JP2006349593A - Gradient estimating device and driving condition determining device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a gradient estimating device for improving estimation accuracy of a road surface gradient. <P>SOLUTION: Longitudinal force F<SB>x</SB>and vertical force F<SB>z</SB>acting on each wheel 5 are detected by a wheel force sensor 6 and a wheel speed V of each wheel 5 is detected by a wheel speed sensor 7. Vehicle weight m in a stationary state is calculated from the detected vertical force F<SB>z</SB>by a vehicle weight calculating section 12. Vehicle acceleration a is detected from the detected wheel speed V by an acceleration detector 11. The road surface gradient is estimated by a gradient estimating section 14 based on these longitudinal force F<SB>x</SB>, vehicle weight m, and vehicle acceleration a. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an apparatus that is mounted on a vehicle and estimates a traveling state of the vehicle.

2. Description of the Related Art Conventionally, various control devices mounted on a vehicle in order to improve the operability of the vehicle are known. For example, in the road gradient estimation device disclosed in Patent Document 1, the road gradient is determined based on the actual acceleration obtained from a change in the rotation speed of a wheel or the like and the acceleration detected by an acceleration sensor such as a pendulum sensor. Presumed. Based on the estimated gradient, the gear stage of the automatic transmission is controlled.
JP-A-11-351864

  However, with a conventional road gradient estimation device, it is difficult to accurately estimate the road gradient due to its structure. Also from the viewpoint of enriching the technology, it is useful to estimate the running state of the vehicle, such as the slope of a hill, based on the state quantity of the vehicle detected by other types of sensors.

  This invention is made | formed in view of this situation, The objective is to provide the novel gradient estimation apparatus which estimates the gradient of a road surface.

  Another object of the present invention is to improve the estimation accuracy of the road surface gradient.

  Furthermore, another object of the present invention is to improve the operability of the vehicle by the vehicle travel control and other controls based on the road surface gradient estimated more precisely.

  In order to solve such a problem, a first invention provides a gradient estimation device that is mounted on a vehicle and estimates a gradient of a road surface on which the vehicle contacts the ground. The first invention includes a wheel force sensor, an acceleration detection unit, and a gradient estimation unit described below. The acting force acting on the wheel is detected by the wheel force sensor. The acceleration detection unit detects the acceleration of the vehicle in a direction parallel to the road surface. In the gradient estimation unit, the gradient of the road surface is estimated based on the acting force of the wheels and the acceleration of the vehicle.

  In the first aspect of the invention, the acting force of the wheel detected by the wheel force sensor includes a vertical force acting on the wheel, further includes a vehicle weight calculating unit shown below, and the gradient estimating unit is as follows. It is preferable that In this vehicle weight calculation unit, the weight of the vehicle in a stationary state is calculated based on the vertical force of the wheels detected by the wheel force sensor when the vehicle is stationary. The gradient estimation unit estimates the road surface gradient using the calculated weight (mass).

  Furthermore, in the first invention, the acting force of the wheel detected by the wheel force sensor includes a longitudinal force acting on the wheel, further includes a traveling state determining unit shown below, and the gradient estimating unit is as follows. As good as That is, the running state determination unit determines whether or not the vehicle is slipping based on the longitudinal force of the wheels detected by the wheel force sensor and the acceleration of the vehicle detected by the acceleration detection unit. . When the vehicle is not slipping as a result of this determination, the gradient estimation unit estimates the road gradient.

  In these first inventions, the gradient estimation unit estimates the gradient of the road surface using the ratio or difference between the vertical force acting on the front wheels and the vertical force acting on the rear wheels of the wheels. Also good.

  In the first invention described above, it is desirable to further include a braking / driving adjustment unit described below. That is, in this braking / driving adjustment unit, an adjustment related to driving or braking of the vehicle is instructed according to the road surface gradient estimated by the gradient estimation unit. The adjustment here is, for example, adjustment of the opening degree of the throttle valve with respect to the operation of the accelerator pedal by the driver on a slope, especially limitation of change in the number of shift stages by the automatic transmission on the downhill.

