EP0573410A1

EP0573410A1 - A method and a system for navigation of unmanned vehicles

Info

Publication number: EP0573410A1
Application number: EP91900971A
Authority: EP
Inventors: Göran L. BERGQVIST
Original assignee: Individual
Current assignee: Individual
Priority date: 1989-12-07
Filing date: 1990-12-07
Publication date: 1993-12-15
Also published as: WO1991009356A1; SE8904128D0; AU6959491A; SE465487B; SE8904128L

Abstract

Selon un procédé de navigation de véhicules sans équipage (4), de préférence des robots mobiles dans les limites d'une zone prédéterminée, sur une surface en béton armé (2), le véhicule est pourvu d'organes de propulsion et d'organes de direction et une structure géométrique (3) présente dans la zone est utilisée comme référence pour la navigation. Cette structure géométrique est formée par l'armature de la surface en béton armé.According to a method of navigating unmanned vehicles (4), preferably mobile robots within the limits of a predetermined area, on a reinforced concrete surface (2), the vehicle is provided with propulsion elements and direction and a geometric structure (3) present in the area is used as a reference for navigation. This geometric structure is formed by the reinforcement of the reinforced concrete surface.

Description

A METHOD AND A SYSTEM FOR NAVIGATION OF UNMANNED VEHICLES

The present invention refers to navigation of unmanned vehicles particularly mobile robots, and it more exactly refers to a method and a system for determining the position of such a vehicle within a predetermined area over a surface of reinforced concrete, such as e.g. the floor plane of a building.

Older known systems of this type are based either on that the vehicle is caused to follow a fixedly installed guide loop, or on that it receives position references from extern so called beacons or markers. Genuine navigation systems use either a compass or inertial navigation.

For shifting the route of travel for a vehicle guided by fixedly installed guide loops it is required that new groo¬ ves are cut in the concrete floor, in which grooves new guide loops thereupon are to be embedded. Another drawback at such guide loops embedded in the concrete floor is that the concrete floor of the building must be constructed thicker than what is required from purely strength technical reasons, as it is necessary thereupon to cut down grooves in the floor, which reduce the carrying thickness of the floor. This will increase the cost for the very building. Genuine navigation systems are furthermore expensive.

The purpose of the present invention is to provide a method for navigation of initially described vehicles, which method proffers a simple and efficient navigation, which eliminates the above mentioned drawbacks, and this has been achieved with the features defined in claim 1.

The invention is based on the basic concept of using, instead of navigation in accordance with a particularly positioned fixed guide loop or the like, a geometric struc¬ ture already present in the building, which is constituted by the reinforcement of the reinforced concrete surface. It must be possible to follow this structure directly from the vehicle in such a manner that a track reference is obtained, which may be stored and repeated an unlimited number of times. With this method and system there shall be no need for mounting and trimming any additional external reference points.

The invention furthermore refers to a navigation system for accomplishing this method and this system is characterized by the features defined in claim 2.

The invention hereinafter will be further described with reference to solutions shown in the accompanying drawings.

Fig. 1 shows in a schematical perspective view a portion of a room in which there is an unmanned vehicle equipped with the navigation system according to the invention. Fig. 2 is a perspective view, which schematically illustra- tes an embodiment of the fitting of detectors to the schema¬ tically shown vehicle.

Fig. 3 intimates an alternative method of application of the detectors for the schematically intimated vehicle.

Fig. 1 shows schematically a portion of a room, e.g. an industry hall 1. Each concrete surface, i.e. particularly the floor 2 has a reinforcement incorporating a specific pattern of reinforcing irons 3, often in the shape of a bar pattern. The reinforcing irons 3 are made from a standardi- zed ferromagnetic material.

All reinforcement is made in accordance with especially established rules and its positions may not vary outside approved tolerances. This shall be controlled prior to the pouring of the concrete. The reinforcement thus forms an ferromagnetic system of coordinates, which according to the present invention is utilized as a navigational basis for an unmanned vehicle 4, which can be driven on the floor within the space limited by the walls. In the vicinity of adjacent walls 5 and holes 6 made in the floor and also at possible pillars, the reinforcing irons are furthermore provided closer to each other, whereby a more strong ferromagnetic field is obtained in the vicinity of such objects 5,6 et¬ cetera, impeding the motion of the vehicle 4, and which can be utilized for the orientation of the vehicle, whereby collisions furthermore may be avoided and the manoeuvra¬ bility may be improved, particularly at corners.

By means of the present invention thus is obtained a system, which is based upon the utilization of an existing geometric structure. This structure can be followed directly from the vehicle and then is obtained a track reference, which may be stored and repeated. No especial external references have to be installed and trimmed.

However it may be advantageous that the starting point for each memorized track is a ferromagnetic reference marking of particular geometry, which is embedded in the concrete.

