JP6135136B2 - Vehicle speed limiter - Google Patents

Description

  The present invention relates to a vehicle speed limiting device that controls an actual vehicle speed by automatically adjusting an output of a drive source and a braking force so that the actual vehicle speed of the vehicle does not exceed a set vehicle speed.

  Conventionally, a vehicle speed limiting device that automatically limits the traveling speed of a vehicle regardless of whether or not an accelerator operation is performed is known. That is, the output of the driving source (engine, driving motor, etc.) and braking force are controlled so that the maximum speed of the vehicle does not exceed a predetermined set speed. In recent years, an adjustable vehicle speed limiter (adjustable speed limiter) that allows a driver to arbitrarily set a set speed has been developed.

  A typical vehicle speed limiter functions to reduce the output of the vehicle and suppress further acceleration when the actual vehicle speed of the vehicle approaches the set vehicle speed. On the other hand, when the actual vehicle speed is sufficiently smaller than the set vehicle speed, the output is not limited, and the degree of acceleration of the vehicle is adjusted as usual according to the accelerator operation amount. Thus, the vehicle speed limiting device is different from the constant speed traveling device (cruise control device) in that it does not limit the output of the vehicle during low speed traveling. Therefore, it is useful for preventing an excessive speed on a general road where it is difficult to maintain a constant cruising speed, or for improving the fuel efficiency of the vehicle.

  By the way, the vehicle speed restriction by the vehicle speed restriction device acts to reduce the acceleration of the vehicle to be accelerated. At this time, the vehicle is controlled in a direction contrary to the driver's intention to travel. Therefore, there is a problem that the acceleration fluctuation accompanying the vehicle speed limitation is easily felt by the driver, and the drive feeling is easily impaired.

  In response to such a problem, a technique has been proposed in which torque shock resulting from vehicle speed restriction is alleviated by suppressing torque fluctuation during vehicle speed restriction. For example, Patent Document 1 describes a control that reduces a sudden change in torque by performing a filtering process on a target torque for suppressing an increase in the traveling speed of a vehicle. By such control, it is said that deterioration of drivability accompanying torque shock can be suppressed.

JP 2008-144594 A

However, the conventional vehicle speed limiting device as described above cannot suppress the acceleration fluctuation immediately after the start of the vehicle speed limitation or when the vehicle speed reaches the set speed.
For example, the magnitude of the acceleration actually acting on the vehicle does not depend on the instantaneous value of the vehicle speed, and corresponds to the time change gradient of the vehicle speed. On the other hand, in the conventional vehicle speed limiting device as described in Patent Document 1, the acceleration at the time when the vehicle speed limit is started and the magnitude of the acceleration when the vehicle speed reaches the set speed are not considered. For this reason, acceleration fluctuations occur immediately after the start of the vehicle speed restriction, and the driver may feel that the vehicle is caught or feels loose. The same is true when the vehicle speed reaches the set speed, and the drive feeling tends to decrease.

  One of the purposes of the present invention was devised in view of the above problems, and is to provide a vehicle speed limiting device that can reduce the uncomfortable feeling of acceleration fluctuations that occur in association with vehicle speed limitation. is there. It should be noted that the present invention is not limited to this purpose, and is a function and effect derived from each configuration shown in the embodiment for carrying out the invention described later, and can also provide a function and effect that cannot be obtained by conventional techniques. Can be positioned as

  (1) The vehicle speed limiting device disclosed here is a vehicle speed limiting device that controls the actual vehicle speed so that the actual vehicle speed of the vehicle does not exceed a set vehicle speed. The vehicle speed limiting device includes target curve setting means for setting a target curve corresponding to a target vehicle speed expressed as a function of time in a speed range from a determination vehicle speed lower than the set vehicle speed to the set vehicle speed. In addition, control means is provided for controlling the actual vehicle speed so that the actual vehicle speed changes along the target curve set by the target curve setting means.

The target curve setting means includes a change gradient (actual acceleration) of the actual vehicle speed at a first time when the actual vehicle speed is equal to or higher than the determination vehicle speed, and an inclination (target acceleration) of the target curve at the first time. And the slope (target acceleration) of the target curve at the second time when the target vehicle speed reaches the set vehicle speed is set to zero.
That is, in the setting of the target curve by the target curve setting means, the inclination at the first time and the inclination at the second time are constrained. The constraint condition at the first time is “the slope matches the actual vehicle speed change gradient (actual acceleration)”, and the constraint condition at the second time is “the target vehicle speed change gradient (target acceleration)”. Is zero. "

Also, based on the actual acceleration of the vehicle, and determining vehicle speed setting means for setting the determination vehicle speed, based on the actual acceleration of the vehicle, the target for setting a target jerk corresponding to that the target vehicle speed and second-order differential with respect to time and jerk setting means, Ru equipped with. Further, the target curve setting means is a vehicle speed deviation (speed difference) between the determination vehicle speed set by the determination vehicle speed setting means at the first time and the set vehicle speed, and the target jerk setting means is set by the target jerk setting means. based on the target jerk, to set the target curve.

( 2 ) Moreover, it is preferable that the said target jerk setting means increases the absolute value of the said target jerk, so that the real acceleration of the said vehicle in said 1st time is large. That is, it is preferable to increase the absolute value of the change gradient of the target acceleration thereafter as the actual acceleration when the actual vehicle speed falls within the speed range increases.
In addition, it is preferable that the target jerk is a constant value (fixed value) until the actual vehicle speed reaches from the determination vehicle speed to the set vehicle speed.

( 3 ) Further, it is preferable that the target curve setting means sets the target curve corresponding to the target vehicle speed expressed as a quadratic function of time.
For example, the vehicle speed deviation between the determination vehicle speed and the set vehicle speed is D, the target jerk is J, and the target vehicle speed V _TGT (t) as a function of time t is V _TGT (t) = (J / 2) It can be expressed as t ² + (− 2JD) ^{1 / 2t} + V _SET −D.

