JP2018052384A - Control device of vehicle and control method of vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To accurately estimate a gradient even if a slip occurs at a wheel.SOLUTION: This control device of a vehicle comprises: a gradient estimation part 100 for estimating a gradient on the basis of a fore-and-aft acceleration sensor value and acceleration acquired from a change amount of a wheel speed; a calculation acceleration speed calculation part 102 for calculating the calculation acceleration of a vehicle on the basis of the torque of a motor which drives the vehicle; and a change amount limit part 104 for limiting the change amount of the wheel speed on the basis of correction calculation acceleration which is obtained by correcting the calculation acceleration at gradient amount acceleration equivalent to a gradient which is estimated by the gradient estimation part 100.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a vehicle control device and a vehicle control method.

  Conventionally, for example, in Patent Document 1 below, the time variation of the wheel speed is calculated from the sensor value of the longitudinal acceleration sensor by adding the limit value of the change rate of the road surface gradient and the limit value of the road surface gradient that are set corresponding to the vehicle speed. It is described that a restriction is provided when the acceleration conversion value Ggrad0 of the estimated gradient value obtained by subtracting the minutes becomes an inaccurate value due to the influence of the disturbance factor.

JP 2009-25081 A

  However, in the method of estimating the gradient by subtracting the time fluctuation of the wheel speed from the sensor value of the longitudinal acceleration sensor, when the wheel slips, the wheel speed and the actual vehicle speed deviate. There is a problem that it is impossible to estimate.

  Therefore, the present invention has been made in view of the above problems, and the object of the present invention is to perform gradient estimation with high accuracy even when a slip occurs on a wheel. It is an object of the present invention to provide a new and improved vehicle control apparatus and vehicle control method.

  In order to solve the above problems, according to an aspect of the present invention, a gradient estimation unit that estimates a gradient based on a longitudinal acceleration sensor value and an acceleration obtained from a change amount of wheel speed, and a torque of a motor that drives the vehicle A calculated acceleration calculation unit for calculating the calculated acceleration of the vehicle based on the vehicle speed, and the wheel speed based on the corrected calculated acceleration obtained by correcting the calculated acceleration with a gradient component acceleration corresponding to the gradient estimated by the gradient estimating unit. There is provided a control device for a vehicle, comprising: a change amount limiting unit that limits the amount of change.

  The change amount limiting unit may calculate the corrected calculated acceleration from a difference between the calculated acceleration and the gradient acceleration.

  The change amount limiting unit subtracts the gradient acceleration corresponding to the gradient estimated in the previous control cycle from the calculated acceleration calculated in the current control cycle to obtain the corrected calculated acceleration in the current control cycle. It may be what you want.

  Further, the calculated acceleration calculation unit may calculate the calculated acceleration based on the torque that is torque-down according to wheel slip.

  Further, the change amount limiting unit may limit the change amount based on a change amount limit value per unit time obtained by adding a correction value to the correction calculation acceleration.

  Further, the change amount limiting unit may limit the change amount when the change amount per unit time of the wheel speed is larger than the change amount limit value.

  In addition, when the driving force range of the motor is a low driving force range, the change amount limiting unit replaces the change amount limit based on the correction calculation acceleration, and sets a predetermined change amount limit value per unit time. The amount of change may be limited based on the above.

  Further, the change amount limiting unit may limit the change amount when the change amount per unit time of the wheel speed is larger than the change amount limit value.

  Further, the change amount limiting unit may limit the change amount based on a predetermined lower limit value when the wheel speed decreases.

  In order to solve the above problem, according to another aspect of the present invention, a step of estimating a gradient based on a longitudinal acceleration sensor value and an acceleration obtained from a change amount of a wheel speed, and a motor driving the vehicle The step of calculating the calculated acceleration of the vehicle based on the torque, and the amount of change in the wheel speed is limited based on the corrected calculated acceleration obtained by correcting the calculated acceleration with a gradient acceleration corresponding to the estimated gradient. A vehicle control method comprising the steps of:

  As described above, according to the present invention, it is possible to perform gradient estimation with high accuracy even when a slip occurs on a wheel.

