JPH0749643B2 - Pavement thickness control method for leveling machine - Google Patents

Description

TECHNICAL FIELD The present invention relates to a pavement thickness control method used for a leveling machine such as an asphalt finisher or a base paver.

[Conventional technology]

As one of the methods for paving the roadbed, there is a method of always paving while keeping the pavement thickness above a preset value. This is a pavement method based on the so-called pavement thickness.

Conventionally, when implementing a pavement method based on the pavement thickness, long skis with a length that is approximately the same as the length of the vehicle along the running direction are placed on the side of the vehicle, and the roadbed shape to be paved is set in advance. While grasping, there was a thing that pavement was performed with the goal of predicting the pavement thickness.

[Problems to be Solved by the Invention]

However, the above-described pavement thickness control method has a drawback in that it requires a long ski in the front-rear direction and thus requires a large apparatus, and accordingly, it is difficult to implement it on a narrow road.

Therefore, the present inventors have devised a method of measuring the height of an unpaved surface, calculating a pavement thickness reference straight line that changes to the long ski from the measured value, and paving with the pavement thickness reference straight line as a reference.

However, this pavement method has a problem that the disturbance interferes when the pavement thickness reference line is calculated, and the pavement thickness does not approach the target pavement thickness.

The present invention has been made in view of the above circumstances, and an object thereof is to perform pavement control without using a large-scale device such as a long ski, and to make the pavement thickness close to a target pavement thickness. It is to provide a pavement thickness control method in a sushi machine.

[Means for Solving the Problems]

In order to achieve the above-mentioned object, the present invention measures the height of the existing pavement surface at every predetermined distance in the traveling direction, and creates a pavement thickness reference straight line from these measured values, while a predetermined distance ahead in the traveling direction from the screed. At the target point, the target pavement thickness is calculated by adding the target pavement thickness to the unpaved surface, and the difference between the position on the pavement thickness reference line at the target point and the position on the target pavement surface is eliminated, and The screed is controlled by obtaining a difference between the pavement thickness position and the target pavement thickness position and feeding back the difference.

[Action]

The pavement thickness reference straight line obtained from the measurement of the existing pavement surface indicates that when the screed is paved as it is, the finished surface becomes a shape close to the pavement thickness reference straight line, and the target pavement surface is literally It represents the target value of the ideal pavement surface.

By comparing the two and controlling so that they do not differ at a target point that is a predetermined distance ahead of the location where the screed is being paved, specifically, paving with a desired thickness is performed a predetermined distance ahead. It means to pave while controlling the inclination of the screed in advance.

The pavement thickness does not change immediately after changing the inclination of the screed, and the result appears when the vehicle runs a predetermined distance. Therefore, as described above, the screed control is performed so that the desired pavement thickness can be achieved at the target point ahead by a predetermined distance, and the pavement with a thickness close to the ideal can be performed.

Further, in performing the above control, the difference between the target pavement thickness and the actual pavement thickness is obtained, and the actual pavement thickness is appropriately corrected by feeding back the difference so that the actual pavement thickness approaches the target pavement thickness. It becomes possible to approach the target pavement thickness.

〔Example〕

The attached drawings show an embodiment of the present invention applied to an asphalt finisher. Reference numeral 1 in FIG. 1 is a traveling vehicle of an asphalt finisher AF. The traveling vehicle 1 is of a crawler type, and a hopper 2 into which an asphalt mixture is put is provided in the front part thereof. The asphalt mixture in the hopper 2 is transferred rearward (to the right in FIG. 1) by a feeder at the bottom of the vehicle body, then spread evenly left and right by a screw, and spread by a pair of left and right screeds 5.

The screed 5 is mounted on the traveling vehicle 1 via the leveling arm 6.
It is supported by a support shaft 7 provided on the substantially central side surface of the. The support shaft 7 is vertically moved by a pivot cylinder 8. The basic structure of the asphalt finisher AF is well known.

Further, reference numeral 11 is a measuring device provided on each of the left and right sides. The measuring device 11 measures a first height sensor 13 provided at the tip of the measuring arm 12, a second height sensor 14 provided at the center of the measuring arm 12, and an inclination angle of the measuring arm 12. And an inclination sensor 15 that operates. Measuring arm 12
The base end (right end in the figure) of the screed 5 is pin-supported by the frame 5a that supports the screed 5, so that the measuring arm 12 can move the screed 5 to the screed 5.
Tilts evenly.

Although various types of first and second height sensors 13 and 14 can be considered, a sensor utilizing ultrasonic waves is used here. Further, as shown in FIG. 3, the distance between the two sensors 13 and 14 is set to 1/2 of the distance M between the second distance sensor 14 and the rear end of the screed 5 (if it is a fraction of an integer). And the relative height H ₀ of both sensors 13, 14 to the screed 5 is
The screed 5, the measuring arm 12 and the like are set to have constant values regardless of the inclination.

Reference numeral 17 denotes a distance sensor provided at the lower end of the front part of the traveling vehicle 1 for calculating a traveling distance.

