JP2018135042A - Slope-descending speed controller for vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To maintain drivability when descending a slope by automatically increasing or decreasing a target vehicle speed of a vehicle according to a change in a gradient of a traveling road surface during a downhill speed control. SOLUTION: A vehicle descending speed control device controls a vehicle so that the vehicle speed matches a target vehicle speed when descending a slope satisfying a predetermined condition. Further, the vehicle descending speed control device includes a gradient change determining means for determining whether or not the gradient of the traveling road surface has changed by a predetermined amount or more, and the gradient change determining means for changing the gradient of the traveling road surface by a predetermined amount or more. When it is determined, the target vehicle speed determining means for changing the target vehicle speed according to the amount of change in the gradient is provided. [Selection diagram] Fig. 3

Description

  The present invention relates to a vehicle downhill speed control device for automatically braking a vehicle traveling on a downhill road to keep the vehicle at a target vehicle speed.

  2. Description of the Related Art Conventionally, a descending plate speed control device (so-called hill descent control) is known that automatically brakes a vehicle traveling on a downhill road so as to maintain an actual vehicle speed at a target vehicle speed (refer to Patent Document 1 below). .

  In such a descending plate speed control device, the descending slope of the traveling road surface is equal to or greater than a predetermined gradient, the vehicle speed is within a predetermined range, and the accelerator and the brake are not operated during the downhill with the control start switch turned ON. When all the conditions are satisfied, control is started with the vehicle speed at the time when these conditions are satisfied as the target vehicle speed. During the control, the target vehicle speed can be appropriately changed by the accelerator operation and the brake operation. For example, when it is desired to increase the target vehicle speed, if the accelerator operation is performed to increase the vehicle speed to a desired vehicle speed and the pedal operation is stopped, the vehicle speed at that time is set as a new target vehicle speed. The same applies to the case where the target vehicle speed is decelerated. When the brake operation is performed to decelerate to the desired vehicle speed and the pedal operation is stopped, the vehicle speed at that time is set to a new target vehicle speed.

Japanese Patent No. 5169565

  By the way, the gradient of the traveling road surface is not always constant. The sensation speed of the driver changes depending on the descending slope of the traveling road surface. For example, if the descending slope of the traveling road surface becomes steep while traveling on a downhill road, the vehicle speed is felt fast at the target vehicle speed until then, but if the descending slope of the traveling road surface becomes gentle, It can happen that the target vehicle speed feels that the vehicle speed is slow. Therefore, the driver needs to change the target vehicle speed by operating the accelerator and the brake pedal in accordance with the change of the road surface gradient, for example, when the gradient of the traveling road surface changes abruptly. However, on mountain roads where there are many changes in slope, pedal operation is required every time the road slope changes, making the operation difficult, and the driver is less likely to concentrate on the steering wheel operation, making full use of the advantages of the descending speed control device. There was room for improvement because there was no situation.

  The present invention has been made in view of the above circumstances, and at the time of descending slope speed control, the target vehicle speed of the vehicle is automatically increased or decreased according to the change in the gradient of the traveling road surface, and drivability at the time of descending slope is maintained. An object of the present invention is to provide a downhill speed control device for a vehicle.

  The downhill speed control device for a vehicle according to the present invention controls the vehicle so that the vehicle speed matches the target vehicle speed when the downhill satisfies a predetermined condition, and whether the gradient of the traveling road surface has changed by a predetermined amount or more. A gradient change determining means for determining whether or not the target vehicle speed is determined in accordance with a change amount of the gradient when the gradient change determining means determines that the gradient of the traveling road surface has changed by a predetermined amount or more. And means.

  In addition, the target vehicle speed determining means changes the target vehicle speed to a speed that is decelerated by a predetermined speed from the target vehicle speed before the change of the gradient when a change of a predetermined amount or more in a direction in which the downward gradient of the traveling road surface increases. The target vehicle speed may be changed to a speed increased by a predetermined speed from the target vehicle speed before the change of the gradient when the downward gradient of the traveling road surface is changed by a predetermined amount or more.

  Furthermore, the predetermined speed that is increased or decreased by the target vehicle speed determining means may be set so as to increase as the gradient change amount increases.