It is a mimetic diagram showing the composition of the vehicles concerning one embodiment of the present invention. It is a schematic diagram which shows the main structures of the control apparatus of the vehicle which concerns on this embodiment. It is a schematic diagram which shows the structure of a gradient estimation part. It is a schematic diagram which shows the map used when a variation | limiting amount restriction | limiting part calculates variation | change_quantity restriction | limiting value Glimit. It is a flowchart which shows the basic processing of this embodiment. It is a flowchart which shows the process of FIG.5 S16 in detail. FIG. 6 is a characteristic diagram showing speed, acceleration, longitudinal acceleration sensor value Gs, and estimated gradient value when a four-wheel slip occurs during travel of the vehicle. It is a schematic diagram which shows a mode that torque reduction is performed.

  Exemplary embodiments of the present invention will be described below in detail with reference to the accompanying drawings. In addition, in this specification and drawing, about the component which has the substantially same function structure, duplication description is abbreviate | omitted by attaching | subjecting the same code | symbol.

  First, with reference to FIG. 1, the structure of the vehicle 500 which concerns on one Embodiment of this invention is demonstrated. FIG. 1 is a schematic diagram showing a configuration of a vehicle 500 according to an embodiment of the present invention. As shown in FIG. 1, a vehicle 500 controls the rotation of four tires (wheels) 12, 14, 16, and 18, a control device (controller) 1000, and tires 16 and 18 on the rear wheels. Two motors 20 and 22, drive shafts 24 and 26 that connect the motors 20 and 22 and the tires 16 and 18, a wheel speed sensor 28 that detects a wheel speed V from the rotation of the rear tires 16 and 18, 30, and includes a longitudinal acceleration sensor 36. Similarly to the rear wheels, the vehicle 500 includes two motors (drive units) that control the rotation of the front tires 12 and 14, a drive shaft that connects the motors and the tires 12 and 14, and each of the front wheels. A wheel speed sensor that detects the wheel speed from the rotation of the tires 12 and 14 is provided. The wheel speed V of each wheel is detected by the wheel speed sensor of each wheel. The vehicle 500 includes a power steering mechanism (P / S) 40, a steering angle sensor 42, and a steering 44 for operating the steering angles of the front wheels 12 and 14. As described above, the vehicle 500 is configured as an electric AWD (All Wheel Drive) vehicle that independently drives the four tires (12, 14, 16, 18).

  FIG. 2 is a schematic diagram showing a main configuration of the vehicle control apparatus 1000 according to the present embodiment. The control device 1000 includes a gradient estimation unit 100, an estimated vehicle body speed calculation unit 200, and a traction control unit 300.

  The gradient estimation unit 100 receives the wheel speed V, the motor torque value Tm, and the longitudinal acceleration sensor value Gs, estimates the road gradient, and outputs the acceleration Gr corresponding to the gradient. The estimated vehicle speed calculation unit 200 receives the longitudinal acceleration sensor value Gs and the acceleration Gr corresponding to the gradient, and calculates the estimated vehicle speed. The traction control unit 300 performs traction control based on the estimated vehicle body speed.

The gradient estimation unit 100 performs gradient estimation from the difference between the longitudinal acceleration sensor value Gs obtained from the longitudinal acceleration sensor 36 and the actual longitudinal acceleration (differential value of wheel speed) of the vehicle for traction control. The longitudinal acceleration sensor value Gs detected by the longitudinal acceleration sensor 36 includes the actual longitudinal acceleration of the vehicle and the acceleration corresponding to the gradient. Accordingly, the gradient estimation unit 100 calculates the difference between the longitudinal acceleration sensor value Gs obtained from the longitudinal acceleration sensor 36 and the actual longitudinal acceleration (differential value of the wheel speed V) of the vehicle based on the following equation (1). By obtaining the acceleration Gr corresponding to the gradient, the gradient is estimated. Assuming that the vehicle is slipping, the wheel speed V is the lowest of the four wheel speeds.
Gr acceleration Gr = longitudinal acceleration sensor value Gs−vehicle longitudinal acceleration (wheel speed differential value) dV / dt (1)

The gradient θ can be calculated from the following equation (2) based on the acceleration Gr for the gradient. In equation (2), g is the gravitational acceleration.
Gradient θ = sin ⁻¹ (Gr / g) (2)

  According to the above method, even if slip occurs in the vehicle, the wheel speed V is the lowest of the four wheel speeds, so that even one of the four wheels can be used. If there is a gripping wheel, the actual longitudinal acceleration of the vehicle (differential value of the wheel speed V) can be obtained from the wheel speed V of the wheel. Then, it is possible to estimate the gradient based on the actual longitudinal acceleration of the vehicle.

