DE102006051090B4 - Method and device for position and position determination of an object using electromagnetic waves - Google Patents

Abstract

Method for determining the position and position of an object using electromagnetic waves which are emitted by a transmitter known with respect to its spatial position and are collected by detectors arranged on the object of a receiver having different, defined directional characteristics, assuming negligible reflections from the surroundings the direction of the object located in the far field region of the transmitter (S) with respect to the transmitter is obtained from the ratio of the reception levels of the received signals (A_SA, A_SB) of the detectors (ASA, ASB) whose measurement planes (A, B) are pairwise cut obtusely or at right angles, that also assuming negligible reflections from the environment, the distance of the object to the transmitter from the power received in the detectors is determined, taking advantage of the fact that the intensities of the received signals (A_SA, A_SB) to inversely proportional to the square of the distance, and that the detectors of the receiver (E) linearly evaluate the energy of the incident electromagnetic wave and have in their relative sensitivity a directional characteristic which is substantially proportional to the cosine of the angle of incidence (α, β) of the electromagnetic wave is characterized in that a transmitter (S) emits three mutually rotated by 60 ° against each other linearly polarized electromagnetic waves and that the detectors of the receiver are adapted to receive the respective emitted electromagnetic waves.

Description

The invention relates to a method for position and position determination of an object using electromagnetic waves which are emitted by a transmitter and are collected by detectors arranged on the object of a receiver with different, defined directional characteristics.

The invention also relates to a device for carrying out the method.

Methods and systems which use electromagnetic waves to position and position an object in the form of light or radio waves are known in many ways. Usually, runtime and / or phase differences of a signal are utilized here. Other known methods and systems evaluate the position of one or more active or passive markers in a video image.

Also known from navigation technology are radio direction finders. These consist of a radio receiver with a directional antenna for determining and indicating the direction to a transmitter. In the case of the cross-frame or goniometer direction finder, the field of the incident wave is split into two components by two crossed loop antennas and transmitted to a goniometer via two high-frequency lines. H. a cheep coil arrangement with a rotatable search coil connected to the receiver.

With the two-channel direction finder (Watson Watt direction finder), the two output voltages of a cross frame or Adcock are amplified in separate receiving channels and fed to the x- and y-deflection of an oscilloscope, on whose screen the luminous line directly indicates the bearing direction. For side determination, the amplified in a third channel voltage of an auxiliary antenna is used.

To determine the position of the self-bearing in the navigation technology, the directions determined by radio bearings (stand lines) are measured to two transmitters by a Bordpeiler with respect to the vehicle longitudinal axis. In order to find the geographical location, the angle of the vehicle longitudinal axis with respect to north with the aid of the compass must be added analogously to the angles of the two Peil-lines.

WO 88/09515 A1 describes a locating method for locating unknown receiving or transmitter positions. In this case, electromagnetic low-frequency signals of a stationary transmitting device are used.

DE 38 25 661 A1 describes a direction finding antenna with directional antennas, which are arranged in four quadrants. By amplitude comparison, the direction of arrival of the received signal is determined.

DE 201 14 245 U1 describes a mobile navigation system for a cellular radio network, wherein the distance to the transmitter is determined from the power or field strength received by the receiving antenna. The radio characteristic of the base station is taken into account during the distance determination.

US 4,346,384 A describes a method for position and attitude determination of an object using electromagnetic waves. These are emitted by a station known with respect to its spatial position and are received by detectors located on the object. These have different directional characteristics.

US 1,839,290 A describes a device for determining the direction of radio waves.

US 6,377,041 B1 describes an apparatus and method for measuring electromagnetic field characteristics.

Object of the present invention is to provide a method and a device with which, especially in small-scale workspaces position and orientation of an object to be determined with a simple and inexpensive sensor array, wherein in the frequency range of electromagnetic waves of visible or infrared light, but also can be worked in the frequency range of radio waves.

According to the invention, which relates to a method of the type mentioned, this object is achieved in that the direction of the object with respect to the transmitter, whose spatial position is known, is obtained from the ratio of the reception levels of the detectors whose measurement planes intersect in pairs at an obtuse angle or at right angles, and that the distance of the object to the transmitter is determined from the power received in the detectors.