  Further, the downhill speed control device for the vehicle predicts whether or not there is a slope changing portion where the slope of the traveling road surface changes within a predetermined distance within a predetermined distance in the traveling direction of the vehicle, and the prediction Vehicle speed decelerating means for temporarily decelerating the vehicle speed until it passes through the predicted gradient change location when it is predicted by the means that the gradient change location is within a predetermined distance. Also good.

  Furthermore, the speed decelerated by the vehicle speed reduction means may be varied according to the actual vehicle speed and the target vehicle speed at that time, and may be set to increase as the actual vehicle speed and the target vehicle speed increase.

  According to the present invention, when the downhill speed control is performed, the target vehicle speed of the vehicle is appropriately changed according to the change in the slope of the road surface. Therefore, the downhill speed control of the vehicle that can maintain drivability during the downhill is possible. Equipment can be provided.

The figure which shows an example of the schematic structure of the vehicle which concerns on the 1st Embodiment of this invention. The map which shows an example of the relationship between the target vehicle speed and gradient which concern on the embodiment. The flowchart which shows an example of the vehicle speed control which the control apparatus which concerns on the same embodiment performs. The flowchart which shows a part of example of the vehicle speed control which the control apparatus which concerns on the 2nd Embodiment of this invention performs. The flowchart which shows the other part of an example of the said vehicle speed control which concerns on the embodiment. The figure for demonstrating an example of the prediction method of the gradient amount change of the traveling road surface which concerns on the embodiment. The figure for demonstrating an example of the prediction method of the gradient amount change of the traveling road surface which concerns on the embodiment. The figure for demonstrating an example of the prediction method of the gradient amount change of the traveling road surface which concerns on the embodiment.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
(First embodiment)
FIG. 1 is a diagram illustrating an example of a schematic configuration of a vehicle 1 according to the present invention. As shown in FIG. 1, the vehicle 1 includes an ECU (Electric Control Unit) 11, which is a downhill speed control device, an HDC (Hill Descent Control) switch 12, a meter 13, an ASC (Active Stability Control) -H / U 14, acceleration. A sensor 15, a brake pedal 16, four wheel brakes 16 a to 16 d and four wheels 17 a to 17 d, a camera unit 18, and a sensor unit 19 are provided. Further, the ECU 11, the HDC switch 12, the meter 13, the acceleration sensor 15, the camera unit 18, and the sensor unit 19 are respectively connected by control lines. The brake pedal 16 is connected to the ASC-H / U14. In addition, although the vehicle 1 also includes other devices for realizing functions as a vehicle, illustration and description thereof are omitted.

  The ECU 11 is a control device including a CPU, a ROM, a memory, and the like, and comprehensively controls each component of the vehicle 1. For example, the ECU 11 performs control (HDC) so that the traveling speed of the vehicle 1 on the downhill coincides with the target vehicle speed. Note that the control for accelerating or decelerating the vehicle 1 to match the target vehicle speed is the same as the conventional control, and thus detailed description thereof is omitted.

  The HDC switch 12 is a switch for turning ON / OFF the HDC control. For example, the HDC switch 12 is disposed at a position where the driver can reach when the driver is positioned at the driver's seat, and is turned ON / OFF by the driver.

  The meter 13 notifies the current actual vehicle speed of the vehicle 1. The driver grasps the actual vehicle speed of the vehicle 1 by confirming the numerical value notified to the meter 13.

  The ASC-H / U 14 issues a braking instruction to the wheel brakes 16a to 16d for braking the wheels 17a to 17d based on an instruction from the brake pedal 16, and automatically controls an engine (not shown) output.

  The acceleration sensor 15 detects the amount of acceleration of the vehicle 1 in each of the vertical direction, the left-right direction, and the front-rear direction. The detection result is output to the ECU 11.

  The brake pedal 16 instructs the braking amount to the ASC-H / U 14 in accordance with the depression amount depressed by the driver.

  The camera unit 18 includes a camera and an image processing unit. The camera is provided, for example, between the driver's seat and the passenger seat in the passenger compartment of the vehicle 1 and on the upper side, and is installed so as to be able to photograph the front and lower traveling road surface of the vehicle 1 through the windshield. The camera outputs the captured image data to the image processing unit. The image processing unit analyzes image data received from the camera, determines whether there is an obstacle on the traveling road surface of the vehicle 1, and outputs the determination result to the ECU 11.