  However, when slip occurs in the four wheels, the wheel speed V deviates from the actual vehicle speed even if the lowest wheel speed of the four wheels is used as the wheel speed V. Therefore, it is difficult to estimate the gradient value by the above-described method. Specifically, when slip occurs on four wheels, even if the speed is the lowest of the four wheel speeds, a value greater than the value corresponding to the actual vehicle speed due to slipping due to slip. It becomes. Therefore, the actual longitudinal acceleration of the vehicle (differential value of the wheel speed) in the equation (1) cannot be obtained accurately. For this reason, in this embodiment, by providing a restriction on the amount of change in the wheel speed V, the gradient estimation using the equations (1) and (2) is performed with high accuracy.

  FIG. 3 is a schematic diagram illustrating a configuration of the gradient estimation unit 100. The gradient estimation unit 100 includes a calculated acceleration calculation unit 102, a change amount limiting unit 104, a differentiation unit 106, and a subtraction unit 108. In addition, the gradient estimation unit 100 includes a conversion unit 110 that converts the acceleration Gr corresponding to the gradient into the gradient θ using Equation (2). Since the wheel speed V deviates from the actual vehicle speed during the four-wheel slip, the gradient estimation unit 100 sets the acceleration variation limit value Glimit based on the calculated vehicle acceleration Gt calculated from the motor torque Tm. Then, the acceleration Gr for the gradient is estimated based on the change amount limit value Glimit. Each component of the control device 1000 shown in FIGS. 2 and 3 can be composed of a circuit (hardware) or a central processing unit such as a CPU and a program (software) for causing it to function. The program can be stored in a recording medium such as a memory.

Therefore, the calculated acceleration calculation unit 102 calculates the calculated acceleration Gt from the equation of motion based on the vehicle specifications such as the motor torque value Tm and the vehicle weight. Specifically, the calculated acceleration calculation unit 102 calculates the calculated acceleration Gt based on the following equation (3).
Gt = (Tm × reduction ratio / tire radius) / vehicle weight (3)

  The change amount restriction unit 104 calculates a change amount restriction value Glimit per unit time of the wheel speed using the calculated acceleration Gt. FIG. 4 is a schematic diagram showing a map used when the change amount limiting unit 104 calculates the change amount limit value Glimit, where the horizontal axis is calculated according to the calculated acceleration Gt, and the vertical axis is calculated according to the calculated acceleration Gt. The change amount limit value Glimit is shown. As shown in FIG. 4, the change amount limit value Glimit is calculated by adding the correction value A to the calculated acceleration Gt in the middle driving force range and the high and low driving force range (Glimit = Gt + A). In the low driving force range, the correction value B is set as the change amount limit value Glimit (Glimit = B). That is, in the low driving force range to the high and low driving force range, the larger one of “Gt + A” and “B” is set as the change amount limit value Glimit.

  As described above, when the change amount limit value Glimit is calculated, the change amount limit value Glimit is calculated by adding the correction value A to the calculated acceleration Gt over the entire driving force in consideration of robustness. If the calculated acceleration Gt is set as the change amount limit value Glimit, unnecessary driving force may be limited. However, by setting the value obtained by adding the correction value A to the calculated acceleration Gt as the change amount limit value Glimit, there is a margin. The degree can be secured and unnecessary driving force limitation can be prevented.

  Further, in the low driving force region, the correction value B assuming a steep downhill is used as the variation limit value Glimit. The correction value B is used assuming that the vehicle travels on a steep downhill in a low driving force range, for example. In such a situation, if the change amount limit value Glimit is reduced, a feeling of deceleration is given when going downhill, so the correction amount B is used to increase the change amount limit value Glimit. The correction value A and the correction value B can be determined by adaptation. By using the correction value A and the correction value B, it is possible to give a margin to the change amount limit value Glimit, and it is possible to suppress malfunction due to disturbance.

