JPH02310158A - Driving force control device of vehicle - Google Patents

Abstract

PURPOSE:To have good driving force and braking force over the whole speed range by controlling the slip ratio under high speed running and the relative speed under low, and weakening the request torque of driving force control when they exceed the target values. CONSTITUTION:A means IV judges the driving/braking conditions of a car on the basis of a driving force control signal for the car generated from a means III. On the other hand, the condition amount of the car consisting of the slip ratio and slip speed are calculated by a means V on the basis of the wheel speed and car speed sensed by means I, II, while the car speed condition is judged by a means Vi. Specific correction factors for the slip ratio and slip speed are calculated by a means VII on the basis of the output signals from these means IV-VI. The optimum drive control amount is calculated by a means VIII on the basis of the abovementioned driving force control signal and the calculated correction factor signals. The drive torque for the wheel is controlled by a means IX according to the calculated drive control amount.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a driving force control device for a vehicle, and more specifically, the present invention relates to a driving force control device for a vehicle, and more specifically, it is safe even on slippery roads with a low coefficient of friction such as snowy roads, and has a maximum The present invention relates to a driving force control device for a vehicle that enables the vehicle to run with acceleration and deceleration.

[Conventional technology and its problems]

In order to drive safely on slippery roads such as snowy roads, it is necessary to avoid extreme acceleration and deceleration when driving a car. However, if this is left solely to the driver's operations, all but the most highly skilled drivers will be able to drive slowly. Therefore, the development of a device that allows even less skilled drivers to safely and appropriately accelerate or decelerate on slippery roads has been delayed.

One such device is the slippery road (hereinafter referred to as
ABS (Antilo Brake) ensures the directional stability of the vehicle during braking operations on low-μ roads, while also increasing the braking force as much as possible within this limited range.
CK Brake System). As shown in Figure 2, this device aims at a slip ratio S of -8o+ that maximizes the braking force without significantly reducing the cornering force, which is the tire's lateral anti-horn. The objective is to control the upper limit of the braking force so that it is as follows. Note that the slip ratio S is defined as follows. This ABS device can accurately detect the slip ratio S at high speeds, and can realize the desired control. However, at low speeds, because the vehicle speed is low, the slip ratio S is greatly affected by small measurement errors and noise between the wheel speed and vehicle speed, so the slip ratio S cannot be detected accurately, and smooth braking cannot be achieved. The problem was that it became difficult.

In addition, one of the above devices is a traction system that allows you to accelerate safely and with the maximum possible torque without causing problems such as spin when accelerating such as when starting on a low μ road. There is a control system. Normally, when a tire slips significantly during acceleration, the cornering force of the tire decreases, and even a slight external force in the lateral direction can cause a spin, making it impossible to drive safely and making it impossible to increase the driving force that can be obtained. . This system targets a relative speed (wheel speed - vehicle speed) that provides near-maximum driving force without significantly reducing cornering force, and weakens the driving force when the relative speed exceeds a set value. The above problem was solved by controlling the relative speed to always be kept within this range. However, although the expected effect can be obtained for drive control at low speeds, the relationship between the driving force and slip ratio S at high speeds is the same as that during braking, and the slip ratio S during driving is If the speed is always set as a constant target, the upper limit slip ratio will decrease as the speed increases, which will unnecessarily suppress the upper limit of the driving force, which will greatly reduce the acceleration ability at high speeds. .

Therefore, the present inventors conducted intensive research to solve the problems of the prior art as described above, and as a result of conducting various systematic experiments, they came up with the present invention.

[Purpose of the invention]

An object of the present invention is to provide a device that is safe and obtains the maximum possible driving force and braking force in both acceleration and deceleration states in all speed ranges.

The present inventors focused on the following points regarding the problems of the prior art described above.

