WO1990012922A1

WO1990012922A1 - A device for painting a line marking on a roadway

Info

Publication number: WO1990012922A1
Application number: PCT/SE1990/000245
Authority: WO
Inventors: Lars MILLGÅRD
Original assignee: Affärsverket Ffv
Priority date: 1989-04-14
Filing date: 1990-04-10
Publication date: 1990-11-01
Also published as: SE461797B; SE8901347D0

Abstract

A device for painting a line marking on a roadway (4) by using a painting unit (10) which is carried on a vehicle (1). The device comprises, on the one hand, a TV camera (3) pointing in the direction of travel of the vehicle and, on the other hand, a screen (6), and also a computer (5) for reproducing on the screen the TV camera image of the edges (12, 13) of the roadway. The computer (5) generates two reference lines (7, 8) whose position and shape can be altered by means of a joystick (9), in such a way that they can be made to lie symmetrically relative to the TV camera image of the edges (12, 13) of the roadway, the computer being designed to detect the position and shape of the reference lines and from these to determine the position of the centre of the roadway in relation to the longitudinal axis of the vehicle, and the painting unit (10) being displaceable in the lateral direction as a function of the determination by the computer (5) of the centre of the roadway.

Description

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TECHNICAL FIELD

The present invention relates to a device for painting a Line marking, for example a centre marking or lane marking, on a roadway by using a painting unit which is carried on a vehicle, the device comprising, on the one hand, a TV camera mounted on the vehicle, pointing in the direction of travel of the vehicle and designed to record an image of the two edges of the roadway ahead of the vehicle, and, on the other hand, a screen mounted on the vehicle, and also a computer unit mounted on the vehicle with the ability to reproduce on the screen the TV camera i age of the edges of the roadway.

PRIOR ART

Line markings are painted on roadways in order to mark the centre of the road, lane markings, no-overtaking etc. It is important that these markings should be positioned correctly so as not to compromise road traffic safety.

In order to determine where the marking is to be positioned, nowadays use is generally made of a special so-called marking truck. When painting of a stretch of roadway is to be carried out, the marking truck is first driven a number of times along this stretch in order to put down paint markings, which show where the line marking is to be painted.

The marking truck stops at regular invervals (every 60 on straight roadways, closer on bends), the driver stepping down and measuring out the centre of the roadway using a measurement rod. The centre is marked out with a spot of paint (a so-called reference point). This is carried out under full traffic conditions, which constitutes an accident risk to both the driver of the marking truck and to other road users. When reference points have been set out, the marking truck is driven once again along the same stretch. A paint spray is then controlled automatically in such a way that a patch of paint is painted approximately every 10 m, so-called machine marking. The driver now uses a "sighting rod", positioned at the front of the truck, in order to carry out aiming so as to guide the truck in such a way that the machine marking is in line with the reference points.

Finally, the finished line marking is carried out using a painting truck, which in turn is guided by means of aiming' at the machine marking.

A device of the type mentioned in the introduction, with a TV camera for reproducing the edges of the roadway, is known from US Patent Specification 4,247,870. The known device is extremely complicated and requires at least two TV cameras, and when travelling round a bend at least four TV cameras. The device preferably also comprises a fifth TV camera for recording the point of convergence of the edges of the roadway.

SUMMARY OF THE INVENTION

The object of the present invention is to provide a device of the type mentioned in the introduction, which device uses only one TV camera, even when travelling round a bend, and which is moreover less complicated and easier to handle than the known device prov ded with TV cameras.

This object is achieved by virtue of the fact that the device according to the invention has the characteristics specified in Cla m 1.

Further developments of the invention are set forth in the subclaims. BRIEF DESCRIPTION OF THE FIGURES

Figure 1 shows a perspective view of a device according to the i nventi on.

Figure 2 shows a screen, forming part of the device, with computei—generated reference lines which are produced by a computer unit forming part of the de ice.