( 4 ) Moreover, it is preferable that the said control means feedback-controls the said actual vehicle speed based on the difference of the said actual vehicle speed and the said target vehicle speed.
( 5 ) Further, the driver required torque calculated by the control means based on the accelerator operation amount of the vehicle is greater than or equal to a vehicle speed limiting required torque calculated based on a difference between the target vehicle speed and the actual vehicle speed. In some cases, it is preferable to implement the feedback control.
In other words, when the driver request torque is small enough that the actual vehicle speed does not increase to the target vehicle speed or higher, it is preferable to perform output control based on the driver request torque with respect to the driver's intention. On the other hand, when the driver required torque is relatively large and the actual vehicle speed may increase to the target vehicle speed or higher, it is preferable to perform output control based on the device required torque.

  The driver request torque is preferably calculated based on the accelerator operation amount and the engine speed. On the other hand, it is preferable that the device required torque is calculated based on a speed difference between the actual vehicle speed and the target vehicle speed.

In the disclosed vehicle speed limiting device, since the inclination of the target curve at the first time coincides with the change gradient (actual acceleration) of the actual vehicle speed, fluctuations in acceleration at the start of control by the control means can be suppressed, and vehicle travel It is possible to reduce the feeling of being caught and the uncomfortable feeling of acceleration fluctuation.
Moreover, since the inclination of the target curve at the second time is set to zero, it is possible to suppress the acceleration fluctuation when the actual vehicle speed reaches the set vehicle speed. If it is assumed that there is no delay in increase of the actual vehicle speed with respect to the target vehicle speed (that is, response delay or error), the acceleration fluctuation at the second time becomes zero, and the actual vehicle speed smoothly matches the set vehicle speed. Further, even if there is a delay in the increase of the actual vehicle speed with respect to the target vehicle speed, the acceleration fluctuation when the actual vehicle speed reaches the set vehicle speed becomes a value very close to zero.

  Thus, while suppressing the speed increase so that the actual vehicle speed does not exceed the set vehicle speed, unnatural acceleration fluctuations before and after the control by the control means can be suppressed, and the uncomfortable feeling that can be given to the driver can be reduced. At the same time, the drive feeling can be improved. Further, the device configuration and the control configuration are simple. For example, the disclosed vehicle speed limiting device can be realized only by applying a calculation configuration for setting a target curve to a conventional vehicle speed limiting device. Therefore, compared to, for example, a method that detects the acceleration / deceleration of the vehicle in real time and controls the engine output, the development man-hours and the man-hours to adapt to the actual vehicle can be greatly reduced, and the product cost Can be made cheaper.

It is a schematic diagram for demonstrating the structure of the vehicle speed limiting apparatus which concerns on one Embodiment, and its application vehicle. It is a typical graph for demonstrating the content of the vehicle speed limiting control implemented with this vehicle speed limiting apparatus. It is an example of the map used by vehicle speed restriction | limiting control, (a) shows the relationship between an actual acceleration and a vehicle speed deviation, (b) shows the relationship between an actual acceleration and a target jerk. It is a graph for demonstrating the target curve used by vehicle speed restriction | limiting control, (a) is a graph of target value W _TGT (t), (b) is a graph which shows the inclination of (a), (c) is (b) It is a graph which shows the inclination of (). It is a flowchart which illustrates the procedure of the normal control in this vehicle speed limiting apparatus. It is a flowchart which illustrates the procedure of the vehicle speed restriction | limiting control in this vehicle speed restriction | limiting apparatus. It is a graph for demonstrating the control effect | action by this vehicle speed limiting apparatus, (a) shows the change of an actual vehicle speed, (b) shows the change of an actual acceleration.

  Hereinafter, embodiments will be described with reference to the drawings. Note that the embodiment described below is merely an example, and there is no intention to exclude various modifications and technical applications that are not explicitly described in the following embodiment. Each configuration of the present embodiment can be implemented with various modifications without departing from the spirit of the present embodiment, and can be selected or combined as necessary.

[1. Device configuration]
The vehicle speed limiting device of this embodiment is applied to the vehicle 1 shown in FIG. The vehicle 1 is provided with an engine 2 and a brake device 3, and an engine ECU 4 (ENG-ECU) and a brake ECU 5 (BRK-ECU) as electronic control devices for controlling these operating states. The engine 2 may be of any type and form as long as it functions to apply a driving force for accelerating the vehicle 1 to the driving wheels. Similarly, the brake device 3 may be of any type or form as long as it functions to apply a braking force that decelerates the vehicle 1 to the drive wheels. The engine ECU 4 and the brake ECU 5 control the engine 2 and the brake device 3 based on the driving operation by the driver, the traveling environment of the vehicle 1, the operating state of the in-vehicle device, and the like.

  Further, the vehicle 1 is provided with a vehicle speed limiting ECU 9 (vehicle speed limiting device) as an electronic control device that can interrupt the operations of the engine ECU 4 and the brake ECU 5. Each of these ECUs 4, 5, and 9 is configured as an LSI device or an embedded electronic device in which a microprocessor, CPU, ROM, RAM, etc. are integrated, and can communicate with each other via a communication line of an in-vehicle network provided in the vehicle. Connected to.

Vehicle speed limiting ECU9, as the actual vehicle speed V of the vehicle 1 does not exceed the set vehicle speed V _SET, the braking force of the output or brake system 3 of the engine 2 to automatically adjust to control the actual vehicle speed V. That is, the vehicle speed limiting ECU 9 functions to limit the maximum speed of the vehicle 1 in preference to normal control performed by the engine ECU 4 and the brake ECU 5. Such control performed by the vehicle speed limiting ECU 9 is referred to as vehicle speed limiting control.

