DE202014007669U1 - Reference sphere for use in laser measuring technology, in particular as a spherical target for terrestrial laser scanning - Google Patents

Abstract

Reference sphere (1) for use in laser measurement technology, in particular as a sphere target for terrestrial laser scanning, with at least one locking element (9) arranged on the lateral surface (2) for fixing the position of the reference sphere, characterized in that the reference sphere (1) consists of several , in each case positively engaged with one another and complementing one another to form a closed hollow ball, ball segments (3), and either a. two matching spherical segments (3) in the form of two spherical half-shells (3.1) or b. at least three spherical segments (3) that are compatible with one another are provided in the form of two spherical caps (3.2) and at least one spherical zone (3.3) placed between the spherical caps (3.2), the two spherical half-shells (3.1) or the spherical caps (3.2) using a are connected to one another within the reference sphere (1) extending rod-shaped connector (4).

Description

The invention relates to a reference sphere for use in laser measurement technology, in particular as a sphere target for terrestrial laser scanning according to the preamble of claim 1.

Laser scanning is a non-contact method of metrological recording of points on the earth's surface, in rooms or on objects using a laser scanner, with which a usually rapid oversize can be created even under the most difficult conditions. The fields of application of this measurement method are very diverse, with the cost-effective 3D measurement of existing buildings, structures and facilities in the field of architecture and historic preservation, the creation of measurements in factory planning and in plant construction, the measurement of cavities and profiles in mountain and Tunneling and the contactless measurement of hard to reach or safety-secured areas of power plants, substations, line routes and channels are mentioned.

Laser scanning is usually a mobile measuring method in which the surveying engineers or surveyors have to transport a large number of measuring devices, including the relevant reference balls for generating reference points for the measurement evaluation, to the place of use. In particular, in surveys in which the large number of measuring devices must be transported by air transport to the measuring location, inevitably poses the problem of space-consuming dimensions and the weight of the measuring equipment. As an example, the pack size of only a single transport case with about 575 × 470 × 205 mm is called, which can accommodate six reference balls as a set with a diameter of 145 mm.

The shape of a sphere is particularly well suited as a measuring mark for laser scanning, since it does not matter from which side the ball is scanned. You get a constant number of hits depending on the measurement distance. The reference sphere in the sense of the measuring mark has the spherical center as a defined reference point and can be identified by its radius.

From the prior art this is the US 20110235143 A1 previously known, which discloses a precision scan ball for use in conjunction with a scanner technology. This precision scan ball is designed as a ball, hollow sphere or hollow sphere segment with a reflective laser detection surface and comprises on its lateral surface a shaft for fixing.

Furthermore, from the DE 3800427 A1 a device for accurately determining the distance of a test point lying on a test surface from a reference surface. For calibration of machines at the place of use, the probe touches a measuring ball whose absolute position in space is known. In this way one obtains information about the starting position of the scanning head. In practice, this device is used to precisely measure the surfaces of a test object even on very small surface contours. However, this invention, in particular the measuring ball, is unsuitable for mobile laser scanning.

Also conceivable is the use of commercially available table tennis balls as a reference ball or measuring mark. However, the practical relevance fails because of the small diameter, which is completely unsuitable for measuring larger distances.

The object of the invention is to propose a reference sphere for use in laser measuring technology, in particular as a spherical target for terrestrial laser scanning, which is dimensionally stable even under fluctuating ambient temperatures, to save the installation space and is easy to fix.

The object of the invention is achieved by a reference ball with the features of the main claim. The claims 2 to 10 describe advantageous developments of the reference sphere.

According to the conception of the invention, the reference sphere for use in laser measurement technology, in particular as a spherical target for terrestrial laser scanning, comprises at least one locking element arranged on the lateral surface for fixing the position of the reference sphere, wherein the reference sphere consists of several, in each case positively engaging with each other and a closed hollow ball is complementary spherical segments, and there are provided either two mutually compatible ball segments in the form of two ball half shells or at least three mutually compatible ball segments in the form of two spherical caps and at least one placed between the spherical caps spherical zone, and the two ball half shells or the spherical caps below Use of a within the reference ball extending rod-shaped connector are interconnected.

The two, preferably each made as a spherical half-shell ball segments engage each other in the edge region positively to form a hollow ball into one another, wherein the positive connection is realized by a tongue and groove connection or by a staircase-like offset.

