JPH04224425A - Constant speed running control device for car - Google Patents

Abstract

PURPOSE:To facilitate matching operation, approach the car running speed to its target value with a constant acceleration so as to result in smooth convergence into the target value without risk of overshooting, by using the sliding mode control to the resume control. CONSTITUTION:The running speed of a car is sensed by a car speed sensor A and adjusted by using an actuator B, and the target value for the running speed is set by a setting means C, and the deviation of the running speed from the target value is sensed by a deviation sensing means D. The actuator B is controlled by No.1 sliding mode control means E so that the running speed approaches to the target value at a constant speed. The actuator B is also controlled by No.2 sliding mode control means F so that convergence of the running speed to the target value is made according to an exponential function. A changeover means G changes over into the No.1 control means E when the deviation is larger than the specified value, and into the No.2 control means F when smaller than the specified value.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a constant speed cruise control device for a vehicle, and more particularly to a constant speed cruise control device for a vehicle equipped with a resume function.

0002

[Prior Art] Conventionally, a constant speed cruise control device for a vehicle has a resume function, and when performing a resume function, a proportional differential function is used to calculate a control amount by multiplying a proportional term and a differential term related to the target vehicle speed and traveling speed by a constant. The traveling speed of the vehicle is controlled by (PD) control.

0003

[Problem to be solved by the invention] However, the above conventional P
When the resume is executed by the D control, since there is no integral term, the acceleration of the vehicle varies depending on the load condition (for example, road surface gradient, vehicle weight, etc.), giving a sense of discomfort to the driver. In addition, the PD is designed to reduce this discomfort and overshoot.
When attempting to determine control constants, there is a problem in that matching is extremely difficult and requires a large amount of man-hours.

[0004] The present invention has been made in view of the above points, and it is an object of the present invention to facilitate matching and to enable resume control that does not cause discomfort or overshoot.

[0005]

[Means for Solving the Problems] The present invention is for this reason shown in FIG.
As shown in FIG. a first deviation detecting means for detecting a deviation;
first sliding mode control means that controls the actuator using a sliding surface; and second sliding mode control means that controls the actuator using a second sliding surface that exponentially converges the traveling speed to the target vehicle speed. and,
switching means for switching to the first sliding mode control means when the deviation is larger than a predetermined value and switching to the second sliding mode control means when the deviation is smaller than a predetermined value; A technical means is proposed in which a two-sliding mode control means controls the actuator to return the traveling speed to the target vehicle speed.

[0006]

[Operation] According to the present invention, when the deviation between the target vehicle speed and the running speed is larger than a predetermined value when resuming, the first sliding surface that commands constant acceleration is used to control the running speed of the vehicle at a constant acceleration. to get closer to the target vehicle speed. Furthermore, when the deviation between the target vehicle speed and the running speed becomes smaller than a predetermined value, the second sliding surface is used to control the running speed of the vehicle to exponentially converge the running speed to the target vehicle speed without causing any discomfort or overshoot.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A constant speed cruise control device for a vehicle to which the present invention is applied will be explained based on the drawings. In FIG. 2, 10 is an electronic control unit (ECU), which includes a CPU 11, a ROM 12, an R
AM13, backup RAM14, AD converter 1
5, an input/output (I/O) port 16, a bus (not shown), and a constant voltage power supply.

The CPU 11 and the like are supplied with voltage from a constant voltage power supply that is turned on and off by the ignition switch 17 of the vehicle, but the backup RAM 14 is supplied with voltage directly from the vehicle battery (not shown), and when the ignition switch 17 is The memory contents are retained even if it is turned off. The driving speed of the vehicle is normally set to 25 on the accelerator pedal.
It is adjusted by the engine throttle valve 23 operated by the engine. The throttle valve 23 is also driven to open and close by an electric actuator 30 during constant speed driving control.

