JP5141565B2 - Driving force control device - Google Patents

Description

  The present invention relates to a driving force control apparatus.

  For example, Patent Document 1 to Patent Document 7 are known as conventional techniques related to vehicle driving force control and the like. Patent Document 1 discloses an invention related to a vehicle steering control device that eliminates a difference between a standard yaw rate obtained from navigation information and an actual yaw rate by steering control. Patent Document 2 discloses an invention relating to a lane departure prevention device that changes the forward gazing distance according to the vehicle speed. Patent Document 3 discloses an invention related to a vehicle driving force distribution control device that distributes driving force before the start of turning. Patent Document 4 discloses an invention relating to a vehicle motion control device including means for obtaining curve information and means for generating a yaw moment by applying braking force to predetermined wheels. Patent Document 5 discloses an invention relating to a driving support device that determines a driving skill from a distribution state of brake operation start points.

  In Patent Document 6, the behavior (slip) of a vehicle is monitored during traveling, and when there is a behavior, information related to the behavior (slip coefficient of the road surface) is stored together with map information of the navigation device. Then, when passing the same point next time, an invention relating to a vehicle control device that reads previously stored information and reflects the information on vehicle stabilization (front and rear wheel driving force distribution of a four-wheel drive vehicle) is disclosed. ing. In Patent Document 7, when the four-wheel drive vehicle repeats acceleration / deceleration or when the four-wheel drive vehicle repeatedly curves or runs straight, the restraining force of the driving force transmission device is given priority over the four-wheel drive tendency mode. The invention relating to a driving force distribution control device and the like for a four-wheel drive vehicle that is controlled in this manner is disclosed.

JP 2000-118423 A JP 2004-341610 A JP 2006-232100 A Japanese Patent No. 3850530 JP 2007-133486 A JP 2002-219957 A JP 2003-31295 A

  However, the conventional left / right driving force distribution control reduces the response time of the vehicle after the driver's operation is performed, and the conventional left / right driving force distribution control takes into account the driver's operation delay and the like. There was a problem that it was not.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a driving force control device that can distribute driving force to each wheel in consideration of a driver's operation delay and the like.

  In order to solve the above-described problems and achieve the object, the driving force control device according to the present invention obtains the current and the previous corner curvature from the map information, calculates the reference yaw rate respectively, and operates the driver's steering wheel The yaw rate desired by the driver is calculated from the above, the yaw rate currently generated in the vehicle is obtained, the necessary yaw moment is obtained from the difference between each of these three yaw rates, and the current vehicle state is determined as an argument for the necessary yaw moment. The sum of the product of the weighting factors is used as the required yaw moment due to the driving force difference, and the driving force of each wheel is obtained from the required yaw moment.

  According to this invention, there is an effect that the driving force can be distributed to each wheel in consideration of the operation delay of the driver.

FIG. 1 is a block diagram illustrating an example of a configuration of a vehicle according to the present embodiment. FIG. 2 is a block diagram showing another example of the configuration of the vehicle according to the present embodiment. FIG. 3 is a flowchart illustrating an example of the driving force control process. FIG. 4 is a flowchart showing an example of processing for acquiring / estimating future map information. FIG. 5 is a diagram illustrating an example of a relationship between road information, a reference vehicle speed, and a reference time. FIG. 6 is a flowchart illustrating an example of processing for determining a driver's skill. FIG. 7 is a map showing an example of the relationship between the integrated value and the skill correction coefficient. FIG. 8 is a flowchart illustrating an example of processing for determining a weighting factor.

  Embodiments of a driving force control apparatus according to the present invention will be described below in detail with reference to the drawings. Note that the present invention is not limited to the embodiments.

[1. Constitution]
A configuration of a vehicle according to the present embodiment including a driving force control apparatus according to the present invention will be described with reference to FIGS. 1 and 2. The vehicle according to the present embodiment can distribute the driving force between the left and right wheels at the front wheels or the rear wheels, and can read map information using GPS or the like.

  First, an example of the configuration of the vehicle according to the present embodiment will be described with reference to FIG. FIG. 1 is a block diagram illustrating an example of a configuration of a vehicle according to the present embodiment.