In Fig. 2 is shown in perspective the configuration of detectors 7,8,9,10 applied on the intimated vehicle 4, and which might be four Hall-elements, or other types of magne- tic field detectors or other detectors for contact-free measurement of the presence of metal, arranged in pairs opposed to each other and adapted to detect the pattern formed by the reinforcing irons 3x and 3y resp., arranged in x and y directions. The distance 7-8 between the pairs of opposed detectors 7, 8 thereby is distinctly bigger than the distance 9-10 between the detectors 9, 10. On a concrete surface having a substantially symmetrical bar pattern reinforcement in this manner is obtained a possibility of measuring at least four parameters, such as direction, speed, density and level in relation to the base. In Fig. 3 is illustrated schematically in perspective a vehicle 4 wherein it is illustrated how the separate detec¬ tor elements - here shown as lines 7a, 8a, 9a and 10a - are positioned at the outer border angles of the vehicle and are positioned outwardly from the vehicle under an angle α bigger than 90° whereby the detector will be facing obli¬ quely outwards/downwards, whereas its angle β is substan¬ tially equal to 90°. In this manner the outer boundaries of the detecting area 11 will be situated outside the limiting surfaces 4a of the vehicle, thus that particularly the measurement of the density increase can take place without risk for collision, whereby perpendicularly adjoining sur¬ faces, e.g. walls, pillars, etcetera, will partly form part of the measuring area.

In the concrete may preferably be embedded at least one ferromagnetic reference marker of a certain geometry, as a starting point for every memorized track.

The navigation system is primarily intended for mobile robots and particularly for robot systems in the building industry. One example of this is so called power floats, which treat a certain area of the floor surface to be. As soon as the reinforcement pattern has been memorized this can act as a basis for all future track generation over the same surface. A cleaning robot then may use the same infor¬ mation when the building of the house has been finished.

Also other types of vehicles, e.g. unmanned industrial trucks can use the same navigation system and the savings then will become big as compared to installation of fixed loop systems.

Therefore the invention is not limited only to robot systems but can be used for all navigation or positioning on surfa¬ ces or structures of reinforced concrete.

Claims

1. A method for navigation of unmanned vehicles (4), prefe¬ rably mobile robots within a predetermined area over a surface of reinforced concrete (2), whereby the vehicle is equipped with driving means for propelling and with steering means for sterring the vehicle, c h a r a c t e r i z e d i n, using a geometric structure present within the area as reference for the navigation, which geometric structure is constituted by the reinforcement (3;3x,3y) of the reinforced concrete surface (2).

2. A method according to claim 1, c h a r a c t e r i z e d i n, providing on the vehicle at least one detector (7,8,9,10), and feeding this with impulses derived from the pattern, which is formed by the reinforcement (3;3x,3y) of the con¬ crete (2).

3. A method according to anyone of the preceeding claims, c h a r a c t e r i z e d i n, storing measurement values obtained during manual travel over desired surface and using such values for generating and comparing track at unmanned travel.

4. A method according to anyone of the preceeding claims, c h a r a c t e r i z e d i n, gathering measurement values for generating and comparison of track for unmanned travel from constructional drawing material in form of computer-readable transfer.

5. A method according to anyone of claims 1 to 3, c h a r a c t e r i z e d i , gathering measurement values for generating and comparison of track for unmanned travel from a computer positioned on the vehicle, which first follows the outer limiting areas of the surface by aid of density measurement and thereupon covers the surface by means of incremental translatory movement or another predetermined motion pattern.

6. A method according to anyone of claims 3, 4 or 5, c h a r a c t e r i z e d i n, that the means for treatment of the measurement signals incorporates a correction and reconstruction function based on a pattern information stored in a computer.

7. A system for navigation of unmanned vehicles (4), prefe¬ rably mobile robots within a predetermined area over a sur¬ ace of reinforced concrete (2), whereby the vehicle is equipped with driving means for propelling and with steering means for steering the vehicle, in accordance with the method according to claim 1, c h a r a c t e r i z e d t h e r e i n, that the system incorporates at least one detector (7,8,9, 10) provided on the vehicle (4) and adapted to receive measurement values from a geometric structure present within the area, and constituted by the reinforcement (3;3x,3y) in a concrete surface, and that the vehicle (4) is equipped with means for treatment of said measurement values, said means being connected to said steering means for feeding said treated measurement values to said steering means for the steering of the vehicle.

8. A system according to claim 7, c h a r a c t e r i z e d t h e r e i n that its detectors are four Hall elements (7,8,9,10) for magnetic field measurement or another detector for contact- free detection of metal.

9. A system according to claim 7 or 8, c h a r a c t e r i z e d t h e r e i n, that the detectors are four magnetic field detectors (7,8,9, 10), which in pairs (7,8;9,10) are positioned opposed to each other and where the distance (7-8) between the detec¬ tors of one of the pairs is distinctly bigger than the distance (9-10) between the two detectors of the second pair.

10. A system according to anyone of claims 7 - 9, c h a r a c t e r i z e d t h e r e i n that the outer detector elements (7,8,9,10) are positioned at the outer border angles of the vehicle (4) and are posi- tioned at an angle (α) outwards from the sides of the ve¬ hicle for giving a detection area (11) extending outside the area (4a) delimited by the vehicle sides.

11. A system according to anyone of claims 7 to 10, c h a r a c t e r i z e d t h e r e i n that at least one ferromagnetic reference marker of a cer¬ tain geometry is embedded in the concrete (2), as a starting point for every memorized track.