JP2010018127A - Vehicle driving force control device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a device capable of controlling a driving force while quickly reflecting a driver's intention to make a turn. <P>SOLUTION: This vehicle driving force control device calculates a desired yaw rate on the basis of a steering angle which is the amount that a steering device is operated and of steering torque corresponding to a twist angle occurring at a steering device, and controls wheel driving forces so that a yaw rate generated in the vehicle approaches the desired yaw rate. The control device includes a correction means (step S3) for correcting the steering torque if the steering angle varies in a range within which steering direction is not changed and if the value of the steering torque is changed from positive to negative or vice versa as the steering angle varies, and a desired yaw rate calculation means (step S6) for calculating the desired yaw rate by use of the steering torque corrected. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an apparatus for controlling a driving force of a vehicle, and more particularly to an apparatus for controlling a driving force so as to control a yaw of a vehicle, and more particularly to an apparatus for obtaining a target yaw rate.

  The yaw of a vehicle is caused by steering the wheel or receiving a lateral force due to a crosswind or inclination, and the yaw rate depends not only on the steering angle of the steered wheels but also on the driving force distribution of the left and right wheels and front and rear wheels Change. Therefore, conventionally, in order to improve the motion performance and behavioral stability of the vehicle, a target yaw rate is obtained and the driving force is controlled so that the vehicle turns along the target yaw rate.

  Since the target yaw rate expresses the intention of turning as the driver turns the steering wheel as a target value of the behavior of the vehicle, it is generally obtained based on a physical quantity generated by operating the steering wheel. is there. For example, in the apparatus described in Patent Document 1, the target yaw rate is obtained based on the steering torque.

JP 2002-37106 A

  A steering system that is a steering mechanism from a steering wheel to a steered wheel constitutes a two-degree-of-freedom torsional vibration system including a steering shaft and a gear box. Therefore, when steering torque acts on the steering wheel, reaction torque resulting from friction between the tire and the road surface is generated, and thus steering torque is generated in the steering system. The device described in Patent Document 1 is a device configured to reflect the steering torque generated in this way on the target yaw rate. However, when the steering angle is large, a control delay may occur. is there.

  That is, when the steering angle is large, the steering torque for calculating the target yaw rate also increases. Therefore, when the steering direction is changed, for example, when the steering wheel is turned back up after being greatly turned up, the steering torque associated with the immediately preceding steering is controlled. Remains as a value. The control value is opposite to the control direction of the steered angle when switching back, and the calculated target yaw rate is different from what the driver intended or expected, and eventually the steering angle is large. In some cases, the driver's intention to steer may not necessarily reflect well.

  The present invention has been made paying attention to the above technical problem, and an object of the present invention is to provide a driving force control device capable of reflecting the driver's intention to turn in the behavior of the vehicle more quickly. .

  In order to achieve the above object, the invention according to claim 1 determines the target yaw rate based on the steering angle which is the operation amount of the steering device and the steering torque corresponding to the twist angle generated in the steering device, and generates the yaw rate generated in the vehicle. In the vehicle driving force control device that controls the driving force of the wheel so that the steering yaw rate approaches the target yaw rate, the steering angle changes in a range where the steering direction does not change and the value of the steering torque for obtaining the target yaw rate A correction means for correcting the value of the steering torque, and a target yaw rate calculation means for calculating the target yaw rate using the corrected steering torque value when the sign is reversed as the steering angle changes. It is characterized by having.

  According to a second aspect of the present invention, in the first aspect of the present invention, the correction means reduces the steering torque value for calculating the target yaw rate before the sign of the steering torque is reversed, and after the reversal, A driving force control apparatus for a vehicle including a means for enlarging.

  According to a third aspect of the present invention, in the first aspect of the invention, the correction means increases the value of the steering torque for calculating the target yaw rate and increases the steering angle to zero when increasing the steering angle. The vehicle driving force control device includes means for reducing a steering torque value for calculating the target yaw rate at the time of returning.

  The invention of claim 4 is characterized in that, in the invention of any one of claims 1 to 3, the correction means is configured to perform the correction when the steering angle is larger than a predetermined angle. This is a driving force control device for a vehicle.