In other words, since the characteristics of the tires installed on the vehicle are as described above, the slip ratio is suppressed and controlled so that it does not exceed s = s a' within the range where the slip ratio can be controlled. I got one goal. That is, the slip ratio S is detected, and if it exceeds the target value, the requested torque is reduced proportionally, for example, according to the amount that exceeds the target value, and the slip ratio S is set to the set slip ratio By making sure that the slip ratio S does not exceed the set slip ratio (which is set near the slip ratio that provides large driving force and braking force without significantly reducing the cornering force even on μ roads), the slip ratio S S. The upper limit of the driving force and the braking force can always be kept large without greatly exceeding the maximum value, and the lateral resistance that causes sideslip to occur can also be kept large, so safety can be ensured.

However, the slip ratio is a quantity standardized by speed, and the influence of the slip ratio on the equivalent measurement error and noise increases as the speed decreases, so the slip ratio S cannot be determined accurately in the low speed region. First, the above-mentioned inhibitory control cannot be realized. Furthermore, at low speeds, tire characteristics also change. Therefore, by repeatedly conducting systematic experiments on tire characteristics, the inventors found that, at low speeds, the horizontal axis of the tire characteristics is the relative speed of the vehicle body, and that this problem could be solved by using the relative speed. We focused on That is, at low speeds, the object to be controlled is not the slip ratio but the relative speed, and the same control as the slip ratio at high speeds is achieved.

As described above, the present invention controls the slip ratio at high speeds and the relative speed at low speeds, weakens the required torque from the driving force control signal generating means when each of them exceeds a target value, and By smoothly connecting both the measuring sections at low speed and high speed, it becomes possible to overcome the problems of the prior art.

[Description of the first invention]

Structure of the Invention As shown in FIG. 1, the vehicle driving force control device of the present invention is a device for controlling the driving force of a vehicle in which the torque of each wheel of the vehicle can be freely changed. A speed detecting means ■, a vehicle speed detecting means ■ detecting the speed of the vehicle, a driving force control signal generating means ■ generating a driving force for driving the vehicle, and a signal output from the driving force control signal generating means ■. A driving/braking state determining means (2) for determining whether the driving force control signal is in a controlled state, an acceleration state, or a decelerating state; and a wheel speed signal output from the wheel speed detecting means (2) and the vehicle speed detecting means. The vehicle speed is in a high state based on the vehicle state quantity calculation means (■) which calculates the slip ratio and slip speed of the wheels from the vehicle speed signal output from (1) and the vehicle speed signal output from the vehicle speed detection means (2). A signal output from the driving/braking state determining means ■, a signal output from the vehicle state quantity calculating means ■, and a vehicle speed determining means ■, which determines whether the vehicle is in a low speed state or not; Based on the output signal indicating the determination result, when the vehicle speed is high, a correction coefficient is calculated to reduce the slip ratio when the slip ratio exceeds the reference value, and when the vehicle speed is low, the slip ratio is calculated. a correction coefficient calculating means (2) for calculating a correction coefficient for decreasing the slip speed by one when the reference value is exceeded; and a driving force control signal outputted from the driving force control signal generating means (2) and the correction coefficient. Based on the drive control amount calculation means ■ which calculates the optimum drive torque according to the external condition from the correction coefficient signal outputted from the calculation means ■, and the drive torque command signal which is the output of the drive control amount calculation means ■. It is characterized by comprising a control means (2) for controlling the driving torque of the wheels.

Functions and Effects of the Invention The functions of the vehicle driving force control device of the present invention having the above configuration are as follows.

That is, first, in the driving force control signal generating means (2),
The required torque τ for the wheels is determined from the control state quantity such as the accelerator pedal state quantity or the brake pedal operation quantity. is output.

On the other hand, the wheel speed detection means 1 detects the wheel speed V, and the vehicle speed detection means 2 detects the vehicle speed U.

Next, the driving/braking state determining means (2) determines whether the required torque τ output from the driving force control signal generating means (2) is in an acceleration state or in a deceleration state, that is, whether it is on the driving side or on the braking side. , outputs the judgment signal s4. Note that this determination is made by determining the sign of the required torque.