The following equation (4) is an equation used when the variation limiting unit 104 calculates the variation limiting value Glimit based on FIG. Then, the change amount restriction unit 104 calculates the wheel speed V ′ after the change amount restriction using the following equation (5). The calculation of the wheel speed V ′ is performed every control cycle (= Δt). In formula (4), the wheel speed V is the lowest among the four wheel speeds.
Glimit = MAX (Gt + A, B) (4)
V ′ = V ′ (previous value) + MAX (MIN (V−V ′ (previous value), Glimit × Δt), −Glm × Δt) (5)

  According to equation (5), when the difference between the wheel speed V (current value) and the wheel speed V ′ (previous value) is smaller than the product of the change amount limit value Glimit and the control period Δt, the wheel speed V ( The value obtained by adding the difference between the current value) and the wheel speed V ′ (previous value) to the wheel speed V ′ (previous value) is the current value of the wheel speed V ′. In this case, since the difference between the wheel speed V (current value) and the wheel speed V ′ (previous value) is small, the wheel speed V (current value) and the wheel speed V ′ are not limited by the change amount limit value Glimit. A value obtained by adding the difference from the (previous value) to the wheel speed V ′ (previous value) is the current value of the wheel speed V ′.

  Further, according to equation (5), when the difference between the wheel speed V (current value) and the wheel speed V ′ (previous value) is larger than the product of the change amount limit value Glimit and the control period Δt, the change amount A value obtained by adding the product of the limit value Glimit and the control cycle Δt to the wheel speed V ′ (previous value) is the current value of the wheel speed V ′. In this case, since the difference between the wheel speed V (current value) and the wheel speed V ′ (previous value) is large, a value obtained by adding the product of the variation limit value Glimit and the control cycle Δt to the wheel speed V ′ (previous value). Is the current value of the wheel speed V ′. Thereby, the wheel speed V ′ restricted by the variation limit value Glimit can be calculated.

  Further, according to the equation (5), either the difference between the wheel speed V (current value) and the wheel speed V ′ (previous value) or the product of the change amount limit value Glimit and the control period Δt is the deceleration side. When it is smaller than the product of the limit value (−Glm) and the control cycle Δt, a value obtained by adding −Glm × Δt to the wheel speed V ′ (previous value) is the current value of the wheel speed V ′. Thereby, it can suppress that the wheel speed V 'changes to the deceleration side excessively. By setting the decrease side limit value (−Glm) to an appropriate value, it is possible to suppress a sudden change in the estimated slope value due to, for example, a sudden grip recovery of the tire during slipping. Note that the value of Glm can be determined by adaptation and is a value larger than 0, but for example, Glm may be set to infinity.

By using the wheel speed V ′ after the change amount restriction, the expression (1) becomes the following expression (1) ′. The wheel speed V ′ calculated by the variation limiting unit 104 is sent to the differentiating unit 106, and the differentiating unit 106 time-differentiates the wheel speed V ′ to calculate dV ′ / dt. The differential value dV ′ / dt of the wheel speed V ′ is sent to the subtracting unit 108, and the subtracting unit 108 calculates the acceleration Gr for the gradient according to the equation (1) ′.
Gr = Gs−dV ′ / dt (1) ′

  Thus, even when the wheel speed V and the actual vehicle speed deviate during four-wheel slip, the acceleration Gr for the gradient is calculated from the equation (1) ′ using the wheel speed V ′ after the amount of change is limited. Therefore, the acceleration Gr corresponding to the gradient is not calculated based on the wheel speed V deviating from the vehicle body speed, and the gradient estimation can be performed with high accuracy.

The correction values A and B described above are set to relatively large values to ensure robustness, but the vehicle body calculated acceleration Gt obtained by subtracting the previous value Gr0 of the acceleration Gr corresponding to the gradient from the current value of the calculated acceleration Gt. By using 'for calculation of the variation limit value Glimit, it is possible to set relatively small correction values a and b. In this case, the variation limit value Glimit is calculated from the following equation (4) ′. The correction value a and the correction value b can be determined by adaptation.
Glimit = MAX (Gt ′ + a, b) (4) ′

In this case, as shown in FIG. 3, the acceleration Gr corresponding to the gradient calculated by the subtraction unit 108 from the expression (1) ′ is sent to the change amount limiting unit 104. The variation limiting unit 104 subtracts the acceleration Gr (previous value Gr0) for the gradient calculated in the previous control cycle from the calculated acceleration Gt calculated in the current control cycle based on the following equation (6). Then, the corrected calculated acceleration Gt ′ is calculated.
Gt ′ = Gt−Gr (6)