This actuator 30 is a DC motor 3
1. It has a reduction gear 32, a clutch 33, and a throttle opening sensor 34, and is connected to a throttle valve 23 by a link mechanism 22. Then, the actuator 30
A signal from U10 connects the clutch 33, drives the motor 31, and operates the throttle valve 23. The throttle valve 23 is provided with a return spring 24, which applies a force so that the throttle valve 23 moves toward the closing side when the clutch 33 is disengaged.

[0010] The throttle opening sensor 34 is connected to the speed reducer 32.
The throttle opening is detected during constant speed driving control. The vehicle speed sensor 26 is provided on a driven wheel of the vehicle, detects the vehicle speed of the vehicle, and outputs a pulse signal corresponding to the vehicle speed. And sensor 26,
34 detection signals are input to the ECU 10. As is well known, the command device 27 consists of a main switch M, a set switch S, a resume switch R, a cancel switch C, etc.
It is transmitted to the CU10.

The constant speed cruise control device sets the vehicle speed at that time as a target vehicle speed when the driver presses a set switch while driving;
Feedback control is performed so that the actual vehicle speed becomes the target vehicle speed. One of the functions of the constant speed cruise control device is a resume function. This is a function that allows the vehicle to quickly return to the original target vehicle speed by pressing the resume switch R even if the constant speed driving control is canceled by the driver stepping on the brake or pressing the cancel switch C. Here, the resume function of the present invention will be explained.

The continuous system perturbation model of a vehicle is expressed as a linear transfer function G(S) as shown in Equation 1.

[0013]

[Equation 1] G(S)=spd(S)/acp(S)=k/
(1+τS) Here, τ is a time constant, k is a gain, S is a Laplace operator, spd is a vehicle speed, and acp is an actuator position. When formula 1 is discretized by sampling time T, formula 2 ~
A first-order discrete value system perturbation model as shown in Equation 4 is obtained.

[0014]

[Math. 2] G(z)=spd(z)/acp(z)=bz
-1/(1-az-1)

[0015]

[Formula 3] a=exp(-T/τ)

[0016]

[Equation 4]b=k(1-exp(-T/τ)) From Equations 2 to 4, Equation 5 is obtained.

[0017]

[Formula 5] spd(k+1)=a・spd(k)+b・a
cp(k) Here, if we use the vehicle model shown by Equation 2 and consider a feedback loop as shown in Fig. 3, the deviation er(k)
is expressed by Equation 6.

[0018]

[Formula 6] er(k)=rs(k)-spd(k) Here, rs represents the target vehicle speed. As shown in Figure 4, the deviation er
Considering the phase plane of (k) and Δ(k), it is expressed as in Equation 7.

[0019]

[Equation 7] Δ(k)=er(k)−er(k−1)=(r
s(k)-spd(k))-(rs(k-1)-spd
(k-1)) Here, Equation 8 holds true at the time of resume.

[0020]

[Formula 8] rs(k)=rs(k-1) Therefore, Δ(k) is expressed by Equation 9.

[0021]

[Equation 9]Δ(k)=-spd(k)+spd(k-1)
Next, a sliding surface 1 (s
(k)) is expressed as in Equation 10.

[0022]

[Formula 10] s(k)=Δ(k)+c・er(k)=-s
pd(k)+spd(k-1)+c・er(k) When the sliding mode existence condition is set as in Equation 11,

[0023]

[Formula 11] When s(k)>0, s(k+1)-s(
k)≦−η When s(k)<0, s(k+1)−s(k)≧
ηAs shown in Figure 5, the actuator position acp(k) calculated this time will ensure that the next s(k+1) will be s=0.
move towards.

[0024]

[Formula 12] s(k)=s(k+1)−s(k)≦−η・
Let it be sgn(s(k)). Here, sgn(k) is a switching function expressed by Equation 13.

[0025]

[Formula 13] sgn(k)=1 (s(k)>0)sg
n(k)=-1(s(k)<0) Equation 12 can be expressed as Equation 14 from Equation 10.

[0026]

[Formula 14] −spd(k+1)+spd(k)+c・er(k
)−(spd(k)+spd(k−1)+c・
er(k-1))=-η・sgn(s(k))spd(
When Equation 5 is substituted for k+1), it is expressed as Equation 15.