The electromagnetic waves can be unambiguously assigned by several spatially distributed transmitters. The transmitters can be operated for differentiation in time, frequency or code multiplex.

The method according to the present invention preferably works with light waves, but can equivalently also be operated with radio waves, and determined by means of reception detectors with defined directivity by the ratio of receive levels the direction and by determining the received power the distance to one or more transmitters.

In principle, the measuring principle on which the method according to the present invention is based can be used in a wide variety of configurations - depending on which degrees of freedom are determined and how many objects are to be located. Common to all configurations is that they have one or more transmitters which emit an electromagnetic wave and a reception configuration specially adapted to the number and type of degrees of freedom to be determined, which captures this wave and supplies it to processing.

To determine the angle of rotation of the receiver about the imaginary axis passing between a transmitter and the receiver, multiple transmitters may be used at different spatial positions. In the time, frequency or code multiplex then the respective angle to the transmitters are determined and from this the instantaneous angle of rotation is calculated.

Advantageously, polarized electromagnetic waves may also be used for detection to determine the angle of rotation of the receiver about the imaginary axis passing between a transmitter and the receiver. In an embodiment not according to the invention, the electromagnetic waves radiated by the transmitter can be uniaxially linearly polarized and received at the receiver by means of a detector tuple in which the planes of polarization are rotated by 90 ° relative to one another and perpendicular to the imaginary connection axis between the transmitter and receiver Level is arranged. From the diagram of the detector tuple output signal with respect to the angle of rotation about the connecting axis transmitter-receiver, the instantaneous angle of rotation is then unambiguously determined in a rotation range of 90 ° in each case.

In a further embodiment not according to the invention, the electromagnetic waves emitted by the transmitter in the multiplex can likewise be linearly polarized in two polarization planes rotated by 90 ° relative to one another and received at the receiver by means of a single detector. In this case, from the diagram of the uniaxially measuring single detector output signal with respect to the angle of rotation about the connecting axis of the transceiver, the instantaneous angle of rotation in a rotation range of 90 ° in each case is uniquely determined. Embodiments in which the electromagnetic waves radiated by the transmitter are linearly polarized in two polarization planes rotated by 90 ° relative to one another are not the subject of the present invention.

A variant of the uniqueness range not variant according to the invention for determining the angle of rotation of the receiver to the imaginary axis extending between a transmitter and the receiver using polarized electromagnetic waves for detection is that the electromagnetic waves emitted by the transmitter are uniaxially linearly polarized and at the receiver by means of a detector triplet are received, in which the polarization planes are rotated by 60 ° from each other and which is arranged on a perpendicular to the imaginary axis connecting the transmitter-receiver plane. From the diagram of the detector triplet output signal with respect to the angle of rotation about the imaginary connecting axis transmitter-receiver, the instantaneous angle of rotation is then unambiguously determined in a range of rotation of 180 °.

According to the invention, the electromagnetic waves radiated by the transmitter in the multiplex can also be linearly polarized in three polarization planes rotated by 60 ° relative to one another and received at the receiver by means of a single-axis measuring single detector. In this case, from the diagram of the single detector output signal with respect to the angle of rotation about the connecting axis transmitter-receiver, the instantaneous angle of rotation in a range of rotation of 180 ° in each case is determined unambiguously.

In principle, several objects can also be localized with the method operating according to the invention in that each object to be located carries its own receiving arrangement. For the sake of simplicity, the description of the localization of a single object is assumed in the further course of the description.

An advantageous device for carrying out the method is characterized in that one transmitter or a plurality of spatially distributed, operated for differentiation in time, frequency or code multiplex transmitter are provided, each having an unpolarized or a linearly polarized in one direction electromagnetic wave or in the time, frequency or code multiplex three radiated by 60 ° against each other, radiate linearly polarized electromagnetic waves that arranged on the object receiver arranged in up to six different spatial directions, each on, above or below a measuring plane lying single detectors, Detektortupel or detector triples always having at least two measurement levels in pairs in dull or optimally intersecting at right angles, and that a single detector is made unpolarized or polarized, detector tuples have polarization planes of relative sensitivity rotated 90 degrees against each other, and detector triples rotated 60 degrees against each other of relative sensitivity polarization planes.