Next, the vehicle state quantity calculating means V calculates the slip ratio S indicating the slip state of the wheels and Calculate and output the slip speed ΔU.

Next, the vehicle speed state determining means (2) determines whether the input vehicle speed signal U is in a high speed state or in a low speed state, and outputs eight determination signals. That is, this judgment is made based on a predetermined set vehicle speed uh, and if the input vehicle speed signal U is faster than the set vehicle speed uh, the vehicle is set to a high speed state, and when the vehicle speed is less than or equal to the set vehicle speed IJh, the vehicle is set to a low speed state. I will do it.

Next, in the correction coefficient calculating means (2), the signal s4 output from the driving/braking state determining means (2), the signal (slip ratio S and slip speed ΔU) output from the vehicle state quantity calculating means V, and the vehicle speed state determination are performed. Based on the signal s6 indicating the determination result output from the means (2), when the vehicle speed is high and the slip ratio S exceeds the reference value, a correction coefficient is calculated to reduce the slip ratio S, and the vehicle speed is adjusted. In a low speed state, when the slip speed ΔU exceeds a reference value, a correction coefficient for reducing the slip speed is calculated. The reference value is a value set in advance so that the slip state of the wheels does not significantly reduce the lateral drag of the tire, and the torque is set to limit the required torque so that the slip state does not exceed the slip state. Calculate correction coefficient β. Further, as described above, depending on the vehicle speed, the slip ratio S was controlled on the high speed side, and the slip speed ΔU was controlled on the low speed side. This is because the slip ratio S is the target of control at high speeds because the cornering force and driving force of the tire characteristics at high speeds are determined by the slip ratio S, and by controlling this appropriately, the cornering force can be significantly reduced. This is because the maximum possible driving force can be obtained without any interference. Also,
The reason why the slip speed ΔU is controlled on the low speed side is that the slip speed is not affected by speed disturbances or noises like the slip ratio at low speeds, so it can be accurately detected, and it can also be used to control cornering of tire characteristics. This is because the force and drive force J are determined by the slip speed, and by appropriately controlling this, good control becomes possible. Further, in any controlled object, the required torque is generated as is until the slip ratio or slip speed exceeds the reference value, so the correction coefficient becomes β-1.

Next, in the drive control amount calculation means (2), the driving force control signal output from the driving force control signal generation means (2) and the correction coefficient signal output from the correction coefficient calculation means (2) are integrated and actually generated. The drive torque is calculated, and then, in the control means (2), the drive torque of the wheels is controlled based on the drive torque command signal which is the output of the drive control amount calculation means (2).

The vehicle drive unit 12 = force control device of the present invention having the above configuration controls the slip ratio S on the high speed side and the slip speed ΔU on the low speed side according to the state of the vehicle speed. Since the slip speed is maintained at a state where the maximum driving force can be obtained without greatly reducing the cornering force, it is safe and the maximum possible driving force can be obtained in all speed ranges and in both acceleration and deceleration conditions. It is possible to obtain driving force and braking force.

Furthermore, by installing the device according to the present invention on a vehicle configured to allow wheel torque to be freely changed between positive and negative sides and for each wheel, it is possible to prevent sideslips that occur due to acceleration and deceleration even on slippery roads such as snowy roads. It is possible to drive on a slippery road without being aware of slippery roads by suppressing speed and spin, and using the largest possible acceleration and deceleration forces.

Furthermore, this device maintains the tire slip condition in such a way that driving force and braking force can be applied to the maximum allowable level without significantly reducing the tire's lateral force resistance, regardless of the road surface condition. On slippery roads such as snow-covered roads, even drivers with -14 level of experience can achieve safe and agile vehicle driving control that enables quick acceleration and deceleration.

[Description of other inventions]

Other inventions of the first invention will be explained below.

Description of the Second Invention As a second invention, an example of the control principle regarding switching between the high-speed state and the low-speed state of control in the vehicle state quantity calculation means V to the correction coefficient calculation means (2) will be described below.