Figure 3 shows a block diagram of the control system of the devi ce.

Figure 4 shows a computer-generated measurement point funct on.

Figure 5 shows the screen according to Figure 2, with examples of indicated instructions.

Figure 6 shows how possible side errors can be calculated.

PREFERRED EMBODIMENT OF THE INVENTION

Figure 1 shows a vehicle in the form of a painting truck 1 which is driven by a driver 2. Mounted on the roof of the painting truck 1 i s a TV camera 3 pointing in the direction of travel of the truck. The TV camera 3 is directed essentially horizontally, so that it covers the entire road width of the roadway 4 lying ahead, from about 5 m ahead of the truck.

In the cabin of the truck there is a computer 5 with a screen 6 showing the image taken by the TV camera 3 of the roadway 4 lying ahead.

On the main shaft of the truck there is an angle sensor 16 (see igure 3) which provides information on the steering wheel position to the computer 5. The odometer 17 of the truck (se Figure 3) is also connected to the computer 5.

Superi posed over the TV image on the screen 6 are two reference lines 7 and 8 generated by the computer 5. The position and shape of the reference lines 7 and 8 can be controlled with the aid of a manoeuvring column in the form of a so-called joystick 9. The painting truck 1 is moreover provided with a painting unit 10, for example a paint spray, which, by means of a drive arrangement 11 shown- di agrammat i ca I ly, can be guided in the lateral direction of the truck 1 approximately 1-2 m relative to the longitudinal axis of the truck.

The dri er, or alternatively an operator (not shown), can continuously control the position and shape of the reference lines 7 and 8 by manoeuvring the joystick 9 in such a way that the reference lines 7 and 8 lie symmetrically in relation to the imaged edges 12 and 13 of the roadway. The operator takes into consideration the direction of the roadway 4 some hundred metres ahead of the truck 1.

The computer 5 records the position and shape of the reference lines 7 and 8 and from these can determine the position Xi of the centre of the roadway (se Figure 4) in relation to the longitudinal axis of the truck. The computer 5 can then guide the painting unit 10 in the lateral direction with respect to the direction of the roadway 4 both a distance (for example 10 m) behind the truck and a distance ahead of the truck.

The function of the device is as follows,

The screen 6 has four different fields 6a-d. Field 6a shows a function menu. Field 6b shows the TV camera image from approximately 5 m ahead of the truck, with the superimposed reference lines 7 and 8. Field 6c shows the position of the painting unit 10 in the lateral direction, ield 6d shows the relevant settings.

The two computer-generated reference lines 7 and 8 can be moved in the lateral direction by the driver, as was indicated above, by means of the joystick 9, or curved in such a way that they follow the imaged edges 12 and 13 of t h e roa dway .

The joystick 9 may, for example, have the ability to execute the following functions.

The joystick is actuated forwards, right/left => r ght/ left curve.

The joystick is actuated rearwards, right/left => right/left lateral d splacement. The knob of the joystick is depressed, right/left => increase/decrease "road width".

The knob of the joystick is depressed, rearwards => longitudinal displacement of centre line.

The knob of the joystick is depressed, forwards => menu activated.

While driving, the driver continuously ad usts the positions and curvature of the reference lines 7 and 8.

The computer 5 draws a centre line 14 on screen. The angular position of the centre line is calculated from the angular position of the reference lines 7 and 8. In addition, other lines can be drawn at a selected distance from the centre line, for example edge lines or lines prohibiting overtaking.

The computer-generated centre line 14 is provided with a cross 15 which marks a po nt, the "measurement point", situated for example 10 m ahead of the truck. The perpendicular distance between the measurement point and the longitudinal axis of the truck is stored for every metre which the truck moves forwards. For every dm which the truck moves forwards, the steering wheel turning is read off in the computer, and the stored measurement point distances are continuously converted with regard to the movement of the truck in the lateral direction. The computer continuously adapts the measurement point calculations to a simple mathematical function in such a way that it agrees as well as possible with the stored measurement points 15' , 15" etc. and with the last 10 painted line (see Figure 4⁾.

