DE102014000987A1 - Mounting system for opto-electronic instrument in carrier vehicle, has mass module whose spatial orientation is provided to increase measurement values of instruments, and terminal pieces provided at mass module by compensation masses - Google Patents

Abstract

The system has spring/damping elements (24) connected with a mass module (3). A mechanical low pass filter filters oscillations of a carrier vehicle, which lies over cut-off frequency of an inertial navigation system (23). The mass module is stabilized in a space while the mass module follows frequent movements of the carrier vehicle. A spatial orientation of the mass module is provided to increase measurement values of instruments (1, 2). Terminal pieces are provided at the mass module by compensation masses.

Description

The invention relates to mounting system for an opto-electronic instrument in a host vehicle, wherein the opto-electronic instrument with an inertial navigation system for detecting at least the orientation of the instrument in space, but possibly also for determining the position thereof in a coordinate system to a rigid module which inertial navigation system is capable of resolving periodic movements up to a defined cutoff frequency, the corresponding data being linked to the readings of the opto-electronic instrument, for example those of a laser rangefinder or a laser scanner, and from the instrument and the module formed the navigation system is connected to the structure of the carrier vehicle via spring / damping elements.

The carrier vehicles may be land or rail vehicles, watercraft or aircraft such as airplanes or helicopters in which, while the vehicle is moving, measurements, photographs or the like may be taken. All these carrier vehicles have in common that they od in these measurements, recordings. Like. Can move around one or more axes. In order to ensure a corresponding assignment to the space to be measured or to be recorded, it is known to combine the opto-electronic instrument with an inertial navigation system (IMU) and to connect it as rigidly as possible, so that for each measurement, recording or the like Alignment of the optical axis of the instrument in space can be detected by data. As a rule, such an instrument is also combined with a navigation system with which its respective position in a superordinate, for example global, coordinate system is determined. As such navigation systems can be used in rail and land vehicles in principle also wheel sensors, but have largely proven for all these applications satellite-based systems (GNNS eg GPS), often with an inertial navigation system (IMU) to an integrated IMU / GNNS system are combined. This gives you the exact coordinates for each measuring point in a higher-level coordinate system.

The opto-electronic instruments are exposed in use not only to the intended movements of the carrier vehicle but also shocks, vibrations, vibrations, etc., which are transmitted from the structure of the carrier vehicle to the instruments. Such instruments typically include shock and vibration sensitive components and therefore must be connected to the structure of the host vehicle with spring / damper elements to protect them.

According to the invention form the spring / damping elements in a conventional manner together with the mass of the module, a mechanical low-pass filter, which substantially absorbs vibrations of the host vehicle, which are above the cut-off frequency of the inertial navigation system and thus stabilizes the module in space, while the module low-frequency Movements of the host vehicle follows and provides the data of each changed spatial orientation of the module for linking with the measured values of the instrument.

Mechanical low-pass filters are, as mentioned above, already known per se and for example in the U.S. Patent No. 6,688,174 B1 (Pierre Gallon et al.) As well as in the German Offenlegungsschrift DE 10 2010 062 017 A1 (Robert Bosch GmbH). The former publication refers to the vibration damped suspension of a laser gyro system, the second to the shock and vibration damping of micro-projectors. The mechanical low-pass filters are described in both applications in a completely different context and therefore could not give any stimulus to the present invention.

In some installations of opto-electronic instruments, these are not mounted directly on the carrier vehicle, but on a stabilized platform arranged on the carrier vehicle. In such a case, according to the invention, at least the module formed by the instrument and the navigation system is mounted on the stabilized platform with the interposition of spring / damping elements, wherein the spring / damping elements together with the mass of the module form a mechanical low-pass filter known per se, which vibrations of the stabilized platform which are substantially absorbed above the cut-off frequency of the inertial navigation system but transmits low-frequency vibrations to the module.