The difficulty in switching the control target between low speed and high speed is as follows.
The key is to perform this switching smoothly and to select the switching point.

Smooth switching can be achieved by selecting target values for both the low-speed control and high-speed control ranges, depending on how the target values are determined.

That is, the target value of the slip ratio is the set slip ratio S, which is set around the slip ratio at which large driving force and braking force can be obtained without significantly reducing the cornering force even on low μ roads based on the characteristics of the tires used.

Select nearby. At switching speed V, relative speed Δ
U and the set slip ratio S. is as follows during acceleration and deceleration, respectively.

■) △U during acceleration (however, ΔU - wheel speed - vehicle speed) 2) ΔU when decelerating (however, △U - vehicle speed - wheel speed) By selecting the relative speed △U obtained from these relationships as the target value. , the slip ratio S at the switching speed Vh
Since the relative speed ΔU changes continuously, smooth control can be achieved. Note that the relative speed ΔU selected in this manner can be set to an appropriate value at low speeds also in the relationship between driving/braking force and cornering force, and good control can be achieved.

The selection of the switching point is a matter of tire characteristics, and should not be selected too low in terms of slip ratio detection accuracy. Vehicle speed 1. If the speed is 0 km/h or more, control with tolerable accuracy can be achieved. In terms of tire characteristics, the characteristics of the tire are no longer used. However, this is not clearly expressed and cannot be determined uniquely. According to the results of the inventors' research and systematic experiments, the characteristics of the tires mentioned above can be used when the vehicle speed is 20 km/h, so if the vehicle speed is 10 km/h, the characteristics of the tire can be used.
km/h to 20 km/h is selected as an appropriate value. However, this switching point changes depending on the tire characteristics and the detection accuracy of the vehicle speed and wheel speed, and is determined based on the relationship between the two.

〔Example〕

The present invention will be explained in detail below.

Embodiment A driving force control system for a vehicle according to an embodiment of the present invention will be explained with reference to FIGS. 3 to 7.

The vehicle driving force control device of this embodiment is applied to drive control of a vehicle in which wheel torque can be freely changed, and includes wheel speed detection means (1), vehicle speed detection means (1), and driving force control signal generation. Means ■1, drive state determining means ■, vehicle state quantity calculating means ■1, vehicle speed state determining means ■, and correction coefficient calculating means ■.

, a drive control amount calculation means (1), and a control means (2).

The wheel speed detection means (1) consists of a wheel speed detector I11 provided between the axles, detects the number of rotations of the wheels, and outputs an electric signal representing the wheel speed (2).

Vehicle speed detection means ■1 is an accelerometer II+1 and a vehicle speed calculator■
1□ to calculate the vehicle speed. Accelerometer ■1□ is
It is installed on the floor of the vehicle interior, which corresponds to the center of gravity of the vehicle.
The longitudinal acceleration of the vehicle is detected and an electrical signal representing the longitudinal acceleration is output. Vehicle speed calculator ■1□ is the accelerometer I1
The vehicle speed U is calculated by integrating the longitudinal acceleration signal output from the 1+, and an electrical signal representing the vehicle speed U is output.

The driving force control signal generating means (2) generates the necessary driving force based on the amount of operation of the driver's accelerator and brake pedals, or the amount of operation or control required to suppress dangerous conditions such as vehicle spin. , outputs the torque signal required for each width unit.

The driving/braking state determining means (1) is a driving/braking torque determiner IV l l which determines whether the driving force control signal (required torque) outputted from the driving force control signal generating means (1) is a driving level or a braking level. Consisting of

Vehicle state quantity calculation means 1 is a slip speed calculation unit V l
1 and a slip ratio calculator V12. The slip speed calculator (11) is the vehicle speed detecting means.

The wheel speed signal V outputted from the vehicle speed detection means ■1
The vehicle speed signal U outputted from the drive state judgment means ■1
A slip speed (relative speed) ΔU is calculated from the drive state signal outputted from the following equation, and an electric signal representing the calculation result is output.