  The sensor unit 19 includes, for example, three distance sensors including a radar and a receiving unit. Each radar is installed below the front surface of the vehicle 1, for example, in the vicinity of the bumper, and radiates radio waves in three different directions on the front lower side of the vehicle 1. Each receiving unit receives a reflected wave of a radio wave radiated from each corresponding radar. The receiving unit measures the distance based on the received reflected wave. The sensor unit 19 outputs the three measured distances to the ECU 11. Details of each distance measuring method will be described later with reference to FIGS. Note that the camera unit 18 and the sensor unit 19 are used in a second embodiment to be described later, and are not essential in the first embodiment.

  Next, a method for calculating the target vehicle speed when traveling downhill will be described. FIG. 2 is a diagram for explaining a specific example of a target vehicle speed calculation method.

  The map shown in FIG. 2 (hereinafter referred to as graph g) shows the relationship between the gradient (%) and the target vehicle speed (km / h). The reference value R is obtained based on the actual vehicle speed of the vehicle 1 obtained at the start of HDC control and the gradient obtained from the acceleration sensor 15. In the present embodiment, the reference value R is obtained from the HDC control start vehicle speed / HDC control start gradient. For example, when the change in the gradient amount is −Δg, the target vehicle speed is obtained as the reference value R1 (> reference value R) based on the graph g, and when the change in the gradient amount is + Δg, The target vehicle speed is obtained as a reference value R2 (<reference value R) based on the graph g. In the present embodiment, the case of obtaining from the graph g will be described. However, the present invention is not limited to this, and another method may be used. In the vehicle 1, speed control is executed so as to coincide with the target vehicle speed obtained based on the gradient as described above.

  Next, vehicle speed control executed by the ECU 11 when traveling downhill will be described. FIG. 3 is a flowchart illustrating an example of vehicle speed control during downhill travel executed by the ECU 11. This process is always executed while the vehicle 1 is traveling downhill.

  The ECU 11 determines whether the HDC switch 12 is ON (ST101). When it is determined that the HDC switch 12 is ON (ST101: YES), the ECU 11 determines whether an HDC control start condition is satisfied (ST102). In this embodiment, the ECU 11 starts the HDC control when the accelerator pedal (not shown) is OFF, the brake pedal 16 is OFF, and the road surface gradient is not less than a predetermined value and not more than a predetermined vehicle speed. It is determined that the start condition is satisfied.

  When it is determined that the HDC control start condition is satisfied (S102: YES), the ECU 11 determines whether or not the setting of the flag F is 0 (ST103). The flag F is a flag for determining whether or not the flow is the first flow that satisfies the HDC control start condition. The flag F is formed in a predetermined area of a memory provided in the ECU 11, for example.

  When it is determined that the setting of the flag F is zero (ST103: YES), the ECU 11 sets the target vehicle speed based on the actual vehicle speed at the start of control (when the condition is satisfied) (ST104). More specifically, when the HDC control start condition is satisfied, the actual vehicle speed when the condition is satisfied is set to the initial target vehicle speed. If ECU 11 determines that flag F is not zero (ST104: NO), the target vehicle speed has already been set, so the process proceeds to step ST105 without executing step ST104.

  Next, the ECU 11 determines whether or not the road surface gradient has changed by a predetermined amount or more (ST105: gradient change determination means). The road surface gradient is calculated from the detection result of the acceleration sensor 15, and the change in the road surface gradient is calculated from the change in the detection result of the acceleration sensor 15. Note that an inclination sensor may be provided instead of the acceleration sensor 15, and a road surface gradient and a change in the road surface gradient may be detected based on the detection result of the inclination sensor.

  When it is determined that the road surface gradient has changed by a predetermined amount or more (ST105: YES), the ECU 11 determines whether or not the gradient has increased (ST106). In other words, it is determined whether the road surface gradient is large (steep) or small (slow). In this embodiment, the determination is made based on whether or not the gradient change amount is + Δg or more. Note that the value of Δg can be arbitrarily set.