  In FIG. 1, reference numeral 1 is a left front wheel, reference numeral 2 is a right front wheel, reference numeral 3 is a left rear wheel, and reference numeral 4 is a right rear wheel. In FIG. 1, reference numeral 5 denotes a left front motor, reference numeral 6 denotes a right front motor, reference numeral 7 denotes a left rear motor, and reference numeral 8 denotes a right rear motor. In FIG. 1, reference numeral 9 is a vehicle ECU, reference numeral 10 is a motor ECU, reference numeral 11 is a stearin device, reference numeral 12 is a G / yaw rate sensor, and reference numeral 13 is a navigation ECU.

  The vehicle ECU 9 is an electronic control unit including the driving force control device according to the present invention. The motor ECU 10 is an electronic control unit that controls the left front motor 5, the right front motor 6, the left rear motor 7, and the right rear motor 8. The steering device 11 is a device for steering the left front wheel 1 and the right front wheel 2. The steering device 11 includes a steering angle sensor that detects a steering angle and a torque sensor that detects torque. The G / yaw rate sensor 12 is a sensor that detects lateral acceleration and yaw rate. The navigation ECU 13 is an electronic control unit that controls a navigation system mounted on the vehicle.

  Next, another example of the configuration of the vehicle according to the present embodiment will be described with reference to FIG. FIG. 2 is a block diagram showing another example of the configuration of the vehicle according to the present embodiment. Note that the description of the same components as those shown in FIG. 1 among the components shown in FIG. 2 may be omitted.

  In FIG. 2, reference numeral 14 is E / G · T / M, reference numeral 15 is a left / right driving force distribution differential, and reference numeral 16 is a differential ECU.

  E / G · T / M14 is an engine and a transmission. The left / right driving force distribution differential 15 is a differential gear that distributes the driving force to the left wheel and the right wheel. The differential ECU 16 is an electronic control unit that controls the left / right driving force distribution differential 15.

[2. processing]
An example of the driving force control process performed by the vehicle ECU 9 having the above-described configuration will be described in detail with reference to FIGS. FIG. 3 is a flowchart illustrating an example of the driving force control process.

First, the vehicle ECU 9 reads the steering wheel operation information of the driver, and calculates the required yaw rate “γ _ref ” from the driver's operation defined by Formula A1 with the steering angle of the driver as “θ” (step SA1). . In Formula A1, “V” is the vehicle speed, “kh” is the stability factor, “L” is the wheel base, “τ” is the delay time constant, “s” is the Laplace operator, and “n” is the steering gear ratio. .

Next, the vehicle ECU 9 reads the current map information, and calculates the requested yaw rate “γ _course ” from the current map information defined by Formula A2 with the current turning curvature as “1 / R _course ” (step SA2). ). In Formula A2, “V” is the vehicle speed, and “R _course ” is the current turning radius obtained from the current map information.
γ _course = V / R _course (Formula A2)

Next, the vehicle ECU 9 reads the future map information, and calculates the requested yaw rate “γ _coursehat ” from the future map information defined by Formula A3 with the future turning curvature as “1 / R _coursehat ” (step SA3). ). In Formula A3, “V _hat ” is the future vehicle speed, and “R _coursehat ” is the future turning radius from the future map information. Here, an example of a process for acquiring / estimating future map information will be described with reference to FIGS. FIG. 4 is a flowchart showing an example of processing for acquiring / estimating future map information.
γ _coursehat = V _hat / R _coursehat (Formula A3)

  First, the vehicle ECU 9 reads the current vehicle speed “V” (step SB1).

  Next, the vehicle ECU 9 reads current road information (for example, a highway, a city area, a main road, etc.) from the navigation information (step SB2).

  Next, the vehicle ECU 9 sets the reference vehicle speed and the reference time based on the road information read in step SB2 and the preset table shown in FIG. 5 (step SB3). FIG. 5 is a diagram illustrating an example of a relationship between road information, a reference vehicle speed, and a reference time.

Next, the vehicle ECU 9 sets the future distance defined by Formula B1 based on the reference vehicle speed and the reference time set in Step SB3 (Step SB4). Expression B1 is an expression when the road information is “general high speed” shown in FIG. 5. In Expression B1, “V _hi ” is a reference vehicle speed, and “T _hi ” is a reference time.

Next, the vehicle ECU 9 corrects the future distance set in step SB4 based on the ratio of the reference vehicle speed set in step SB3 and the actual vehicle speed read in step SB1 according to the formula B2 (step SB5). Expression B2 is an expression when the road information is “general high speed” shown in FIG. 5, where “V” is the actual vehicle speed and “V _hi ” is the reference vehicle speed.
Future distance after vehicle speed correction = future distance × (V / V _hi ) (Formula B2)

  Next, the vehicle ECU 9 calculates a skill correction coefficient “k” based on the travel history (step SB6). Here, an example of processing for determining the skill of the driver will be described with reference to FIGS. 6 and 7. FIG. 6 is a flowchart illustrating an example of processing for determining a driver's skill.

