DE102004051565B4 - Optoelectronic arrangement for detecting relative movements or relative positions of two objects as well as force and / or moment sensor, pan / zoom sensor and PC keyboard with such an arrangement - Google Patents

Abstract

Optoelectronic arrangement for detecting relative movements or relative positions of two objects, which comprises at least one one-dimensional position-sensitive detector, the position-sensitive detector being illuminated by at least two light emission devices in order to form at least two measuring cells with a common detector, each of the measuring cells formed by a common detector has a slit diaphragm arranged in the beam path of the corresponding light-emitting device between said light-emitting device and the position-sensitive detector, the position-sensitive detector being functionally connected to two adjacent slit diaphragms, the two adjacent slit diaphragms enclosing an angle together and each having slots arranged perpendicular to one another, the one-dimensional position sensitive detector at 45 ° to each through the slots of the two adjacent S The resulting light planes are twisted, and each of the two adjacent slit diaphragms is arranged in the direction of the light emission device belonging to the adjacent slit diaphragm.

Description

BACKGROUND OF THE INVENTION

The invention relates to an optoelectronic arrangement for detecting relative movements or relative positions of two objects, which arrangement comprises at least one position-sensitive detector, wherein each position-sensitive detector is illuminated by a light-emitting device in order to form a measuring cell. Furthermore, the invention relates to a force and / or torque sensor, which makes use of such an arrangement. Finally, the invention relates to a PC keyboard having the force and / or torque sensor according to the invention.

For the computer user, it is becoming increasingly important to control three-dimensional movements through a peripheral device. In this case, a three-dimensional deflection is detected by the peripheral device and described as translation (X, Y, Z) and / or as rotation (A, B, C) in space. The most important component is the sensor, which can measure the deflection in up to six (6) degrees of freedom.

STATE OF THE ART

DE 36 11 337 A1 discloses an optoelectronic assembly housed in a plastic sphere that can simultaneously detect six components, namely translations along three axes and angular rotations about three axes. For this purpose, six light emitting devices are arranged at substantially equal angular intervals to each other in a plane. Each light emitting device is preceded by a fixed slit diaphragm. The relative or relative positions are taken by photosensitive detectors which are movably arranged relative to the array of light emitting devices and slit diaphragms and whose detector axis is perpendicular to the slit direction. The arrangement requires relatively little design effort, since the light-emitting devices and diaphragms, and possibly other electronic devices for driving and evaluating with conventional soldering can be arranged on a single board, which can be firmly connected to a first object. The position sensitive detectors are connected to the second object. The disadvantage, however, is that the arrangement requires a relatively large area. The reason is the relatively large spatial extent of the diaphragms and detectors, which are arranged in a ring around the light emitting devices. As a result, a miniaturization of the arrangement limits set.

The DE 43 08 456 C2 shows a device for determining the position of a position body with projectors that illuminate a common scale in the form of a CCD line. The device detects the distances between the illuminated by the projectors of the scale.

The US 2001/0038380 A1 relates to a joystick with optical position sensors. This includes at least one linear position detecting diode disposed on a stator or "floater" and a plurality of projectors producing plane light beams. For this purpose, two precision masks are used in a diode holder.

Other documents without claim of completeness, which show the technical background of the invention, are: DE 27 27 704 C3 . DE 36 11 336 C2 . US 3,921,445 A . US Pat. No. 3,628,394 . US 4,999,483 A and DE 101 58 776 A1 ,

THE PROBLEM CONSTITUTING THE INVENTION

Optoelectronic arrangements for measuring relative movements or relative positions, as well as force and / or moment sensors, which use such arrangements, have gained importance in the past, especially in industrial applications. Examples include controlling robots and measuring forces on vehicle test benches. The arrangements and sensors offer in principle, however, in the office sector and in consumer electronics commercially very interesting applications. Here you have the function of an input device, with which up to six components can be entered, in contrast to a joystick, a mouse or a trackball, which generally allow the input of only two components. A simple and convenient input of six components, as permitted by a force and / or moment sensor with an opto-electronic device, is desirable, for example, for controlling 3D design software and demanding computer games. However, the previous input devices are extremely cumbersome due to their surface / volume requirements, which was substantially contrary to wider dissemination. A miniaturization would the installation z. As in game consoles, PC keyboards or notebook computers, and thereby enable a broad market penetration.

The typical 3D input devices are used for manipulating the views of three-dimensional objects in 6 degrees of freedom (6DOF = 3 translations and 3 rotations). The cap or the ball of the 3D input device is spring-mounted and allows any deflection in space (6DOF). This group of input devices are aimed at customers with real 3D applications (6DOF), such as: Catia or other CAD applications.

In addition to the true 6DOF applications, there is also a large group of applications in which an object is not desired to rotate. Examples of such applications are the Office products (Word, Excel, Powerpoint, etc.) and image processing programs (Adobe Photoshop, Acrobat Reader, etc.). The manipulated object is usually a two-dimensional template ("labeled and / or painted paper"), in which a rotation of the template is not wanted. The customer's desire to change the view remains, but it is limited to moving (Pan - 2 DOF) and zooming in / out (Zoom - 1 DOF) of the object.

The aim of a development for this customer group is the construction of an input device, which is especially suitable for Pan / Zoom applications. This would save you the costly overhead of a full 3D sensor (6DOF), ignoring the three rotatory movements.