  If it is determined that the gradient has increased (ST106: YES), the ECU 11 recalculates the target vehicle speed according to the gradient change amount + Δg (ST107). As a result, the target vehicle speed is reduced from the current target vehicle speed. If it is determined that the gradient is not large (ST106: NO), the ECU 11 recalculates the target vehicle speed in accordance with the gradient change amount −Δg (ST108). As a result, the target vehicle speed is increased from the current target vehicle speed. In the recalculation of the target vehicle speed, the target vehicle speed is calculated from, for example, the above-described map (refer to FIG. 2). Therefore, the magnitude of the increase / decrease speed of the target vehicle speed varies according to the magnitude of the gradient change amount, and the increase / decrease speed of the target vehicle speed increases as the gradient change amount increases. When the target vehicle speed is recalculated in this way, the ECU 11 updates the target vehicle speed (ST109: target vehicle speed determining means). That is, the ECU 11 sets a recalculated new target vehicle speed, and controls the vehicle speed so as to coincide with the new target vehicle speed (ST111). On the other hand, if it is determined in step ST105 described above that there is no change in the road surface gradient by a predetermined amount or more (ST105: NO), the target vehicle speed is not changed (ST110), and the ECU 11 continues to match the current target vehicle speed. Next, the vehicle speed is controlled (ST111). Next, the ECU 11 sets the flag F to 1 (ST112). Then, the process returns to step ST101.

  On the other hand, if it is determined in step ST101 that the HDC switch 12 is not ON (ST101: NO), or if it is determined in step ST102 that the HDC control start condition is not satisfied (ST102: NO), the ECU 11 sets the flag F Is set to zero (ST113). This process ends when the flag F is set to zero.

  As described above, the ECU 11 determines whether or not the gradient of the traveling road surface has changed by a predetermined amount Δg or more, and determines that the gradient of the traveling road surface has changed by a predetermined amount Δg or more, according to the change amount of the gradient. The target vehicle speed can be changed. Therefore, during downhill speed control, the target vehicle speed of the vehicle can be automatically increased or decreased according to the change in the gradient of the traveling road surface, and drivability during downhill can be maintained.

  In the present embodiment, the ECU 11 increases or decreases the target vehicle speed based on the map described with reference to FIG. 2, and changes the target vehicle speed before the change in the gradient when the gradient of the traveling road surface changes by a predetermined amount or more. If the target vehicle speed is changed from the target vehicle speed to a speed that has been decelerated by a predetermined speed from the current speed, and the target vehicle speed before the slope change is increased by a predetermined speed, the target speed is increased by a predetermined speed. Change the vehicle speed. More specifically, the ECU 11 sets the predetermined speed so as to increase as the change amount of the gradient increases.

(Second Embodiment)
The second embodiment is different from the first embodiment in that a process of predicting a road surface location where the gradient changes and temporarily reducing the vehicle speed before that is added to the first embodiment. is there. In addition, the same code | symbol is attached | subjected about the structure same as 1st Embodiment, and detailed description is abbreviate | omitted.

  The vehicle speed control executed by the ECU 11 when traveling downhill will be described. 4A and 4B are flowcharts illustrating an example of vehicle speed control executed by the ECU 11. This process is always executed while the vehicle 1 is traveling downhill as in the first embodiment.

  Similar to the first embodiment, the ECU 11 determines whether or not the HDC switch 12 is ON (ST201). If the ECU 11 determines that the HDC switch 12 is ON (ST201: YES), the HDC control start condition is satisfied. If it is determined that the HDC control start condition is satisfied (S202: YES), it is determined whether the setting of the flag F is 0 (ST203). When it is determined that the setting of the flag F is zero (ST203: YES), the ECU 11 sets the target vehicle speed based on the actual vehicle speed at the start of control (when the condition is satisfied) (ST204). If the ECU 11 determines that the flag F is not zero (ST204: NO), the process proceeds to step ST205 without executing the process in step ST204. The processes in steps ST201 to ST204 are the same as those in steps ST101 to ST104 described above.

  Next, the ECU 11 executes a gradient change prediction process for predicting a gradient change in the road surface (ST205: prediction means). The gradient change prediction process is a process of predicting whether there is a gradient of a predetermined amount or more ahead. A detailed description of the gradient change prediction process will be described later with reference to FIGS.

  Next, the ECU 11 determines whether or not there is a gradient change of a predetermined amount or more ahead based on the result of the gradient change prediction process (ST206). If it is determined that there is a gradient change of a predetermined amount or more (ST206: YES), the ECU 11 determines whether or not the current position is within a predetermined distance from the predicted gradient predicted change position (ST207). The process of step ST207 is a process that serves as a criterion for determining when to start deceleration of the vehicle.