  According to the present invention, when the target yaw rate is obtained, the target yaw rate is calculated in consideration of the steering torque in addition to the steering angle, and therefore, an appropriate target yaw rate can be calculated with less influence of the twist angle of the steering device. The steering performance or the behavior of the vehicle can be obtained according to the intention of the person. The steering torque can be determined in advance corresponding to the twist angle. When the steering angle is large, the target yaw rate is increased. On the contrary, when the steering angle is small, the steering angle is The target yaw rate obtained based on the value can be reduced. That is, the value of the steering torque may change between positive and negative within the range where the steering angle is positive or negative or the calculated steering direction is not switched. Such a state occurs when the steering angle is reduced after a large steering operation, or when the steering angle is greatly increased in the middle of the switching back. In that case, when the steering direction is reversed, a steering torque value based on the previous steering state is generated, and this causes a yaw in a direction opposite to the yaw corresponding to the determined steering direction. ing. That is, since the effect of the previous steering remains, the correction means corrects the steering torque to correct this, and as a result, the target yaw rate is determined so that the vehicle behaves in accordance with the driver's intention.

  In particular, according to the second aspect of the present invention, when the sign of the steering torque is reversed by increasing or reverting, the steering torque value is decreased before the reversal, so that the influence of the immediately preceding steering state is eliminated or reduced. After the rotation, the steering torque value is reflected in the target yaw rate, so that the target yaw rate that matches the driver's intention expressed as the steering angle and the steering torque can be obtained. There can be no yaw control or driving force control therefor.

  According to the invention of claim 3, since the value of the steering torque is relatively increased when the cut is increased, the target yaw rate is relatively increased, and the value of the steering torque is relatively decreased when the switch is returned. Therefore, the target yaw rate becomes relatively small. In other words, since the value of the steering torque is corrected in the direction intended by the driver, the target yaw rate is optimized, and as a result, yaw control without delay or driving force control therefor can be performed.

  According to the invention of claim 4, since the above correction is executed when the steering angle is large, it is possible to prevent or suppress the delay in the behavior of the vehicle during yawing.

  Next, the present invention will be described more specifically. The present invention is a device for controlling a driving force so as to generate a yaw rate in a vehicle or to reduce the yaw rate, and the driving force is controlled so as to approach the target yaw rate, for example, the yaw rate matches the target yaw rate. The For example, increasing the driving force of a rear wheel that is not a steering wheel increases during turning, increasing the yaw moment, and increasing or decreasing the yaw moment by changing the difference in driving force between the inner and outer wheels during turning. To do. Therefore, the control device of the present invention is configured to control the driving force of the front and rear wheels, the driving force of the left and right wheels, or the driving force of each of the four wheels.

  An example of such a vehicle is shown in FIGS. FIG. 7 shows a four-wheeled vehicle including a left front wheel 1, a right front wheel 2, a left rear wheel 3, and a right rear wheel 4. Each wheel 1, 2, 3, 4 has in-wheel motors 5, 6, 7, 8 Is provided. Therefore, all four wheels are configured so that the driving force is individually controlled. The front wheels 1 and 2 are steered wheels, and the steering angle is changed by the steering device 9. The steering device 9 has a conventionally known power steering structure including a handle 10, a steering shaft 11, a gear box (not shown), a tie rod 12, and the like. Further, the steering device 9 is provided with a sensor for detecting a steering angle which is a rotation angle of the handle 10 and a steering torque sensor (each not shown) for detecting a steering torque.

  Furthermore, various sensors for detecting the behavior of the vehicle are provided. For example, a G sensor 13 for detecting longitudinal acceleration and lateral acceleration, a yaw rate sensor 14 for detecting yaw rate, and the like are provided. Each of these sensors is configured to transmit data to the vehicle electronic control unit (vehicle ECU) 15. The vehicle electronic control device 15 is mainly composed of a microcomputer, and performs calculations using data inputted from each sensor, data stored in advance and arithmetic expressions, and a driving force control signal or the like. The control signal is output. The vehicle electronic control unit 15 is connected to a motor electronic control unit 16 for controlling the in-wheel motors 5, 6, 7, and 8 so as to be able to communicate with each other. Based on this, a command signal for controlling the driving force of the motor electronic control device 16 is outputted to each of the in-wheel motors 5, 6, 7, 8.