Starting from the prior art, the present invention is therefore based on the object to provide an arrangement for detecting relative movements or relative positions of two objects, which provides a manoeuvrable design compared to the known arrangements. For example, the design of the assembly could be more efficient and / or more flexible or have a smaller footprint. Furthermore, the design of the assembly could be cheaper and / or more suitable for pan / zoom applications.

In addition, the invention has for its object to provide a force and / or torque sensor, which also allows a more elegant compared to the known sensors design. Finally, the invention has for its object to provide an input device for use in the office, which allows an uncomplicated input of up to six force or torque components.

INVENTION SOLUTION

To achieve this object, the invention teaches an optoelectronic device for detecting relative movements or relative positions of two objects, which is defined by the features of claim 1. The invention further teaches a force and / or torque sensor, which is defined by the features of claim 9. Preferably, the force sensor serves as a pan / zoom sensor for image processing and other similar office applications. Finally, it also teaches a personal computer keyboard, which is defined by the features of claim 20.

CONSTRUCTION AND TRAINING OF THE INVENTION SOLUTION

An optoelectronic arrangement for detecting relative movements or relative positions of two objects according to a form of the invention comprises at least one position-sensitive detector and is characterized in that the position-sensitive detector is illuminated by at least two light-emitting devices in order to form two measuring cells with a common detector.

According to the invention, each of the two measuring cells formed by a common detector has a slit diaphragm arranged in the beam path of the corresponding light emitting device between said light emitting device and the position sensitive detector. Each position sensitive detector is associated with two adjacent slit diaphragms.

In this case, a slot direction of at least one of the slit diaphragms can be aligned obliquely with respect to the photosensitive part of the detector. In a preferred embodiment of the optoelectronic device, a plane of light radiating through at least one of the slit diaphragms and incident on the detector forms an angle with a plane of a photosensitive part of the detector.

In this case, it is preferred that each detector is illuminated alternately (eg periodically) by a light emission device, wherein a measured value of the detector is read out at the same time. In other In other words, the detector of each measuring cell is illuminated by a light-emitting device at a specific time only, with the measured value of the detector being read out at the same time.

In a preferred embodiment of the optoelectronic device, the light plane forms an angle with a plane of the photosensitive part of the detector. Preferably, a slot direction of one of the slit diaphragms is substantially perpendicular to the photosensitive part of the detector.

In the embodiment of this optoelectronic device according to the invention, the position-sensitive detector is associated with two adjacent slit diaphragms, the position-sensitive detector serving as part of two different measuring cells. Preferably, each slit is illuminated by its own light emitting device so that each position sensitive detector is illuminated by two light emitting devices to form two measuring cells with a common detector.

In a particularly preferred construction, each of the two adjacent slit diaphragms is illuminated by a respectively arranged light emitting device. The two adjacent slit diaphragms together enclose an angle and according to the invention each have mutually perpendicular slits.

The optoelectronic arrangement may further be characterized in that the measuring cells are arranged in groups.

In a preferred embodiment of the optoelectronic device of the invention, one element of each measuring cell consisting of light emitting device, slit diaphragm and detector is movable relative to the other two elements. The movable element is preferably arranged in the center of rotation of the measuring cell, so that the measuring cell can detect mainly only (that is to say exclusively) translatory movements. Therefore, this measuring cell can basically detect any rotational movements. Rotations can only be detected when the moving element is at a distance from the center of rotation. If this distance from the center of rotation is zero or minimal, the measuring cell is "blind" or "almost blind" for the rotational movement.

In a preferred embodiment of the optoelectronic device of the invention, the device comprises at least three measuring cells, preferably from three to six measuring cells or even more than six measuring cells.

In a preferred embodiment of the optoelectronic device of the invention, at least one measuring cell comprising light emitting device, slit diaphragm and detector is provided with a movable light emitting device, this measuring cell having a larger working range or range of motion.

In one possible development of the invention, all light emitting devices, preferably infrared light emitting diodes (ILEDs), and position sensitive detectors, preferably position sensitive infrared detectors, are arranged in a common (first) plane.

According to another aspect of the invention, a force and / or torque sensor is provided, which is characterized by an optoelectronic arrangement according to the invention for detecting relative movements or relative positions of two objects. The two objects are preferably made of a first plate and a second plate, wherein the first plate and the second plate are elastically connected to each other and movable relative to each other.

The 3D input devices according to the invention can be equated with a force and / or torque sensor. The translational movements (X, Y, Z) correspond to the forces (F _x , F _y , F _z ) and the rotational movements (A, B, C) correspond to the moments (M _x , M _y , M _z ). A pan / zoom sensor corresponds to a force sensor (F _x , F _y , F _z ), since the pan / zoom sensor can only detect translational movements (X, Y, Z).

Further preferred embodiments of the invention are disclosed in the independent claims and in the following description of exemplary embodiments.