  If it is determined that the distance is within the predetermined distance (ST207: YES), the ECU 11 maintains the vehicle speed in a state where the vehicle speed is reduced by a predetermined speed (ST208: vehicle speed reduction means). The predetermined speed to be decelerated here is not constant, and may be varied according to the actual vehicle speed at that time and the set target vehicle speed. For example, if the actual vehicle speed or the target vehicle speed is high, the predetermined speed to be decelerated is large.

  Next, the ECU 11 determines whether or not the predicted gradient change position has been passed (ST209). When it is determined that the vehicle has not passed the predicted gradient change position (ST209: NO), the process returns to step ST208. In other words, the process of temporarily decelerating the vehicle speed by a predetermined speed is continued until the predicted gradient change position is passed. For this reason, the process of step ST209 is a criterion for maintaining the vehicle speed in a decelerated state until the vehicle passes through the gradient change point (predicted position).

  When it is determined that the vehicle has passed the predicted gradient change position (ST209: YES), the ECU 11 determines whether or not the road surface gradient has changed by a predetermined amount or more, as in the first embodiment (ST210: gradient change determination). means). More specifically, the ECU 11 calculates a gradient change amount at the time when the vehicle has passed the gradient change point (predicted position) and the gradient has changed, and determines whether or not the road gradient has changed by a predetermined amount or more. doing.

  When it is determined that the road surface gradient has changed by a predetermined amount or more (ST210: YES), it is determined whether or not the gradient has increased (ST211). If the ECU 11 determines that the gradient has increased (ST211: YES), it recalculates the target vehicle speed according to the gradient change amount + Δg (ST212), and if it determines that the gradient has not increased (ST211: NO), The target vehicle speed is recalculated according to the gradient change amount -Δg (ST213), and the target vehicle speed is updated (ST214: target vehicle speed determining means).

  When the target vehicle speed is updated (ST214), or when it is determined that there is no gradient change of a predetermined amount or more ahead (ST206: NO), when it is determined that the gradient change predicted distance is not the predetermined distance (ST207: NO), In addition, when it is determined that there is no change in the road surface gradient by a predetermined amount or more (ST210: NO) and there is no change in the target vehicle speed (ST215), the ECU 11 controls the vehicle speed so as to continuously match the target vehicle speed. (ST216.). Next, the ECU 11 sets the flag F to 1 (ST217). Then, the process returns to step ST201.

  On the other hand, if it is determined in step ST201 that the HDC switch 12 is not ON (ST201: NO), or if it is determined in step ST202 that the HDC control start condition is not satisfied (ST202: NO), the ECU 11 As in the first embodiment, the flag F is set to zero (ST218). This process ends when the flag F is set to zero.

  Next, a method for predicting a change in the gradient amount of the traveling road surface when descending will be described in detail. FIG. 5 to FIG. 7 are diagrams for explaining an example of the prediction method of the gradient amount change. For example, when it is confirmed that there is no obstacle based on information from the camera unit 18, the following processing is executed.

  As shown in FIG. 4, it is assumed that distance sensors S1, S2, and S3 (not shown) that calculate distances for three different angles are provided in the sensor unit 19, respectively. The distance sensor S1 emits radio waves in the traveling direction of the vehicle 1, receives the reflected waves, and measures the distance L1. The distance sensor S3 radiates radio waves in the vertical direction with respect to the traveling road surface D of the vehicle 1, receives the reflected waves, and measures the distance L3. The distance sensor S2 is a sensor for measuring the distance between the distance sensor S1 and the distance sensor S3. More specifically, the distance sensor S2 is an angle A (which forms a predetermined angle with respect to the distance measured by the distance sensor S1. A radio wave is radiated in the <90 degrees direction, and the reflection is received to measure the distance L2.

  Here, it is assumed that there is a gradient of an angle θ formed with respect to the traveling road surface D at a predetermined distance ahead of the traveling road surface D. Then, since the angle B is 90 degrees, it is possible to calculate the distance L4 from the intersection position of the distance L2 and the traveling road surface D to the distance L1. When the distance L4 and the distance L3 are substantially the same distance, the ECU 11 can determine that the inclination of the traveling road surface D has not changed.

  Next, a method for determining when the change in the gradient amount of the traveling road surface D is smaller than a predetermined amount will be described with reference to FIG.