  On the other hand, FIG. 8 is an example of a so-called rear wheel drive vehicle, which includes front, rear, left and right four wheels 21, 22, 23, 24, of which the left and right rear wheels 23, 24 are drive wheels, Power is transmitted from an engine 25 such as an internal combustion engine, a motor, or a hybrid power source combining these. That is, the engine 25 is mounted rearward on the front side of the vehicle, and a differential 28 is connected to the output shaft of the transmission 26 connected to the engine 25 via the propeller shaft 27. The differential 28 is disposed between the left and right rear wheels 23 and 24, and is configured to divide the input power into left and right and transmit the power to the rear wheels 23 and 24 via axles 29 and 30, respectively. Has been. The differential 28 transmits part of the input torque to either the left or right via a clutch or the like, or transmits the torque of the attached motor to either the left or right via the clutch. The torque distribution ratio for the rear wheels can be changed.

  The left and right front wheels 21 and 22 are so-called steering wheels and are configured to be steered by the steering device 31. The steering device 31 may have the same configuration as the steering device 9 shown in FIG. 7, and thus includes a handle 32, a steering shaft 33, a gear box (not shown), a tie rod 34, and the like. A sensor for detecting a steering angle, which is a rotation angle, and a steering torque sensor (not shown) for detecting steering torque are provided.

  Further, similarly to the vehicle shown in FIG. 8, various sensors for detecting the behavior of the vehicle such as the G sensor 35 for detecting the longitudinal acceleration and the lateral acceleration and the yaw rate sensor 36 for detecting the yaw rate are provided. Each of these sensors is configured to transmit data to the vehicle electronic control unit (vehicle ECU) 37. The vehicle electronic control device 37 is mainly composed of a microcomputer, and performs calculations using data input from each sensor, data stored in advance and arithmetic expressions, and a driving force control signal or the like. The control signal is output. The vehicle electronic control unit 37 is connected to a differential electronic control unit 38 for controlling the differential 28 so as to be able to communicate with each other. The differential electronic control unit 38 is controlled based on the driving force control signal. A command signal for controlling the torque distribution ratio by the differential 28, that is, the driving force of the left and right rear wheels 23, 24, is output.

  The control device according to the present invention obtains a target yaw rate for a vehicle configured to control a driving force so as to give a yaw moment as shown in FIG. 7 or FIG. The driving force is controlled to match or approach the target yaw rate. An example of the control is shown in a flowchart in FIG. 1, and the routine shown here is for a case where the vehicle is running or a case where the main switch (not shown) of the vehicle is ON and the steering angle is predetermined. When the angle is equal to or greater than a predetermined angle, the process is repeatedly executed every predetermined short time. Here, the predetermined angle is a reference value for determining that the amount of operation (steering angle) of the steering wheel 10, 32 by the driver is large, such as the size of lateral G (lateral acceleration), the size of yaw rate, and the like. Can be determined based on

  When the routine shown in FIG. 1 is started, first, the steering angle and the steering torque are read (step S1). As described above, since the steering devices 9 and 31 are provided with the sensor for detecting the steering angle and the steering torque sensor, the detected values of these sensors are read in step S1.

  Next, a twist angle of a steering system such as a steering shaft is calculated based on the read steering torque (step S2). The calculation can be performed by taking into account factors such as cornering power at the left and right front wheels 1, 2, 21, and 22 that are the steered wheels. It can also be modeled and calculated simply. Referring to the simplified example of the latter, FIG. 2 is a schematic diagram showing a side surface and a plane of a wheel of a single-wheel model. A handle 41 and a wheel 42 are connected via a steering shaft and a gear box 43. Reference numeral 42 denotes a king pin that is inclined at a predetermined angle. Moreover, each code | symbol written together in FIG. 2 is as follows.

I _H : Value obtained by converting the moment of inertia of the handle around the kingpin axis δ _H : Value obtained by converting the rotation angle of the handle around the kingpin axis C _H : Coefficient indicating the friction of a mechanism related to a steering shaft such as a column and a yoke K _S : Stiffness value of steering shaft and gear box C _S : Coefficient indicating the friction of the gear box I _S : Moment of inertia around the kingpin axis of the two front wheels (steering wheels) δ _f : Actual steering angle of the front wheels (steering wheels) Rudder angle)
K _f : Cornering power of the front wheel (steering wheel) L _f : Distance from the center of gravity of the vehicle body to the axle of the front wheel V: Vehicle speed γ: Yaw rate β: Slip angle around the center of gravity of the vehicle body ξ: Pneumatic trail and caster rail Trail that is the sum of

Formulas (1) and (2) are obtained when the equation of motion of the steering system is established based on FIG. In Expression (1), “TH” represents the steering torque, and in Expression (2), “N” represents the steering gear ratio.