[0027]

[Formula 15] −a・spd(k)−b・acp(k)+(c−1
)・Δ(k) =
-η・sgn(s(k)) Here, in order to suppress hunting of the actuator position acp, which is the control input, sg
Replace n(s(k)) with a saturation function sat(s(k)) as shown in FIG. 6 and Equation 16.

[0028]

[Formula 16] sat(s(k))=1(s(k)
≧φ) sat(s(k))=-1 (s(k)≦φ)sat
(s(k))=S/φ(-φ<s(k)<φ) As a result, the sliding surface 1 is reached smoothly. From Equations 15 and 16, the target actuator position rp(k) is derived from Equation 17.

[0029]

[Formula 17] rp(k)=(1/b)・{(1-a)・spd(
k) + (c-1) ・Δ(
k)+η·sat(s(k))} Next, as shown in FIG. 7 and Equation 18, the sliding surface 2 is defined.

[0030]

s=Δ(k)+kacc Furthermore, as shown in FIG. 7 and Equation 19, the sliding surface 3 is defined.

[0031]

[Equation 19] Define s=Δ(k)−kacc. In Equations 18 and 19, kacc means the target uniform acceleration. Further, +p and -p in FIG. 7 are values of er(k) at the intersections of sliding surface 1 and sliding surfaces 2 and 3, and are sliding surface switching values.

When |er(k)|>p, Equation 20 is obtained by similar conversion.

[0033]

[Formula 20] rp(k)=(1/b)・{(1-a)・spd(
k)−Δ(k)+η・s
at(s(k))}, that is, based on the intersection point p=kacc/c of the sliding surfaces, |er(
k) Use Equation 20 when |>p, and use Equation 17 when |er(k)|<p.

FIGS. 8 and 9 show flowcharts of this sliding mode control. First, in step 51, the deviation er(k) between the target vehicle speed rs(k) and the actual vehicle speed spd(k)
) is calculated using Equation 6. In step 51, the vehicle speed perturbation spdc (k) and the actuator position perturbation acpc (k) are derived based on Equation 21.

[0035]

[Formula 21] spdc (k) = spd (k) - spdi
acpc(k)=acp(k)-offsetwhere,
spdi is the vehicle speed at the start of resume, offset
indicates the actuator position relative to the target vehicle speed in a predetermined static characteristic curve.

In step 53, the vehicle speed perturbation spdc
The rate of change Δ(k) of (k) is calculated using Equation 22.

[0037]

[Formula 22] Δ(k)=-spdc (k)+spdc
(k-1) When the rate of change Δ(k) is positive, the vehicle speed is decelerating, and when it is negative, the vehicle speed is accelerating. step 54,
55 is a step of determining whether the vehicle speed spd(k) is approaching the target vehicle speed rs(k). First, in step 54, er(k)>0 holds, and in step 55, Δ
When (k)>0 does not hold, that is, vehicle speed spd(k)
is smaller than the target vehicle speed rs(k) and the vehicle is accelerating, it is determined that the vehicle speed spd(k) is approaching the target vehicle speed rs(k), and the process branches to step 57.

When er(k)>0 does not hold in step 54 and Δ(k)<0 does not hold in step 56, that is, the vehicle speed spd(k) is greater than the target vehicle speed rs(k) and the vehicle is decelerating. If so, it is determined that the vehicle speed spd(k) is approaching the target vehicle speed rs(k), and the process branches to step 57. In step 57, the magnitude of the deviation er(k) is determined. When the deviation er(k) is smaller than the switching value -p, the process branches to step 58, the sliding surface is switched to the surface 3 that commands negative uniform acceleration, and the coefficient w is set to zero.

When it is determined in step 57 that -p≦er(k)≦p, the process branches to step 59, and the surface 1 that converges the sliding surface exponentially is
and set the coefficient w to a predetermined value C. In this embodiment, the predetermined value C is set to 0.67. Also, the deviation er
When (k) is larger than the switching value +p, the process branches to step 60, the sliding surface is switched to surface 2 that commands positive uniform acceleration, and the coefficient w is set to 0.

