the vehicle is 100 km, the collision prevention control start distance Dc exceeds at least 90 m. Collisions can be avoided by setting a certain distance.

  Of course, the braking distance depends on the weather, the condition of the tire, the road surface gradient, and the like, and these may be added to the setting of the collision prevention control start distance Dc. Moreover, in order to set it as the termination conditions of collision prevention control, it is good also as a value made different at the time of collision prevention control start, and during collision prevention control.

  Next, in step S202 in FIG. 2, the distance Ds to the front obstacle acquired by the camera sensor a113 in FIG. 1 is compared with the collision prevention control start distance Dc calculated in step S201, and Ds <Dc. Transitions to step S203.

  In step S203, it is determined whether or not the collision prevention control is already being executed. If it is being executed, the process proceeds to step S205. If the collision prevention control is not executed in step S203, the process proceeds to step S204 to start the control, and the process proceeds to step S205.

In step S205, the scheduled collision time Tc with the front obstacle is calculated during the execution of the collision prevention control. The scheduled collision time Tc is a value obtained by simply dividing the distance Ds to the front obstacle by the vehicle speed. For example, at the current time To, when heading to a stationary obstacle 100 meters ahead at 100 km / h, the expected collision time Tc is 3.6 seconds later.
<Collision prevention 2: clutch operation>
Next, a collision preventing clutch operation in one embodiment of the present invention will be described.

  In step S206 of FIG. 2, the clutch engagement or clutch release during the collision prevention control is determined based on the collision avoidance possibility.

  That is, when the predicted collision time Tc with the front obstacle is equal to or shorter than the clutch operation time Td, the process proceeds to step S209 to step S210, and clutch release control is performed. Here, the clutch operation time Td varies depending on the type and specification of the clutch, and is a variable or constant that can be freely set.

  This clutch release control assumes an emergency vehicle collision. By separating the engine and the automatic transmission by releasing the clutch, the drive system components are chain damaged by the impact at the time of the collision. Can be prevented.

When the estimated collision time Tc is equal to or longer than the clutch operation time Td, the process proceeds to step S207 to step S208, and clutch engagement control is executed.
<Collision Prevention 3: Engine Brake>
Next, an engine brake for preventing a collision in one embodiment of the present invention will be described.

  In the collision preventing apparatus according to one embodiment of the present invention, the vehicle control unit a101 in FIG. 1 performs the engagement control of the clutch mechanism a107 before performing the control for operating the pressure of the wheel brake a112 as shown in Patent Document 1. The engine a106 that is stopped and the automatic transmission a108 that is rotating by the wheels are engaged.

  Then, the frictional force that rotates the stopped engine a106 acts in a direction opposite to the direction in which the normal engine driving force is transmitted to the automatic transmission, and becomes a braking force that decelerates the wheels. The gear position at the time of the clutch engaging operation at this time is a gear position other than neutral, and is determined during coasting.

  For example, when the forward gear is set to the same gear as that at the start of inertial travel control or a higher gear than that at the start of inertial travel control, the rotational speed at which the engine a106 after the clutch mechanism a107 is engaged and the automatic transmission a108 is synchronized is The engine braking effect is reduced, but the sudden shock of the vehicle when the clutch is engaged is alleviated and the time until the rotation of the output shaft of the engine a106 and the input shaft of the automatic transmission a108 is synchronized is reduced. It can be shortened, and the transition to engine braking can be performed quickly.

Contrary to the above example, when the gear for starting the clutch engagement is selected to be a lower speed gear than the gear position at the start of inertial running control, the engine a106 is automatically operated at a higher rotational speed than the above example. Since the transmission a108 is synchronized, the effect of engine braking can be greatly obtained from the beginning although there is a ride comfort before and after clutch engagement and a delay in time until clutch engagement is completed.
<Collision prevention 4: Fuel cut>
Next, a fuel cut for preventing collision in one embodiment of the present invention will be described.

  The vehicle control device a101 maintains the fuel injection stop state of the engine a106 before and after the clutch engagement control described above. By maintaining this fuel injection stop, if a collision with a front obstacle cannot be avoided, it is possible to prevent the engine a106 from colliding in a combustion state and developing to a secondary disaster such as a fire.

Further, by maintaining the fuel injection stop, the driving force of the engine a106 is maintained at “0”, and the effect of the engine brake can be utilized to the maximum.
<Collision prevention 5: Wheel brake braking>
Next, collision prevention wheel brake braking in one embodiment of the present invention will be described.

  In the flowchart of FIG. 2, after step S207 to step S208 are executed, the brake control of steps S211 and S212 is executed.

  In one embodiment of the present invention, in the collision prevention control during inertial running, clutch engagement control is executed at least before the start of brake braking by wheel brake control, and the vehicle control unit a101 issues an engagement command for the clutch mechanism a107. After that, the braking force of the wheel brake a112 is determined. The braking force of the wheel brake a112 is calculated by the vehicle control unit a101 at predetermined intervals from the distance from the front obstacle obtained by the camera sensor a113 and the current vehicle speed obtained by the vehicle speed sensor a114.