The set vehicle speed V _SET here may be a preset fixed value (for example, 100 [km / h], 120 [km / h], etc.), or the value can be freely set by the driver. It may be a variable value. In the former case, the legal maximum speed set for each section of the road is searched based on the travel position of the vehicle 1 specified by a car navigation system (not shown), and this is set as the set vehicle speed V _SET. . In the latter case, the driver can set an arbitrary speed value via an input device attached to the instrument panel or the steering wheel, and this may be set as the set vehicle speed V _SET .

  The vehicle speed restriction ECU 9 is connected with an engine speed sensor 6, an accelerator opening sensor 7, and a vehicle speed sensor 8 as sensors for acquiring information used in the vehicle speed restriction control. The engine rotational speed sensor 6 acquires the rotational speed Ne (or information corresponding thereto) of the engine 2 and detects and calculates the rotational speed Ne of the engine 2 based on, for example, the angular speed of the crankshaft. The accelerator opening sensor 7 acquires information corresponding to the driver's intention to accelerate. For example, the accelerator opening sensor 7 detects the depression amount of the accelerator pedal as the accelerator opening APS. Information on the rotational speed Ne and the accelerator opening APS detected here is transmitted to the vehicle speed limiting ECU 9.

  Further, the vehicle speed sensor 8 acquires information corresponding to the actual vehicle speed V (actual travel speed) of the vehicle 1 and detects, for example, the angular speed of the rotation shaft of the drive wheel. Information on the angular velocity detected here is transmitted to the vehicle speed limiting ECU 9 and converted into a value of the actual vehicle speed V. Instead of calculating the actual vehicle speed V by the vehicle speed limiting ECU 9, the vehicle speed sensor 8 may calculate the actual vehicle speed V.

[2. Control configuration]
Speed limiting control, as shown in FIG. 2, the threshold determination vehicle speed V _TH is set to a value lower than the set vehicle speed V _SET, when the actual vehicle speed V of the vehicle 1 is in the range of above determination vehicle speed V _TH To be implemented. In this vehicle speed limit control, the target vehicle speed V _TGT (t) is set in the speed range from the judgment vehicle speed V _TH to the set vehicle speed V _SET , and feedback control for bringing the actual vehicle speed V closer to the target vehicle speed V _TGT (t). Is implemented. Target vehicle speed V _TGT (t) is set so as to asymptotically from determination vehicle speed V _TH As the time passes the set vehicle speed V _SET. As a result, even if the accelerator pedal is fully depressed for a long time, the actual vehicle speed V is controlled so as not to exceed the set vehicle speed V _SET , and finally the actual vehicle speed V is set to the set vehicle speed V _SET . It is controlled to almost the same speed.

However, even if the actual vehicle speed V of the vehicle 1 is equal to or higher than the determination vehicle speed _VTH , there may be a case where it is not necessary to limit the vehicle speed again if the vehicle 1 is decelerating. Therefore, in this embodiment, vehicle speed limit control is performed in consideration of not only the actual vehicle speed V but also the accelerator opening APS.
The vehicle speed limiting ECU 9 is provided with a calculation unit 10 and a control unit 20. Various functions included in each of these elements may be realized by an electronic circuit (hardware), may be programmed as software, or some of these functions may be provided as hardware. The other part may be software.

[2-1. Calculation unit]
The calculation unit 10 calculates various parameters used in the vehicle speed limit control. Here, an actual vehicle speed calculation unit 11, an actual acceleration calculation unit 12, a vehicle speed deviation calculation unit 13, a determination vehicle speed calculation unit 14, a target jerk calculation unit 15, and a target curve calculation unit 16 are provided.

  The actual vehicle speed calculation unit 11 calculates the actual vehicle speed V based on the information acquired by the vehicle speed sensor 8. Here, for example, the actual vehicle speed V at that time is calculated based on the angular velocity and circumference of the rotating shaft of the drive wheel. Further, the actual vehicle speed calculation unit 11 is provided with a memory that holds and stores at least two values of the actual vehicle speed V, that is, the latest value of the actual vehicle speed V and the past value obtained in the immediately preceding calculation cycle. These two values of the actual vehicle speed V are used for calculating the actual acceleration A, which will be described later.

  The actual acceleration calculation unit 12 calculates the actual acceleration A based on the two actual vehicle speeds V calculated by the actual vehicle speed calculation unit 11. Here, for example, based on the difference between the two actual vehicle speeds V and the difference between the times when the actual vehicle speeds V are calculated, the actual acceleration A at that time is calculated. Instead of calculating the actual acceleration A based on the amount of change in the actual vehicle speed V, the actual acceleration A of the vehicle 1 may be calculated based on the detection value of a longitudinal acceleration sensor (not shown).

The vehicle speed deviation calculating unit 13 calculates the vehicle speed deviation D based on the actual acceleration A calculated by the actual acceleration calculating unit 12. And the vehicle speed deviation D, are those corresponding to the difference between the determined vehicle speed V _TH is the rate threshold for starting the vehicle speed limiting control the set vehicle speed V _SET, having a positive value. Here, the greater the actual acceleration A, the greater the vehicle speed deviation D is calculated. In the present embodiment, as shown in FIG. 3A, the relationship between the actual acceleration A and the vehicle speed deviation D is mapped in advance, and the vehicle speed deviation D is calculated based on this map. Further, the value of the vehicle speed deviation D is set so as to gradually approach the minimum vehicle speed deviation D ₀ as the actual acceleration A approaches zero in a positive range. The range where the actual acceleration A is negative is a region corresponding to the deceleration of the vehicle 1. Therefore, when the vehicle speed limit control is not started during deceleration, the setting of the vehicle speed deviation D when the actual acceleration A is negative can be omitted.