BRIEF DESCRIPTION OF THE DRAWINGS

In the following figures, embodiments are shown, wherein functionally identical or functionally similar components are identified by the same reference numerals. It shows:

1 a measuring cell consisting of an LED (Light Emitting Diode, LED), a diaphragm and a PSD (Position Sensitivity Detector);

2 the parameters of a measuring cell according to 1 ;

3 the considerations of the cut surface and the idealized point of intersection;

4 a graphical representation for calculating a translational movement of the diaphragm;

5a - 5c possible changes to the parameters of the measuring cell without functional influence; 6a . 6b a measuring cell of an optoelectronic device with a rotation of the diaphragm around the vector LEDdir;

7 an optoelectronic device with six measuring cells according to the 6a and 6b ;

8th a measuring cell of an optoelectronic device with a rotation of the aperture around the vector IRISdir;

9 an optoelectronic device with six measuring cells according to the 8th ;

10 an optoelectronic arrangement with three measuring cells, each corresponding to three Cartesian axes;

11a - 11c the construction of measuring cells of an optoelectronic device, wherein a plurality of measuring cells are combined, ie the measuring cells have a common position-sensitive detector;

12a . 12b a variation of the optoelectronic device according to the 11c ;

13a . 13b the construction of an opto-electronic device, which is suitable for measuring six degrees of freedom;

14a - 14c the construction of yet another optoelectronic device, which is suitable for measuring six degrees of freedom;

15 an opto-electronic device consisting of three pairs of parallel measuring cells;

16a - 16c a pair of adjacent apertures for an opto-electronic device according to the invention;

17a an optoelectronic device according to the invention, which consists of three pairs of measuring cells combined with each other, which form the diaphragms according to FIGS 16a - 16c exhibit;

17b the optoelectronic device according to the 17a in which each LED is activated alternately (eg periodically);

18 a graphical representation of the elements of a measuring cell;

19 a graphical representation for calculating a translational movement of the optical element (LED);

20 a graphical representation for calculating a translational movement of the diaphragm;

21 a graphical representation for calculating a translational movement of the position sensitive detector (PSD);

22 another opto-electronic device consisting of three measuring cells in the same plane;

DETAILED DESCRIPTION

Optical sensor

Sensors for detecting the three-dimensional deflection have been constructed by optical elements. In this case, the arrangement of an LED (Light Emittent Diode, LED), a diaphragm and a PSD (Position Sensitivity Detector) has proven itself as a measuring cell of a total sensor. In the 1 a single measuring cell is shown.

An LED emits a cone of light that strikes a slit and the light plane remaining behind the panel intersects with a one-dimensional PSD. The intersection of the light plane with the PSD can be described by a scalar factor λ. It indicates the signed distance of the point of intersection on the PSD from the rest position (starting position). Later, the factor λ is understood as the detected voltage of the PSD. The arrangement of the three optical elements to form a measuring cell results in an important property. The measuring cell detects certain movements (X, Y, Z, A, B or C) and at the same time can not measure other movements. Thus, each individual measuring cell can be considered as a sensor for certain movements. The sum of all detected movements gives the measuring space of the entire sensor.

Parameters of a measuring cell

For the exact description of the measuring cell, the position of the LED, the aperture and the PSD is required. The position of the LED indicates the source of the generated light. The aperture and the PSD use the center of the optical element. Although this is not urgently required, it makes the further calculation clearer and causes the scalar factor in the rest position to have the value λ = 0. In addition, the direction of the slot in the aperture is needed, as well as the direction of the position sensitive area of the PSD. 2 shows the necessary positions and directions that describe the measuring cell. LED Position of the LED. IRISpos Position of the diaphragm (midpoint), IRISdir Direction of the slot in the aperture, PSDpos Position of the PSD (center), PSDdir Direction of the photosensitive Part of the PSD Parameters of the measuring cell

When defining the parameters, some assumptions apply. The light cone of the LED sheds its light on the screen and the resulting light plane intersects with the PSD throughout the working area.

For later considerations, it is useful to define the viewing direction of the LED. It results from the LED position and the aperture position, as well as the LED position and the PSD position. It is assumed that the three points (LED, IRISpos and PSDpos) are arranged so that they are on a straight line.

The vector of viewing direction LEDdir is normalized to length 1. The normalization to length 1 also applies to the direction of the slit and to the direction of the photosensitive area of the PSD.

The thickness of the slit and the position sensitive area are considered to be ideally thin. Crossing the light plane with the PSD ideally results in an intersection and no intersection. The size λ indicates the distance of the point of intersection from the rest length. There are positive values for the Size λ when the intersection moves from the rest position toward PSDdir and negative values for the opposite displacement. Of course, the determination of the size λ can be made differently as desired and the rest position does not necessarily have to be in the center. Another specification has an influence on the calculation / working range of the individual measuring cells, but not on the basic function or the arrangement of several measuring cells.

In the 3 the considerations of the cut surface and the idealized intersection are shown.

Later, the distance of the crossing point from the rest position (size λ) by an electrical voltage U _{1 ... 6 of} the associated PSD's is specified. The greater the amount of voltage, the greater the distance of the crossing point from the rest position. The sign of the voltage indicates on which side (PSDdir) from the rest position the crossing point lies.

Calculation of the point of intersection

The measuring cell detects the relative movement of the three optical elements to each other. The size λ is determined. It is assumed that one optical element (LED, aperture or PSD) moves and the other two elements are firmly positioned. The case of moving two optical elements can be transferred to the case with a movable optical element as long as the moving elements move in the same way (rigidly coupled). There are three different scenarios:

Detected movement 1. LED movable

2. Aperture mobile

3. PSD mobile

The vector Translate indicates the displacement of the movable optical element. The Matrix Rotate describes the rotation of the moving optical element around the origin of the coordinates (eg with the angles roll, pitch, yaw). In the rest position, the vector is Translate 0 and the matrix Rotate is equal to the unit matrix.

