Method and system for determining the position of a receiver unit

#The invention relates to a method for determining the position of a receiver unit and a system for determining the position.

#In many geodetic applications, methods and systems for determining the position, i.e. for determining the location and/or orientation, of a surveying instrument are used. From a location determined by means of such a system, further measurements which are linked to the location and generally also require knowledge of the orientation of the measuring device in space are then generally carried out. In principle, the orientation of the instrument can also be derived from the determination of the location of two or more points. For measuring applications, in general 6 degrees of freedom of a hand-held measuring device, but generally the location and hence 3 degrees of freedom, have to be determined for unambiguously fixing the absolute position in space. If constraining conditions are present, such as, for example, movement in a defined plane, the determination of fewer degrees of freedom may also be sufficient for fixing location and orientation. The problem therefore comprises the determination of location and orientation as two objects which can in principle be achieved separately but which must be carried out in association for many applications. As a rule, both location and orientation of a generally hand-held device are therefore required.

#An example of location determination systems is global positioning systems, such as, for example, GPS, GLONASS or the European Galileo system currently being set up. These systems are based on as far as possible undisturbed reception of satellite signals, which however may also be obstructed by obstacles and therefore limited in their usability. Owing to their shading effect, the reception of signals may be limited or completely impossible in the immediate vicinity of obstacles, so that a location determination is no longer possible with this system. These limitations relate in particular to measurements in interior rooms of buildings in which the reception of a number of satellites which is required for positioning can generally be ruled out. A further problem is that global positioning systems do not always provide the required accuracy of position determination or require greater effort, for example through the use of a reference station or longer measuring times.

#The method according to the invention and a system according to the invention comprising corresponding receiver units and radiation projectors are described in more detail below, purely by way of example, with reference to working examples shown schematically in the drawing. Specifically,

#FIG. 1 shows the diagram of a first use example for the method according to the invention for determining the location of a construction machine;

#FIG. 2-3 show the diagram of a second use example for the method according to the invention for determining the location of a construction machine;

#FIG. 1 shows, by way of example, a first use example for the method according to the invention for determining the position of a construction machine 4. In this example, the construction machine 4 is present in a trench, so that direct sighting by a centrally placed unit, such as, for example, by at total station, is not possible. According to the invention, a set of reference points 2, which in turn can be detected by the construction machine 4, is projected by a radiation projector 1. For this purpose, electromagnetic radiation S, preferably laser light, is sent to locations which can be seen from the construction machine 4. In order to achieve a corresponding coverage of the space to be processed, it is advantageous under certain circumstances to use special components, such as, for example, the projection panels 3 shown here purely by way of example. These projection panels 3 may have, for example, a white or spectrally optimized surface which is arranged on a stand so as to be extendible. By means of a plurality of such projection panels 3, coverage of the processing region can be achieved.

#FIG. 2-3 show the diagram of a second use example for the method according to the invention for determining the location of a construction machine 4. As shown in FIG. 2, natural surfaces can also be used instead of the projection panels of the first working example, it also being possible, if appropriate, for said natural surfaces to be adapted in their back-radiating characteristic by special treatment, such as, for example, smoothing, or the mounting of components, such as, for example, mirror foils or reflector foils, reflective paint or spheres. The radiation projector 1 now projects the electromagnetic radiation S onto existing structures and thus produces a set of reference points 2′. For example, spheres can be illuminated by means of a collimated laser beam so that a relatively large part of the space is illuminated by the reflected radiation. For this purpose, beam diameter and sphere diameter are tailored to one another. However, it is of course also possible to use the special components, such as, for example, the projection panels of FIG. 1, and natural structures together.

#FIG. 3 explains the determination of the position of the construction machine 4 on the basis of the projected reference points 2′. Those reference points 2′ of the set of the reference points which are within the detection region 6 of a receiver unit 5 are detected by the construction machine 4. The number of reference points 2′ required for determining the position, i.e. location and/or orientation, is dependent on the desired accuracy and on possible limitations of the degrees of freedom by specified information or constraints, for example movement on a horizontal surface without irregularities. In general, however, four reference points 2′ are required for determining the position of the receiver unit 5 and hence of the construction machine 4 in a manner similar to a global positioning system.