  Here, since the correction value a and the correction value b take into consideration only the robustness excluding the influence of the gradient, the values are small. That is, when the correction value a and the correction value b are used, since the gradient is not considered as a disturbance, the correction value a is smaller than the correction value A, and the correction value b is smaller than the correction value B. The assumed disturbance includes a gradient, unevenness of the road surface, modeling error, and the like. However, since the influence of the gradient is greatly related to the calculation of the change amount limit value Glimit, the change amount limit value Glimit is calculated by Expression (4). In this case, the correction value A and the correction value B are set to relatively large values as margins. On the other hand, the corrected calculated acceleration Gt ′ calculated by the equation (6) excludes the acceleration Gr corresponding to the gradient. Therefore, when calculating the variation limit value Glimit from the equation (4) ′, the gradient is disturbed. Therefore, the calculation accuracy of the change amount limit value Glimit can be increased, and the correction value a and the correction value b can be reduced. As a result, the change amount limit value Glimit can be obtained with higher accuracy, and the accuracy of gradient estimation can be improved. In addition to the gradient, the correction value a and the correction value b are provided although they are small values in order to consider the influence of the above-described modeling error and the like as disturbances.

  When the acceleration Gr for the gradient is calculated as described above, the estimated vehicle speed calculation unit 200 calculates the estimated vehicle speed based on the acceleration Gr for the gradient and the longitudinal acceleration sensor value Gs. Specifically, by removing the factor of the acceleration Gr corresponding to the gradient from the longitudinal acceleration sensor value Gs, the actual longitudinal acceleration of the vehicle can be obtained, and the estimated vehicle body speed can be obtained from the integrated value of the longitudinal acceleration.

  The traction control unit 300 performs traction control based on the estimated vehicle body speed. The traction control unit 300 reduces the torque of the motor torque that drives each wheel by traction control during four-wheel slip. For traction control during four-wheel slip, it is necessary to accurately estimate the vehicle body speed. On the other hand, since the longitudinal acceleration sensor value Gs includes the acceleration Gr corresponding to the gradient, in order to accurately estimate the vehicle body speed from the longitudinal acceleration sensor value Gs, highly accurate gradient estimation is important. In this embodiment, since the gradient estimation can be performed with high accuracy by the above-described method, the vehicle body speed during the slip can be accurately estimated. Therefore, the traction control unit 300 can accurately perform traction control based on the estimated vehicle body speed.

  The basic control by the traction control unit 300 when a slip occurs in the vehicle body is as follows. The traction control unit 300 determines how much the torque is reduced from the motor torque (requested torque) according to the accelerator opening of the driver, and whether the motor speed matches the target vehicle speed (target speed). (Feedback control) is used for calculation, and the obtained torque reduction amount is subtracted from the motor torque corresponding to the accelerator opening to output the final motor torque Tm. Here, the target rotational speed is a rotational speed obtained by multiplying the estimated vehicle body speed by an arbitrary slip ratio and converted to the rotational speed of the motor shaft. The motor rotation speed is a rotation speed obtained by converting the value of the motor rotation speed sensor or the wheel speed into the rotation speed of the motor shaft. The disturbance observer is a mechanism for monitoring (observing) input and output, measuring disturbances and fluctuations, and feeding back to the control system.

FIG. 8 is a schematic diagram showing how torque is reduced. The horizontal axis indicates the slip ratio, and the vertical axis indicates the required torque of the motor. The slip ratio on the horizontal axis can be expressed by the following equation (7). When the slip ratio = 0, the difference between the vehicle speed and the wheel speed is small, and when the slip ratio = 1, the difference between the vehicle speed and the wheel speed is large. As the vehicle body speed and the wheel speed, values converted into the rotation speed of the motor shaft can be used.
Slip ratio = (wheel speed−vehicle speed) / wheel speed (7)
The characteristics shown in FIG. 8 indicate the maximum driving force that can be output on the road surface in accordance with the slip ratio when the road surface friction coefficient is high and low. When the torque before torque reduction corresponds to P in FIG. 8, if the road surface friction coefficient is low, the slip ratio is large and the maximum driving force cannot be output. For this reason, torque reduction as shown by arrow A1 in the figure is performed, and the maximum driving force can be output by reducing the slip ratio to the target slip ratio.

  When slipping, the motor of each wheel is controlled based on the motor torque Tm that has been torque-down as described above. Further, the motor torque Tm after the torque reduction output from the traction control unit 300 is input to the gradient estimation unit 100 (calculated acceleration calculation unit 102) in order to estimate the acceleration Gr corresponding to the gradient.