The determination vehicle speed calculation unit 14 (determination vehicle speed setting means) calculates the determination vehicle speed V _TH based on the set vehicle speed V _SET and the vehicle speed deviation D. Here, a speed obtained by subtracting the vehicle speed deviation D calculated by the vehicle speed deviation calculating unit 13 from the set vehicle speed V _SET is calculated as the determination vehicle speed V _TH (that is, V _TH = V _SET -D). The determination vehicle speed V _TH calculated here is lower as the actual acceleration A is larger, and is higher as the actual acceleration A is smaller (that is, closer to the set vehicle speed V _SET ). The maximum value determination vehicle speed V _TH can take is the rate obtained by subtracting the minimum vehicle speed difference D ₀ from set vehicle speed V _SET. Since the vehicle speed deviation D is calculated based on the actual acceleration A, the determination vehicle speed calculation unit 14 functions as a determination vehicle speed setting unit that sets the determination vehicle speed V _TH based on the actual acceleration A.

The target jerk calculation unit 15 (target jerk setting means) calculates the target jerk J based on the actual acceleration A. The target jerk J corresponds to a target vehicle speed V _TGT (t) obtained by second-order differentiation with respect to time, and has a negative value. Here, the absolute value of the target jerk J is set so that the target vehicle speed V _TGT (t) quickly approaches the set vehicle speed V _SET as the actual acceleration A increases. Further, where the value of the target jerk J calculated by, after the actual vehicle speed V becomes equal to or higher than the determination vehicle speed V _TH, while the decreased below again determination vehicle speed V _TH, recalculated Without being fixed value ( Constant value).

  In the present embodiment, as shown in FIG. 3B, the relationship between the actual acceleration A and the target jerk J is mapped in advance, and the target jerk J is calculated based on this map. Here, the value of the target jerk J is given so that the vehicle speed deviation D, the target jerk J, and the actual acceleration A satisfy the following formula 1.

As shown in FIG. 3B, the target jerk J is a negative value having an absolute value corresponding to the actual acceleration A at the time when the vehicle speed limit control is started. Further, the value of the target jerk J is set so as to gradually approach the maximum target jerk J ₀ as the actual acceleration A approaches zero in a positive range. Similar to the setting of the vehicle speed deviation D, the target jerk J need not be set in the range where the actual acceleration A is negative. The target jerk calculation unit 15 functions as target jerk setting means for setting the target jerk J based on the actual acceleration A.

The target curve calculation unit 16 (target curve setting means) is based on the vehicle speed deviation D calculated by the vehicle speed deviation calculation unit 13 and the target jerk J calculated by the target jerk calculation unit 15, and the target vehicle speed at the time of vehicle speed restriction control. V _TGT (t) is calculated. Here, as the value of the target vehicle speed V _TGT (t) is asymptotic to the set vehicle speed V _SET from determination vehicle speed V _TH with time, the target vehicle speed V _TGT (t) is calculated as a function of time t. In this embodiment, first, following the vehicle speed as a quadratic function of time t shown in equation 2 of the target value W _TGT (t) is calculated, the target vehicle speed V _TGT (t based on the target value W _TGT (t) ) Is calculated.

FIG. 4A is a graph of the function of Equation 2. This graph is a `` upward convex '' parabola where the target value W _TGT (t) is 0 when t is 0 or 2 (-2D / J) ^1/2 , and the coordinates of the vertex are ( (-2D / J) ^1/2 , D). Of this parabola, the portion of 0 ≦ t ≦ (−2D / J) ^1/2 is a target curve corresponding to the target vehicle speed V _TGT (t) at the time of vehicle speed limit control. In other words, the curve connecting the point corresponding to t = 0 and V _TGT (t) = 0 and the vertex is the target curve.

The above target value W _TGT (t) is calculated using the speed at the time when the vehicle speed deviation D and the target jerk J are calculated as a reference (origin), and comparing the value as it is with the actual vehicle speed V is Can not. Therefore, the target curve calculation unit 16 converts the target value W _TGT (t) into the actual target vehicle speed V _TGT (t) of the vehicle 1 using a conversion formula as shown in the following formula 3. Also, since the W _TGT (t) coordinate of the vertex of the target curve is D, the value of the target vehicle speed V _TGT (t) when the time t is (-2D / J) ^1/2 is the set vehicle speed V _SET Matches. Therefore, the target curve calculation unit 16 fixes the value of the target vehicle speed V _TGT (t) when the time t is (−2D / J) ^1/2 or later to the set vehicle speed V _SET as shown in Equation 4 below. The period during which the target vehicle speed V _TGT (t) is fixed to the same value as the set vehicle speed V _SET is until normal control is started.

The graph of FIG. 4 (b) is a graph obtained by differentiating the target value W _TGT (t) shown in FIG. 4 (a) by time t [W _TGT ′ (t) = Jt + (− 2JD) ^1/2 ]. _Yes , the graph of FIG. 4C is a graph of [W _TGT ″ (t) = J] obtained by differentiating this with time t. In these graphs of FIGS. For the time axis value t, t = 0 corresponds to the time (first time) when the actual vehicle speed V in FIG. 2 is equal to or higher than the judgment vehicle speed _VTH , and t = (− 2D / J) ^1/2 is This corresponds to the time (second time) when the actual vehicle speed V reaches the set vehicle speed _VSET .

From the graph of FIG. 4B, it can be seen that the gradient of change of the target value W _TGT (t) at the start time (first time) of the vehicle speed limit control coincides with the actual acceleration A at that time. That is, the gradient of change in the target vehicle speed V _TGT (t) (that is, the target acceleration) matches the actual acceleration A at that time. It can also be seen that when the target vehicle speed V _TGT (t) matches the set vehicle speed V _SET (second time), the gradient of change of the target value W _TGT (t) becomes zero. In other words, the change gradient of the target vehicle speed V _TGT (t) when the target vehicle speed V _TGT (t) has reached the set vehicle speed V _SET is zero.

In this way, the target curve calculation unit 16 functions to match the change gradient of the actual vehicle speed V at the first time with the slope of the target curve, and to set the slope of the target curve at the second time to zero. To do. In the vehicle speed limiting control of the present embodiment, feedback control is performed so that the actual vehicle speed V changes along the graph of the target vehicle speed V _TGT (t) corresponding to this target curve. Information on the target vehicle speed V _TGT (t) calculated here is transmitted to the control unit 20.