Height sensors 13 and 14, tilt sensor 15 and distance sensor 1
An arithmetic unit 30 is connected to 7 (see FIG. 2). The arithmetic unit 30 receives the analog outputs of the height sensors 13 and 14 and the tilt sensor 15 and converts them into digital outputs.
(Analog-digital) converter 31 and this A / D converter 31
And I / O to which each digital output of the distance sensor 17 is input
(Input-output) Interface 32 and operation unit that performs operations based on data from this I / O interface 32
33 and the numerical value obtained by this calculation unit 33 is input and stored,
In addition, the data storage unit 34 that outputs to the calculation unit 33 and the I / O interface 3 that processes the numerical values calculated by the calculation unit 33
It is composed of 5 and. And I / O interface
The signal output from 35 is sent to a solenoid valve 36 for adjusting the expansion and contraction of the pivot cylinder 8.

The calculation device 30 performs a required calculation based on the output signal generated from the height sensors 13 and 14 every time the traveling vehicle 1 travels the distance between the height sensors 13 and 14.

The main calculation contents of the calculation device 30 are a pair of height sensors 13, 1
Two measurement points P ₁ , P ₂ , P ₂ , P measured simultaneously by 4
₃ , P ₃ , P ₄ , P ₄ , P ₅ , P ₅ , P ₆ ... Height differences δ ₁ , δ ₂ ... are calculated (see Fig. 6) and at the same time measurement points P ₁ , P ₂ ... pavement thickness T ₁ of the, T ₂ ... computing the measurement point to Q ₁ already paved surface obtained when measuring pavement thickness _{T 1 ..., Q 2, Q} 3, Q 4 ... a coordinated to example minimum 2 The multiplication of the pavement thickness reference straight line 1 (y = ax + b) is performed to introduce the target pavement surface S by adding the target pavement thickness T ₀ to the unpaved surface at the target point ahead of the screed 5 by a predetermined distance (M). The position on the target pavement surface at the target point and the pavement thickness reference straight line l
To calculate the operation amount L of the pivot cylinder 8 so as to change the position of the screed 5 so as to eliminate the difference ε between the upper positions, and to select a plurality of continuous points from the pavement thicknesses T ₁ , T _{2 on the} paved surface. Calculate the average value Ta of them and calculate the target pavement thickness
The difference E from T ₀ is calculated, and when the value exceeds a certain range, the target pavement thickness T ₀ is corrected.

At this time, the pavement thickness influences not only the inclination of the screed 5, but also the properties and supply amount of the asphalt mixture, the traveling speed of the vehicle, etc., and these are also taken into consideration.

Then, the operation amount L of the pivot cylinder 8 calculated above
The command signal of the solenoid valve 36 is inserted in the hydraulic circuit (not shown).
And the solenoid valve 36 is operated to extend and retract the pivot cylinder 8.

Here, two measurement points P ₁ , P ₂ , P ₂ , P ₃ , P ₃ , P ₄ , P ₄ , P ₅ , which are simultaneously measured by the pair of height sensors 13, 14,
Based on Fig. 4, the method of calculating the height difference δ ₁ , δ ₂ ... of P ₅ , P ₆ ... and the method of calculating the pavement thickness T ₁ , T ₂ ... of each measurement point P ₁ , P ₂ ... Explain.

The height difference δ is calculated by the following equation.

δ = H _2- (H ₁ -Mtan θ ₁ ) (1) where, H ₁ : the value detected by the first height sensor H ₂ : the value detected by the second height sensor M: Distance between first and second height sensors θ ₁ : Tilt of measuring arm 12 The pavement thickness T is calculated by the following equation.

T = H ₂₁ + δ−Mtan θ ₂ −H ₀ (2) where H ₂₁ : value detected by the second height sensor δ: value calculated by the above formula (1) M: same as above θ ₂ : Tilt of measuring arm H ₀ : Height difference between height sensor and screed The above formulas (1) and (2) are shown for easy understanding of the height difference δ and the pavement thickness T. It is slightly different from that by the measuring device 11 shown in the asphalt finisher AF shown in FIGS. 1 and 3. Actually, in order to actually measure with the measuring device 11 of the present embodiment, the double height sensor 1
Since 3 and 14 are arranged at a distance of M / 2, the height difference δ and the pavement thickness T for each distance M / 2 are calculated (see FIG. 5).

In the calculation formulas (1) and (2), since the height difference δ and the pavement thickness T do not consider the inclination θ, there are some differences from the actual values, but they can be ignored in practice.

Next, a pavement thickness control method by the leveling machine configured as described above will be described.

Asphalt finisher AF is used for paving roads in the same way as before, while the traveling vehicle 1 is traveling at a constant speed, the asphalt mixture in the hopper 2 is sent to the screw by the feeder and spread evenly in front of the screed 5. Spread the mix with screed 5 and level it.

In the above, the traveling distance of the vehicle 1 is measured by the distance sensor 17, and the distance from the roadbed surface is measured by the first and second height sensors 13 and 14 each time the traveling distance becomes M / 2. The result is output to the arithmetic unit 30.