Calculation of a translatory movement

The above equations are further resolved. The rotatory component is converted into the translational component. A rotational movement can only be detected by the measuring cell, because due to a lever, the rotation also leads to a shift. 4 shows an example in which a diaphragm is twisted. Only because of the glare distance from the center of rotation (in which the LED is located in the example) is the rotation measurable. The measuring cell thus detects the displacement X and the displacement Y. The simultaneous rotation of the diaphragm remains ineffective or negligible. The size of the rotation is low in the arrangements presented here and are limited to a few degrees. Thus, translation is the dominant factor.

The rotation is "translated" into the Translate vector and then also contains the translational motion that occurs due to the rotation of the moving part. This translational part can only occur when the moving part is not in the center of rotation. The actual rotation of the moving part is ignored. The simplification of the proportion Rotate · Translate ≈ Translate is applied.

The relative translational movement of the movable part of the measuring cell is redetermined and is thus: Translate → Rotate · <moving part> - <moving part> + Translate

Under the condition: 0 = IRISdir · (LED × PSDpos - IRISpos × PSDpos + IRISpos × LED) λ = 0 for the case of no deflection (translation = rotation = (0 0 0) ^T ). Thus, the following simplifications result for the above equations (E = unit matrix):

Changes without functional influence on the measuring cell

The above equations generally describe the construction of a measuring cell. Due to the geometric arrangement, it becomes apparent that parameters can be changed in the measuring cell without the functioning of the measuring cell changing. Certain changes to one or more parameters of the measuring cell are therefore not relevant to the actual function. This results in an additional "margin" for the arrangement of the measuring cell, which causes a changed geometric structure, but has no influence on the function of the measuring cell.

In the 5a It can be seen that the rotation of the PSD by the vector PSDdir or the turning around the vector LEDdir × PSDdir, and / or the shifting along the vector LEDdir × PSDdir does not affect as long as light still falls on the PSD. Prevents a real PSD with a rotation of z. B. 90 ° the light, of course, the functionality of the measuring cell is no longer given. All twists of the PSD until the occurrence of this situation have no functional influence on the measuring cell.

In the 5b it can be seen that the same applies to the aperture. Rotating the aperture around the vector IRISdir, and / or moving the aperture along the IRISdir vector or rotating around the vector IRISdir × LEDdir will not affect the measuring cell as long as light can shine through the aperture of the aperture.

In the 5c it is shown that the LED around the vector LEDdir can be rotated arbitrarily. Even a rotation around the perpendicular vectors or a shift along the IRISdir vector is without Functional influence on the measuring cell possible as long as the light cone of the LED covers the entire work area.

Turn the light plane around the LEDdir vector

There are other changes to the arrangement of the measuring cell that affect the functionality of the measuring cell. The usual vertical or quasi-vertical arrangement is abandoned. The rotation of the aperture around the LEDdir vector causes the light plane to strike the PSD only in one direction perpendicular or quasi-perpendicular. The 6a and 6b show such an arrangement in which the aperture has been rotated by 45 °. In the 6a you can see the rotation of the slit diaphragm to the PSD. The 6b shows how in this case the light plane falls on the PSD.

sind als Punkte der einzelnen optischen Elemente zu verstehen und die Parameter

sind die Richtungsvektoren der Messzelle, mit der Eigenschaft |IRISdir| = |PSDdir| = 1.In the 7 (Aperture movable), a complete sensor arrangement is shown in which each aperture is rotated by 45 °. Table 6a lists the parameters of all 6 cells. The details of the parameters are arranged with respect to the Cartesian coordinate system in the order x, y and z. The parameters

are to be understood as points of the individual optical elements and the parameters

are the directional vectors of the measuring cell, with the property | IRISdir | = | PSDdir | = 1.

Tabelle 6a

Table 6a

Translationsfehler 3.9%, Rotationsfehler 9.1% Tabelle 6b

Translation error 3.9%, rotation error 9.1% Table 6b

Turn the light plane around the IRISdir vector

Another change of the measuring cell is achieved by turning the light plane around the IRISdir vector. The 8th shows a corresponding arrangement in which the LED has been rotated by 45 °.

In the 9 (Aperture movable), a complete sensor arrangement is shown in which all the LEDs have been moved out of the planar arrangement and the light planes obliquely fall on the PSD's. Only with the vertically arranged PSDs, this leads to a change in the measuring cell. The horizontally arranged PSDs register no change in the measuring cell.

Tabelle 8a

Table 8a

Translationsfehler 7.3%, Rotationsfehler 5.5% Tabelle 8b

Translation error 7.3%, rotation error 5.5% Table 8b

Rules for the design of an optical 3D sensor

grouping

From the individual measuring cells, a complete 3D sensor (Pan / Zoom - 3 degrees of freedom or with 6 degrees of freedom) should be set up. The basic rule is that with N measuring cells at best an N dimensional sensor can be built up. The sensor is always seen in a Cartesian coordinate system, which corresponds to the right hand rule. The goal of subsequent group formation is to create rules with which groups of measuring cells (one or more measuring cells) can detect certain degrees of freedom in Cartesian space.