  A second aspect of the invention provides a traveling state determination device that is mounted on a vehicle and determines a traveling state of the vehicle. The second aspect of the invention has the following wheel force sensor, wheel speed sensor, and travel state determination unit. The longitudinal force acting on the wheel is detected by the wheel force sensor, and the wheel speed of the wheel is detected by the wheel speed sensor. The traveling state determination unit determines whether or not the wheel (or vehicle) is slipping based on the longitudinal force and the wheel speed.

  In the second aspect of the present invention, it is desirable to further include a recovery control unit described below. That is, in the recovery control unit, when the vehicle is slipping as a result of the determination by the traveling state determination unit, control related to recovery from slip is instructed. By the instruction here, for example, the opening degree of the throttle valve is reduced, and the brake pressure for the wheel is reduced.

  According to the present invention, the value of the acting force acting on the wheel directly detected by the wheel force sensor is used when specifying the gradient of the ground contact surface of the vehicle. For this reason, it is possible to estimate the road surface gradient with high accuracy. Since the driving and braking of the vehicle are controlled based on the gradient estimated with high accuracy in this way, the control becomes more appropriate, and the stability of traveling with respect to the operation of the vehicle can be improved. In other words, the driver can drive the vehicle in the same manner through the same operation without being aware of whether the road is a flat road or an uphill / downhill road. In particular, the present invention uses a wheel force sensor that can be said to have a novel configuration for gradient estimation, and is useful for enriching the technology.

  Further, according to the present invention, it is determined whether or not the vehicle is slipping based on the detected value of the wheel acting force by the wheel force sensor and the detected value of the wheel speed (and the detected value of the vehicle acceleration) by the wheel speed sensor. Then, control for its recovery is performed. For this reason, the driver can expect high running stability at the time of vehicle slip.

(First embodiment)
FIG. 1 is a diagram showing a schematic configuration of a vehicle equipped with a gradient estimation device 10 according to the first embodiment. This vehicle is a four-wheel drive vehicle, and the front, rear, left and right four wheels are driven. The gradient of the road surface on which the vehicle contacts is estimated by the gradient estimation device 10. The gradient estimation device 10 and a control device (not shown) for controlling the engine 1, the automatic transmission 2, the brake, the steering, and the like each include a microcomputer, a control program, and the like. The gradient estimation device 10 can apply control based on the estimation of the gradient to the traveling control of the vehicle by transmitting data to each connected control device.

  Each part of the vehicle will be described sequentially. The power of the engine 1 is transmitted to the front and rear axles 4 through the automatic transmission 2, the center differential 3a, the front differential 3b, the rear differential 3c, and the like. By transmitting this power to the axle 4, driving torque is applied to the left and right front wheels 5fl, 5fr and the left and right rear wheels 5rl, 5rr, and each wheel 5 is driven. Wheel force sensors 6fl, 6fr, 6rl, 6rr are provided inside the axle 4 in the vicinity of the wheels 5fl, 5fr, 5rl, 5rr, respectively.

Each wheel force sensor 6 detects a longitudinal force F _x , a lateral force F _y , and a vertical force F _{z that} are component forces of the acting force acting on the tire (wheel 5). FIG. 2 is an explanatory diagram of these forces acting on the wheel 5. The longitudinal force F _x is a component force in the direction parallel to the wheel center plane (x-axis direction) with respect to the friction force generated on the ground contact surface of the tire covering the outer periphery of the wheel 5, and the lateral force F _y is the wheel force This is a component force in a direction (y-axis direction) perpendicular to the center plane. The vertical force F _z is a ground load acting in the vertical direction (z-axis direction).

More specifically, each wheel force sensor 6 shown in FIG. 1 includes a strain gauge and a signal processing circuit that processes the output electric signal to generate a detection signal. Since the stress generated in each axle 4 is proportional to the force acting on each corresponding wheel 5, by detecting the stress in the x-axis, y-axis, and z-axis directions with a strain gauge embedded in the axle 4, The longitudinal force F _x , lateral force F _y , and vertical force F _z are directly detected, respectively.

  A wheel speed sensor 7fl, 7fr, 7rl, 7rr is provided for each of the wheels 5fl, 5fr, 5rl, 5rr, and the wheel speed (rotational speed) V of each wheel 5 is detected. The individually detected wheel speed V is used for calculating the speed and acceleration of the vehicle. For example, as the wheel speed sensor 7, a magnetic sensor that detects the rotation of a gear attached to the center of the wheel 5 is used.