(i) Driving level... Δu:=v-u (ii) Braking level... Δu=u-v... (1) In addition, the slip ratio calculator V1° is calculated from the wheel speed detecting means ■1. From the outputted wheel speed signal V, the vehicle speed signal U outputted from the vehicle speed detection means 1, and the drive state signal outputted from the drive state judgment means 1, the slip ratio ΔS is calculated as shown in the following equation. Then, an electrical signal representing the result of the calculation is output.

(i) Drive level...s--□...(2) Vehicle speed state determining means ■1 determines, based on the vehicle speed signal U output from the vehicle speed detecting means, that the vehicle speed signal U is equal to or higher than a preset vehicle speed IJh. If so, the slip ratio S is selected as the target of slip control, and if the vehicle speed signal U is smaller than the vehicle speed uh (u<uh), the slip speed ΔU is selected as the target of the slip control, and the selected information is represented. It consists of a controlled object selector VTI+ that outputs an electrical signal.

Correction coefficient calculation means ■1 is first correction coefficient calculation means ■11
, the second correction coefficient calculating means ■1□, and the corrected image -]!
J -- Number selector ■1. A signal output from the driving/braking state determining means (■1), a signal output from the vehicle state quantity calculating means (1), and a vehicle speed state determining means (2).
A correction coefficient is calculated from the signal output from the.

When the signal output from the vehicle state quantity calculation means ■1 is a signal related to the slip ratio, the first correction coefficient calculating means ■1□ combines the signal output from the driving/braking state determining means ■ with the A first correction coefficient β is calculated as follows from the signal output from the vehicle state quantity calculation means V,
An electrical signal representing the correction coefficient is output.

(1) When s≦S, β5-1 (ij) When so<s≦so゛ (iii) When so'<s, β5-〇In addition, the relationship between this slip ratio S and the correction coefficient β5Kichi is It is shown in Figure 4.

The second correction coefficient calculation means ■1□ is the vehicle state quantity calculation means V1. When the signal output from J is a signal related to slip speed, the set slip speed is determined from the signal output from the driving/braking state determining means (1) and the signal output from the vehicle state quantity calculating means (1). Set Δuo and maximum slip speed Δuo+ as shown below depending on whether it is a drive level or a braking level. Case n Furthermore, a second correction coefficient β1 is calculated as follows, and an electrical signal representing the correction coefficient is output.

(i) If △u and △lJo, βu-1 (ii) If △uo and ΔU≦△uo゛, (iii) Δu
If o'<ΔU, βu-0. The relationship between the slip speed ΔU and the correction coefficient β is shown in FIG.

The correction coefficient selection means (13) is means for selecting the signal output from the first correction coefficient calculation means (11) and the signal output from the second correction coefficient calculation means (2), and selects the signal output from the second correction coefficient calculation means (2). (2) If the slip ratio S is selected as the target of slip control based on the signal output from the first correction coefficient calculation means (1). The first correction coefficient β5 outputted by As the correction coefficient β, an electrical signal representing the correction coefficient β is output.

Next, the drive control amount calculation means II1. The driving force control signal τ output from and a torque command calculating means (11) which calculates a drive command torque τ from the correction coefficient signal β outputted from the correction coefficient calculating means (1) and outputs an electric signal representing the command torque τ. The command torque τ is calculated by the torque command calculation means (1) using the following equation.

τ = τ0 Φβ Next, the control means (1) controls the drive torque of the wheels based on the drive torque command signal (τ) which is the output of the drive control amount calculation means (2).

The functions and effects of this embodiment having the configuration described in item 1 are as follows.

First, the rotational speed of the wheel is detected or calculated by the wheel speed detector 1.1 of the wheel speed detecting means (1), and the vehicle speed is detected or calculated by the vehicle speed detecting means (1), and is input to the vehicle state quantity calculating means (2).