Here, the coefficient w is used to calculate equations 17 and 20 as one equation in step 65 (FIG. 9), which will be described later. Steps 61-64 are steps for calculating a saturation function. In step 61, the sliding surface s(k)=0
When it is determined that s(k), which indicates the normal distance from , is smaller than the predetermined value -φ, the process branches to step 62, and the saturation function sat(s(k)) is set to -1.

Further, in step 61, −φ≦er(k)
When it is determined that ≦φ, the process branches to step 63, and the saturation function sat(s(k)) is set to s(k)/φ. When it is determined in step 61 that s(k) is larger than the predetermined value φ, the process branches to step 64 and the saturation function sat(s(k)) is set to 1. In this embodiment, the predetermined value is set to 1.

Next, in step 65 (FIG. 9), calculation is performed based on Equations 17 and 20 to calculate the target actuator position perturbation frpC (k). And step 66
Now let's calculate a digital filter to suppress control input hunting. In step 67, the target actuator position rp(k) is set by adding offset.

In this embodiment, each constant was set as shown in Equation 23 in consideration of the feeling of acceleration and the smoothness of approaching the target.

[0044]

[Equation 23] C=0.67 η=0.5 kacc =2km/n/sec φ=1 In other words, the intersection (switching value) p of each sliding surface is 3km/h, |er(k)|> 3km
/h, the vehicle speed is controlled to accelerate at a constant rate of 2 km/h per second to approach the target vehicle speed, |er(k)|
At ≦3 km/h, the vehicle speed converges to the target vehicle speed according to the exponential function exp (-0.67t).

Note that when each condition is satisfied in step 55 (deceleration determining means) or step 56, the process advances to step 67 and the processes of steps 57-66 are not performed. The reason for this is that the vehicle is often decelerating when the resume is started (the condition in step 54 is met and the condition in step 55 is met). At this time, as shown in FIG. 10, since the deceleration state is still maintained immediately after the resume is started, the target actuator position rp moves in a stiff manner. FIG. 11 shows the movement on the phase plane at that time.

Since the acceleration of the vehicle on the phase plane moves in a direction away from the sliding surface immediately after the start of resume, the target actuator position rp moves in a stiff manner. In order to minimize this stiff movement, after calculating the actuator position rp once at the start of resume, during deceleration (points A to I in Figure 11), the calculated value at point A is held and the actuator is set at the predetermined position. After holding the position and entering the acceleration side, the actuator is driven using the calculated value obtained in normal steps 57-66 as the target actuator position rp.

At this time, the operation of the actuator 30 is as follows.
As shown in FIG. 12, the stiff movement is eliminated. Therefore, engine revving and sudden shock can be reduced. Next, a block diagram of the control method of the entire constant speed cruise control device is shown in FIG. 13.

In FIG. 13, reference numeral 71 denotes a throttle servo system that controls the throttle opening to follow the target throttle opening, and is composed of an actuator 30. 7
2 is a vehicle system to be controlled. Reference numeral 73 denotes vehicle model identification means for estimating vehicle model parameters from the throttle opening and vehicle speed using the least squares method, and 74 provides feedback based on the model parameters estimated by this vehicle model identification means 73 using a pole placement method. Optimum gain calculation means for calculating the gain; 75 is an arithmetic unit that calculates the deviation between the target vehicle speed rs and the actual vehicle speed spd; 76 is an integrator that accumulates the deviation;
Reference numeral 77 denotes a calculation unit that obtains a target throttle opening rθ by feedback-gaining each of the actual vehicle speed spd, the deviation integral, and the throttle opening θ using an optimum gain.

Reference numeral 78 denotes a sliding mode control section that calculates the target throttle opening degree at the time of resume, and 79 a digital filter section that performs filter processing on the target throttle opening degree calculated by the sliding mode control section 78. 80
is a switching unit that switches between constant speed running control and resume control. In this way, vehicle model identification means 73 to calculation section 77
Then, the target throttle opening degree rθ during constant speed driving is calculated, and the sliding mode control section 78 to digital filter section 7
9, the target throttle opening degree (target actuator position rp) at the time of resume is calculated. Each target throttle opening is determined by the throttle servo system 7 via the switching section 60.
1, and the throttle opening is controlled.