The gradient estimation device 10 is constituted by a microcomputer as described above, and includes a CPU, a ROM, a RAM, an input / output interface, and the like. A program for estimating the gradient of the road surface is executed in the gradient estimation device 10. FIG. 3 is a block diagram showing the main configuration of the program executed here. This gradient estimation program functionally includes an acceleration detection unit 11, a vehicle weight calculation unit 12, a traveling state determination unit 13, a gradient estimation unit 14, a braking / driving adjustment unit 15, and an accelerator operation which are outlined below. It has the quantity detection part 16, the acceleration performance map 17, and the slip recovery control part 18. The acceleration detector 11 detects the acceleration a of the vehicle based on the wheel speed V of each wheel 5 detected by the wheel speed sensor 7. The vehicle weight calculation unit 12 calculates the vehicle weight m based on the vertical force F _z of each wheel 5 detected by the wheel force sensor 6 when the vehicle is stationary. The traveling state determination unit 13 uses the longitudinal force F _{x of} each wheel detected by the wheel force sensor 6, the acceleration a detected by the acceleration detection unit 11, and the vehicle weight m calculated by the vehicle weight calculation unit 12. Determine whether the vehicle is slipping. When the vehicle is not slipping, the gradient estimation unit 14 estimates the gradient θ based on the longitudinal force F _x (or vehicle longitudinal force F _xs described later), the acceleration a, and the vehicle weight m, and the braking / driving adjustment unit 15. Adjusts the control related to driving and braking based on the gradient θ. Accelerator operation amount detection unit 16 detects an operation amount of an accelerator pedal (accelerator opening), the acceleration performance map 17 in the ROM correspondence relationship between the accelerator operation amount H and the target acceleration a _H is stored. The braking / driving adjustment unit 15 reads the target acceleration a _H corresponding to the detected accelerator pedal operation amount H from the acceleration performance map 17. Then, based on the acceleration a _H and the acceleration a based on the wheel speed V of the wheel 5 detected by the acceleration detector 11, the engine control device and the automatic transmission control are adjusted so as to adjust the driving force or the braking force. Instruction data is transmitted to the device, the brake control device, and the like. At this time, the braking / driving force (driving force or braking force) is adjusted according to the gradient θ so that the vehicle acceleration a becomes constant at the target acceleration a _H according to the driver's operation. When the running state determination unit 13 determines that the vehicle is slipping, the slip recovery control unit 18 causes the engine control device, the brake control device, etc. to recover the vehicle from the slip (relaxes the slip). )

  The gradient control process according to this embodiment will be described in detail. FIG. 4 is a flowchart showing a detailed procedure of the gradient estimation process. This process is called at predetermined time intervals. First, in steps 1 and 2, it is determined whether or not the vehicle is running. If the vehicle is not running, the stationary vehicle weight m is calculated in steps 3 and 4, and if the vehicle is running, whether or not the vehicle is further slipping in steps 5 to 7. Is determined. If the vehicle is not slipping, the braking / driving force is adjusted according to the gradient in steps 8-11. When the vehicle is slipping, the braking / driving force is adjusted in steps 12 to 14 so that the vehicle recovers from the slip.

  More specifically, in steps 1 and 2, it is determined whether or not the vehicle is traveling in order to determine whether or not it is time to calculate the stationary vehicle weight m. First, in step 1, a wheel speed V (an average value or the like for any one of the wheels 5 or four wheels) is detected. In step 2, it is determined based on the wheel speed V whether the vehicle is traveling. . If a negative determination is made in step 2, that is, if the detected wheel speed V is 0, the vehicle is determined to be stopped, and the process proceeds to step 3. On the other hand, if the determination in step 2 is affirmative and the detected wheel speed V is not 0, it is determined that the vehicle is traveling and the process proceeds to step 5.

In steps 3 and 4 executed when the vehicle is stopped, the vehicle weight m in a stationary state used in steps 7 and 8 is calculated. In step 3, the vertical force F _z of each wheel 5 is detected by wheel force sensor 6, from the detected vertical force F _z, as the sum for the four-wheel vehicle vertical force F _zs is calculated. In step 4, the ground load (mass, vehicle weight) m of the stationary vehicle is calculated from the vehicle vertical force F _zs , and after this calculation, the routine is exited. For example, on a flat road where the ground contact gradient θ of the vehicle is 0, (vehicle vertical force F _zs ) = (mass m) × (gravity acceleration g). Thus, by calculating the vehicle weight m when the vehicle is stopped, the calculation using the vehicle weight m in Steps 7 and 8 can be made to correspond to fluctuations in the load including passengers.