Next, the driving/braking state determining means (2) determines the level state of the required torque of the drive control amount calculating means (2), and outputs it to the correction coefficient calculating means (2).

Next, the vehicle state quantity calculation means (1) outputs the wheel speed signal (2) outputted from the wheel speed detection means 11, the vehicle speed signal U outputted from the vehicle speed detection means (11), and the drive state determination means (2). Based on the generated drive state signal, slip speed ΔU and slip ratio S are calculated as objects of slip control in slip speed calculator V11 and slip ratio calculator ■1□. Note that the vehicle speed is the set vehicle speed U,
In the following, the slip speed ΔU, which is the relative speed between the vehicle speed and the wheel speed, is selected, and when the vehicle speed is higher than the set vehicle speed uh, the slip ratio S is selected, which is a generalization of =25−slip speed ΔU. In addition, in calculating the slip speed △U and the slip ratio S, since the calculation formula differs depending on the state of the required torque of the driving force control signal generating means (■1), the driving state output from the driving/braking state determining means (■1) The signal is calculated depending on whether it is a driving level or a braking level.

Next, in the vehicle speed state determining means (1), the control object selector VI
11, a vehicle speed signal 1'' and a preset vehicle speed 1. l
Based on the comparison with h, the slip ratio S or the slip speed Δ1 is selected as the target for slip control, and the selected information is output.

Next, in the correction coefficient calculating means (2), the signal output from the driving/braking state determining means (2), the signal output from the vehicle state quantity calculating means (1), and the signal output from the vehicle speed state determining means (2), A correction coefficient is calculated from the output signal. When the signal output from the vehicle state quantity calculation means (■1) is a signal relating to the slip ratio, the first correction coefficient calculation means (11) calculates a correction coefficient β3, and the signal is output from the vehicle state quantity calculation means (26-1). When the detected signal is a signal related to slip speed, the second correction coefficient calculation means 2j2 calculates the correction coefficient β. is calculated, and then the correction coefficient selector ■1. Then, the correction coefficient β5 or the correction coefficient β1 is selected as the correction coefficient β according to the vehicle speed state and outputted.

That is, as shown in Fig. 6, the cornering force, which is the tire's sideslip resistance, decreases monotonically as the slip ratio S and slip speed ΔU increase, while the driving force
The braking force is determined by the small value of slip ratio S and slip speed △U (
s = 0.1 to 0.2), the slip ratio S and slip speed Δ are at or near the maximum value.
By suppressing U, it is possible to apply a large amount of force without significantly reducing cornering force. Therefore, the slip speed ΔU or slip ratio S is as much as possible the target slip speed Δuo or slip ratio S. need to be close to. However, the purpose is to always maintain a large cornering force, and there is no need to reduce the slip speed △U or the slip ratio S to the target slip speed △uo or the target slip ratio So. However, if the calculated slip speed △U or slip ratio S is greater than the target value, the slip speed △U and slip ratio S
need to move closer to the goal. Based on these, using the calculated slip speed ΔU and slip ratio S, the correction coefficient β5 or β is determined from the relationship shown in FIGS. 4 and 5.

is determined by the first correction coefficient calculation means ■o1 or the second correction coefficient calculation means ■1□. Furthermore, the correction coefficient selector ■I3
Then, depending on the vehicle speed state, the correction coefficient β5 or the correction coefficient β is selected as the correction coefficient β and outputted.

Next, in the drive control amount calculation means (1), the torque command calculation means (2) calculates the driving force control signal τ. and correction coefficient signal β
is integrated to output the drive command torque τ. Next, the control means (1) controls the drive torque of the wheels based on the drive torque command signal τ.

In the slip control achieved by the device of this embodiment, the relationship between the vehicle speed U, the wheel speed V, and the correction coefficient can be summarized as shown in FIG.

As is clear from FIG. 7, it can be seen that smooth control is achieved in the entire speed range.