An advantageous application of the invention is in particular in robotics, but also in other devices, devices and instruments whose instantaneous, but also continuous accurate local position and orientation is to be determined by means of simple sensor technology in a workspace. For example, there is another expedient application of the invention for determining the position of a head-mounted display, but also as an operating element for personal computers or game consoles, the invention can be used advantageously.

Advantageous developments and refinements of the method according to the present invention are specified in claims 1 and 16 directly or indirectly back referring claims.

The invention is explained below with reference to drawings in detail. Show it:

1 to 3 Transmitter or receiver with different polarization directions,

4 the example of a directional characteristic of the detectors,

5 the example of a detector arrangement in two measurement planes intersecting at 90 °,

6 for the detector arrangement according to 5 a diagram showing the intensity profile of the two detector signals as a function of the angle of incidence of the electromagnetic wave,

7 a schematic view of an arrangement with transmitter and receiver to illustrate the rotation about the imaginary connection axis transmitter-receiver,

8th in a diagram, the course of the detector output signals in a non-inventive biaxial polarized system for determining the angle of rotation about the connection axis transmitter-receiver in an arrangement accordingly 7 , and

9 in a diagram, the course of the detector output signals in a triaxial polarized system for determining the angle of rotation about the connection axis transmitter-receiver in an arrangement accordingly 7 ,

The method according to the present invention may be performed in an overall system comprising a single transmitter or multiple transmitters spatially distributed. Basically, a transmitter can emit an unpolarized electromagnetic wave. But he can also, like 1 shows radiating a linearly polarized in one direction electromagnetic wave. It is also possible that the transmitter in the time, frequency or code multiplex either two by 90 ° against each other twisted linearly polarized electromagnetic waves with the planes of polarization X and Y emits, such as 2 shows. These embodiments are not part of the invention. According to the invention, the transmitter emits three linearly polarized electromagnetic waves rotated by 60 ° with respect to one another with the planes of polarization U, V and W, such as 3 shows. The receiver of the system located on the object must be polarized in order to receive the electromagnetic waves radiated by the transmitter.

The directional characteristic of the transmitter / the transmitter can be spherical or - if the receiver can only be in a defined area - be addressed accordingly.

If several transmitters are used in the system, they are also operated in the time, frequency or code multiplex to distinguish them.

In principle, three transmitters arranged on three sides of an imaginary cube or cuboid are sufficient for the determination of all six degrees of freedom of an object with a suitable design of the transmitter. Nevertheless, to increase the accuracy of measurement or to avoid occlusion even more suitably arranged in space transmitters can be used.

A receiver consists of individual detectors, detector tuples or detector triplets arranged in up to six different spatial directions, each on, above or below a measuring plane. At least two measuring levels must always be cut in pairs in blunt or optimally right angles.

A single detector linearly evaluates the energy of the incident electromagnetic wave and has in its sensitivity a directivity optimally proportional to the cosine of the angle of incidence of the electromagnetic wave. An exemplary directional characteristic, ie the relative sensitivity of a single detector as a function of the angle of incidence of the shaft, shows 4 , A single detector can be designed unpolarized or polarized evaluating. Linearly polarized detector tuples have two mutually rotated by 90 ° polarization planes of sensitivity and linearly polarized detector triples three by 60 ° against each other twisted polarization levels of sensitivity.

The measuring principle underlying the method according to the invention is described below.

Be as in 5 is shown, at the receiver E two of the above-described uniform-area single detectors A _SA and A _{SB arranged} without polarization on two planes A and B of a cube Q, which are at right angles (90 °) to each other and of which in 5 only the side lines are shown because of the cut cube view, and these are irradiated by a suitable transmitter S (assuming approximately that the distance of the receiver E to the transmitter S is far in comparison to the dimensions of the receiver E, so that from plane Wavefronts can be assumed and reflections in the environment are negligible), so deliver them in 6 represented signals A_SA and A_SB, which behave on the one hand in their intensities inversely proportional to the square of the distance and, on the other hand, due to the directional characteristic with the angle α or β, under which the respective detector A _SA and A _SB to the remote transmitter stands, change. A _EA and A _EB are the parts of the wavefront coming from the transmitter S that arise on the surfaces of the detectors A _SA and A _SE , which coincide with respect to their surface area.