[2-2. Control unit]
The control unit 20 performs vehicle speed restriction control based on the target vehicle speed V _TGT (t) calculated by the calculation unit 10 and the actual vehicle speed V. Here, a feedback control unit 21, a driver request torque calculation unit 22, and a vehicle speed limiting request torque calculation unit 23 are provided.

The feedback control unit 21 performs vehicle speed limit control while applying feedback to the control amount so that the actual vehicle speed V approaches the target vehicle speed V _TGT (t). Here, even if the driver is remained operated fully opened accelerator opening, so that the actual vehicle speed V is equal to stably set vehicle speed V _SET without exceeding the set vehicle speed V _SET, the driving of the vehicle 1 The magnitude of the driving torque acting on the wheel is controlled.

The driving torque referred to here is an added value of a value obtained by converting engine torque generated in the engine 2 into torque of driving wheels and braking torque generated in the brake device 3. The feedback control unit 21 functions to control the magnitude of the drive torque by controlling at least one of the engine torque and the braking torque. The target vehicle speed V _TGT (t) is given as a function of time t in the target curve calculation unit 16. In response to this, the feedback control unit 21 functions to cause the actual vehicle speed V to follow the target vehicle speed V _TGT (t) that changes from moment to moment.

The specific method of feedback control is arbitrary, and it is conceivable to apply PID control, cascade control, or the like. For example, when PID control is applied, the speed difference ΔV between the actual vehicle speed V and the target vehicle speed V _TGT (t) is reflected in the control amount (engine torque or braking torque), and the time differential value of the speed difference ΔV and The integrated value may be reflected in the control amount. Depending on the specific method of feedback control, the time until the actual vehicle speed V substantially matches the target vehicle speed V _TGT (t), convergence, response to disturbance, and the like change.

Execution conditions of the feedback control in the feedback control unit 21, the actual vehicle speed V is not more determination vehicle speed V _TH or more, the driver demanded torque T ₁ is assumed that it is required torque T ₂ or more vehicle speed limit. The driver request torque T ₁ and the vehicle speed limiting request torque T ₂ under these conditions are calculated by a driver request torque calculating unit 22 and a vehicle speed limiting request torque calculating unit 23 to be described later.

Based on the rotational speed Ne detected by the engine rotational speed sensor 6 and the accelerator opening APS detected by the accelerator opening sensor 7, the driver requested torque calculating unit 22 calculates the driver required torque T corresponding to the driver's acceleration request. ₁ is calculated. Here, for example, based on a map in which the relationship between the rotational speed Ne, the accelerator opening APS, and the driver required torque T ₁ is defined, the value of the driver required torque T ₁ is determined using the rotational speed Ne and the accelerator opening APS as arguments. Calculated. The value of the driver request torque T ₁ calculated here is transmitted to the feedback control unit 21.

The vehicle speed limiting required torque calculation unit 23 limits the vehicle speed required to change the actual vehicle speed V along the target vehicle speed V _TGT (t) based on the speed difference ΔV between the target vehicle speed V _TGT (t) and the actual vehicle speed V. Required torque T ₂ is calculated. The magnitude of the required vehicle speed limiting torque T ₂ is, for example, based on a preset map, the larger the speed difference ΔV between the target vehicle speed V _TGT (t) and the actual vehicle speed V, or the target vehicle speed V _TGT (t) The larger the gradient, the larger the value.

If, when the required torque T ₂ for the vehicle speed limit is greater than the driver required torque T _1, even if the engine torque is controlled to a magnitude corresponding to the driver required torque T _1, the actual vehicle speed V is the target vehicle speed V _TGT ( t) is not exceeded. On the other hand, when the vehicle speed limiting torque demand T ₂ is greater than the driver required torque T _1, the engine torque is controlled to a magnitude corresponding to the driver required torque T _1, the actual vehicle speed V is the target vehicle speed V _TGT (t ), And thus the vehicle speed V _SET may be greatly exceeded. Therefore, the feedback control unit 21 determines that the driver request torque T ₁ is equal to or greater than the vehicle speed limiting request torque T ₂ as one of the feedback control execution conditions, and the actual vehicle speed V is the target vehicle speed V _TGT (t). When there is a possibility of exceeding, the output restriction of the vehicle 1 is applied.

[3. flowchart]
[3-1. Normal control]
FIG. 5 is a flowchart illustrating a control procedure when normal control is performed by the vehicle speed limiting ECU 9. Here, it is assumed that a set vehicle speed V _SET arbitrarily set by the driver is given in advance. This flow is repeatedly performed when the actual vehicle speed V of the vehicle 1 is less than the determination vehicle speed _VTH .

In step A10, the actual vehicle speed calculation unit 11 calculates the actual vehicle speed V of the vehicle 1, and the actual acceleration calculation unit 12 calculates the actual acceleration A. In subsequent step A20, the vehicle speed deviation calculation unit 13 calculates the vehicle speed deviation D based on the actual acceleration A. Here, for example, the vehicle speed deviation D is calculated based on a map as shown in FIG. In step A30, the vehicle speed difference D is subtracted from the set vehicle speed V _SET at determining vehicle speed calculating unit 14, determines the vehicle speed V _TH is calculated.

In step A40, the feedback control unit 21 determines whether or not the actual vehicle speed V is _{equal to} or higher than the determination vehicle speed _VTH . Here, if V ≧ V _TH is satisfied, one of the conditions for executing the vehicle speed limit control is satisfied, and thus the process proceeds to Step A50. On the other hand, when V ≧ V _TH is not satisfied, the execution condition is not satisfied, and thus this flow is ended. In this case, control is performed again from step A10 in the next calculation cycle, and normal control is continued. Thus, the vehicle speed restriction control is not performed when the actual vehicle speed V of the vehicle 1 is less than the determination vehicle speed _VTH . Further, for example, the engine ECU 4 controls the magnitude of the engine torque based on the rotational speed Ne of the engine 2 and the accelerator opening APS.