FIG. 1 shows the operation of the above constant speed cruise control system as a whole.
This will be explained based on the flowcharts shown in FIGS. 4 to 16. First, in step 101 initial values are set, and in step 10
At step 2, whether the main switch M is on or off is detected, and if it is off, the process waits until the main switch M is turned on at step 102.

If the main switch M is on, it is determined in step 103 whether a predetermined control cycle has elapsed. In this embodiment, the control period is 16 times less than 1/10 of the vehicle's time constant, which indicates the vehicle's time response to actuator fluctuations.
It is set to 0msec. If it is determined that the control period has elapsed, the process proceeds to step 104, where the vehicle speed and various switches are detected. After that, in step 105, it is determined whether or not the control is currently in progress. If the control is not in progress, step 1
Branches to 06 to perform uncontrolled processing.

At steps 106 and 107 (FIG. 15), the set switch S and resume switch R are monitored, and if the set switch is pressed down, the process proceeds to step 108, where the vehicle speed detected at step 104 is set as the target vehicle speed. Step 109 is a process at the start of setting,
As shown in steps 201 to 203 shown in FIG. 17, processes such as coupling the clutch, calculating the offset value of the actuator, and setting the initial value of the integral term are performed. After that, the process proceeds to step 122 (FIG. 16) where the feedback control (PI
D control) to perform constant speed driving control.

If it is determined in step 107 (FIG. 15) that the resume switch has been turned on, the resume processing in step 112 (FIG. 16) and subsequent steps is performed. If neither the set switch S nor the resume switch R is turned on, the process advances to step 110. In step 110, if the vehicle speed is below the lower limit, in step 111, for safety,
The stored vehicle speed is erased to prohibit resuming below the lower limit, and if the vehicle speed does not fall below the lower limit, the stored vehicle speed is maintained and the process returns to step 102.

When resuming, it is determined in step 112 whether or not there is a memorized vehicle speed. If there is no memorized vehicle speed, the process returns to step 102, and if there is, the memorized vehicle speed is set as the target vehicle speed in step 113. Then step 114
Control start processing (steps 201 to 203) is performed. Further, if it is determined in step 105 (FIG. 14) that control is currently in progress, the process proceeds to step 115, and cancel switch C
, determines whether there is a cancellation request due to the brake or the like. Here, if there is a cancellation request, the target vehicle speed is held as a stored vehicle speed in step 116 in preparation for the next resume control, the control termination process shown in FIG. 18 is performed in step 117, and the process returns to step 102. In the control termination process, as shown in steps 211 and 212, the clutch 33 is released and the target vehicle speed is deleted.

If there is no cancellation request in step 115, the process proceeds to step 118, where it is determined whether constant speed driving control is being performed or resumed. If it is determined in step 118 that the resume control is in progress, the process proceeds to step 119, where the deviation er(k) is compared with a predetermined value KM in order to determine whether the actual vehicle speed has approached the target vehicle speed. Deviation er(k
) is smaller than the predetermined value KM, the process proceeds to step 120, where a command is given to end the resume, and an initial integral value is set to smoothly transition to constant speed driving control.

When the deviation er(k) is larger than the predetermined value KM, sliding mode processing is performed in step 121. The sliding mode process has already been explained in the flowcharts of FIGS. 8 and 9. Step 122 is the calculation part of PID control during constant speed driving, and the outline is as shown in the flowchart shown in FIG.
224, the deviation er(k), the integral term ierr(k
), the differential term dspd(k) is derived.

Then, in step 224, each term is multiplied by the gains kgp, kgi, kgd, and the target actuator position is calculated based on Equation 24.

[0058]

[Formula 24] rp(k)=kgp・er(k)+kgi・ier
r(k) + kgd・ds
pd(k), the target actuator position rp
is determined in step 121 or step 122.

