JPH0331606B2 - - Google Patents

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a duty control type constant speed cruise control device, and in particular to a device for controlling the difference between a set vehicle speed and an actual vehicle speed (hereinafter referred to as vehicle speed deviation ΔV) to zero. In order to achieve this, two integral elements, a fast integral element 1 and a slow integral element 2, are provided to simultaneously perform control to rapidly reduce the vehicle speed deviation and control to gently bring the vehicle speed deviation to zero. This is intended to improve stability by varying the dynamic control gain depending on vehicle speed.

(Prior art) A duty control type constant speed driving control device sets the duty value necessary for constant speed driving at a target vehicle speed (set vehicle speed) as the set duty, and sets the duty amount according to the difference between the target vehicle speed and the traveling vehicle speed. Constant speed driving control is performed while adding or subtracting from the set duty and outputting the result. However, the required duty amount changes depending on variations in the characteristics of the actuator, throttle drive system, and engine, road slope, the presence or absence of engine loads such as air conditioners, and changes in vehicle loads such as transmission gears. A vehicle speed deviation occurs depending on the difference with the duty amount.

Figure 6 is a system configuration diagram showing an example of this type of constant speed cruise control device.The controller ECU is turned on/off by a magnet that rotates in proportion to the rotation of the vehicle drive shaft.
The vehicle speed is detected by the signal from the vehicle speed sensor, which is equipped with a reed switch that turns off. When the set switch is turned on, the ECU memorizes the vehicle speed and
After OFF, the control valve of actuator ACT is duty-controlled. control valve
When ON, negative pressure is introduced, increasing the force generated by the diaphragm linked to the throttle SL. When OFF, atmospheric air is introduced and weakens the diaphragm generating force. During this time, the release valve is turned on to cut off the atmosphere. Cancel signal (clutch switch (neutral start switch for A/T vehicles),
parking switch or brake switch)
When input, both the control valve and release valve are turned OFF, atmospheric air is introduced from both, and the control is immediately stopped. If you turn on the resume switch after canceling, driving control at the previously memorized vehicle speed will be restored.

A microcomputer is used for the ECU, and the processing there is divided into blocks as shown in Figure 7. The output duty D that controls the control valve on and off is the target vehicle speed stored in memory.
It is determined according to the difference between V _M and the running vehicle speed Vn, but in detail, the cap vehicle speed Vs, which is the sum of the vehicle speed change component (differential component), is used instead of the running vehicle speed Vn itself. This is to advance and compensate for dead time due to actuator delay, throttle, drive system hysteresis, and play. Therefore, the skip vehicle speed Vs is determined by the following formula.

Vs=Vn+K×(Vn−V _o-1 ) (1) Vn: Current vehicle speed V _o-1 : Previous vehicle speed K: Proportionality constant Further, the output duty D is determined by the following equation.

D=G×ΔV+SD ₀ ...(2) G: Gain SD ₀ : Set duty ΔV: Vehicle speed deviation (=V _M −Vs) [Problem to be solved by the invention] The constant speed cruise control device described above is When the vehicle speed changes, the output duty D is changed on the control line shown in FIG. 8 in an attempt to converge the vehicle speed to the set vehicle speed V _M. The slope of this control line is the gain G. The important point in this control is to focus on the duty to maintain the set vehicle speed. However, conventional systems only have one duty (the aforementioned set duty SD ₀ ) that should be the center of control, or a duty that only depends on the vehicle speed, and in reality, it has various values depending on the vehicle, road surface, weight, vehicle speed, etc. Due to the gap that it is necessary to take, the occurrence of vehicle speed deviation ΔV could not be avoided. For example, as shown in Figure 8, if a duty of A is required to run at a certain set speed, the vehicle speed will decrease along the line and the vehicle will run at point B where the duty and vehicle speed are balanced. This vehicle speed difference remains as a set deviation. Therefore, the state in which such a vehicle is traveling at a constant speed is as shown in FIG. 9, and the traveling speed changes depending on the road surface load.

The above-mentioned set deviation becomes 0 if the control line is corrected so as to pass through point C. The present invention proposes one such method.