First, the vehicle ECU 9 determines whether or not the calculation is the first time. If the calculation is the first time (step SC1: Yes), the vehicle ECU 9 initializes the integrated value “Adddltr” and the skill correction coefficient “k” (step SC2). Specifically, the integrated value “Addtltr” is cleared (the integrated value “Addlttr” is set to zero), and the skill correction coefficient “k” is set to the initial value “1”. If the calculation is not the first time (step SC1: No), the vehicle ECU 9 reads the current actual yaw rate “γ” and the requested yaw rate “γ _req ” (step SC3).

Next, the vehicle ECU 9 obtains the yaw rate deviation “Δγ” defined by Formula C1, and if the absolute value “| Δγ |” of the yaw rate deviation “Δγ” is equal to or greater than a predetermined threshold “dltrth” (step SC4: Yes). The absolute value “| Δγ (n) |” of the yaw rate deviation obtained this time is added to the previous integrated value “Addltr (n−1)”, and the current integrated value “Addtltr (n) defined by the formula C2 is added. "Is calculated (step SC5). In the formula C2, “n” is an integer value indicating a calculation cycle.
Δγ = γ _req −γ (Formula C1)
Addtltr (n) = Adddltr (n−1) + | Δγ (n) |
... (Formula C2)

  Next, the vehicle ECU 9 calculates (determines) the skill correction coefficient “k” based on the map shown in FIG. 7 using the integrated value “Addtltr” calculated in step SC5 as an argument (step SC6). FIG. 7 is a map showing an example of the relationship between the integrated value and the skill correction coefficient.

  Further, if the absolute value “| Δγ |” of the yaw rate deviation is not equal to or greater than the predetermined threshold value “dltrth” (step SC4: No), the vehicle ECU 9 determines that the absolute value “| Δγ |” of the yaw rate deviation is a predetermined value. It is determined whether or not the threshold “dltrth” is not more than the predetermined time “T” seconds. If not (step SC7: No), it is determined that the skill of the driver is improved (stable). First, the integrated value “Addlttr” is held as it is, and the skill correction coefficient “k” is also used as it is (step SC8). Further, if the absolute value “| Δγ |” of the yaw rate deviation is not equal to or greater than the predetermined threshold value “dltrth” for a predetermined time “T” seconds (step SC7: Yes), the vehicle ECU 9 determines the driver's skill. Is improved (stable), and the integrated value “Addtltr” and skill correction coefficient “k” are initialized (step SC9). Specifically, the integrated value “Addtltr” is cleared (the integrated value “Addlttr” is set to zero), and the skill correction coefficient “k” is set to the initial value “1”. This completes the description of the process for determining the skill of the driver.

Returning to FIG. 4, the vehicle ECU 9 calculates the future distance after the vehicle speed correction based on the future distance after the vehicle speed correction after the correction at step SB5 and the skill correction coefficient “k” calculated at the step SB6. Correction is performed according to B3 (step SB7). That is, when the driver's skill is low, the future distance is corrected to be longer.
Future distance after driver skill correction = k x Future distance after vehicle speed correction (Formula B3)

  Then, the vehicle ECU 9 acquires / estimates future map information based on the future distance after the driver skill correction that is the future distance after the vehicle speed correction after the correction at step SB7. This completes the description of the process of acquiring / estimating future map information.

Returning to FIG. 3, the vehicle ECU 9 reads the yaw rate “γ _cur ” currently generated in the vehicle (step SA4).

Next, the vehicle ECU 9 determines the deviation “Δγ _ref ” between the required yaw rate “γ _ref ” and the yaw rate “γ _cur ” defined by Formula A4, the required yaw rate “γ _course ” and the yaw rate “γ _cur ” defined by Formula A5. and deviation of the "[Delta] [gamma] _course" and request yaw rate _"γ coursehat" defined by the equation A6 and calculates a deviation _"Δγ coursehat" yaw rate "gamma _cur", from the deviation of the calculated respectively according to the method of calculating the following required yaw moment _{"M θ",} calculates the _{"M course"} and _{"M coursehat"} (step SA5).
Δγ _ref = γ _ref −γ _cur (Equation A4)
Δγ _course = γ _course −γ _cur (Equation A5)
_{Δγ coursehat} = γ _coursehat− γ _cur (formula A6)