In Steps 5 to 7 executed when the vehicle is traveling, whether or not the vehicle is slipping is determined. In step 5, the detected longitudinal force F _x of each wheel 5 by the wheel speed sensor 6, further from the longitudinal force F _x of the vehicle, as the sum of the four wheels, the vehicle longitudinal force acting in the longitudinal direction across the vehicle F _xs is calculated. In step 6, the vehicle acceleration a is calculated from the amount of change per unit time of the wheel speed V (or vehicle speed) calculated in step 1. Subsequently, in step 7, it is determined whether or not the vehicle is in a slip state. Specifically, depending on whether or not the vehicle weight m, the vehicle longitudinal force F _xs, and the vehicle acceleration a calculated in Steps 4, 5, and 6 have the relationship of the following Equation 1, It is determined whether or not a slip has occurred.

Here, the absolute value of the product of the vehicle weight m and the vehicle acceleration a (determined from the wheel speed V of the wheel 5) is the vehicle longitudinal force F _xs (determined from the longitudinal force F _x acting on the wheel 5). It is determined that the vehicle is slipping when the absolute value is greater than or equal to. If a negative determination is made in Step 7, that is, if Formula 1 is not satisfied and no slip occurs, the process proceeds to Step 8. Further, when an affirmative determination is made in step 7, the formula 1 is satisfied, and when the vehicle is slipping, the process proceeds to step 12.

In steps 8 to 11 executed when the vehicle is not in the slip state, the gradient θ of the ground contact surface of the vehicle is estimated, and the control amount of the engine control device or the like related to braking / driving is adjusted based on this θ. . Here, in particular, in steps 9 to 11, the throttle valve opening in the engine 1 is adjusted according to the gradient θ. In addition, for example, adjustment (limitation) of the gear position in the automatic transmission 2, The fastening force may be adjusted. First, in step 8, the gradient θ of the road surface on which the vehicle contacts the ground is estimated from the vehicle weight m, vehicle longitudinal force F _xs and vehicle acceleration a calculated in steps 4 to 6. FIG. 5 is a diagram showing the relationship of forces acting on the vehicle. As is apparent with reference to this figure, there is a relationship of Formula 2 among the vehicle weight m, the vehicle longitudinal force F _xs, and the vehicle acceleration a.

α is a disturbance such as road surface unevenness that affects the vehicle longitudinal force F _xs . As shown in Formula 2, the vehicle longitudinal force F _xs can be regarded as the force ma due to the vehicle acceleration a plus the force (mg · sinθ) due to the influence of gravity and the force α due to disturbance. is there. The vehicle weight m, the vehicle longitudinal force F _xs and the vehicle acceleration a have already been calculated, and when the disturbance α is not taken into account, the gradient θ is specified by the following Equation 3. In order to eliminate the influence of the disturbance α on the vehicle longitudinal force F _xs or the like, digital filter processing or the like can be performed. As a result, the gradient θ can be estimated more accurately.

In the subsequent step 9, the accelerator pedal operation amount H is detected as a previous stage of control for the subsequent throttle opening (throttle valve opening), and the target acceleration a _H corresponding to this detected value is determined as an acceleration performance map. 17 is read out. The target acceleration _aH is an acceleration corresponding to the pedal operation amount H on a flat road (gradient θ = 0). That is, even on a slope, the target acceleration _aH is set so that the driver operates the vehicle with the same operational feeling as that on a flat ground, and acceleration performance corresponding to this operation is obtained. In Step 10, whether the vehicle acceleration a and thus set target acceleration a _H are substantially equal is determined. If an affirmative determination is made in step 10, i.e., when the vehicle acceleration a has reached the target acceleration a _H, the process exits the routine. Further, a negative determination in step 10, if the vehicle acceleration a is not the target acceleration a _H, in step 11, the throttle opening is increased or decreased based on the road surface gradient theta. For example, when the vehicle is traveling uphill, data for instructing the engine control device to increase the throttle opening is generated so as to accelerate acceleration according to the magnitude of the gradient, and the data is transmitted as appropriate. . When the vehicle is traveling on a downhill, the engine control apparatus is instructed to reduce the throttle opening so as to suppress acceleration according to the slope. After such braking / driving control, this routine is exited.