When the steering device is configured as an electric power steering (EPS), the right side of the equation (2) can be seen as a sign inversion value of the torque sensor value in the EPS, and therefore the right side of the equation (2) is expressed as “−TQeps”. When the steering torque TH is solved from the equations (1) and (2), the following equation (3) is obtained.

Here, since the inertia term and the attenuation term of the front wheel are small, if it can be ignored, Equation (3) becomes Equation (4).

Then, from equation (1), inputs the steering torque TH, when the output was the handle corresponds angle [delta] _H, the handle corresponds angle [delta] _H is the secondary delay system to the steering torque TH. Here, since the steering angle for calculating the target yaw rate when performing direct yaw moment control (DYC control) is aimed to ensure that there is no delay with respect to the steering torque MT at the steering wheel, a steady-state term is obtained from equation (1). Is extracted as Equation (5).

In this formula (5), (δ _H −δ _f ) represents the twist angle of the steering system. Therefore, when formula (5) is arranged with respect to the twist angle (δ _H −δ _f ) and formula (4) is substituted for the steering torque TH, formula (6) is obtained.

In general handle operation, since the angular velocity of the handle is small, there is no particularly large error even if the above transient movement of δ _H is ignored. If this is ignored, the twist angle (δ _H −δ _f ) is represented by the formula (7).

  In step S2 shown in FIG. 1, the twist angle is calculated based on the above equation (7) as an example. If the torsion angle is represented by ΔMA, the torsion angle ΔMA is multiplied by a predetermined correction gain K2 to obtain a steering torque term (ΔMA ′ = ΔMA · K2). However, the steering torque term is reflected in the target yaw rate. Alternatively, the way of reflection is preferably made different depending on the running state of the vehicle or the steering state. Therefore, in the present invention, the steering torque term is corrected. As an example, an effective / invalid gain K1 that enables or disables the steering torque term is obtained (step S3).

A subroutine for obtaining the valid / invalid gain K1 is shown in FIG. In the example shown here, first, the steering angle is read (step S30), and then it is determined whether only the steering wheel 10 or 32 is increased or returned (step S31). This determination can be performed by various conventionally known methods. For example, when the steering angle is θ and the number of executions of the routine shown in FIG. 3 is n,
When θ is positive (θ ≧ 0),
If θ (n) −θ (n−k) ≧ 0, it is rounded up,
If θ (n) −θ (n−k) <0, it is a switch back.
When θ is negative (θ <0),
If θ (n) −θ (n−k) ≧ 0, switch back,
If θ (n) −θ (n−k) <0, rounding is performed. However, k> 1 is sufficient. The sign of the steering angle θ is for distinguishing between leftward steering and rightward steering, and one of them is determined to be positive, and the opposite direction is determined to be negative.

  If the determination of increase in turning is made in the above step S31, a map that defines the steering torque at the time of switching back is referred to in order to correct the steering torque term as necessary at the time of switching back after the increase in the number of steps (step S31). S32). An example of the map is shown in FIG. 4, and the thick solid line in FIG. 4 indicates the steering torque corresponding to the steering angle at the time of switching back. As can be seen from FIG. 4, when the steering angle is greater than or equal to a predetermined value, the steering torque value is in the same direction as the steering direction, and in a range smaller than the predetermined value and greater than or equal to zero, the direction opposite to the steering direction. It becomes the value of.

  It is determined whether or not the sign of the map value obtained from FIG. 4 is opposite to the sign of the steering angle. For example, when the steering angle θ is a positive value, it is determined whether or not the map value is equal to or less than zero (step S33). If the determination in step S33 is affirmative, the valid / invalid gain K1 is set to "1" (step S34). This is because the steering torque term is reflected in the calculation of the target yaw rate. On the other hand, if a negative determination is made in step S33, the valid / invalid gain K1 is set to “0” (step S35). This is because the steering torque term is not reflected in the calculation of the target yaw rate.