In step A50, the target jerk calculation unit 15 calculates the target jerk J based on the actual acceleration A. Here, for example, as shown in FIG. 3B, the target jerk J is calculated based on the map. This target jerk J corresponds to the target vehicle speed V _TGT (t) obtained by second-order differentiation with respect to time, that is, it corresponds to the time change gradient of the target acceleration.

In step A60, the target curve calculation unit 16 calculates the target vehicle speed V _TGT (t) based on the vehicle speed deviation D and the target jerk J. Here, for example, the target vehicle speed V _TGT (t) is calculated as a quadratic function of time t as shown in Expressions 2 to 4. As a result, at the start of the vehicle speed limit control, the time change gradient of the target acceleration matches the actual acceleration A, and the time change gradient of the target acceleration when the target vehicle speed V _TGT (t) and the set vehicle speed V _SET match. Becomes 0. In step A70, the measurement of the time t for specifying the value of the target vehicle speed V _TGT (t) is started, and the control proceeds to the flow of the vehicle speed restriction control shown in FIG.

[3-2. Vehicle speed limit control]
FIG. 6 is a flowchart illustrating a control procedure of the vehicle speed limit control performed by the vehicle speed limit ECU 9. This flow is repeatedly performed when the actual vehicle speed V of the vehicle 1 is _{equal to} or higher than the determination vehicle speed _VTH .
In step B10, at driver required torque calculating unit 22, the driver demanded torque T ₁ is calculated based on the rotational speed Ne and the accelerator opening APS of the engine 2. The driver required torque T ₁ here may be a control configuration for calculating the engine ECU 4. In step B <b> 20, the actual vehicle speed V of the vehicle 1 is calculated by the actual vehicle speed calculation unit 11.

In step B30, the feedback control unit 21 subtracts the actual vehicle speed V from the current target vehicle speed V _TGT (t) to calculate a speed difference ΔV. In step B40, the speed limiting torque demand calculator 23, based on the speed difference ΔV and the target vehicle speed V _TGT (t) is the vehicle speed limiting torque demand T ₂ is calculated. The speed difference ΔV corresponds to the difference between the actual vehicle speed V and the target vehicle speed V _TGT (t) at that time, and the required torque T ₂ for limiting the vehicle speed is determined by changing the actual vehicle speed V to the target vehicle speed V _TGT (t) at that time. This corresponds to the torque required to change to.

In step B50, the driver demanded torque T ₁ is whether or not the torque demand T ₂ than the vehicle speed limit is determined. Here, when T ₁ ≧ T ₂ is satisfied, the execution condition of the vehicle speed limit control is satisfied, so the process proceeds to Step B60, and the control for forcibly changing the magnitude of the engine torque to the vehicle speed limit request torque T ₂ is performed. A signal is transmitted from the vehicle speed limiting ECU 9 to the engine ECU 4. As a result, the upper limit value of the engine torque is limited even when the driver is stepping on the accelerator pedal, and the increase in the actual vehicle speed V is suppressed.

On the other hand, when T ₁ ≧ T ₂ is not satisfied in step B50, the execution condition of the vehicle speed limit control is not satisfied, and thus the process proceeds to step B70. In step B70, the magnitude of the engine torque is controlled in response to the driver demand torque T ₁ at the engine ECU 4. Thereby, the vehicle behavior according to a driver | operator's intention is implement | achieved similarly to the time of normal control. At this time, since the driver required torque T ₁ is less than the vehicle speed limiting required torque T ₂ , it is possible to prevent the actual vehicle speed V from exceeding the target vehicle speed V _TGT (t) at that time.

In step B80, the feedback control unit 21 determines whether or not the actual vehicle speed V is _{equal to} or higher than the determination vehicle speed _VTH . Here, when V ≧ V _TH is satisfied, one of the execution conditions of the vehicle speed restriction control is continuously satisfied, and thus this flow is terminated. In this case, in the next calculation cycle, the control is performed again from step B10, and the vehicle speed limiting control is continued. In the calculation cycle after the next time, feedback control is performed so that the actual vehicle speed V approaches the target vehicle speed V _TGT (t) having a value corresponding to the time t (time).

On the other hand, if V ≧ V _TH is not satisfied in step B80, one of the conditions for executing the vehicle speed limit control is not satisfied, and the process proceeds to step B90. In step B90, the measurement of the time t is completed, and the value of the target jerk J is reset to 0. Then, the control proceeds to the normal control flow shown in FIG.

[4. Action, effect]
FIGS. 7A and 7B are graphs illustrating changes in the actual vehicle speed V and the actual acceleration A over time when the vehicle speed restriction control is performed in the vehicle 1. In the vehicle speed limiting control described above, the determination vehicle speed V _TH is set lower than the set vehicle speed V _SET , and the value is set according to the actual acceleration A. For example, when the actual acceleration A at time t ₁ is A ₁ and the corresponding vehicle speed deviation D is D ₁ , the determination vehicle speed V _TH is a value lower by D ₀ than the set vehicle speed V _SET .

When the actual vehicle speed V to the time t ₁ is equal to or higher than the determination vehicle speed V _TH, is the target vehicle speed V _TGT the target curve computation unit 16 (t) is calculated as a function of time t, as shown by the broken line in FIGS. 7 (a) A target curve is set. Since this target curve is expressed by a quadratic function of time t, the target acceleration graph obtained by differentiating the target curve with respect to time t is linear as shown by a broken line in FIG. The acceleration gradient is constant. Further, when the vehicle speed deviation D and the actual acceleration A are given, the target jerk J is set so as to satisfy Equation 1, so that the inclination of the target curve at the time t ₁ matches the actual acceleration A.