1 group

With the 1 group, a single measuring cell is arranged so that approximately only one degree of freedom is detected. The measuring cell can actually detect no rotations, only if the rotation also causes a shift (translation due to a rotation, "carousel ride"), this is measurable.

Conversely, the measuring cell can only measure one translation if the moving optical element (LED, aperture or PSD) is in or near the center of rotation of the sensor. The 10 (Moving LED) shows such an arrangement for a Pan / Zoom sensor, which can detect due to the arrangement no or almost no rotations. The measuring cell 1 can only detect movements along the Y axis. With the measuring cell 2, the movements along the X axis are determined, while the measuring cell 3 is responsible for measuring the movement along the Z axis.

Tabelle 10a

Table 10a

Translationsfehler 7.2% Tabelle 10b

Translation error 7.2% Table 10b

In the next step, the above 3D sensor (Pan / Zoom) is further changed. Instead of the LED's in the turning center, the PSD's are now positioned there. Although it would be possible to place three PSDs in the center of rotation, only a single PSD is used here. However, the only PSD is used by all three measuring cells (multiple use). Of course, this can not happen at the same time, because the PSD can only detect a crossing point of a light plane. Three crossing points at the same time result in an arithmetic Means as a result, which can not be sensibly further processed. However, it is possible to interrogate the measuring cells one after the other and to switch the LEDs on at different times (without overlapping) and to determine the crossing points on the PSD one after the other.

In the first step a group of 1 is formed. It is used to determine the movement along a major axis (here along the X axis). 11a shows the measuring cell.

motion vector

In the 11a the motion vector for this measurement line is also drawn. It indicates to which movement of the movable optical element the measuring cell can detect. All movements perpendicular to the motion vector can not be detected. The motion vector results from the vector product of IRISdir × LEDdir. It is thus independent of the orientation of the PSD (PSDdir). The orientation of the PSD is important for the working range of the measuring cell, but not for the measurable direction of movement of the measuring cell.

2er group

In a group of two, two measuring cells are combined so that each measuring line can detect up to two movements along the axes (X, Y or Z). By combining the two measuring cells, the two movements must be distinguishable. This can be read off from the respective motion vectors. The motion vectors may not be equal BEW1 ≠ BEW2, or in other words, the tetrahedron (cross product) spanned by the motion vectors should be as large in volume as possible (sufficient condition). | BEW1 × BEW2 | = MAX> 0

For the group of 2, the first measuring cell is combined with another measuring cell. The second measuring cell is attached laterally so that the light plane strikes the PSD at 45 °. It is therefore able to detect not only the movements along the X axis but also the up and down movements along the Y axis. Both measuring cells together form a 2-group, as each measuring cell can detect up to 2 degrees of freedom and the combination of the two detected movements on the individual degrees of freedom can be clearly concluded. This relationship will later be seen again in the calibration matrix of the complete sensor (Pan / Zoom). The requirements for a group of two does not require that a measuring cell only detects one direction of movement (such as the one along the X axis). A group of two would also be given if the measuring cell 1 were arranged in mirror image to the measuring cell 2. In the 12b such a compilation is shown.

The third measuring cell must now at least detect the movement along the Z axis. This could be a 1er group. However, it can no longer be used here because the already positioned PSD is positioned along the X axis. A movement in the Z axis can only be detected by a plane of rotation twisted in the X / Z plane on the PSD. This results in an arrangement of the third measuring cell where the LED is offset (eg along the Z axis) and the light plane falls onto the PSD as desired by a twisted shutter. 11c (PSD mobile) shows a possible arrangement.

Tabelle 11a

Table 11a

Translationsfehler 4.2% Tabelle 11b

Translation error 4.2% Table 11b

Table 11b shows the calibration matrix, which can be interpreted very easily due to group formation. For determining the movement along the X axis, only the first measuring cell is responsible. Only U1 is needed to determine this movement. The voltage U2 (second measuring cell) detects movement along the X axis in the same way as the first measuring cell. The difference of the voltage U2 and U1 eliminates the X movement and leaves only the Y movement, which is detected only by the second measuring cell. The third measuring cell actually represents a group of 3 because it can measure translational movements along all axes. With the help of the 2-group, which is formed with the first two measuring cell, the already known movements along the X and the Y axis can be eliminated. The factor for U1 eliminates the movement along the X axis for the 2nd and the 3rd measuring cell. The factor for U2 additionally removes the motion along the Y axis from the third measuring cell. Remaining by the calibration matrix in the third line remains the movement along the Z axis, which is measured only by the third measuring cell.

Two other variations are in the 12a and 12b shown. They were designed using the same methodology as the pan / zoom sensor in the 11c , They show how with simple changes other but equivalent or advantageous sensors can be developed.

In the 12a (PSD movable), the third measuring cell was moved along the Z axis and not along the X axis as in the sensor of 11c , In the 12b (PSD movable), the symmetrically arranged measuring cells 1 and 2 form a 2-group. However, a symmetrical arrangement is not absolutely necessary for group formation. It serves more to obtain a simpler calibration matrix and to symmetrically build up the working area of the complete sensor. The third measuring cell forms with the first group of 2 (measuring cell 1 and 2) another group of 2, since the measuring cell can not detect the movement along the Y axis.