  That is, since the return after the increase is an operation for returning the rotation angle (operation amount) of the handles 10 and 32 to zero, the target yaw rate is reduced. Therefore, when the steering angle θ is a positive value at the time of switching back, it is preferable not to reflect the positive steering torque term in the control. Similarly, when the steering angle θ is a negative value, the steering angle θ is negative. Since it is preferable not to reflect the steering torque term of the value in the control, when the determination is negative in step S33, the valid / invalid gain K1 is set to "0". In contrast, when the steering angle θ is positive and the map value of the steering torque is negative, and when the steering angle θ is negative and the map value of the steering torque is positive, the steering torque is reflected in the control. As a result, the target yaw rate is actively reduced, which matches the driver's intention appearing as a switchback, and in this case, the effective / invalid gain K1 is set to "1". Thus, the steering torque term is reflected in the yaw rate control.

  On the other hand, when the determination of switchback is established in step S31, a map that defines the steering torque at the time of switchback is referred to in order to correct the steering torque term as necessary when the switchover is performed after switchback (step S31). S36). An example of the map is shown in FIG. 5, and the thick solid line in FIG. 5 shows the steering torque corresponding to the steering angle at the time of increase. As is known from FIG. 5, the steering torque value is a value in the same direction as the steering direction.

  It is determined whether or not the sign of the map value obtained from FIG. 5 is the same as the sign of the steering angle. For example, when the steering angle θ is a positive value, it is determined whether or not the map value is positive (step S37). If the determination in step S37 is affirmative, the valid / invalid gain K1 is set to "1" (step S38). This is because the steering torque term is reflected in the calculation of the target yaw rate. On the other hand, if a negative determination is made in step S37, the valid / invalid gain K1 is set to “0” (step S39). This is because the steering torque term is not reflected in the calculation of the target yaw rate.

  That is, the increase after the return is an operation to increase the rotation angle (operation amount) of the handles 10 and 32 in the positive direction or the negative direction, and thus increases the target yaw rate. Therefore, when the steering angle θ is a positive value when increasing, it is preferable to reflect a positive steering torque term in the control. Similarly, when the steering angle θ is a negative value, the negative value is negative. Since it is preferable to reflect the steering torque term of the value in the control, when the determination in step S33 is affirmative, the valid / invalid gain K1 is set to "1". In contrast, when the steering angle θ is positive and the map value of the steering torque is negative, and when the steering angle θ is negative and the map value of the steering torque is positive, the steering torque is reflected in the control. Therefore, the target yaw rate is relatively reduced, which is contrary to the driver's intention appearing as an increase or is reduced. Therefore, in this case, the effective / ineffective gain K1 is set to “0”. The steering torque term is not reflected in the yaw rate control.

The steering torque value (steering shaft twist angle) is corrected by the effective / invalid gain K1 thus determined and the predetermined coefficient K2 to obtain a steering torque term (step S4). That is, ΔMA ′ = ΔMA · K1 · K2

  The correction is not limited to multiplication, and may be an appropriate numerical process such as addition, subtraction, or division. Further, the correction coefficient or the correction gain K2 is for finely adjusting the steering characteristic, and is tuned according to the vehicle type, corrected for the amount ignored when calculating the torsion angle ΔMA, or the steering device. A numerical value that adjusts the difference in characteristics according to the format is adopted. This can be prepared in advance by experiments or simulations.

  The steering torque term ΔMA ′ thus calculated is added to the steering angle MA detected by the sensor to obtain a target yaw rate calculation steering angle MA ′ (= MA + ΔMA ′) (step S5). This process can be said to be a process for correcting a delay caused by twisting of the steering system. Further, the torsion angle ΔMA changes depending on the friction coefficient of the road surface, so that the state of the road surface is reflected in the control.

Then, the target yaw rate is calculated using the target yaw rate calculation steering angle MA ′ (step S6), and the process returns. Specifically, the target yaw rate (γref = MA ′ × Gγ) is calculated by multiplying the target yaw rate calculation steering angle MA ′ by a predetermined gain. The gain Gγ can be said to be a coefficient for converting or reflecting the target yaw rate calculation steering angle ΔMA ′ to the target yaw rate. Therefore, the gain Gγ is a positive value based on experiment, simulation, or an appropriate arithmetic expression. Can be determined. An example of the arithmetic expression is given by Expression (8).

In formula (8), V is vehicle speed, K _h is a stability factor, L is wheelbase, N_gear is steering gear ratio. In addition to the above, it is possible to perform calculation in consideration of parameters representing vehicle characteristics and behavior.