In a particularly easy to handle embodiment of the invention, the two ball half shells or the two spherical caps on its inner side in each case a threaded connection, which are arranged so that they are diametrically opposed in the final assembled state, wherein extending over the diameter of the reference ball rod-shaped connector to his each axial end includes a passable thread which engages positively into each of the threaded neck of the ball half shells or spherical caps and thus forms a releasable connection between the ball half shells or spherical caps.

For manufacturing reasons, it has proved particularly advantageous if the two ball half shells or the two ball caps each comprise a placed on its inside material thickening, in which the corresponding threaded connector is enclosed. In the simplest case, however, a thread is already incorporated or formed in the material thickening - that is, the threaded neck thus a part of the material thickening. Also conceivable is a solution in which, for example, a metallic, cylindrical threaded connector is glued to the material thickening or otherwise anchored in it.

To further reduce the packaging dimensions of the reference ball, it is provided that the reference ball is preferably constructed in three parts, namely with two spherical caps and a spherical zone placed between the spherical caps, wherein each of the two spherical caps is releasably locked to the ball zone in a positively locking manner, and the two spherical caps are used of the inside of the reference ball extending rod-shaped connector are interconnected. The positive connection is realized in this case analogous to the positive connection of the two spherical segments made as a spherical half-shell, namely with a tongue and groove connection or optionally a staircase-like offset. For the sake of completeness, it should be mentioned that in the case of a reference sphere comprising more than two spherical segments, for example two spherical caps and one or two spherical zones placed therebetween, the positive connection between the spherical segments can also be designed differently, always at a predetermined arrangement / assignment of the spherical segments to ensure.

The positive connection between the ball half-shells in a two-part constructed reference ball or between the two spherical caps and the or sandwiched therebetween spherical zone / n in a three-piece or constructed of more than three parts reference ball ensures that the maximum allowable shape deviation of the reference ball in the assembled state is not exceeded.

The packing dimensions of the reference ball can also be further optimized, in which the two ball caps are made with a different height or a different diameter, to allow for the purpose of transport nesting in the smallest space.

For metrological reasons, there is a need for reference spheres, which have different diameters, in order to detect larger distances or points far apart. For this purpose, it has proved to be advantageous if the reference ball according to the invention is part of a reference ball series, which comprises differently sized reference balls in diameter with respectively associated rod-shaped connectors of corresponding length.

The ball segments, spherical caps and ball zone / s are made of plastic, preferably carbon fiber reinforced plastic (CFRP), glass fiber reinforced plastic (GRP), basalt fiber reinforced plastic or aramid fiber reinforced plastic (AFK), all of which have a low coefficient of thermal expansion. The reason for the choice of material is the dimensional stability under temperature change. For example, assuming a temperature change of about 50 Kelvin, such as in a representative temperature range between the summer and winter months in the Northern Hemisphere, and a desired maximum shape deviation of ± 0.05 mm, a coefficient of thermal expansion of about 10 x 10 -6 is 1 / K required. The material GRP is characterized by such a thermal expansion coefficient. However, if there is a requirement for even greater dimensional stability, the CFRP material must be selected, with which the thermal expansion compared to GFRP material can be further reduced by a factor of ten.

The rod-shaped connector assumes the function of obtaining a normal force on the positive connection of the two ball segments to be joined together or the ball zone / s to be joined with the two ball caps. The rod-shaped connector should be as light as possible and as stiff as necessary, so that an (unwanted) deformation of the reference ball is not possible. Due to its brittle material behavior and high strength, a fiber composite material offers perfect rod properties. Preferably, a rod-shaped connector made of CFK material. The modulus of elasticity is greater than that of aluminum combined with lower density and higher strength than steel. When using metallic materials, the same mass could only be achieved via a suitably selected geometry. The resulting disadvantage would be that the Connector is sensitive to any bending is. The concept of the invention is also not in the way if the rod-shaped connector consists of the material GFK, the material AFK or the material BFK.

For metrological detection of distances, angles and heights are particularly reference balls and their hemispherical shells, spherical caps and ball zone / n, which have a coating and possibly a mark for the purpose of simplified handling. A sufficiently good adhesion for the coating is provided by the thermoset matrix of the fiber composites.