According to a further feature of the invention, the mounting system comprises a two-stage mechanical decoupling, on the one hand, the rigid module is mechanically decoupled from the support structure by means of damping elements to not transmit deformations of the same to the module and on the other hand, the spring / damping elements together with the mass of the module and its support structure form a per se known mechanical low-pass filter, which substantially absorbs vibrations of the host vehicle that are above the cut-off frequency but transmits low-frequency vibrations to the module.

For the most commonly used inertial navigation systems (IMU) and host vehicle / instrument configurations, the cut-off frequency is preferably about 25 Hz.

According to a further feature of the invention, the module is movably suspended or braced in all three coordinate directions.

Preferably, the spring and damping elements are designed at the individual points of attack on the module, taking into account their position relative to the center of gravity of the module so that both longitudinal and torsional vibrations or deformations are largely damped.

According to the invention, the spring / damping elements are designed and positioned on the module that, based on the center of gravity of the module, the sum of the moments of those forces that are transferable to the module is substantially zero.

In applications where the measurement distance is significantly greater than the dimensions of the instrument module, displacements of the module in longitudinal directions have little effect on the measurement results, while the system is extremely sensitive to rotational movement of the module. To avoid the excitation of such rotational movements or torsional vibrations as much as possible, according to the invention, the spring and damping elements at the individual points of attack on the module, taking into account their position with respect to the center of gravity of the module designed so that torsional vibrations are largely damped.

Preferably, the spring / damping elements are designed and positioned on the module that based on the center of gravity of the module, the sum of the moments of those force components that are transferable to the module and normal to the optical axis of the opto-electronic instrument, substantially Is zero. By this measure, longitudinal movements are allowed in the direction of the optical axis of the instrument and normal to this, however, an excitation of torsional vibrations is suppressed.

In order to avoid interference with the module when mounting additional devices such as digital photo or video cameras or navigation devices or their sensors, fittings for the rigid attachment of these accessories are provided on the outside of the module. Since the total mass of the module is changed by the installation of such accessories, which has an effect on tuning the mechanical low-pass filter formed from the spring / mass system, it is advantageous to provide the connection pieces on the outside of the module first Kompensationsmassen, which are reduced accordingly during assembly of additional equipment ,

Further features of the invention will become apparent from the following description of some embodiments and with reference to the drawings. In the 1 As an example of an opto-electronic instrument, a laser scanner for airborne applications is shown, partially in section. The 2 shows a ready to install instrument in axionometric representation, the 3 and 4 illustrate two different mounting systems for two substantially similar instrument modules.

The Indian 1 The laser scanner for "airborne" applications shown as an example of an optoelectronic instrument essentially comprises a laser rangefinder 1 after the pulse transit time method and a downstream beam deflection device 2 consists. In the illustrated example, the beam deflector includes a glass wedge prism 11 moving at high speed around the optical axis 7 of the laser rangefinder 1 rotates.

The instrument is on a mounting plate 31 built with four columns 32 with a plate 33 is connected and forms a stable and rigid frame with these. Within this framework 31 - 33 is a laser source 4 arranged over a mirror system 5 . 6 a laser beam in the optical axis 7 of the instrument. Instead of the mirror system 5 . 6 It is also possible to use a flexible glass fiber optic cable.