  As shown in FIG. 5, if the distance L4 becomes smaller than the distance L3, it can be estimated that the inclination of the traveling road surface D becomes small. First, the ECU 11 calculates a change angle (change amount) θ of the inclination of the traveling road surface D. The change angle θ can be obtained as follows. The distance X1 is calculated from the angle A and the distance L2. Next, the distance X2 is calculated by subtracting the distance X1 from the distance L1. The change angle θ is calculated from the distance X2 and the distance L4. When it is determined that the calculated change angle θ is equal to or greater than the angle A, the ECU 11 can determine that the inclination of the traveling road surface D is smaller than the angle A. In this case, for example, the ECU 11 uses the distance calculated from the distance L2 and the change angle θ (that is, the angle A) when the change angle θ becomes the angle A as the predicted position of the gradient change described above. Is stored in a predetermined area in the ECU 11. Using the stored predicted position, the determination in step ST209 is executed.

  Next, a method for determining when the change in the gradient amount of the traveling road surface D is greater than a predetermined amount will be described with reference to FIG.

  As shown in FIG. 6, when the distance sensor S2 cannot receive the reflected wave, that is, when the distance L2 cannot be measured, it can be determined that the inclination of the traveling road surface D has changed in a direction in which the inclination is greater than the angle A. it can. In this case, the ECU 11 stores the distance calculated from the distance L3 and the angle A when the distance L2 cannot be measured, that is, the distance calculated from the angle A, in the predetermined area in the ECU 11 as described above.

  The ECU 11 configured as described above predicts whether or not there is a slope changing portion where the gradient of the traveling road surface changes by a predetermined amount or less within a predetermined distance in the traveling direction of the vehicle, and there is a slope changing portion within the predetermined distance. If the vehicle speed is predicted, the vehicle speed of the vehicle can be temporarily reduced until it passes through the predicted gradient change point. For this reason, it becomes possible to maintain the drivability until the predicted downhill change point is passed.

  The speed to be decelerated is varied according to the actual vehicle speed and the target vehicle speed at that time, and is set to increase as the actual vehicle speed and the target vehicle speed increase. For this reason, it becomes possible to further maintain the drivability until the predicted downhill change point is passed.

  In addition, the said embodiment is shown as an example and is not intending limiting the range of invention. The novel embodiments and modifications can be implemented in various other forms, and various omissions, rewrites, and changes can be made without departing from the spirit of the invention. In these embodiments and modifications, the scope of the invention is included in the gist, and is included in the invention described in the claims and the equivalents thereof.

  DESCRIPTION OF SYMBOLS 1 ... Vehicle, 11 ... ECU, 12 ... HDC switch, 14 ... ASC-H / U, 15 ... Acceleration sensor, 16a-16d ... Wheel brake, 18 ... Camera part, 19 ... Sensor part, D ... Running road surface

Claims (5)

A downhill speed control device for a vehicle that controls the vehicle so that the vehicle speed matches a target vehicle speed when the downhill satisfies a predetermined condition,
A gradient change determining means for determining whether or not the gradient of the traveling road surface has changed by a predetermined amount or more;
Target vehicle speed determining means for changing the target vehicle speed according to the amount of change in the gradient when the gradient change determining means determines that the gradient of the traveling road surface has changed by a predetermined amount or more;
A downhill speed control device for a vehicle, comprising: The target vehicle speed determining means changes the target vehicle speed to a speed decelerated by a predetermined speed from the target vehicle speed before the slope change when the downward gradient of the traveling road surface changes by a predetermined amount or more, The target vehicle speed is changed to a speed that is increased by a predetermined speed from the target vehicle speed before the slope change when the downward slope of the traveling road surface changes by a predetermined amount or more. The vehicle downhill speed control apparatus as described. The downhill speed control device for a vehicle according to claim 2, wherein the predetermined speed that is increased or decreased by the target vehicle speed determining means is set to increase as the change amount of the gradient increases. Predicting means for predicting whether or not there is a slope change portion where the slope of the traveling road surface changes within a predetermined distance within a predetermined distance in the traveling direction of the vehicle;
Vehicle speed decelerating means for temporarily decelerating the vehicle speed until it passes through the predicted gradient change location when the prediction means predicts that the gradient change location is within a predetermined distance;
The downhill speed control device for a vehicle according to any one of claims 1 to 3, further comprising: The speed decelerated by the vehicle speed reduction means is variable according to an actual vehicle speed and a target vehicle speed at that time, and is set to increase as the actual vehicle speed and the target vehicle speed increase. Vehicle downhill speed control device.

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