  In Steps 12 to 14 executed when the vehicle is in a slip state, control for recovering the vehicle from the slip is performed. In step 12, it is first determined whether the vehicle is in a driving state (accelerating) or in a braking state (decelerating). If an affirmative determination is made in step 12 and the vehicle is in a driving state, a decrease in throttle opening is instructed to the engine control device in step 13. If a negative determination is made in step 12 and the vehicle is in a braking state, the brake control device is instructed to reduce the brake pressure in step 14. After this, the routine is exited. In this way, when the vehicle is slipping, by controlling so that the absolute value of the driving force or the braking force becomes small, the recovery from the slip is accelerated, and the driver can improve the stability of the vehicle during the slip. Improvement can be expected.

According to the present embodiment, the road surface gradient θ is estimated based on the vehicle weight m (vehicle vertical force F _zs ), vehicle longitudinal force F _xs, and vehicle acceleration a. The vehicle weight m is calculated from the vertical force F _z of each wheel 5 detected by the wheel force sensor 5, and the vehicle longitudinal force F _xs is calculated from the detected longitudinal force F _s of each wheel 5. The reliability of the value of the heavy m and the vehicle vertical force F _zs is high. Therefore, the accuracy of the gradient θ estimated from these is high, and as a result, the operability of the vehicle on the gradient road surface can be improved.

In this embodiment, the sum of the front / rear force F _{x for} the four front / rear left and right wheels 5 is the vehicle front / rear force F _xs and the sum for the four wheels for the vertical force _z is the vehicle vertical force F _zs. Is not limited to this. The vehicle longitudinal force F _xs and the vehicle vertical force F _zs may be estimated based on the detected values of these acting forces with respect to a specific one or two or more wheels 5 out of the four wheels. For example, a value obtained by doubling the sum of the front / rear forces F _x related to the right front / rear wheel can be used as the vehicle front / rear force F _xs .

  In the present embodiment, the vehicle is driven by the engine 1. However, the driving force in the traveling on the slope road surface or in the slip state is obtained by using the motor instead of the engine 1 or using the motor together with the engine 1 and controlling the rotation of the motor. In addition, it is possible to control the braking force. In addition, the driving force and the braking force can be simultaneously controlled by combining the engine 1, the automatic transmission 2, the motor, and the brake device.

(Second Embodiment)
In the present embodiment, the gradient estimation method is different from that of the first embodiment. This gradient estimation is processed by a processing unit corresponding to the gradient estimation unit 14 in FIG. 3, but the configuration, operation, effect, and the like of the other units are the same as those in the first embodiment except for the following description. . FIG. 6 is a diagram for explaining the relationship between the road surface gradient θ and the force applied to the vehicle used in the present embodiment. Wheel vertical force F _zf is the sum of the vertical forces F _z for the left front wheel and right front wheel, rear wheel vertical force F _zr is the sum of the vertical force F _z for the left rear wheel and the right rear wheel . Furthermore, wheelbase l _w is the distance between the axle of the rear wheels and the front wheel axle. Of these, the distance from the front wheel axle to the center of gravity is l _f, and the distance from the center of gravity to the rear wheel axle is l _r . Let h be the distance from the road surface to the center of gravity of the slope θ where the vehicle contacts the ground. According to these, the front wheel vertical force F _zf, the rear wheel vertical force F _zr, respectively, can be represented by the following formula 4,5.

The gradient estimation unit in the gradient estimation apparatus of the present embodiment, based on the ratio of the front wheel vertical force F _zf and the rear wheel vertical force F _zr, road slope θ is estimated. This ratio can be expressed by Equation 6 below.

Here, 1 / cos θ can be replaced with 1 in order to simplify the calculation. This is because, for example, assuming that the inclination is about 20%, that is, the gradient θ is about 11.3 degrees, the value of 1 / cos θ is 1.02, which can be regarded as being very close to 1. Further, when the F _zf / F _zr x, a l _f + l _r and l _w, for theta, Equation 7 shown below is derived. Here, the gradient θ is obtained by assigning each value to the right side.