The driving force is controlled based on the target yaw rate γref. In other words, the driving force that generates the yaw moment is controlled so that the yaw rate generated in the vehicle body becomes the target yaw rate. In the case of the vehicle shown in FIG. 7, the torques of the in-wheel motors 5, 6, 7, and 8 are controlled. In the case of the vehicle shown in FIG. 8, the torque distribution rate in the differential 28 is controlled. As an example, an example in which a yaw moment is generated by the differential 28 will be described. First, the target yaw rate γref is obtained by the following equation, for example, as conventionally known.

  Here, V is a vehicle body speed, khref is a target stability factor, L is a wheel base, θ is a steering angle, and n is a steering gear ratio.

A target yaw moment Moreq is obtained using this target yaw rate γref. First, the following equation of state is set.

  Where γ is the yaw rate and β is the slip angle at the wheel.

A00, a01, a10, a11, b00, b10, b11 are as follows.

  In these equations, Kf is the front wheel cornering power, Kr is the rear wheel cornering power, Lf is the distance from the center of gravity of the vehicle to the rotation center axis of the front wheel, and Lr is the axis of the drive shafts 13 and 14 of the rear wheels from the center of gravity of the vehicle. The distance to the heart, Iz is the yaw moment of inertia, and M is the weight of the vehicle body.

Solving for the above β and γ gives the following equation.

Next, when Laplace transform is performed, the following equation is obtained.

When this is changed to a discrete time function and the yaw rate γ is replaced with the target yaw rate γref, the following equation is obtained.

On the other hand, if the driving force of the front left and right wheels or rear left and right wheels connected via a differential is FFL and FFR, respectively, and the tread width of the front or rear wheels is TR,
Moreq = (FFR−FFL) × TR / 2
Is established. Therefore, the difference in driving force between the left and right wheels (FFR-FFL) is
(FFR-FFL) = 2 × Moreq / TR
It becomes. The differential 28 is controlled so as to generate the driving force difference (FFR−FFL) obtained in this way, and this is, for example, a control that performs torque assist of one wheel by a motor or performs differential limitation. In addition, the in-wheel motor causes a difference in driving force between the left and right wheels.

  By the way, when the steering wheels 10 and 32 are increased, the twist of the steering shaft becomes a delay factor of the yaw control. Therefore, it is preferable that the steering torque term is positively reflected in the yaw control. Basically, it is preferable to reduce the influence of the steering torque term. Therefore, instead of the above-described correction by the valid / invalid gain K1, an addition term to be added to the steering angle in calculating the steering angle for calculating the target yaw rate can be provided, and the addition term can be increased or decreased.

  FIG. 6 is a flowchart for explaining an example thereof. First, the steering angle and the steering torque are read (step S101). As described above, since the steering devices 9 and 31 are provided with the sensor for detecting the steering angle and the steering torque sensor, the detected values of these sensors are read in step S101. Next, the sign of the read steering angle is determined (step S102). This positive / negative sign can be determined in advance with either the left or right steering direction being positive and the other being negative.

  When it is determined in step S102 that the sign of the steering angle is positive, it is determined whether the steering angle is increased or decreased (step S103). This determination can be performed in the same manner as the determination in step S31 in FIG. If the determination of increasing the number is established in step S103, the absolute value of the twist angle of the steering shaft calculated from the steering torque detected by the steering torque sensor is adopted as an addition term (step S104). That is, when the handles 10 and 32 are increased, the steering angle of the steered wheels is smaller than the steering angle of the steering wheels 10 and 32 by the twist angle of the steering shaft, but the twist angle is added in step S104. Therefore, the delay or shortage due to the twist angle is corrected. As a result, the influence of the twisting of the steering shaft on the target yaw rate is eliminated or reduced, and the target yaw rate according to the driver's intention is set, and yaw control or driving force control with good responsiveness becomes possible.

  On the other hand, when the determination of switching back is established in step S103, a value obtained by multiplying the absolute value of the twist angle of the steering shaft calculated from the steering torque detected by the steering torque sensor by “−1” is added. It is adopted as a term (step S105). That is, the turning back of the steering wheels 10 and 32 is an operation in a direction to reduce the yawing of the vehicle, whereas the twist generated in the steering shaft is a twist in the same direction as when the steering is increased. Therefore, if the steering torque value based on the twist angle is directly reflected in the calculation of the target yaw rate, a target yaw rate different from the driver's intention of steering is calculated. Therefore, the value multiplied by “−1” is used as an addition term to avoid or suppress the influence of twisting and steering torque based thereon.