The above examples show that a variety of arrangements yield a pan / zoom sensor. It is not crucial for the basic functionality whether the obliquely incident light plane is at 45 ° or at another angle. The angle of incidence influences the resolution and the working range of the motion to be detected. By tilting the light plane (in two degrees of freedom, rotation around the LEDdir vector and around the IRISdir vector), the measuring cell can also be used for "unfavorable" movements. In vertical or quasi-vertical light incidence these additional options are not available.

Design of 3D sensors with 6 degrees of freedom

Similar to the Pan / Zoom sensor, a 3D sensor with 6 degrees of freedom is now being set up. First the groups of 1 are set. In this example, the apertures should be the movable optical element. The apertures are positioned on the major axes to form the 1's groups. In the 13a The first three measuring cells are positioned.

The aperture of the first measuring cell is positioned on the X axis. Thus, this measuring cell can only detect movements along the X axis. It offers itself as a partner for a group of 2, because the movement along the X axis can be completely excluded from a group of two. The second measuring cell is positioned in the same way. It can only measure the movements along the Z axis. So that the third measuring cell likewise forms a group of 1, its diaphragm is placed in the coordinate origin. It can thus only detect the movements along the Y axis. With these three measuring cells, only the translatory movements are measured. Since each measuring cell is responsible for exactly one main axis, the remaining three measuring cells need only be arranged in such a way that they can detect the rotational degrees of freedom. The 13b (Aperture movable) shows a possible arrangement of all six measuring cells. By forming groups of 1, it is sufficient to detect each of the remaining rotations by only one measuring cell.

Tabelle 13a

Table 13a

In addition to the movement along the Y axis, the measuring cell 4 also detects the rotation about the Z axis (C value). The same applies to the measuring cell 5, it detects the movement along the Y axis and the rotation about the X axis (A value). The remaining rotation about the Y axis is measured by the measuring cell 6. Which can also detect the movement along the X axis. This results in the following calibration matrix.

Translationsfehler 4.9%, Rotationsfehler 13.6% Tabelle 13b

Translation error 4.9%, rotation error 13.6% Table 13b

The calibration matrix shows very clearly the chosen arrangement. For example, the movement along the X axis is determined only by the first measuring cell (voltage U1), although the measuring cell 6 can also detect the movement along the X axis. Overall, the calibration matrix is very sparse. Table 13c shows the calibration matrix in which very small values have been removed.

Tabelle 13c

Table 13c

The errors of the calibration matrix for the translation and the rotation, arise due to the applied linearization. Due to the chosen arrangement but also the exact model can be used very easily.

2er group

For the next arrangement two groups are formed immediately. The measuring cells in a group of two is arranged so that two degrees of freedom are detected by a group of two. As a result, the movable optical element no longer has to be arranged in the origin or along the main axis. 14a shows the first group of 2, which is responsible for measuring the Y and C movements. Both measuring cells can each detect the Y and the C movement. For a single measuring cell, one movement is indistinguishable from the other.

Only by combining the measuring cells (into a group of 2) can the individual movements be clearly distinguished.

By the lateral displacement of the measuring cell 2 to the measuring cell 1, although the second measuring cell can also detect rotations about the X axis (movement A). Due to the small distance to the axis, this is not very pronounced.

Another group of 2 now covers two additional degrees of freedom. It is positioned in a similar way to the first group of 2, but rotated by 90 °. In the 14b is the second group of 2 shown. It can detect the movements along the X axis, as well as the rotation about the Y axis (B movement).

A group of 2, which can detect the missing movements (Z and A), could be arranged along the Y axis. This could be done with the same arrangement as in the first two groups of two. Since this would complicate the construction, the two remaining degrees of freedom are detected separately. Each measuring cell complements the previously positioned groups of two to form a group of three. 14c (Aperture movable) shows the entire arrangement.

Tabelle 14a

Table 14a

The measuring cell 5 detects the A and the Y movement. It completes the first group of 2 (measuring cell 1 and 2 - Y / C) to a group of 3. Equivalent this happens with the measuring cell 6. It detects the movement Z and B. The second group of 2 (measuring cell 3 and 4 - X / B) we to the 3 group and can measure the movements X, B and Z.

Translationsfehler 3.5%, Rotationsfehler 6.9% Tabelle 14b

Translation error 3.5%, rotation error 6.9% Table 14b

3 group

In the 15 (Aperture movable), an arrangement is shown, which consists of two groups of 3 forms. The first group of 3 consisting of measuring cell 1, 3 and 5 measure the movements Y, A and B. The remaining movements X, Z and C are detected by the measuring cells 2, 4 and 6.

Tabelle 15a

Table 15a

Translationsfehler 3.0%, Rotationsfehler 3.0% Tabelle 15b

Translation error 3.0%, rotation error 3.0% Table 15b

Starting from the above arrangement, two measuring cells are combined according to the invention. The two LEDs throw the light on the same PSD. In other words, the PSDs of the two measuring cells are in the same place and have the same orientation. Thus, a PSD is saved from the two PSD's. The PSD is usually the most expensive optical element of the measuring cell.