  At this time, the braking force of the wheel brake a112 is controlled so that the slip of the wheel is detected by the vehicle speed sensor a114 and the slip ratio of the wheel does not exceed a predetermined value by the antilock brake system.

  The inertial traveling control unit is configured so that when the vehicle a100 is coasting and the rotational speed of the clutch mechanism a107 on the power source a106 side is lower than the rotational speed on the driving wheel side of the clutch mechanism a107, the collision prevention control unit a112 is operated.

In the present invention, it is not necessary to consider the engine stall even under the condition that the anti-lock brake system is operated. Therefore, it is possible to maintain the engaged state of the clutch mechanism a107 and continuously use the braking force by the engine brake. is there.
<Collision prevention 6: End of collision prevention control>
Next, the end of the collision prevention control in the embodiment of the present invention will be described.

  If the distance Ds to the front obstacle is greater than or equal to the collision prevention control start distance Dc in step S202 of FIG. 2, the vehicle control unit a101 transitions to step S213 to step S214 and performs the collision prevention control. Then, the collision prevention control is terminated.

  After completion of the collision prevention control, in steps S215 to S216, if the clutch release control is not being executed, the clutch release control is executed.

By performing the clutch release control, when the vehicle is safely stopped by the collision prevention control, the vehicle control unit a101 is shifted to the engine stall control or the idle stop control, so that it is possible to prepare for the next engine restart. It is. In addition, when the vehicle continues to run after the collision prevention control is completed, the engine can be restarted quickly by performing the clutch release control, while the gear change is performed when the gear position of the automatic transmission a108 is high. Can be implemented promptly.
<Timing chart>
Next, the timing of the control operation according to an embodiment of the present invention will be described.

  FIG. 3 is a timing chart showing the vehicle state in the operation control of the embodiment of the present invention.

  In FIG. 3, at time T0, vehicle control is automatically performed without the driver's operation, and the engine is stopped (fuel injection amount is 0) and the inertial running is started by releasing the clutch. .

  The coasting is continuously performed from time T0 to time T1.

  Next, from time T1 to time T2, the camera sensor a113 in FIG. 1 detects a front obstacle, but in step S202 in FIG. 2, the distance Ds (solid line) from the front obstacle is calculated in step S201. Since the collision prevention control start distance Dc (broken line 1) is exceeded, it is determined that the collision prevention control is not started, and coasting is continued.

  At the time point T2, the collision prevention control is started because the distance Ds to the front obstacle is equal to or less than the collision prevention control start distance Dc. At this time, the clutch state is in an open state because the vehicle has been coasting until the start of the collision prevention control. Then, in steps S205 to S206 in FIG. 2, since the expected collision time Tc> the clutch operation time Td, the clutch engagement operation is started. By starting the clutch engagement operation, the engine speed increases (however, the fuel injection amount is 0).

  In the chart of the distance Ds with respect to the obstacle in FIG. 3, the process Ds with the obstacle when the brake is not operated at the time point T2 follows the locus indicated by the broken line 2, and the estimated collision time Tc is obtained at the point where the point becomes zero. Come back.

  Next, at time T3, after the clutch engagement control is started in step S207 in FIG. 2, wheel brake braking in steps S211 to S212 in FIG. 2 is performed.

  Time T4 is a state in which the clutch engagement is completed. At this time, the engine speed is synchronized with the input shaft of the automatic transmission, but the fuel injection amount is maintained at 0, and the engine is in a state of performing fuel cut. For this reason, the engine speed decreases from time T4.

  Time T5 is a state where the vehicle is stopped by avoiding a collision with a front obstacle. At this time, since the vehicle speed becomes 0, the collision prevention control start distance Dc <the distance Ds with the front obstacle, the process proceeds to step S213, and the collision prevention control ends. And step S215-step S216 are implemented and the release operation | movement of a clutch is performed.

  In the illustrated example, the brake braking force decreases in the middle of the time T4 to the time T5. However, when an emergency state occurs, the brake braking force is maintained at the maximum state. You may comprise as follows.

  From time T5 to time T6, the engine is stopped in the idling stop control or the engine stall state, and the normal control is restored.

At time T6, in response to a request for engine restart by the driver or automatic operation control, fuel injection is started and the engine is restarted. At time T7, the engine speed becomes the idle speed.
<Summary>
As described above, the vehicle collision prevention control according to the embodiment of the present invention is performed immediately after the start of the collision prevention control in which the distance Ds to the front obstacle is equal to or less than the collision prevention control start distance Dc during coasting. It is possible to expect the maximum use of the engine brake by performing the fastening operation and quickly synchronizing the engine output shaft and the automatic transmission input shaft.

  In addition, even if there is a request for acceleration from the driver or the automatic speed control device, the fuel cut over the entire period from the start to the end of the collision prevention control (the fuel injection amount is set to 0) does not respond to the request. Can be prevented, the safety at the time of collision can be improved, and the fuel consumption can be effectively improved.