  Next, processing performed in the present embodiment will be described based on the flowcharts of FIGS. 5 and 6. FIG. 5 is a flowchart showing the basic processing of this embodiment. Hereinafter, a case where the change amount limit value Glimit is calculated using the correction value a and the correction value b will be described. First, in step S10, the longitudinal acceleration sensor value Gs, the wheel speed V, and the actual motor torque Tm are acquired. In the next step S12, the previous value Gr0 of the acceleration Gr corresponding to the gradient is acquired.

  In the next step S14, a calculated acceleration Gt 'is calculated based on the equation (6). In the next step S16, the wheel speed V 'after limiting the amount of change is calculated based on the equations (4)' and (5). In the next step S18, a differential value dV '/ dt of the wheel speed V' is calculated. In the next step S20, the acceleration Gr for the gradient is calculated based on the equation (1) '. In the next step S22, the gradient θ is calculated from the acceleration Gr based on the equation (2).

  FIG. 6 is a flowchart showing in detail the process in step S16 in FIG. First, in step S30, an increase side change amount limit value Glimit is calculated. In the next step S32, a change amount limit value Glm on the deceleration side is calculated. The deceleration side limit value can be a predetermined value. In the next step S34, the previous value V'0 of the wheel speed V 'after the change amount restriction is acquired.

  In the next step S36, a value f1 is calculated by subtracting the previous value V'0 of the wheel speed V 'after the change amount restriction from the current value of the wheel speed V. In the next step S38, a value f2 obtained by multiplying the change amount limit value Glimit by the control period Δt is calculated.

  In the next step S40, it is determined whether or not f1 <f2. If f1 <f2, the process proceeds to step S42. In step S42, f3 = f1. On the other hand, if f1 ≧ f2 in step S40, the process proceeds to step S44, where f3 = f2. After steps S42 and S44, the process proceeds to step S46.

  In step S46, a value f4 obtained by multiplying the change amount limit value (−Glm) by the control period Δt is calculated. In the next step S48, it is determined whether or not f3> f4. If f3> f4, the process proceeds to step S50, where f5 = f3. On the other hand, if f3 ≦ f4 in step S48, the process proceeds to step S52, where f5 = f4. After steps S50 and S52, the process proceeds to step S54 where V '= V'0 + f5. With the above processing, the processing described in the equation (5) is executed, and the wheel speed V ′ after the change amount restriction is calculated.

  FIG. 7 is a characteristic diagram showing the speed, acceleration, longitudinal acceleration sensor value Gs, and estimated gradient value when a four-wheel slip occurs when the vehicle 500 is running. In FIG. 7, tires 12, 14, 16, and 18 are gripped until time t0, and four wheel slips occur after time t0. FIG. 7 shows a case where it is estimated that there is a slope when a four-wheel slip occurs when there is no slope on the road surface.

  In the speed characteristics of FIG. 7, the two-dot chain line indicates the wheel speed V, the one-dot chain line indicates the estimated vehicle speed when the amount of change is limited using the correction value A and the correction value B, and the broken line indicates the correction value a and correction. The estimated vehicle speed when the amount of change is limited using the value b is shown, and the solid line shows the actual vehicle speed.

  In the acceleration characteristics of FIG. 7, the two-dot chain line indicates the wheel speed V ′ when the change amount is limited using the differential value dV / dt of the wheel speed V, and the one-dot chain line indicates the correction value A and the correction value B. The differential value dV ′ / dt, the broken line indicates the differential value dV ′ / dt of the wheel speed V ′ when the change amount is limited using the correction value a and the correction value b, and the solid line indicates the actual vehicle acceleration. Show.

  In the gradient value characteristics of FIG. 7, the alternate long and two short dashes line indicates the gradient value estimated using the differential value dV / dt of the wheel speed V, and the alternate long and short dash line uses the correction value A and the correction value B to limit the amount of change. The gradient value estimated when it is performed, the broken line indicates the gradient value estimated when the amount of change is limited using the correction value a and the correction value b, and the solid line indicates the actual gradient.

  As shown in the speed characteristics of FIG. 7, the wheel speed V increases due to slip, but the estimated vehicle speed estimated using the correction values A and B is smaller than the wheel speed V. Further, the estimated vehicle body speed estimated using the correction values a and b is smaller than that estimated using the correction values A and B, and is closer to the actual vehicle speed. Also in the characteristics of acceleration, the acceleration (differential value of speed) obtained when the correction values A and B are used is smaller than the acceleration obtained from the wheel speed V. Further, the acceleration obtained when the correction values a and b are used is closer to the actual acceleration than when the correction values A and B are used.