The calculations are still based on two separate PSD's. The arrangement according to the invention is modified so that an adjacent LED shines on the PSD of the neighbor. So that both light levels on the PSD causes an intersection, the two PSD's are rotated. The two PSDs thus have the same orientation, which is rotated by 45 ° to both light levels. The light planes of the two Measuring cells are at right angles to each other. The aperture is the movable optical element. It is arranged in such a way that the LED of the partner measuring cell can not throw its light plane onto the PSD through the wrong slit diaphragm. The partner slotted diaphragm ("wrong slit diaphragm") is arranged so that the diaphragm is arranged in the direction of the partner LED and thus no light incidence is possible. The aperture uses the degree of freedom (see changes without functional influence on the measuring cell) on the one hand to be the correct slit for the own LED and on the other hand to stand along the direction of the partner LED and thus to shade the light. The bezel can be extended at the end to ensure that no extraneous light from an LED falls on the PSD. The 16a to 16c show a possible arrangement.

The measuring cells 1, 3, 5 and the measuring cells 2, 4, 6 each form a group of 3. With the measuring cells 1, 3, 5, the movements X, Z and C are detected. The measuring cells 2, 4, 6 are responsible for the movements Y, A and B. The 17a (Aperture mobile) shows the appropriate arrangement and in the 17b the arrangement is shown with one active LED each.

Tabelle 17a

Table 17a

Translationsfehler 10.7%, Rotationsfehler 9.5% Tabelle 17b

Translation error 10.7%, rotation error 9.5% Table 17b

An equally functioning 3D sensor can be obtained by turning all PSDs around the respective LEDdir vector with the same angle. Accordingly, the slit diaphragms must be rotated so that the light planes again fall by 45 ° (or a similar angle) twisted on the PSDs and form measurable points of intersection.

Further variations to the arrangement of measuring cells

coordinate transformation

The arrangement of the individual measuring cells takes place in a predetermined Cartesian coordinate system. However, the definition of a coordinate system can be arbitrary. The relation between two Coordinate system is described by a linear coordinate transformation. The figure ensures that the proportions remain unchanged and the relation of the elements remains the same. For a 3D sensor with 6 degrees of freedom, therefore, the used coordinate system may be arbitrarily defined in space. A 3D sensor can thus be considered equivalent if, with the aid of a linear coordinate transformation, the used coordinate system can be transferred to a coordinate system described here.

Different moving optical elements

For the operation of a measuring cell, a movable element is needed in addition to the fixed optical elements. In all previous arrangements, it is always assumed that this is of the same type (LED, aperture or PSD). Of course, measuring cells with different moving elements can be combined with each other. For example, measuring cells with movable diaphragms and movable PSDs can be arranged. The above rules for the arrangement of 3D sensors remain valid.

Shared slit diaphragm

The movement that can be detected by a measuring cell is described by the motion vector. The motion vector is calculated from the product IRISdir × LEDdir. It can be seen that with a slit diaphragm two different motion vectors can be formed if the directions of the two LEDs are different.

Signal routing via the springs

It is possible to connect the movable optical element and the two fixed optical elements via wire springs. This connection can also be used for electrical wiring of moving and fixed part of the sensor. Thus, in addition to a power supply and various control signals are performed. If the LEDs are the movable optical elements, they can be operated via the springs, for example in a matrix arrangement.

Movable LED's for extending the workspace

From the equations of "computation of a translatory motion", one more interesting feature becomes clear and experience confirms this. In a movable LED measuring cell, the working range of the movable optical element may be affected by the arrangement of the fixed optical elements.

In equation 1 (LED movable), the distance vector PSD diaphragm is in relation to the distance vector LED diaphragm. If the shutter is positioned closer to the PSD than to the LED, this increases the range of movement of the LED. In the opposite case, the range of movement of the LED is restricted. The smaller range of motion is then resolved finer.

In equation 2 (movable aperture), the distance vector LED - PSD is in the ratio of the LED aperture. After the aperture must always be in front of the PSD, the distance LED - PSD is always greater than the distance LED - aperture. With a movable panel, therefore, only a limitation of the range of motion can occur.

In Equation 3 (PSD moveable), the distance vector LED aperture is in the numerator as well as in the denominator. The range of movement of the PSD is thus always the same and corresponds to the maximum extent of the photosensitive part of the PSD

3D sensor with more than 6 measuring cells

For the construction of a 3D sensor with 6 degrees of freedom at least 6 measuring cells are necessary. Of course, more measuring cells can be used than would actually be required. This redundancy of the 3D sensor can be used to increase the accuracy of the sensor or keep the sensor in operation, even if one or more measuring cells fail. Equivalently, this also applies to a Pan / Zoom sensor.

Appendix A

example calculation

18 shows a graphical representation of the position of the elements (ie, an LED, a diaphragm and a PSD) of a measuring cell. For an exemplary arrangement, the calculation of the size λ shall be shown. In this case, the three possible variants for the movable optical element are taken into account.

1. LED movable - Figure 19

2. Aperture movable - Figure 20

3. PSD mobile - Figure 21

Appendix B

Alternative arrangement according to the 22 (LED movable).

Translationsfehler 9.8%

Translation error 9.8%

In this in 22 illustrated arrangement, only the LEDs are movable and they are located in or near the center of rotation. As a result, the measuring cells can only detect translational movements and are "blind" to rotational movements.