The flowchart shown in FIG. 20 is processing of the actuator position servo system that is processed at the timing of the actuator drive cycle. In this embodiment, the actuator uses a DC motor, and its drive cycle requires a cycle of 5 msec or less due to duty drive. In step 231, the current actuator position acp(k) is detected, and in step 232, the deviation erac between the target actuator position and the actual actuator position is detected.
t(k) is calculated using Equation 25.

[0060]

[Equation 25] eract(k)=rp(k)−acp(k
) Then, in step 233, the rate of change dacp(k) in the position of the actuator is calculated using Equation 26.

[0061]

[Formula 26] dacp(k)=acp(k)−acp(k
-1) Next, in step 234, the deviation eract(k) and the rate of change dacp(k) are each multiplied by the gains kap and kad,
The duty ratio duty is calculated using Equation 27.

[0062]

[Formula 27] duty=kap・eract(k)+ka
d·dacp(k) Then, in step 235, the motor 31 is driven based on this duty ratio.

[0063]

As described above, according to the present invention, by using sliding mode control for resume control, matching is facilitated, the vehicle running speed can be brought close to the target vehicle speed with constant acceleration, and the This has the excellent effect of smoothly converging the speed to the target vehicle speed without overshooting.

[Brief explanation of the drawing]

FIG. 1 is a block diagram illustrating the present invention.

FIG. 2 is a schematic configuration diagram showing an embodiment of the present invention.

FIG. 3 is a block diagram for explaining the operation of the present invention.

FIG. 4 is a characteristic diagram for explaining the operation of the present invention.

FIG. 5 is a characteristic diagram for explaining the operation of the present invention.

FIG. 6 is a characteristic diagram for explaining the operation of the present invention.

FIG. 7 is a characteristic diagram for explaining the operation of the present invention.

FIG. 8 is a flowchart for explaining the operation of the present invention.

FIG. 9 is a flowchart for explaining the operation of the present invention.

FIG. 10 is a characteristic diagram for explaining the operation of the present invention.

FIG. 11 is a characteristic diagram for explaining the operation of the present invention.

FIG. 12 is a characteristic diagram for explaining the operation of the present invention.

FIG. 13 is a block diagram showing an embodiment of the present invention.

FIG. 14 is a flowchart for explaining the operation of the present invention.

FIG. 15 is a flowchart for explaining the operation of the present invention.

FIG. 16 is a flowchart for explaining the operation of the present invention.

FIG. 17 is a flowchart for explaining the operation of the present invention.

FIG. 18 is a flowchart for explaining the operation of the present invention.

FIG. 19 is a flowchart for explaining the operation of the present invention.

FIG. 20 is a flowchart for explaining the operation of the present invention.

[Explanation of symbols] 10 Electronic control device 23 Throttle valve 26 Vehicle speed sensor 27 Command device 30 Actuator

Claims (2)

[Claims] Claim 1: A vehicle speed sensor that detects the traveling speed of a vehicle;
an actuator that adjusts the running speed of the vehicle; a setting unit that sets a target vehicle speed of the vehicle; a deviation detection unit that detects a deviation between the target vehicle speed and the running speed; a first sliding mode control means that controls the actuator using a first sliding surface that approaches the vehicle speed; and a second sliding mode control means that exponentially converges the travel speed to the target vehicle speed.
a second sliding mode control means for controlling the actuator using a sliding surface; switching to the first sliding mode control means when the deviation is larger than a predetermined value; and switching to the second sliding mode control means when the deviation is smaller than a predetermined value; constant speed driving for a vehicle, characterized in that the first or second sliding mode control means controls the actuator to return the traveling speed to the target vehicle speed when resuming. Control device. 2. Deceleration determining means for determining whether or not the vehicle is decelerating; and when it is determined by the deceleration determining means that the vehicle is decelerating at the start of resume, driving of the actuator is prohibited at least during deceleration, and the actuator is activated. 2. The constant speed cruise control device for a vehicle according to claim 1, further comprising a holding means for holding the fixed speed at a predetermined position.