  Further, as shown in the characteristic of the gradient value, when a four-wheel slip is generated, if the gradient value is estimated using the differential value dV / dt of the wheel speed V, the vehicle is traveling on a road surface that originally has no gradient. Even in this case, since a relatively large gradient value is estimated, an error in gradient estimation becomes large. On the other hand, the gradient value estimated using the correction values A and B is smaller than the gradient value estimated using the differential value dV / dt of the wheel speed V. In addition, the gradient value estimated using the correction values a and b is closer to the actual gradient than when the correction values A and B are used. Therefore, according to the present embodiment, it is possible to significantly improve the accuracy of the gradient estimation by limiting the change amount of the wheel speed V ′ based on the change amount limit value Glimit.

  As described above, according to the present embodiment, when the gradient is estimated from the difference between the longitudinal acceleration sensor value Gs and the longitudinal acceleration of the vehicle obtained from the change amount of the wheel speed (the differential value dV / dt of the wheel speed). Since the change amount of the wheel speed is limited based on the calculated acceleration Gt of the vehicle, the gradient can be estimated with high accuracy even when the wheel speed V and the actual vehicle speed are different during the slip. It becomes possible.

  The preferred embodiments of the present invention have been described in detail above with reference to the accompanying drawings, but the present invention is not limited to such examples. It is obvious that a person having ordinary knowledge in the technical field to which the present invention pertains can come up with various changes or modifications within the scope of the technical idea described in the claims. Of course, it is understood that these also belong to the technical scope of the present invention.

DESCRIPTION OF SYMBOLS 1000 Control apparatus 100 Gradient estimation part 104 Change amount restriction | limiting part 200 Calculation acceleration calculating part

Claims (10)

A gradient estimator that estimates a gradient based on the longitudinal acceleration sensor value and the acceleration obtained from the amount of change in wheel speed;
A calculated acceleration calculation unit for calculating the calculated acceleration of the vehicle based on the torque of the motor driving the vehicle;
A variation limiting unit that limits the amount of change in the wheel speed based on a corrected calculated acceleration obtained by correcting the calculated acceleration with a gradient component acceleration corresponding to the gradient estimated by the gradient estimating unit;
A vehicle control device comprising:   The vehicle control device according to claim 1, wherein the change amount limiting unit calculates the corrected calculated acceleration from a difference between the calculated acceleration and the gradient acceleration.   The change amount limiting unit obtains the corrected calculated acceleration in the current control cycle by subtracting the acceleration corresponding to the gradient estimated in the previous control cycle from the calculated acceleration calculated in the current control cycle. The vehicle control device according to claim 2, wherein:   The vehicle control device according to any one of claims 1 to 3, wherein the calculated acceleration calculation unit calculates the calculated acceleration based on the torque that is torque-down according to a slip of a wheel.   The change amount limiting unit limits the change amount based on a change amount limit value per unit time obtained by adding a correction value to the correction calculation acceleration. The vehicle control device according to any one of the above.   The vehicle according to claim 5, wherein the change amount restriction unit restricts the change amount when a change amount per unit time of the wheel speed is larger than the change amount restriction value. Control device.   When the driving force range of the motor is a low driving force range, the change amount limiting unit is based on a predetermined change amount limit value per unit time instead of the change amount limit based on the corrected calculation acceleration. The vehicle control device according to claim 1, wherein the amount of change is limited.   8. The vehicle according to claim 7, wherein the change amount restriction unit restricts the change amount when a change amount per unit time of the wheel speed is larger than the change amount restriction value. Control device.   8. The vehicle control device according to claim 1, wherein when the wheel speed decreases, the change amount restriction unit restricts the change amount based on a predetermined lower limit value. 9. . Estimating the gradient based on the longitudinal acceleration sensor value and the acceleration determined from the amount of change in wheel speed;
Calculating a calculated acceleration of the vehicle based on a torque of a motor driving the vehicle;
Limiting the amount of change in the wheel speed based on a corrected calculated acceleration obtained by correcting the calculated acceleration with a gradient acceleration corresponding to the estimated gradient;
A vehicle control method comprising:

Images