According to the present embodiment, the gradient θ of the ground contact surface of the vehicle is accurately estimated using the vertical force F _z detected by the wheel force sensor 6 or the like. Such estimation of the gradient leads to an improvement in the operability as in the first embodiment.

(Third embodiment)
Furthermore, the road surface gradient θ can be expressed using the difference between the front wheel vertical force F _zf (the above formula 4) and the rear wheel vertical force F _zr (the above formula 5) instead of the ratio thereof. That is, this difference is expressed by the following formula 8.

In the equation, as described above, replacing 1 / cos [theta], the l _f + l _r respectively 1, l _w, also when the F _zf -F _zr and x, the theta, Equation 9 shown below is obtained. By assigning each value to the right side, the gradient θ is obtained.

  According to the gradient estimation in the present embodiment, the driver can expect an improvement in the running stability of the vehicle with respect to the operation.

1 is an overall configuration diagram of a vehicle equipped with a gradient estimation device 10 according to a first embodiment. Explanatory drawing about acting force of wheel 5 The block diagram which shows the main structures of the gradient estimation apparatus 10 Flow chart showing the procedure of gradient estimation processing The figure which shows the relationship between road surface gradient (theta) and the force which acts on a vehicle The figure which shows the relationship between road surface gradient (theta) and the force which acts on a vehicle in 2nd Embodiment.

Explanation of symbols

1 Engine 2 Automatic transmission 3a Center differential 3b Front differential 3c Rear differential 4 Axle 5fl, fr, rl, rr Wheel 6fl, fr, rl, rr Wheel force sensor 7fl, fr, rl, rr Wheel speed sensor 10 Gradient estimation device 11 Acceleration Detection unit 12 Vehicle weight calculation unit 13 Traveling state determination unit 14 Gradient estimation unit 15 Braking / driving adjustment unit 16 Accelerator operation amount detection unit 17 Acceleration performance map 18 Slip recovery control unit

Claims (8)

In a gradient estimation device that is mounted on a vehicle and estimates a gradient of a road surface on which the vehicle contacts the ground,
A wheel force sensor for detecting an acting force acting on the wheel;
An acceleration detector for detecting acceleration in a direction parallel to the road surface of the vehicle;
A gradient estimation apparatus, comprising: a gradient estimation unit that estimates the gradient of the road surface based on the acting force of the wheel and the acceleration of the vehicle. The acting force of the wheel detected by the wheel force sensor includes a vertical force acting on the wheel,
A vehicle weight calculating unit that calculates the weight of the vehicle in a stationary state based on the vertical force of the wheel detected by the wheel force sensor when the vehicle is stationary;
The gradient estimation apparatus according to claim 1, wherein the gradient estimation unit estimates the gradient of the road surface using the calculated weight. The acting force of the wheel detected by the wheel force sensor includes a longitudinal force acting on the wheel,
A traveling state determination unit that determines whether the vehicle is slipping based on the longitudinal force of the wheel detected by the wheel force sensor and the acceleration of the vehicle detected by the acceleration detection unit; Have
The gradient estimation device according to claim 1 or 2, wherein the gradient estimation unit estimates the gradient of the road surface when the vehicle is not slipping as a result of the determination.   The slope estimation unit estimates the slope of the road surface using a ratio of a vertical force acting on a front wheel and a vertical force acting on a rear wheel of the wheels. Gradient estimation device.   The gradient estimation unit estimates the gradient of the road surface using a difference between a vertical force acting on a front wheel and a vertical force acting on a rear wheel of the wheels. Gradient estimation device.   6. The braking / driving adjustment unit for instructing an adjustment related to driving or braking of the vehicle according to the gradient of the road surface estimated by the gradient estimation unit. Gradient estimation device. In a traveling state determination device that is mounted on a vehicle and determines the traveling state of the vehicle,
A wheel force sensor for detecting the longitudinal force acting on the wheel;
A wheel speed sensor for detecting a wheel speed of the wheel;
A traveling state determination device comprising: a traveling state determination unit that determines whether or not the wheel is slipping based on a longitudinal force of the wheel and a wheel speed of the wheel.   The travel state according to claim 7, further comprising a recovery control unit that instructs control related to recovery from the slip when the vehicle slips as a result of the determination by the travel state determination unit. Judgment device.

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