Under the laser rangefinder 1 is a cylinder 8th provided in camps 9 around the optical axis 7 of the laser rangefinder 1 rotatably mounted and by an electric motor 10 is driven at high speed. In this cylinder is the glass wedge prism 11 mounted, through which the transmitting laser beams are deflected. These laser beams 12 form during rotation of the wedge prism 11 in its entirety, a beam cone, which scans a plane lying underneath the laser scanner flat terrain like a circle. The laser beams are generally diffusely reflected from the terrain and the objects, vegetation, etc. present thereon. A small part of this radiation reaches the laser scanner again, is through the wedge prism 11 parallel to the optical axis 7 aligned and through the receiver optics 14 on the photosensitive cell of the receiver 15 displayed. In the receiver 15 the incoming optical pulses are converted into electrical signals. In an evaluation device, not shown, which may also be arranged externally and connected to the laser scanner with a cable, the electrical impulses may be digitized. From the time from the emission of the laser pulses to the arrival of the received pulses, the distance from the laser scanner is determined. On the rotating cylinder 8th or on the drive motor 10 An unillustrated angle decoder is attached. From the data of this decoder results the respective direction of the laser beam 12 in an instrument-related coordinate system. On the fixed instrument base 16 can digital still cameras 17 and / or video cameras 18 be arranged. These cameras and the laser scanner are through an exit window 19 protected against environmental influences. The distance data provided by the evaluation device is linked with the instrument-related coordinates derived from the angle decoder and together with the data of any digital cameras 17 . 18 as each stored a record.

In order to be able to transform the instrument-related data into a superordinate, for example, global coordinate system, it is necessary, on the one hand, to orient the instrument 1 . 2 to determine in space and to link this with data derived from a navigation system. An inertial navigation system (IMU) is used to determine the position of the instrument in space. 23 used. The navigation system used for determining the position is generally based on a satellite-based system (GNNS, eg GPS). In the arrangement of this navigation system 23 on the instrument 1 . 2 It is crucial that the Inertia Navigation Unit (IMU), 23 completely rigid with the instrument, in this case with the laser scanner 1 . 2 to a module 3 connected is. This module 3 includes a platform 20 on which on the one hand the lower part of the instrument 16 with the rotating wedge prism 11 is arranged, on the other hand carries the platform 20 the receiver optics 14 with the receiver unit 15 , as well as four columns 21 which with a plate 22 are welded. At this plate 22 is the inertial navigation unit (IMU), 23 rigidly attached.

With this framework 21 . 22 is also the laser source 4 connected. That from laser scanner 1 . 2 and the inertial navigation unit IMU, 23 existing module 3 is with the mounting plate 31 and the plate 33 with damping elements 24 connected. These elements 24 primarily serve to deform the outer structure 31 - 33 of the instrument, which may result, for example, from uneven heating of the same, not on the module 3 transferred to.

The optoelectronic instruments installed in the carrier vehicles, for example in fixed-wing aircraft and helicopters, are exposed to vibrations and a wide range of vibrations and shocks, which are excited by drive motors as well as external influences. The same applies to water, land and rail vehicles. When the instruments are subjected to these forces, many of these opto-electronic instruments are relatively insensitive to dislocations in the direction of the optical axis 7 and normal to this. On the other hand, it is critical if these forces induce torsional vibrations of the instruments about axes that are normal to the optical axis. As a rule, the measuring distance is orders of magnitude greater than the instrument, so that significant displacements of the measuring points result even with small rotational vibration amplitudes. For low-frequency oscillations, this can be compensated by using the Inertial Navigation System (IMU), 23 the changes in the orientation of the instruments are measured and assigned to the measured values according to changed instrument-related coordinates. However, with higher frequency vibrations that the IMU can not follow, unacceptable measurement errors will occur. This problem not only occurs with laser scanners, but also, for example, with digital still and video cameras and many other instruments with a wide variety of opto-electronic sensors. According to a feature of the invention, this problem can be solved in that the mounting points of the instrument are selected in the carrier vehicle so that the forces introduced into the system are directed to the instrument's center of gravity, or compensate for the center of gravity related moments of these forces.

In the 2 such an arrangement is shown. The laser scanner 1 . 2 is opposite to in 1 shown slightly changed and in particular what the arrangement of the damping elements 24 and their support on the outer frame and the instrument module 3 arrives. Under the mounting plate 31 of the laser scanner 1 . 2 is another plate 25 provided, on which four so-called wire rope springs 26 are attached. The other side of these feathers 26 is with the platform 27 connected, which can be fastened with screws, not shown, to the structure of the carrier vehicle. The springs are with the mass of the instrument module 3 tuned so that they form together with this a mechanical low-pass filter. The cutoff frequency is chosen so that only oscillations on the instrument module 3 the IMU, 23 can still be measured. The plate 25 is positioned on the instrument such that the plane of its underside, via which forces induced by the carrier vehicle are introduced into the system, is the center of gravity 28 of the instrument including the plate 25 contains. Thus, torsional vibrations of the instrument about axes which are normal to the optical axis, suppressed as far as possible.