The reference ball has known on its outer surface on a locking member. This locking member is designed as a magnet or as a threaded connector to allow the fixation of the reference ball on a metallic surface or a tripod. Laser scanner reference points can therefore be permanently marked because the reference ball can be easily screwed onto the fixed points by means of their threaded connection. About unspecified adapter, the reference ball can also be mounted on standard accessories, such as surveying tripods or Tachymeterstäbe or even unusual for surveying surfaces.

• • ein Bauraum sparender Aufbau durch zumindest zwei zueinander passfähige Kugelsegmente, die formschlüssig miteinander in Eingriff stehen, welche sich im Montageendzustand zu einer geschlossenen Hohlkugel ergänzen und im Transportzustand ineinander liegen,
• • bei einem drei- oder mehrteiligen Aufbau der Referenzkugel mit zwei Kugelkappen und einer zwischen den Kugelkappen platzierten Kugelzone kann das Packmaß bzw. der Bauraum signifikant verkleinert werden,
• • die Formabweichung ist durch die Materialwahl, nämlich Kohlestofffaser verstärktem Kunststoff (CFK), Glasfaser verstärktem Kunststoff (GFK), Basaltfaser verstärktem Kunststoff (BFK) oder Aramidfaser verstärktem Kunststoff (AFK), in Verbindung mit dem zwischen den Kugelsegmenten sich erstreckenden stabförmigen Verbinder äußerst gering und
• • gute Handhabung bei der Montage der zumindest zwei zueinander passfähigen Kugelsegmente, da die beiden jeweils als Kugelhalbschale gefertigten Kugelsegmente oder die beiden Kugelkappen in Verbindung mit der zumindest einen Kugelzone jeweils im Randbereich formschlüssig mittels Nut-Feder-Verbindung oder durch einen treppenartigen Versatz ineinander greifen.

The significant advantages and features of the invention over the prior art are essentially:

• A space-saving construction by at least two mutually compatible ball segments which are positively engaged with each other, which complement each other in the final assembled state to form a closed hollow sphere and lie in the transport state,
• In the case of a three-part or multi-part construction of the reference ball with two spherical caps and a spherical zone placed between the spherical caps, the pack size or the installation space can be significantly reduced,
• • The shape deviation is extremely low due to the choice of materials, namely carbon fiber reinforced plastic (CFRP), glass fiber reinforced plastic (GRP), basalt fiber reinforced plastic (BFK) or aramid fiber reinforced plastic (AFK), in conjunction with the rod-shaped connector extending between the ball segments and
• Good handling in the assembly of at least two mutually compatible ball segments, since the two ball segments each made as a ball half shell or the two spherical caps in conjunction with the at least one spherical zone in the edge region in each case form-fit by tongue and groove connection or by a staircase-like offset mesh.

The foregoing features and advantages of this invention will become better understood and appreciated upon a study of the following detailed description of the preferred non-limiting example embodiments of the invention, together with the accompanying drawings. The drawings show in

1 FIG. 2: a cross-section of a two-part reference sphere, in FIG

2 : an enlarged view of the cross section of a two-piece constructed reference ball with a staircase-like offset as positive locking, in

3 : a cross-section of a three-part constructed reference sphere, in

4 : An enlarged view of the cross section of a three-part constructed reference ball with a staircase-like offset as positive locking in a first embodiment, in

5 : An enlarged view of the cross section of a three-part constructed reference ball with a staircase-like offset as positive locking in a second embodiment and in

6 : a pack size comparison between a one-piece, two-piece and three-piece hollow sphere.

The 1 shows a cross section of a two-part constructed reference ball 1 , The example of GFK existing reference sphere 1 for use in laser measuring technology, in particular as a spherical target for terrestrial laser scanning, comprises at least one on the lateral surface 2 arranged Arretierungsorgan 9 for fixing the position of the reference sphere 1 according to the prior art. As can be seen, the reference sphere 1 two mutually compatible ball segments 3 in the form of two half-shells 3.1 on, which are positively engaged with each other. These two ball half shells 3.1 complement each other in the final assembled state to a closed hollow sphere, wherein the two ball half shells 3.1 using one within the reference sphere 1 extending rod-shaped connector 4 , which is preferably made of CFK, are interconnected. The two each as a ball half shell 3.1 manufactured spherical segments 3 grab each in the border area 5 positively to form the hollow ball into one another, wherein the positive connection by in the 2 exemplified variant is realized. The two ball half shells 3.1 show on their inside 6 , that is, on the side facing the ball inside, in each case a threaded connector 7 which are diametrically opposed in the final assembled state, wherein which is about the diameter of the reference sphere 1 extending rod-shaped connector 4 at its two axial ends in each case a passable thread 4.1 includes, which in each case in the threaded connector 7 the ball half shells 3.1 positively engages and thus a detachable connection between the ball half shells 3.1 formed. The two threaded connectors 7 are each in material thickening 8th edged on the corresponding insides of the two ball half shells 3.1 are placed.