  In other words, the engine brake braking time can be extended by starting the engine brake immediately, and the risk of collision can be reduced by improving the braking force of the entire vehicle.

  In addition, when the stopped engine and the rotating transmission are fastened, energy lost until the engine is synchronized with the transmission can also be used for the braking force of the entire vehicle.

  Further, according to the present invention, the engine and the transmission are forcibly connected in the scene where the collision prevention control from the inertia running state in which the engine is stopped is executed, but the engine is cut off by maintaining the fuel cut state. Recombustion is not performed, and in the unlikely event of a collision, a collision in the engine combustion state can be avoided and safety can be ensured.

  In addition, this invention is not limited to an above-described Example, Various modifications are included in the technical scope of this invention. The above embodiments have been described in detail for easy understanding of the present invention, and are not necessarily limited to those having all the configurations described.

  Also, a part of the configuration of one embodiment can be replaced with the configuration of another embodiment. Moreover, the structure of another Example can also be added to the structure of a certain Example. In addition, with respect to a part of the configuration of each embodiment, the configuration of another embodiment can be added, deleted, or replaced.

  For example, in the above-described embodiment, the example in which the camera sensor a113 is used as the means for measuring the distance to the front obstacle has been described. However, it is also conceivable to divert other external field determination means found in millimeter wave radars, stereo cameras, and the like. It is done.

  In the above-described embodiments, the drive source mounted on the vehicle is the engine (internal combustion engine), but the drive source may be an electric motor. In this case, the power at the time of recovering the regenerative energy of the electric motor can be used as an engine brake.

  a100 ...: automobile, a101 ... vehicle control unit (control unit), a106 ... engine, a107 ... clutch mechanism (control target), a108 ... transmission, a112 ... wheel brake ( Control target), a113 ... camera sensor (distance measuring device), a114 ... vehicle speed sensor (detection means), a1011 ... ECU (engine control unit), a1012 ... ATCU (clutch control unit), a1013 ... BCU (brake control part), a1014 ... ADAS (automatic travel control part), Dc ... Collision prevention control start distance, Ds ... Distance to front obstacle, Tc ... Collision scheduled time , Td: clutch operation time

Claims (5)

Vehicle power source,
A clutch mechanism for fastening or releasing the power source and the driving wheel of the vehicle;
A distance measuring device for detecting an obstacle in front of the vehicle and measuring a distance to the obstacle;
A wheel brake attached to each wheel of the vehicle;
A vehicle speed sensor for measuring the traveling speed of the vehicle;
Based on the distance between the vehicle and the front obstacle measured by the distance measuring device, it is determined that the vehicle and the front obstacle may collide, and the driver of the vehicle is Instead, a collision prevention control unit that performs collision prevention control that automatically performs the operation of the wheel brake,
An inertial traveling control unit for performing inertial traveling in which the vehicle travels in a state where the power source and the driving wheel of the vehicle are released by the clutch mechanism and the power source is stopped;
The inertial traveling control unit determines that the collision prevention control unit may collide with the obstacle in front of the vehicle while the vehicle is performing the inertial traveling. The vehicle control device is characterized in that before the collision prevention control unit operates the wheel brake, the clutch mechanism starts a fastening operation between the power source and the driving wheel of the vehicle. The vehicle control device according to claim 1,
The inertial traveling control unit is configured to perform the collision prevention control when the rotational speed on the power source side of the clutch mechanism is lower than the rotational speed on the drive wheel side of the clutch mechanism during the inertial traveling of the vehicle. The vehicle control device, wherein the unit operates the wheel brake. The vehicle control device according to claim 1,
A fuel injection control unit configured to control a fuel injection amount to the power source, and the fuel injection control unit supplies fuel to the power source during a fastening operation between the power source and the drive wheels of the vehicle by the clutch mechanism; Vehicle control device characterized by not injecting fuel. The vehicle control device according to claim 1,
The inertial traveling control unit determines that the collision prevention control unit may collide with the vehicle and the front obstacle, and determines the distance between the vehicle and the front obstacle, When the estimated collision time is calculated from the traveling speed of the vehicle and the calculated estimated collision time is equal to or less than a predetermined value, the power source and the driving wheels of the vehicle are opened by the clutch mechanism. ,
When the calculated estimated collision time exceeds a predetermined value, the clutch mechanism starts an engagement operation between the power source and the drive wheel of the vehicle,
After the fastening between the power source and the drive wheel of the vehicle, when the collision prevention control unit determines that there is no danger of a collision with the vehicle and the front obstacle, the power source and the vehicle are A vehicle control device that opens the drive wheels of the vehicle. The vehicle control device according to claim 1,
The vehicle has a transmission for decelerating the rotational speed of the power source, and the gear of the transmission in the fastening operation of the power source and the drive wheel of the vehicle by the clutch mechanism is a forward gear other than neutral. One of the vehicle control devices.

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