The spring arrangement 25 to 27 represents an integral part of the instrument, which is specially adapted to the system and is installed together with this in the carrier vehicle or removed. In the illustrated example, a two-stage mechanical decoupling is realized. A first, 24 which prevents the transfer of deformations to the module and a second, 25 to 27 which minimizes the effects of vibrations, vibrations and forces introduced into the system by the host vehicle.

In the 3 is another example of the assembly of an opto-electronic instrument shown, which is intended for use in a carrier vehicle, being omitted for reasons of clarity on the presentation of the rigid, fixed to the carrier vehicle frame construction. That from laser scanner 1 . 2 and IMU, 23 existing module 3 supports on the one hand with the plate 31 and three spring / damping elements 29 and with the IMU housing over a single, similar spring / damping element 29 on this frame construction. Vibrations, vibrations, etc. of the carrier vehicle act on the frame construction, the three on the mounting plate 31 attached spring / damping elements 29 , as well as the individual element attached to the IMU housing 29 , The focus 28 of the module 3 lies in this example on the instrument axis 7 at a distance a from this single element 29 , To the three elements 29 on the mounting plate 31 is the distance of the center of gravity 28 b, where a is equal to 3 × b. Thus, the moments of the initiated, normal to the optical axis 7 directed force components balanced and it is the excitation of a torsional vibration of the module avoided.

The 4 shows an alternative arrangement of the spring / damping elements 29 , These are arranged in the corners of a virtual cube and aligned with the center of the cube. The Elements 29 are based on the other side by analogy 3 to a not shown connected to the structure of the carrier vehicle frame construction. The center of the virtual cube is essentially in line with the center of gravity 28 of the module 3 match, so that by the introduced forces no torsional vibrations of the module 3 be stimulated. The Elements 29 are in their entirety with the mass of the module 3 tuned and represent a spring / mass system, which acts as a mechanical low-pass filter and passes only forces in a frequency range on the module, which movements of the module 3 stimulated by the IMU, 23 can be detected metrologically.

Instead of an arrangement of the spring / damping elements 29 at the vertices of a virtual cube, these may also be arranged at the vertices of other regular bodies, for example at the vertices of a regular virtual tetrahedron.

Unlike the in 2 show instruments with a two-stage mechanical decoupling, have the in the 3 and 4 shown systems via a one-stage mechanical decoupling.

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 6688174 B1 [0005]
• DE 102010062017 A1 [0005]

Claims (12)