The arithmetic unit 30 calculates the height difference δ and the pavement thickness T from the output signals of the height sensors 13 and 14, the distance sensor 17 and the inclination sensor 15 as described above. Then, the pavement thickness reference straight line l: y = ax + b is calculated based on these values. When the pavement thickness reference straight line 1 is calculated, for example, it is calculated from the latest several points (four points Q ₁ , Q ₂ , Q ₃ , and Q ₄ in FIG. 6) of the existing pavement surface.

Next, the pavement surface S at the target point, which is a distance M (× N integer) away from the screed 5 in the forward direction, is subjected to the above-mentioned height difference δ ₄ , δ _5.
And the ideal pavement thickness T ₀ , and the position of the screed 5 is changed so as to eliminate the difference ε between the position on the pavement thickness reference straight line 1 at the target value point and the position on the target pavement surface. Determine the manipulated variable.

The calculated value is transferred to the solenoid valve 36 via the I / O interface 35.
And the pivot cylinder 8 is expanded and contracted.

The above operation is repeated every time the vehicle 1 travels the distance M / S, so that the screed 5 is controlled so that the pavement thickness in front of the distance M always becomes an ideal value. On the other hand, every time the vehicle 1 travels the predetermined distance (for example, 5 m), it is judged whether the average value Ta of the actual pavement thickness T is largely deviated from the target pavement thickness T ₀ as described above, and the difference is determined. If it exceeds the preset range, the target pavement thickness T ₀ is corrected. As a result, in the above-mentioned assault finisher, it becomes possible to bring the actual pavement thickness closer to the target pavement thickness T ₀ .

Examples and technical matters other than the above will be listed below.

(1) In the above-mentioned embodiment, the distance between the height sensors 13 and 14 is set to M / 2, but the present invention is not limited to this.
It may be set to M or M / 3. However, the use of M / 2 or M / 3 as in the embodiment has an advantage that the measuring device 11 can be downsized.

(2) The height sensors 13 and 14 are not limited to ultrasonic sensors, but laser type or expandable cylinders may be used, and their specific structures are arbitrary.

(3) In the above embodiment, the pavement thickness reference straight line 1 is calculated by the least squares method using the latest 4 points after pavement, but the present invention is not limited to this, and the latest 3 points can be calculated. You may calculate based on five points.

(4) In the above embodiment, the average value of the actual pavement thickness T is used as a means for bringing the actual pavement thickness T close to the target pavement thickness T _0.
If Ta is found, it is judged whether it is close to the target pavement thickness T ₀ or not, and if it is significantly deviated, the target pavement thickness T ₀ is corrected. The thickness T is directly taken out directly without obtaining the average value,
It is judged whether or not it is close to the target pavement thickness T _0, and if it is greatly deviated, an output signal is directly issued to the solenoid valve 36, and the pivot cylinder 8 is forcibly controlled to extend and retract by a certain distance. Good.

〔The invention's effect〕

As described above, according to the pavement thickness control method for a leveling machine according to the present invention, the pavement thickness in front of the screed is predicted without using a large-scale device such as a long ski that has been conventionally used. Since the pavement thickness control is performed so that the value becomes an ideal value, the ideal pavement thickness reference control can be performed. Moreover, the difference between the target pavement thickness and the actual pavement thickness is obtained, and the actual pavement thickness is fed back to obtain the actual pavement thickness. Since the pavement thickness is appropriately corrected so as to approach the target pavement thickness, the actual pavement thickness can be brought closer to the target pavement thickness.

[Brief description of drawings]

The attached drawings show an embodiment of the present invention. Fig. 1 is a side view of an asphalt finisher for carrying out the method of the present invention, Fig. 2 is a block diagram of a computing device, and Fig. 3 is a measuring device and a screed. 4 (a) and 4 (b) are explanatory diagrams for obtaining the height difference of the roadbed and the pavement thickness, and FIGS. 5 (a), 5 (b) and 5 (c) are examples. FIG. 6 is an explanatory diagram for obtaining the height difference and the pavement thickness of the roadbed in accordance with the above, and FIG. 6 is a diagram for explaining the method of the present invention. 1 ... Vehicle, 5 ... Screed, 8 ... Pivot cylinder, 11 ... Measuring device, 13 ... First height sensor, 14 ...
The second height sensor, 15 ...... tilt sensor 17 ...... distance sensor, 30 ...... controller, l ...... pavement thickness reference line, T ₀ ...... ideal pavement thickness (target pavement thickness).

Claims (1)

[Claims] 1. A pavement thickness control method for a leveling machine for controlling the thickness of pavement spread by the screed by changing the inclination of a screed provided in the rear part of a vehicle so as to be tiltable in the front-rear direction. The height of the paved surface is measured every predetermined distance in the running direction, and the pavement thickness reference straight line is created from those measurements, while the target pavement thickness is added to the unpaved surface at the target point ahead of the screed in the running direction by the target distance. The pavement surface is obtained, and the difference between the pavement thickness position of the existing pavement surface and the target pavement thickness position is calculated so as to eliminate the difference between the position on the pavement thickness reference line at the target point and the position on the target pavement surface. A pavement thickness control method in a leveling machine, characterized in that the screed is controlled while feeding it back.