[Means for solving problems]

In the present invention, a control valve of an actuator that adjusts the throttle opening is controlled on and off by an output duty D obtained from a control line with a predetermined slope indicating the conversion characteristics between vehicle speed and duty, and the actual traveling vehicle speed is memorized. In a duty control type constant speed cruise control device that approaches the target vehicle speed, the set duty SD corresponding to the target vehicle speed is calculated as SD=SD1+(DM-SD1)/n, and the output duty D is calculated as D=G×ΔV+SD G : Slope of control line ΔV: Vehicle speed deviation DM: Integral element that responds quickly to duty changes SD1: Calculates using an integral element that responds slowly to duty changes, and further processes to switch the value of n according to the traveling vehicle speed, The present invention is characterized in that it includes a controller that integrally corrects the set date SD in a direction toward the output duty D.

[Effect]

In the present invention, the output duty D is calculated as D=G×ΔV+SD (3). SD is a variable set duty and is expressed as SD=SD1+(DM-SD1)/n (4). DM is a high-speed integral element that has the function of quickly responding to changes in duty (also known as changes in vehicle speed) and reducing set deviation. The operating concept is to rotate the control line at high speed in a direction that reduces the deviation, as shown in Figure 1a. On the other hand, SD1 is a low-speed integral element that responds slowly to changes in duty and has the function of reducing set deviation. The concept of operation is to move the control line in parallel in a direction that reduces the deviation, as shown in FIG. 1b.

The initial values of both DM and SD1 correspond to SD ₀ in equation (2),
It changes as shown in FIG. 2 in response to a change in duty D. Figure a shows an operation example when the vehicle speed decreases (duty increases) as the vehicle moves from a flat road to an uphill road, and figure b shows an operation example including a downhill road. Figure a
As shown in , when the duty D changes with the change in vehicle speed, both DM and SD1 start to change.
Since MD has a faster response, DM follows first.
And since SD1 follows with a delay, the overall SD
changes like a dashed line, and eventually the duty D
matches. This is because SD moves from SD ₀ to D=A, and in this case, equation (3) is ΔV=0, SD=A
becomes stable.

The output duty D is obtained from equations (3) and (4). D=G×ΔV+{SD1+(DM-SD1)/n} ……(Five) It is expressed as

The difference between duty and SD is the static control gain, which is the gain when stable. On the other hand, duty and SD1
The difference is the dynamic control gain, which is the gain during movement.

FIG. 3 is a basic flowchart of the present invention, and the seventh
This corresponds to the block diagram in the figure.

These processes are executed every 50msec. first,
Calculate the current vehicle speed based on the output of the vehicle speed sensor. Next, the high-speed integral element DM is calculated, and in this example, the high-speed integral element DM is changed in proportion to the difference from the output duty D. In other words, DM(i) = DM _(i-1) + α, so that the current element DM(i) is changed from the previous DM _(i-1) by α, and this α is, for example, α = (D(i)− Calculate as DM _(i-1) )/K. Therefore, the difference between the current duty D(i) and the previous element DM _(i-1) is reflected, and the correction speed is varied (K is a constant).

Next, calculate the low-speed integral element SD1. This slow integral element SD1 is calculated using the variable β smaller than α as follows: SD1(i)=SD1 _(i-1) +β. If this β is set to a fixed value, the correction speed will be constant. For example, when D _(i-1) > SD1 _(i-1), β = 0.2%, and when D _(i-1) < SD1 _(i-1) , β = -0.2%.

Once the high-speed integral element DM and low-speed integral element SD1 at each point in time are determined in this way, the set duty SD is calculated by substituting them into equation (4) in the next step, and the set duty SD is calculated based on this set duty SD and the vehicle speed deviation ΔV. In the next step, the output duty D is calculated from equation (3), and a duty control signal is output from the output port. Therefore, when a road surface change occurs and a vehicle speed deviation occurs, from equation (3), the output duty D changes first, and the high speed integral element DM and the low speed integral element SD1 change to follow this output duty D, and this The set duty SD changes accordingly. and,
The set duty SD will settle down when the set duty SD changes to correspond to the road surface slope.