With a suitable function - in the previous example the arctangent (adjusted for non-optimal detector characteristic) - the angle to the transmitter S can be determined. The distance of the receiver E to the transmitter S is inversely proportional to the square of the distance and can easily be determined by the radiation intensity of the transmitter S and the sensitivity of the detector at the receiver E.

Twisting the hatched square, so the cube Q, in the example shown by 5 by more than α = 90 ° in the plane of the drawing with respect to the transmitter S, only one detector, namely the detector A, is illuminated and the angle to the transmitter. S can no longer be determined. This can be circumvented by the fact that - depending on which range of motion is to be detectable - at three or all four sides of the cube Q in 5 representing square detectors.

In order to allow a determination of the rotation in two axes, further detectors must be arranged, whose measurement planes are perpendicular to the previously specified measurement levels. At a twist by two. To be able to completely determine axes, at least six detectors must be mounted on the sides of a cube or cuboid. If only restricted angles are of interest, then corresponding sides of - also oblique - cuboid sections can serve as measurement planes, such as, for example, As well as three-sided pyramids with 90 ° angles between the sides or prisms with triangular-rectangular cross-section.

Recalling 7 However, it should be noted that the previously discussed systems do not allow a determination of the angle of rotation δ to the imaginary axis R extending from the receiver E to the transmitter S. Here one can either help by using several transmitters in different positions and determining the respective angles to the transmitters by using time, frequency or code multiplexing or by using polarized electromagnetic waves for the detection.

In the last-mentioned case results in a uniaxially polarized waves emitting transmitter S and a receiver E with Detektortupel whose two polarization planes are rotated by 90 ° from each other and which is disposed on a plane perpendicular to the imaginary axis R between the transmitter S and receiver E level , an intensity profile of the two relevant for the polarization planes X and Y detector output signals with respect to the twist angle δ about the imaginary axis connecting transmitter-receiver R, as shown in the diagram of 8th is shown.

An equivalent output signal results when the transmitter S is multiplexed in two polarization axes and measured in the receiver E with a uniaxially polarized single detector.

It is easy to see that a clear determination of the twist angle δ is possible only in a range of 90 °. Such an application of the measuring principle is therefore primarily suitable for applications in which the range of rotation is limited or do not disturb the ambiguities that arise.

To reduce such ambiguities can be transferred to a triaxial polarized system, either via a uniaxially polarized transmitter S and a receiving side detector triples in which the polarization devices are rotated by 60 ° to each other, or with a triaxial polarized multiplexed transmitter S and a uniaxial polarized measuring detector is being worked in the receiver E.

A course of the intensities of the three relevant for the polarization planes U, V and W detector output signals with respect to the twist angle δ about the imaginary axis connecting transmitter-receiver R is in the diagram of 9 represented.

The position in the range of 180 ° can be determined unambiguously from the intensity distribution of the three detector values. In order to extend the measuring range to a clear 360 °, if the starting range is known and the angle change is slow in relation to the measuring speed, tracking of the angle of rotation is also possible via the repeat position at 180 °.

LIST OF REFERENCE NUMBERS

A, B

measuring levels

A _SA , A _SB

detectors

A _EA , A _EB

Wavefront shares

A_SA, A_SB

signal intensities

e

receiver

Q

cube

R

Imaginary connection axis transmitter-receiver

S

transmitter

AND MANY MORE

polarization planes

X, Y

polarization planes

α, β

angle of incidence

δ

twist angle

Claims (17)