-Calculation method-
First, a transfer function between a yaw rate generated by steering and a yaw rate generated by a yaw moment caused by a driving force difference is shown in Formula A7. In Formula A7, “G _γθ (0)” is defined by Formula A8, “G _γM (0)” is defined by Formula A9, and “T _γθ ” is defined by Formula A10. , “T _γM ” is defined by Formula A11, “ξ” is defined by Formula A12, “ω _n ” is defined by Formula A13, “θ” is the steering angle, and “s” is Laplace operator, “n” is the steering gear ratio. In the formulas A8 to A13, “kh” is defined by the formula A14. In Formulas A8 to A14, “m” is the vehicle body mass, “I” is the yaw moment of inertia, “K _f ” is the front tire Cp, “L _f ” is the distance from the center of gravity to the front axis, and “K _r ” _. "L" is the rear tire Cp, " _Lr " is the distance from the center of gravity to the rear axis, and "L" is the wheel base.

Here, if “γ” in Expression A7 is “γ _ref ”, “Δγ _ref ” can be expressed in the form of Expression A15. The same _{applies to} “ _{Δγ course} ” and “ _{Δγ course hat} ”.

Then, when the mathematical formula A15 is solved for the moment “M (s)”, the necessary yaw moment “M _θ ” is obtained. The same applies to the necessary yaw moments “M _course ” and “M _{course hat} ”.

Next, the vehicle ECU 9 determines the weight coefficient “i” of the necessary yaw moment “M _θ ” obtained in step SA6, the weight coefficient “j” of the necessary yaw moment “M _course ”, and the weight coefficient of the necessary yaw moment “M _coursehat ”. “K” is calculated (determined) (step SA6). The weight coefficients “i”, “j”, and “k” satisfy the expression “i + j + k = 1”. Here, an example of processing for determining the weighting coefficient will be described with reference to FIG. FIG. 8 is a flowchart illustrating an example of processing for determining a weighting factor.

First, the vehicle ECU 9 calculates the current center-of-gravity point slip angular velocity “dβ” based on the mathematical formula D1 (step SD1). In Formula D1, “Gy” is the lateral acceleration, “V” is the vehicle body speed, and “γ” is the yaw rate.
dβ = (Gy / V) −γ (Equation D1)

Next, the vehicle ECU 9 estimates the future actual yaw rate “γ _hatvh ” from the current actual yaw rate “γ” of the vehicle based on the equation D2 (step SD2).

Next, the vehicle ECU 9 compares the center-of-gravity point slip angular velocity “dβ” calculated in step SD1 with a predetermined threshold value “dβth” to determine whether or not Formula D3 is satisfied (absolute value of center-of-gravity point slip angular velocity “| If dβ | ”is less than the absolute value“ | dβth | ”of the threshold value, and if Formula D3 is not satisfied (step SD3: No), the vehicle is very unstable and the vehicle is kept on the course. _{Therefore, the} weighting factor “i” multiplied by the yaw moment “M _θ ” required from the steering angle and the weighting factor “k” multiplied by the yaw moment “M _coursehat ” required from the future course are set to 0 (step SD4). ). Note that the weighting factor “j” multiplied by the yaw moment “M _course ” required from the current course is 1 from the formula “i + j + k = 1”.
| Dβ | <| dβth | (Formula D3)

Further, if Formula D3 is satisfied (step SD3: Yes), the vehicle ECU 9 deviates from the current yaw rate “γ _course ” from the current map information and the actual yaw rate “γ” of the current vehicle and a predetermined threshold “dγth”. ”And whether or not Formula D4 is satisfied (the absolute value“ | γ _course −γ | ”of the deviation between the requested yaw rate from the current map information and the actual yaw rate of the current vehicle is less than the threshold“ dγth ”) If the formula D4 is satisfied (step SD5: Yes), the vehicle is stable, so that it is required from the current course to reflect the driver's intention to the maximum. that the yaw moment _{"M course"} weighting factor applied to the "j" and the weighting factor applied to the yaw moment _{"M coursehat"} that is required from the future of the course "k A is set to 0 (step SD6). Note that the weighting factor “i” to be applied to the yaw moment “M _θ ” required from the steering angle is 1 from the formula “i + j + k = 1”.
| Γ _course −γ | <dγth (Formula D4)

Further, if Formula D4 is not satisfied (step SD5: No), the vehicle ECU 9 may cause the vehicle to deviate from the course. Therefore, the weight coefficient “i” to be multiplied by the yaw moment “M _θ ” required from the steering angle. Is set to 0 (step SD7). The weighting factor “j” to be multiplied by the yaw moment “M _course ” required from the current course and the weighting factor “k” to be multiplied from the yaw moment “M _coursehat ” required from the future course are expressed by the equation “i = 0”. ”And the formula“ i + j + k = 1 ”, the formula“ j + k = 1 ”is satisfied.