The device of this embodiment having the above configuration always maintains the slip state of the drive wheels in a state where the lateral drag of the tire does not decrease regardless of the road surface condition, so it can be used even on slippery roads such as snowy roads. It is possible to achieve safe vehicle motion control without special driving techniques.

In addition, in the device of this embodiment, in the entire speed range from starting/stopping to high-speed conditions, the resistance of the tire's lateral force does not decrease significantly, making it difficult to cause dangerous conditions such as sideslip, and increasing the slip ratio. Since the slip speed can be used to the maximum value at which driving or braking force is effective, even inexperienced drivers can achieve the maximum possible acceleration even on slippery snowy or icy roads. Alternatively, it is possible to achieve vehicle motion control that allows deceleration to be performed without special operations.

=29- Modifications of the above embodiment will be described below.

Modification 1 Modification 1 of the above-mentioned embodiment is such that the driving/braking state determining means (1) furthermore outputs the driving force control signal (required torque) from the driving force control signal generating means (2) so that slip is less likely to occur. It has a means for detecting and determining whether the amount is within the range and outputting a vehicle speed calibration signal to the vehicle speed detecting means (1) when the amount is within the range, and a vehicle speed calculator (2) of the vehicle speed detecting means (1).
1□ is characterized by having means for changing the value of the integrator to the wheel speed during an appropriate period during which the vehicle speed calibration signal is inputted from the driving/braking state determining means 1. shall be.

The vehicle speed detecting means (I) of the above embodiment includes an accelerometer (1) and a vehicle speed calculator (II+1), and calculates the vehicle speed by integrating the longitudinal acceleration of the vehicle body.
If long-time integration is performed in step 2, many errors will be included, and it is impossible to accurately calculate the vehicle speed due to these error components. Therefore, by using the driving power control device having the above configuration, it is possible to calibrate the integral calculation error of the vehicle speed calculator l112 to a range that does not cause any practical problems.

Modification 2 In a modification 2 of the embodiment, the maximum slip ratio sO' is inversely proportional to the vehicle speed U, where so' at the vehicle speed u'' is set to uh Sa-56'' ・□-. S.” is determined.

In the device of the above embodiment, the maximum slip ratio S. ′ was fixed regardless of the vehicle speed, so as the vehicle speed increases,
Since the control gain for speed decreases, the correction coefficient β =
The range from 0 to 1 becomes wider in proportion to the speed, and control accuracy deteriorates.

On the other hand, in the device of Modification Example 2, by having the above-described configuration, the speed width in the range of correction coefficient β-0 to 1 is set to a constant width regardless of the vehicle speed, and control accuracy is made uniform. I can do it.

Modified Example 3 As a modified example 3 of the above embodiment, a modified example other than the above will be described below.

First, in the embodiment described above, the vehicle speed detection means T1. Although the configuration is adopted in which the vehicle speed is calculated using the accelerometer (1) and the vehicle speed calculator (12), it is also possible to use a vehicle speed detection means that does not measure the wheel rotation speed. In this case, the vehicle speed detection means (1) requires an integrator and the vehicle speed calibration means of the modification 1, so the structure is complicated, but by adopting the vehicle speed detection means, the structure can be simplified. can do.

Furthermore, the device of the embodiment shown in FIG. 3 is configured so that common parts are shared, although in a vehicle with multiple rows of control wheels, a device having the configuration shown in FIG. 3 is required accordingly. By doing so, the device can be simplified.