Assembly system for an opto-electronic instrument in a carrier vehicle, wherein the opto-electronic instrument is connected to an inertial navigation system for detecting at least the orientation of the instrument in space, but possibly also for determining the position thereof in a coordinate system to a rigid module, which inertial navigation system is capable of resolving periodic movements up to a defined cutoff frequency, the corresponding data being linkable to the readings of the opto-electronic instrument, such as those of a laser rangefinder or a laser scanner, and the module formed by the instrument and the navigation system is connected to the structure of the carrier vehicle via spring / damping elements, characterized in that the spring / damping elements ( 24 . 26 . 29 ) in a manner known per se together with the mass of the module ( 3 ) form a mechanical low-pass filter which detects vibrations of the host vehicle that exceed the cut-off frequency of the inertial navigation system ( 23 ) are absorbed, and thus the module ( 3 ) in the room while the module ( 3 ) follows lower-frequency movements of the host vehicle and the data of the respectively changed spatial orientation of the module ( 3 ) for linking to the measured values of the instrument ( 1 . 2 ). Mounting system for an optoelectronic instrument according to claim 1, with a support platform provided on the stabilized platform, characterized in that at least that from the instrument ( 1 . 2 ) and the navigation system ( 23 ) formed module ( 3 ) with the interposition of spring / damping elements ( 24 . 26 . 29 ) is mounted on the stabilized platform, wherein the spring / damping elements ( 24 . 26 . 29 ) together with the mass of the module ( 3 ) form a known mechanical low-pass filter which oscillates the stabilized platform above the limit frequency of the inertial navigation system ( 23 ) are essentially absorbed, but low-frequency vibrations are absorbed by the module ( 3 ) transmits. Mounting system for an opto-electronic instrument in a carrier vehicle according to claim 1 or 2, characterized in that the mounting system comprises a two-stage mechanical decoupling, on the one hand, the rigid module ( 3 ) relative to the support structure by means of first damping elements ( 24 ) is mechanically decoupled so as not to deform it on the module ( 3 ), and second spring / damping elements ( 26 ) together with the mass of the module ( 3 ) and its support structure form a known mechanical low-pass filter, the vibrations of the host vehicle, which are substantially above the cutoff frequency substantially absorbs low-frequency vibrations but on the module ( 3 ) transmits. ( 2 ) Mounting system for an opto-electronic instrument according to one of the claims 1 to 3, characterized in that the cutoff frequency is about 25 Hz. Mounting system for an opto-electronic instrument according to one of the claims 1 to 4, characterized in that the module ( 3 ) is movably suspended or braced in all three coordinate directions. Mounting system for an opto-electronic instrument according to one of the claims 1 to 5, characterized in that the spring and damping elements ( 24 . 26 . 29 ) at the individual points of attack on the module ( 3 ) taking into account their position with regard to the center of gravity ( 28 ) of the module ( 3 ) are designed so that both longitudinal and torsional vibrations or deformations are largely damped. ( 4 ) Mounting system for an opto-electronic instrument according to claim 6, characterized in that the spring / damping elements ( 24 . 26 . 29 ) and on the module ( 3 ), that in relation to the focus ( 28 ) of the module ( 3 ) the sum of the moments of those forces acting on the module ( 3 ) are substantially zero. ( 4 ) Mounting system for an opto-electronic instrument according to one of the claims 1 to 5, characterized in that the spring and damping elements ( 24 . 26 . 29 ) at the individual points of attack on the module ( 3 ) taking into account their position with regard to the center of gravity ( 28 ) of the module ( 3 ) are designed so that torsional vibrations are largely damped. ( 3 ) Mounting system for an opto-electronic instrument according to claim 8, characterized in that the spring / damping elements ( 24 . 26 . 27 ) and on the module ( 3 ), that in relation to the focus ( 28 ) of the module ( 3 ) the sum of the moments of those force components that are on the module ( 3 ) are transferable and normal to the optical axis ( 7 ) of the opto-electronic instrument ( 1 . 2 ) is substantially zero. ( 3 ) Mounting system for an opto-electronic instrument according to one of the preceding claims, characterized in that on the module ( 3 ) Fittings for the rigid attachment of Video- ( 18 ) and / or photo cameras ( 17 ) and / or of navigation systems or their sensors and optionally provided by compensation masses. Opto-electronic instrument with a mounting system according to one of the preceding claims, characterized in that the instrument ( 1 . 2 ) a platform ( 27 ) or the like, which is rigidly connectable to the structure of the carrier vehicle and that spring / damping elements ( 26 ) between the module ( 3 ) and the platform ( 27 ) are provided. ( 2 ) Opto-electronic instrument according to claim 11, characterized in that the housing of the module ( 3 ) a flange ( 25 ) od. Like. And between this flange ( 25 ) and the platform ( 27 ) Spring / damping elements ( 26 ) and the focus ( 28 ) of the module ( 3 ) substantially in the plane of the flange ( 25 ) lies. ( 2 )

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