Method for determining the position and position of an object using electromagnetic waves which are emitted by a transmitter known with respect to its spatial position and are collected by detectors arranged on the object of a receiver having different, defined directional characteristics, assuming negligible reflections from the surroundings the direction of the object located in the far field region of the transmitter (S) with respect to the transmitter is obtained from the ratio of the reception levels of the received signals (A_SA, A_SB) of the detectors (A _SA , A _SB ) whose measurement planes (A, B) intersecting in pairs at an obtuse angle or at a right angle so that, assuming negligible reflections from the environment, the distance of the object to the transmitter is determined from the power received in the detectors, taking advantage of the fact that the intensities of the received signals (A_SA, A_SB ) inversely proportional to the square of the distance, and that the detectors of the receiver (E) linearly evaluate the energy of the incident electromagnetic wave and have in their relative sensitivity a directional characteristic which is substantially proportional to the cosine of the angle of incidence (α, β) of the electromagnetic Wave is characterized in that a transmitter (S) emits three mutually rotated by 60 ° against each other linearly polarized electromagnetic waves and that the detectors of the receiver are adapted to receive the respective emitted electromagnetic waves. A method according to claim 1, characterized in that electromagnetic waves are radiated unambiguously attributable to a plurality of spatially distributed transmitters. A method according to claim 2, characterized in that electromagnetic waves are emitted from three transmitters arranged on three sides of an imaginary cube. A method according to claim 2 or 3, characterized in that the transmitters are operated for differentiation in the time, frequency or code division. Method according to one of the preceding claims, characterized in that the radiation characteristic of the transmitter (S) or the transmitter is spherical. Method according to one of claims 1 to 4, characterized in that the radiation characteristic of the transmitter (S) or the transmitter is directed, if the / the receiver (E) in a delimited area / s. Method according to one of the preceding claims, characterized in that for determining the twist angle (δ) of the receiver (E) around the imaginary axis (R) extending between a transmitter (S) and the receiver, a plurality of transmitters are used at different spatial positions and in the Time, frequency or code division, the respective angle to the transmitters are determined and from this the angle of rotation is calculated. Method according to one of Claims 1 to 6, characterized in that for the determination of the angle of rotation (δ) of the receiver (E) about the axis (R) polarized between a transmitter (S) and the receiver, polarized electromagnetic waves are used for the detection, wherein the electromagnetic waves emitted by the transmitter in the multiplex are linearly polarized in three polarization planes (U, V, W) rotated by 60 ° and received at the receiver by means of a uniaxially measuring single detector, and that from the diagram of FIG Single detector output signal compared to the angle of rotation about the imaginary axis connecting transmitter-receiver of the instantaneous angle of rotation is determined uniquely in a range of rotation of 180 °. Method according to one of the preceding claims, characterized in that the electromagnetic waves are in the frequency range of the visible or infrared light. Method according to one of claims 1 to 8, characterized in that the electromagnetic waves are in the frequency range of radio waves. Device for carrying out the method according to one of the preceding claims, characterized in that a transmitter (S) or a plurality of spatially distributed, operated for differentiation in the time, frequency or code multiplex transmitter are provided, each unpolarized or one in one direction linearly polarized electromagnetic wave or in time, frequency or code multiplex three by 60 ° against each other twisted, linearly polarized electromagnetic waves radiate that arranged on the object receiver (E) arranged in up to six different spatial directions, each on, above or below single detectors (A _SA , A _SB ), detector tuples or detector triplets lying at the measuring plane, where at least two measurement planes (A, B) intersect in pairs in blunt or optimally at right angles, and in that a single detector is made unpolarized or polarized, detector tuple twist 90 ° against each other The polarization planes of the relative sensitivity and the detector triples each have mutually rotated polarization planes of relative sensitivity at 60 °. Device according to claim 11, characterized in that the measurement planes (A, B) of the detectors (A _SA , A _SB ) are planes of a cuboid, cube (Q), prism, pyramid or similar body. Device according to claim 11 or 12, characterized in that in the case of the use of light waves in the visible or infrared range, the detectors (A _SA , A _SB ) are opto-electronic photodetectors. Use of a device according to one of claims 11 to 13 in robot technology for determining the position and orientation of an object in space. Use of a device according to one of claims 11 to 13 for determining the position of a head-mounted display. Use of a device according to one of Claims 11 to 13 as a control element for personal computers. Use of a device according to one of claims 11 to 13 as an operating element for game consoles.

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