In addition, in the above embodiment, various setting values (So+S
O'+ △uo, ΔuOZ uh ), but the set sliding speed △U, and the maximum sliding speed △uo
', in order to smoothly connect the two types of control, set slip ratio So + maximum set slip dl-- ratio S. '8 It is related to the set vehicle speed Vh. Here, the set slip ratio S. is set in relation to the tire characteristics, but the slip ratio s = 0.1 - provides near maximum driving and braking force without significantly reducing cornering force.
It can be set according to the range based on about 0.2. Regarding the maximum setting slip ratio sal, if it is set close to a value related to control stability, the control gain will become too high and cause vibrations, and if it is set far from the reading value, control accuracy will deteriorate and weak control will be required. Since the range of is too wide, So””S. +0.01-s o +
It is preferable to set it in the range of 0°05. The control switching speed uh is determined by the applicable range of tire characteristics, and depending on the tire characteristics, it is only possible to indicate it independently of speed in the high speed range, and in the low speed range, the horizontal axis is determined by the slip ratio rather than the slip ratio. Therefore, this switching point can be set as uh. This speed uh cannot be clearly determined because the characteristics differ depending on the tire, but the range that shows good results from the experimental results is 10~
A range of approximately 40km/h-33 to -32= is selected.

Further, in the above embodiment, the vehicle state quantity calculating means (1) calculates both the slip speed and the slip ratio, and then the first correction coefficient calculating means (2) calculates both the slip speed and the slip ratio in the first correction coefficient calculating means (2) based on the slip amounts of both of them. 11 and the second correction coefficient calculation means ■ 1° calculates the correction coefficient, and the correction coefficient selector ■ I3 calculates the correction coefficient ■
The vehicle speed state determining means 1 is configured to select one of the slip control target signals output from 1, and the correction coefficient of the one selected as the control target based on the slip control target signal output from 1. It may be configured such that only the calculation is performed.

[Brief explanation of the drawing]

FIG. 1 is a schematic configuration diagram showing the concept of the present invention, FIG. 2 is a diagram showing the slip characteristics between the tire and the road surface, FIGS. 3 to 7 show the first embodiment of the present invention, and FIG. 4 is a diagram showing the relationship between the slip ratio and the correction coefficient in the first correction coefficient calculation means, and FIG. 5 is a diagram showing the relationship between the slip speed and the correction coefficient in the second correction coefficient calculation means. A diagram showing the relationship with the correction coefficient, FIG. 6 is a diagram showing the slip characteristics between the tire and the road surface,
FIG. 7 is a diagram showing the relationship between vehicle speed, wheel speed, and correction coefficient achieved in this embodiment. ■, ■1... Wheel speed detection means ■, ■,... Vehicle speed detection means ■, ■1... Driving force control signal generation means ■, ■1...
Driving status determining means ■, ■1... Vehicle state quantity calculating means ■, ■1... Vehicle speed state determining means ■, ■1... Correction coefficient calculating means ■, ■1... Drive control amount calculating means ■、■１・・・Control means

Claims (1)

[Claims] (1) A device for controlling the driving force of a vehicle in which the torque of each wheel of the vehicle can be freely changed, comprising: a wheel speed detection means for detecting the rotational speed of the wheels; a vehicle speed detection means for detecting the speed of the vehicle; a driving force control signal generating means for generating a driving force to cause the vehicle to move; and determining whether the control state is in an acceleration state or a deceleration state based on the driving force control signal output from the driving force control signal generating means. a driving/braking state determining means; a vehicle state quantity calculating means for calculating a wheel slip ratio and a slip speed from a wheel speed signal output from the wheel speed detecting means and a vehicle speed signal output from the vehicle speed detecting means; , a vehicle speed state determining means for determining whether the vehicle speed is in a high speed state or a low speed state based on a vehicle speed signal outputted from the vehicle speed detecting means; and a signal output from the driving/braking state determining means. To reduce the slip ratio when the slip ratio exceeds a reference value when the vehicle speed is high, based on the signal output from the vehicle state quantity calculation means and the signal indicating the judgment result output from the vehicle speed state judgment means. a correction coefficient calculating means for calculating a correction coefficient for reducing the slip speed when the slip speed exceeds a reference value when the vehicle speed is low; drive control amount calculation means for calculating an optimal drive torque according to external conditions from the driving force control signal output from the correction coefficient calculation means and the correction coefficient signal output from the correction coefficient calculation means; A driving force control device for a vehicle, comprising: control means for controlling driving torque of wheels based on a torque command signal.