By the way, in the above-mentioned method, if the entire vehicle speed is controlled with a constant control gain, the gain of the entire control system becomes high in the low-speed driving range where the vehicle gain is high, and hunting is likely to occur, whereas in the high-speed driving range where the vehicle gain is low, hunting is likely to occur. The gain of the entire control system becomes low, resulting in poor responsiveness. To avoid this, it is possible to change the gain of the entire control system, but the commonly used method of varying the static control gain is as follows:
Stability deteriorates. Therefore, in the present invention, the gain of the entire control system is changed by varying the dynamic control gain due to responsiveness.

Specifically, the n value in equation (4) is changed according to the vehicle speed.

〔Example〕

FIG. 4 is a flowchart showing an embodiment of the present invention, in which a vehicle speed determination step (60
Is it more than Km/h? ) and a step of calculating the set duty SD by switching the value of n according to the result. That is, after measuring the vehicle speed, it is determined whether the vehicle speed is 60 km/h or more. If the result is 60km/h or more, calculate the high-speed integral element DM and the low-speed integral element SD1, then set n to 2 and follow the above (4).
Calculate the set duty SD based on the formula. If the speed is 60 km/h or less, after calculating DM and SD1, set duty SD is calculated based on equation (4) using n and 4. The output duty D is calculated using the set duty SD thus calculated. The rest is the same as in FIG. 3. The value of n is arbitrary, but when n=1, the control line in FIG. 1a stands upright and the gain is maximum. As the n value increases, the slope of the control line becomes gentler (the gain becomes smaller). Therefore, in Fig. 4, the dynamic control gain is set to n=2 to increase the dynamic control gain when the vehicle gain decreases over 60 km/h, and conversely, when the vehicle gain increases below 60 km/h, the dynamic control gain is decreased by setting n to 4. ing.

Figure 5 is an operating waveform diagram, and the broken lines are the characteristics of Figure 3.
The solid line is the characteristic shown in FIG.

In addition, although the example shows only an example in which the dynamic control gain is changed in a low speed driving range (for example, less than 60 km/h), even in a high speed driving range (for example, over 100 km/h),
It is possible to change the dynamic control gain (reduce n). Further, by dividing the set vehicle speed into smaller categories, more detailed control becomes possible.

〔Effect of the invention〕

As described above, according to the present invention, when it is necessary to move the set duty due to changes in the road surface, etc.
The dynamic control gain is increased by the movement of the DM,
By moving the element SD1 while keeping the vehicle speed deviation small, it is possible to reduce the vehicle speed deviation to zero while suppressing fluctuations in the vehicle speed. Furthermore, since the dynamic control gain is controlled to vary depending on the vehicle speed, it is possible to improve running stability in a high-speed driving range and to improve responsiveness to changes in vehicle speed in a low-speed driving range.

[Brief explanation of drawings]

FIG. 1 is a diagram explaining the principle of the present invention, FIG. 2 is a diagram explaining the operation of the present invention, FIG. 3 is a basic flow chart of the present invention, FIG. 4 is a flow chart showing an embodiment of the present invention, and FIG. Figure 6 is a diagram of its operating waveforms, Figure 6 is a system configuration diagram of the duty control type constant speed traveling device, Figure 7 is a block diagram of its microcomputer processing, Figure 8 is a characteristic diagram of conventional duty control, and Figure 9 is It is an explanatory diagram of the operation. In the diagram, ECU is a controller, ACT is an actuator,
SL is throttle.

Claims (1)

[Claims] 1. A control valve of an actuator that adjusts the throttle opening is controlled on and off using an output duty D obtained from a control line with a predetermined slope indicating the conversion characteristics between vehicle speed and duty, and the actual traveling vehicle speed is controlled. In a duty control type constant speed cruise control device that approaches a stored target vehicle speed, the set duty SD corresponding to the target vehicle speed is calculated as SD=SD1+(DM-SD1)/n, and the output duty D is calculated as D=G. ×ΔV+SD G: Gradient of control line ΔV: Vehicle speed deviation DM: Integral element that responds quickly to duty changes SD1: Calculates using an integral element that responds slowly to duty changes, and further processes to switch the value of n according to the traveling vehicle speed. 1. A duty control type constant speed cruise control device, comprising: a controller that integrally corrects the set date SD in a direction approaching the output duty D.