The mathematical function is the basis for the order given by the computer 5 to the drive arrangement 11 of the painting unit 10 to displace the painting unit 10 in the lateral direction. Certain restrictions can be introduced such as, for example, minimum permitted radius of curvature of the painted line.

The centre line 14 is drawn as a broken line with a division corresponding to the future centre line marking. The pattern can be moved on screen in such a way that it fits over a former centre line marking. This means that the new painting is carried out over the old painting.

Information relating to the function of the painting equipment (for example the Lateral movement of the paint spray) is displayed along the bottom edge of the screen.

Along the upper edge of the screen 6 there is a function menu 6a. If the joystick is moved to the forward position and the knob is depressed, one of the menu headings is "lit up" and its associated instructions are displayed. By then moving the joystick in the lateral direction, the desired heading can be selected. The topmost instruction in the list is shown "illuminated" and is in this way singled out. If the joystick knob is raised in this position, this instruction will apply, as is indicated along the lower edge of the screen. If another instruction s desired, it is singled out by moving the joystick forwards or backwards until the desired instruction is shown illuminated (see Figure 5). Cali ration must be carried out with regard to the position of the measurement point in the longitudinal direction and lateral direction, of the minimum turning radius of the truck as a function of the steering wheel deflection and of the guiding of the paint spray in the lateral direction. This can be carried out, for example, by means of a patch being painted on the roadway with the paint spray 10, after which the truck is reversed exactly 10 m straight back or 10 m with a certain steering wheel deflection. The position of the measurement point on the screen is then adjusted in such a way that it lies straight over the patch of paint, and is fed into the computer. This is repeated with several different movements of the paint spray and several different deflections of the steering wheel.

When monitoring the calibration, a certain point is singled out against the measurement point cross as starting point for painting. Thereafter, the truck is driven over the singled-out point with the painting equipment initiated. The difference between the conceived and the actual starting point is then measured.

Provided that the driver manages to position the reference lines 7 and 8 correctly, i.e. symmetrically, in relation to the edges of the roadway, the greatest source of error will be a non-symmetrically cambered roadway, for example at bends.

If the camera positioning is selected in such a way that the angle between the edges of the roadway on the screen is a maximum of 90 degrees, the lateral error will amount at maximum to the cambering height (see Figure 6). The inclination of the truck in the lateral direction will probably have a negligible effect.

Claims

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1. Device for painting a line marking, for example a centre line or lane marking line, on a roadway (4), by using a painting unit (10) which is carried on a vehicle (1), the device comprising, on the one hand, a TV camera (3) mounted on the vehicle, pointing in the direction of travel of the vehicle and designed to record an image of the two edges (12, 13) _,of the roadway ahead of the vehicle, and, on the other hand, a screen (6) mounted on the vehicle, and also a computer (5) mounted on the vehicle with the ability to reproduce on the screen the TV camera image of the edges of the roadway, characterized in that the computer (5) has the ability to generate on the screen (6) two reference lines (7, 8) whose position and shape can be altered by means of a joystick (9) or the like, in such a way that they can be made to lie symmetrically relative to the TV camera image of the edges (12, 13) of the roadway on the screen, the computer being designed to detect the position and shape of the reference lines and from these to determine the position of the centre of the roadway in relation to the longitudinal axis of the vehicle, and the painting unit (10) being displaceable in the lateraL direction as a function of the determination by the computer of the centre of the roadway.

2. Device according to Claim 1, characterized in that the computer (5) has the ability to generate a centre line (14) between the two edge lines (12, 13).

3. Device according to any of Claims 1-2, characterized in that the computer (5) has the ability to use stored measurement values from both the forward- lyi ng and rearward-lying roadway for calculation of the displacement of the painting unit (10) in the lateral direction.