An enlarged view of the cross section of a two-piece constructed reference ball 1 with a staircase-like offset as positive locking is in the 2 shown. The two each as a ball half shell 3.1 manufactured spherical segments 3 grab each in the border area 5 staircase to form a hollow ball into one another, wherein the offset a larger contact surface is achieved than in a blunt abutment. The contact area forming as a staircase or all three contact lines or surfaces in this case have an identical length or area.

From the 3 is a cross section of a three-part constructed reference ball 1 refer to. The three-part relationship refers exclusively to the number of sphere segments 3 , here in the form of two spherical caps 3.2 and one between the spherical caps 3.2 placed spherical zone 03.03 available. Each of the two spherical caps 3.2 is in their respective border area 5 positive fit with the corresponding edge area 5 the only sphere zone 03.03 releasably connected. To form the positive connection between the spherical caps 3.2 and the sphere zone 03.03 is on the ball caps 3.2 a pass ring 10 arranged. The pass ring 10 is with the associated ball cap 3.2 bonded. The two spherical caps 3.2 are in addition, analogous to the two ball half shells 3.1 the embodiment according to the 1 and 2 using the inside of the reference sphere 1 extending rod-shaped connector 4 connected with each other. The connector 4 is hollow to reduce weight.

The 4 shows an enlarged view of the cross section of a three-part constructed reference ball 1 with a staircase-like offset as positive locking in a first embodiment. The two each as a ball cap 3.2 manufactured spherical segments 3 each grab in their border area 5 staircase in the border area 5 the sphere zone 03.03 and form together to form a closed hollow sphere. The step-like offset is structurally symmetrical, ie the contact area between each ball cap 3.2 and the sphere zone 03.03 is equal. This allows a very good dimensional stability can be achieved.

The 5 shows an enlarged view of the cross section of a three-part constructed reference ball 1 with a step-like offset as a positive connection in a second embodiment. Basically, the structure corresponds to the reference sphere 1 the the 4 , However, the decisive difference lies in the design of the positive connection or the contact region in the edge region 5 , While at the in 4 shown reference ball 1 the step-like offset is formed on both sides with a right-angled step, in accordance with the embodiment of the positive connection 5 an oblique and a right-angled step provided. The positive connection between spherical caps 3.2 and sphere zone 03.03 is therefore not symmetrical, since the lower ball cap 3.2 the contact area to the sphere zone 03.03 and the sphere zone 03.03 the contact area to the upper ball cap 3.2 cover.

In the 6 is a significant advantage of the invention figuratively as Packmaßvergleich between a one-piece, two-piece and three-piece designed as a hollow ball reference sphere 1 demonstrated. It can be seen that a two-part constructed reference sphere 1 with two ball half shells 3.1 about only 2/3 of the space of a one-piece reference sphere 1 occupies. It was known that originally (only) six reference spheres could be built in one piece 1 be stowed in a transport case. Against the background that by the two-part design now three ball half shells 3.1 can be placed instead of a one-piece hollow sphere, that results in six berths, each with three ball half shells 3.1 a total of eighteen ball shells 3.1 leading to nine assembled reference spheres 1 supplement, can be transported. The space-saving gain is therefore 50%. Just as clearly recognizable is the reduced space of a three-piece constructed reference ball 1 opposite a two-piece constructed reference ball 1 , Instead of a one-piece reference sphere 1 can have almost two tripartite reference balls 1 comprising two spherical caps 3.2 and a sphere zone 03.03 , are transported per berth in the transport case, which corresponds to a space saving of almost 100%.