  Next, the vehicle ECU 9 is a predetermined map using as arguments the deviation between the yaw rate required from the current course and the yaw rate of the current vehicle, and the deviation between the yaw rate required from the future course and the deviation of the current yaw rate of the vehicle, Also, the weighting factors “j” and “k” are determined from the equation “j + k = 1” (step SD8). This is the end of the description of the process for determining the weighting factor.

Returning to FIG. 3, the vehicle ECU 9 determines that the necessary yaw moments “M _θ ”, “M _course ” and “M _coursehat ” calculated in step SA5 and the weight coefficients “i”, “j” and “k” calculated in step SA6. Based on the above, the yaw moment sum “M _all ” defined by Formula A16 is obtained (step SA7).
M _all = i × M _θ + j × M _course + k × M _coursehat (Formula A16)

Next, the vehicle ECU 9 obtains the driving force of each wheel from the yaw moment sum “M _all ” calculated in step SA7 (step SA8). Here, when the driving force of the right wheel is “F _r ” and the driving force of the left wheel is “F _l ”, Formula A17 is established for the yaw moment sum “M _all ”, and the required driving force “F _all ” for the left and right wheels is established. Formula A18 is established for “. From these equations, the driving force “F _r ” for the right wheel is obtained in the form of Equation A19, and the driving force “F _l ” for the left wheel is obtained in the form of Equation A20. In Expressions A17, A19, and A20, “T _r ” is the tread width. This ends the description of the driving force control process.
M _all = T _r (F _r −F _l ) / 2 (Formula A17)
F _all = F _r + F _l (Equation A18)
F _r = F _all / 2 + M _all / T _r (Equation A19)
F _l = F _all / 2-M _all / T _r (Equation A20)

[3. Summary of this embodiment]
As described above, according to the present embodiment, the current and the other corner curvatures are obtained from the map information, the standard yaw rate is calculated for each, the driver's steering operation is used to calculate the yaw rate desired by the driver, and the current vehicle is generated. The required yaw moment is calculated from the difference between each of these three yaw rates, and the sum of the required yaw moment multiplied by the weighting factor determined with the current vehicle state as an argument is used as the required yaw rate based on the driving force difference. The driving force of each wheel is obtained from the required yaw moment. As a result, the driving force can be distributed to each wheel in consideration of the operation delay of the driver.

  Further, according to the present embodiment, the future time for acquiring / estimating the future map information is determined from the current vehicle speed, the current road information, and the driver skill estimated from the past driving history, A future distance is predicted from the future time, and the map information is referenced. Thereby, appropriate future map information can be acquired / estimated.

  Further, according to the present embodiment, an integrated value of deviation of the requested yaw rate is obtained from the past driving history, and the driver skill is determined from the integrated value. As a result, the driver skill can be determined accurately.

  As described above, the driving force control apparatus according to the present invention can be preferably implemented particularly in the automobile manufacturing industry and is extremely useful.

9: Vehicle ECU
10: Motor ECU
11: Steering device 12: G / yaw rate sensor 13: Navigation ECU
16: Differential ECU

Claims (3)

From the map information, obtain the current and previous corner curvatures, calculate the normative yaw rate for each, calculate the yaw rate desired by the driver from the driver's steering wheel operation, find the current yaw rate generated in the vehicle, these three The required yaw moment is obtained from each difference in yaw rate, and the sum of the required yaw moment multiplied by the weighting factor determined using the current vehicle state as an argument is used as the required yaw moment due to the driving force difference. A driving force control device characterized by obtaining the driving force of the motor. The future time for acquiring / estimating the map information in the future is determined from the current vehicle speed, the current road information, and the driver skill inferred from the past driving history, and the future distance is predicted from the future time. The driving force control apparatus according to claim 1, wherein the map information is referred to. The driving force control apparatus according to claim 2, wherein an integrated value of deviations of the requested yaw rate is obtained from a past driving history, and the driver skill is determined from the integrated value.

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