Here, placing the time corresponding to the vertex of the target curve and t _2, the value of the target vehicle speed V _TGT (t) at time t ₂ corresponds to the vehicle speed deviation D as shown in Equation 2. That is, the gradient of the target curve becomes zero when the target vehicle speed V _TGT (t) reaches the set vehicle speed V _SET . Therefore, the target vehicle speed V _TGT (t) gradually and gradually _approaches from the determination vehicle speed V _TH toward the set vehicle speed V _SET as indicated by a broken line in FIG.

After the target vehicle speed V _TGT (t) that draws such a target curve is set, the feedback control unit 21 drives the driving torque (engine torque, braking torque so that the actual vehicle speed V matches the target vehicle speed V _TGT (t). ) Is controlled. On the other hand, the angular acceleration of the drive wheel is proportional to the magnitude of the drive torque. Therefore, the actual acceleration A of the vehicle 1 changes so as to follow the target acceleration indicated by a broken line in FIG.

(1) As described above, in the vehicle speed limiting control, the actual vehicle speed V is controlled so that the inclination of the target curve at the time t ₁ and the actual acceleration A coincide with each other. Thereby, the acceleration fluctuation | variation at the time of the start of vehicle speed restriction | limiting control can be suppressed, and the feeling of being caught by vehicle travel and the uncomfortable feeling of acceleration fluctuation | variation can be reduced. Further, since the slope of the target curve at time t ₂ is set to zero, it is possible to suppress the acceleration variation just before the actual vehicle speed V reaches the set vehicle speed V _SET. The time (delay time) between the time and the time t ₂ when the actual vehicle speed V reaches the set vehicle speed V _SET is dependent on the convergence of the feedback control. However, the difference between the actual vehicle speed V and set vehicle speed V _SET at time t ₂ is small. Therefore, the time t _2, the may be regarded as the actual vehicle speed V is time to reach the set vehicle speed V _SET.

Thus, according to the vehicle speed limit ECU 9 (vehicle speed limiting device), while suppressing an unnatural acceleration variation before and after the vehicle speed limiting control, the actual vehicle speed V does not exceed the set vehicle speed V _SET And drive feeling can be improved. In addition, the control configuration is simple, the number of development man-hours and the number of man-hours for adapting to actual vehicles can be reduced, and the product cost can be reduced.

(2) In the vehicle speed limiting control, the vehicle speed deviation D corresponding to the difference between the determination vehicle speed V _TH and the set vehicle speed V _SET is calculated based on the actual acceleration A, and the target acceleration during the vehicle speed suppression control is calculated. The target jerk J corresponding to the gradient is also calculated based on the actual acceleration A. By setting the target curve based on these vehicle speed deviation D and target jerk J, the target curve can be set according to the time margin and speed margin until the actual vehicle speed V reaches the set vehicle speed V _SET. Can do.

For example, when the vehicle speed deviation D is relatively large or when the actual acceleration A is relatively small when the actual vehicle speed V exceeds the judgment vehicle speed _VTH , it is considered that the time margin and the speed margin are relatively large. . In such a case, the acceleration fluctuation can be further reduced by setting the slope of the target curve gently. On the other hand, even if the time margin and speed margin are relatively small, the target curve is set according to each situation, so the actual vehicle speed V is accurately kept within the set vehicle speed V _SET or less. be able to. Therefore, it is possible to enhance the effect of suppressing the acceleration fluctuation while improving the accuracy of suppressing the increase in the actual vehicle speed V.

(3) In particular, in the vehicle speed limiting control described above, as shown in FIG. 3B, the absolute value of the target jerk J is set larger as the actual acceleration A increases. In other words, the stronger the acceleration of the vehicle 1 at the time of starting the vehicle speed limit control, the time required until the target vehicle speed V _TGT (t) reaches the set vehicle speed V _SET is estimated short, reasonably in that short period of time The target jerk J is determined so that the target acceleration is reduced to zero. Therefore, an appropriate target vehicle speed V _TGT (t) corresponding to the acceleration behavior of the vehicle 1 can be obtained, and an overshoot in which the actual vehicle speed V exceeds the set vehicle speed V _SET can be more reliably suppressed. Drive feeling can be improved.
In addition, since the target jerk J becomes a constant value during the vehicle speed limiting control, the acceleration can be gradually decreased, and the actual vehicle speed V can be naturally converged to the set vehicle speed V _SET .

(4) In the above vehicle speed limiting control, as shown in Equation 2, the vehicle speed target value W _TGT (t) is calculated as a quadratic function of time t, and 0 ≦ t ≦ (−2D / J) ^1/2 A graph in the range is set as the target curve. Further, the target vehicle speed V _TGT (t) is set so as to change in the same manner as the graph shape of the target curve as shown in Equation 3, that is, the target vehicle speed V _TGT (t) is also a quadratic function of time t. It is expressed by At this time, the target acceleration is given by a linear function of time as shown by a broken line in FIG.

  As a result, the acceleration fluctuation during the vehicle speed limiting control can be made substantially constant, and the actual vehicle speed V can be limited while reducing the actual acceleration A of the vehicle 1 at a substantially constant rate. Therefore, it is possible to further improve drive feeling while appropriately suppressing the actual vehicle speed V. In addition, the target curve can be easily set, and the calculation configuration can be further simplified.

(5) Further, in the vehicle speed limiting control described above, feedback control is performed based on the difference between the actual vehicle speed V and the target vehicle speed V _TGT (t), so that the actual vehicle speed V can be smoothly changed without abruptly changing. It can approach the set vehicle speed V _SET and drive reeling can be improved. In addition, for example, even when the difference between the actual vehicle speed V and the target vehicle speed V _TGT (t) is increased due to a change in the road surface gradient, the control result can be easily reflected in the control amount. The actual vehicle speed V can be brought close to the target vehicle speed V _TGT (t).