LIST OF REFERENCE NUMBERS

1

reference sphere

2

lateral surface

3

ball segment

3.1

Ball half-shell

3.2

ball cap

3.3

spherical zone

4

Rod-shaped connector

4.1

thread

5

border area

6

inside

7

threaded connector

8th

material allowance

9

detaining

10

fitting ring

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• US 20110235143 A1 [0005]
• DE 3800427 A1 [0006]

Claims (10)

Reference sphere ( 1 ) for use in laser metrology, in particular as a spherical target for terrestrial laser scanning, with at least one on the lateral surface ( 2 ) arranged locking member ( 9 ) for fixing the position of the reference sphere, characterized in that the reference sphere ( 1 ) of a plurality of each form-fitting mutually engaging and complementary to a closed hollow sphere spherical segments ( 3 ), and either a. two mutually compatible ball segments ( 3 ) in the form of two spherical half-shells ( 3.1 ) or b. at least three mutually compatible ball segments ( 3 ) in the form of two spherical caps ( 3.2 ) and at least one between the spherical caps ( 3.2 ) placed spherical zone ( 03.03 ), wherein the two ball half shells ( 3.1 ) or the spherical caps ( 3.2 ) using one within the reference sphere ( 1 ) extending rod-shaped connector ( 4 ) are interconnected. Reference sphere ( 1 ) according to claim 1, characterized in that the two each as a spherical half-shell ( 3.1 ) manufactured spherical segments ( 3 ) each in the border area ( 5 ) form fit to form a hollow ball engage each other, wherein the positive connection is realized by a tongue and groove connection or a staircase-like offset. Reference sphere ( 1 ) according to claim 1 or 2, characterized in that the two ball half shells ( 3.1 ) or the two spherical caps ( 3.2 ) on its inside ( 6 ) each have a threaded connector ( 7 ) diametrically opposite one another in the final assembled state, the diameter being larger than the diameter of the reference sphere ( 1 ) extending rod-shaped connector ( 4 ) at its two axial ends in each case a passable thread ( 4.1 ), which in each case in the threaded connector ( 7 ) of the ball half shell ( 3.1 ) or spherical caps ( 3.2 ) engages positively and thus a detachable connection between the ball half shells ( 3.1 ) or spherical caps ( 3.2 ) trains. Reference sphere ( 1 ) according to one of claims 1 to 3, characterized in that the two ball half shells ( 3.1 ) or the two spherical caps ( 3.2 ) each one placed on its inside material thickening ( 8th ) into which the corresponding threaded connector ( 7 ) is enclosed. Reference sphere ( 1 ) according to one of claims 1 to 4, characterized in that the reference sphere ( 1 ) in three parts, namely with two spherical caps ( 3.2 ) and one between the spherical caps ( 3.2 ) placed spherical zone ( 03.03 ), wherein each of the two spherical caps ( 3.1 ) in their respective margins ( 5 ) positively with the corresponding edge region ( 5 ) of the spherical zone ( 03.03 ) Is releasably connected and the positive connection is realized by a tongue and groove connection or a staircase-like offset. Reference sphere ( 1 ) according to one of claims 1 to 5, characterized in that the two ball caps ( 3.2 ) have a different height or different diameters, in order to allow for the purpose of transport a nesting with the smallest packing size. Reference sphere ( 1 ) according to one of claims 1 to 6, characterized in that the reference sphere ( 1 ) Is part of a reference ball series, the differently sized in diameter reference balls ( 1 ) with respectively associated rod-shaped connectors ( 4 ) of corresponding length. Reference sphere ( 1 ) according to one of claims 1 to 7, characterized in that all spherical segments ( 3 ), namely the ball shells ( 3.1 ), the spherical caps ( 3.2 ) and the sphere zone (s) ( 03.03 ) and / or the rod-shaped connector ( 4 ), plastic, carbon fiber reinforced plastic (CFRP), glass fiber reinforced plastic (GRP), basalt fiber reinforced plastic or aramid fiber reinforced plastic (AFK). Reference sphere ( 1 ) according to one of claims 1 to 8, characterized in that the ball shells ( 3.1 ), the spherical caps ( 3.2 ) and the sphere zone (s) ( 03.03 ) have a coating and optionally a marking. Reference sphere ( 1 ) according to one of claims 1 to 9, characterized in that on the lateral surface ( 2 ) of the reference sphere ( 1 ) arranged Arretierungsorgan ( 9 ) is designed as a magnet or as a threaded connector in order to fix the reference sphere ( 1 ) on a metallic surface or a tripod.

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