  In addition, when the determination of “negative” is established in step S102 described above, determination of whether to increase or decrease the steering angle is performed (step S106). This determination can be performed in the same manner as the determination in step S103 and step S31 in FIG. When the determination of increasing the number is established in step S106, a value obtained by multiplying the absolute value of the twist angle of the steering shaft calculated from the steering torque detected by the steering torque sensor by “−1” is used as the addition term. (Step S107). This is because the absolute value of the target yaw rate calculation steering angle is increased by setting the value added to the steering angle to a negative value because the steering angle is a negative value. By so doing, it is possible to reduce the influence of the twist angle of the steering shaft at the time of additional cutting, quickly reflect the driver's intention in the yaw control, and generate yaw.

  On the other hand, when the determination of switching back is established in step S106, the absolute value of the twist angle of the steering shaft calculated from the steering torque detected by the steering torque sensor is adopted as an addition term (step S108). ). That is, the steering angle is a negative value, and by adding a positive value to this value, the absolute value of the steering angle for calculating the target yaw rate is reduced, and the effect of torsion caused by the steering torque is reduced. It is to do. By doing so, it is possible to avoid or suppress the influence of twisting and the steering torque based thereon as in the case where the control of step S105 is performed at the time of additional cutting.

  Here, the relationship between the above-described specific example and the present invention will be briefly described. Functional means for executing the control such as step S3, step S34, S35, S38, S39 or step S104, 105, 107, 108 described above. However, it corresponds to the correcting means in the present invention, and the functional means for executing the control in step S6 corresponds to the target yaw rate calculating means in the present invention.

  The present invention is not limited to the above-described specific example, and the above-mentioned valid / invalid gain K1 as a correction coefficient takes an intermediate value other than “0” or “1”. Alternatively, the value may be determined using other factors such as the vehicle speed as parameters.

It is a flowchart for demonstrating an example of the control by the driving force control apparatus which concerns on this invention. It is a schematic diagram which shows the single-wheel model of a steering device. It is a flowchart which shows the subroutine for demonstrating the control content of step S3 shown in FIG. It is a figure which shows an example of the map which has defined the steering torque at the time of the switchback after a round increase. It is a figure which shows an example of the map which has determined the steering torque at the time of the increase after the switch back. It is a flowchart for demonstrating the control content which calculates | requires the steering torque term added to a steering angle when calculating | requiring the steering angle for target yaw rate calculation. It is a schematic diagram which shows an example of the vehicle which can be made into object by this invention. It is a schematic diagram which shows the other example of the vehicle which can be made into object by this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1,21 ... Left front wheel, 2,22 ... Right front wheel, 3,23 ... Left rear wheel, 4, 24 ... Right rear wheel, 5, 6, 7, 8 ... In-wheel motor, 9, 31 ... Steering device, 10 , 32 ... Handle, 15, 37 ... Electronic control device for vehicle (vehicle ECU), 16 ... Electronic control device for motor, 38 ... Electronic control device for differential.

Claims (4)

A vehicle that obtains a target yaw rate based on a steering angle that is an operation amount of a steering device and a steering torque that corresponds to a twist angle generated in the steering device, and controls a driving force of wheels so that a yaw rate generated in the vehicle approaches the target yaw rate In the driving force control device of
The steering torque value is corrected when the steering angle changes within a range in which the steering direction is not switched and the sign of the steering torque value for obtaining the target yaw rate is reversed as the steering angle changes. Correction means;
A vehicle driving force control device comprising: a target yaw rate calculating means for calculating the target yaw rate using the corrected steering torque value.   The correction means includes means for decreasing the steering torque value for calculating the target yaw rate before the sign of the steering torque is inverted and increasing the value after the inversion. The driving force control apparatus for a vehicle as described.   The correction means increases a steering torque value for calculating the target yaw rate when the steering angle is increased, and steering for calculating the target yaw rate when returning the steering angle to zero. The vehicle driving force control apparatus according to claim 1, further comprising means for reducing a torque value.   4. The vehicle driving force control device according to claim 1, wherein the correction unit is configured to perform the correction when the steering angle is larger than a predetermined angle. 5.

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