(6) In the vehicle speed limiting control described above, it is determined as one of the feedback control execution conditions that the driver required torque T ₁ is equal to or higher than the vehicle speed limiting required torque T ₂ . As a result, the vehicle speed restriction can be prioritized over the driver's intention to accelerate, and the actual vehicle speed V can be reliably kept within the range below the set vehicle speed V _SET . On the other hand, when the driver required torque T ₁ is less than the vehicle speed limiting required torque T ₂ , such a restriction is not made. For example, when the accelerator pedal is depressed, the vehicle responds to the driver's intention to decelerate. 1 driving torque can be reduced, and the vehicle speed can be reduced.

[5. Modified example]
The above-described embodiment can be implemented with various modifications without departing from the gist thereof, and each configuration of the above-described embodiment may be selected or combined as appropriate.
For example, in the above-described embodiment, the target value W _TGT (t) and the target vehicle speed V _TGT (t) are set as quadratic functions of time t as shown in Equations 2 and 3, but specific functions The type of is not limited to this. That is, the target vehicle speed V _TGT (t) may be expressed as a part of a quadratic curve such as an ellipse or a hyperbola, or may be set as a cubic function of time t. The target is set so that at least the slope of the broken line graph at time t ₁ in FIG. 7A matches the slope of the actual vehicle speed V graph, and the slope of the broken line graph at time t ₂ becomes zero. The vehicle speed V _TGT (t) may be set.

The correspondence relationship between the actual acceleration A, the vehicle speed deviation D, and the target jerk J is not limited to that shown in FIGS. 3A and 3B, and can be arbitrarily set. For example, the vehicle speed deviation D may be set to change linearly with respect to the change in the actual acceleration A. The same applies to the setting of target jerk J.
Incidentally, as the actual acceleration A is larger, since it is considered that easily exceeds the set vehicle speed V _SET, it is preferable that the actual acceleration A increases the vehicle speed deviation D As the increase. With such a setting, the vehicle speed limit can be implemented earlier (the start time is advanced) as the possibility that the actual vehicle speed V exceeds the set vehicle speed V _SET is higher (the urgency of the vehicle speed limit is higher). Similarly, it is preferable to increase the absolute value of the target jerk J as the actual acceleration A increases. As a result, the higher the possibility that the actual vehicle speed V exceeds the set vehicle speed V _SET (the urgency of the vehicle speed limit is high), the vehicle speed limit can be strengthened (the target acceleration decreasing gradient is increased).

  In the above-described embodiment, the drive torque (engine torque, braking torque) is set as the control target of the feedback control, but the control target is not limited to these. At least the actual vehicle speed V of the vehicle 1 may be increased or decreased. It is also possible to adopt a control configuration in which feedforward control is performed instead of feedback control.

In the above-described embodiment, the actual vehicle speed V and the accelerator opening APS are used as the execution conditions for the vehicle speed limit control. However, specific start conditions and end conditions for the vehicle speed limit control are not limited to these. The vehicle speed limit control may be any control that controls the actual vehicle speed so that at least the actual vehicle speed of the vehicle does not exceed the set vehicle speed.
In the above-described embodiment, the vehicle speed limit control of the vehicle 1 equipped with the engine 2 has been described in detail. However, this vehicle speed limit control uses an electric vehicle equipped with an electric motor instead of the engine 2 or the engine 2 and the electric motor in combination. The present invention can also be applied to a hybrid vehicle that runs on the road. For example, when applied to an electric vehicle, the motor torque generated by the electric motor or the magnitude of the regenerative torque absorbed by regenerative power generation may be set as the control target of the feedback control.

9 Vehicle speed limit ECU
10 Calculation unit 14 Determination vehicle speed calculation unit (determination vehicle speed setting means)
15 Target jerk calculation part (target jerk setting means)
16 Target curve calculation unit (target curve setting means)
20 Control unit (control means)
V Actual vehicle speed
A Actual acceleration
D Vehicle speed deviation
J target jerk
V _SET setting vehicle speed
V _TH judgment vehicle speed
V _TGT (t) Target vehicle speed

Claims (5)

In the vehicle speed limiting device for controlling the actual vehicle speed so that the actual vehicle speed of the vehicle does not exceed the set vehicle speed,
A target curve setting means for setting a target curve corresponding to a target vehicle speed expressed as a function of time in a speed range from a determination vehicle speed lower than the set vehicle speed to the set vehicle speed;
Control means for controlling the actual vehicle speed so that the actual vehicle speed changes along the target curve set by the target curve setting means;
Determination vehicle speed setting means for setting the determination vehicle speed based on the actual acceleration of the vehicle;
A target jerk setting means for setting a target jerk corresponding to the second derivative of the target vehicle speed with respect to time based on the actual acceleration of the vehicle ,
The target curve setting means matches a change gradient of the actual vehicle speed at a first time when the actual vehicle speed becomes equal to or higher than the determination vehicle speed and an inclination of the target curve at the first time, and the target vehicle speed Set the slope of the target curve at the second time when the vehicle reaches the set vehicle speed to zero ,
The target curve setting means is based on a vehicle speed deviation between the determined vehicle speed and the set vehicle speed set by the determination vehicle speed setting means at the first time, and the target jerk set by the target jerk setting means, The vehicle speed limiting device, wherein the target curve is set . The target jerk setting means, the higher the actual acceleration of the vehicle is greater in the first time, characterized in that to increase the absolute value of the target jerk, vehicle speed limiting device according to claim 1. The vehicle speed limiting device according to claim 1 or 2 , wherein the target curve setting means sets the target curve corresponding to the target vehicle speed expressed as a quadratic function of time. It said control means, based on the difference between the target vehicle speed and the actual vehicle speed, characterized by feedback controlling the actual vehicle speed, vehicle speed limiting device according to any one of claims 1-3. When the driver request torque calculated based on the accelerator operation amount of the vehicle is equal to or greater than the vehicle speed limiting request torque calculated based on the difference between the target vehicle speed and the actual vehicle speed, The vehicle speed limiting device according to claim 4 , wherein feedback control is performed.

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