The sensor design is therefore only suitable for Pan / Zoom applications and not for applications with 6 degrees of freedom (6DOF). The design goal for a Pan / Zoom sensor is therefore to move the moving element into the turning center.

When it is spoken in this description that a measuring cell "mainly" or "exclusively" can detect translational movements, it is meant that the measuring cell or the sensor can measure at least to a first approximation only translational movements. Rotatory movements can also have a small influence on the measurement. This part is small and therefore negligible, but still available. The displacement and rotation of the sensor causes the individual measuring cell to leave its ideal position somewhat (eg the moving element is no longer exactly in the center of rotation) in the sensor, so that small errors occur.

This situation is treated with the following methodology:
Method for determining relative movements or relative positions of two objects in an arrangement according to the invention, which can detect translational and rotational movements or the mainly only translational movements, with the steps:
one gives the exact equations for the detected movements of the measuring cells; (see section "detected movement")
one gives a first approximation, which neglects the coupled movements between rotation and / or translation; or
For each measuring cell, the calibration matrix of the linearization and the maximum error are indicated.

LIST OF REFERENCE NUMBERS

101

LED

102

light cone

103

cover

104

light plane

105

PSD

301

light plane

302

PSD

303

section

304

intersection

401

PSD

402

cover

403

aperture spacing

404

Shift X

405

Shift Y

406

LED

1001

Measuring cell 1

1002

Measuring cell 2

1003

Measuring cell 3

1100

Measuring cell 1

1101

Motion vector 1

1102

Measuring cell 2

1103

Motion vector 2

1104

Measuring cell 3

1105

Motion vector 3

1300

Measuring cell 1

1301

Measuring cell 2

1302

Measuring cell 3

1303

Measuring cell 4

1304

Measuring cell 5

1305

Measuring cell 6

1400

Measuring cell 1

1401

Measuring cell 2

1402

Measuring cell 3

1403

Measuring cell 4

1404

Measuring cell 4

1405

Measuring cell 5

1500

Measuring cell 1

1501

Measuring cell 2

1502

Measuring cell 3

1503

Measuring cell 4

1504

Measuring cell 5

1505

Measuring cell 6

1700

Measuring cell 1

1701

Measuring cell 2

1702

Measuring cell 3

1703

Measuring cell 4

1704

Measuring cell 5

1705

Measuring cell 6

1710

No LED active

1711

LED 1 active

1712

LED 2 active

1713

LED 3 active

1714

LED 4 active

1715

LED 5 active

1716

LED 6 active

1800 1900 2000 2100

LED

1801 1901 2001 2101

cover

1802 1902 2002 2102

PSD

2200

Measuring cell 1

2201

Measuring cell 2

2202

Measuring cell 3

Claims (20)

Optoelectronic arrangement for detecting relative movements or relative positions of two objects comprising at least one one-dimensional position-sensitive detector, wherein the position-sensitive detector is illuminated by at least two light-emitting devices in order to form at least two measuring cells with a common detector, each of the measuring cells formed by a common detector having a slit disposed in the beam path of the corresponding light emitting device between said light emitting device and the position sensitive detector, the position sensitive detector being operatively associated with two adjacent slit diaphragms, wherein the two adjacent slit diaphragms enclose an angle together and each have mutually perpendicular slits, wherein the one-dimensional position-sensitive detector is rotated by every 45 ° to each of the light planes formed by the slits of the two adjacent slit apertures, and wherein each of the two adjacent slit diaphragms is arranged in the direction of the light emitting device associated with the adjacent slit diaphragm. An optoelectronic assembly according to claim 1, characterized in that a plane of light radiating through at least one of the slit apertures and incident on the detector subtends an acute angle with a plane of a photosensitive portion of the detector. Optoelectronic device according to claim 1 or 2, characterized in that the optoelectronic device is set up to illuminate each detector alternately by a light emitting device and to read out a measured value of the detector at the same time. Optoelectronic device according to claim 3, characterized in that the optoelectronic device is set up to illuminate the detector of each measuring cell only by a light emitting device at a certain time and to read out the measured value of the detector at the same time. Optoelectronic device according to one of claims 1 to 4, characterized in that an element of each measuring cell consisting of light emitting device, slit diaphragm and detector is movable relative to the other two elements. Optoelectronic arrangement according to one of claims 1 to 5, characterized in that the arrangement comprises at least three measuring cells, preferably three to six measuring cells. Optoelectronic arrangement according to claim 6, characterized in that the arrangement comprises more than six measuring cells. Optoelectronic arrangement according to one of claims 1 to 7, characterized in that the measuring cell consisting of light-emitting device, slit diaphragm and detector is provided with a movable light-emitting device. Force and / or torque sensor characterized by an optoelectronic arrangement for detecting relative movements or relative positions of two objects according to one of claims 1 to 8. Force and / or moment sensor according to claim 9, characterized in that the two objects consist of a first plate and a second plate, wherein the first plate and the second plate are elastically connected to each other and movable relative to each other. Force and / or torque sensor according to claim 10, characterized in that the first and the second plate are connected to each other via at least one spring and / or damping device. Force and / or torque sensor according to claim 11, characterized in that a spring (preferably made of electrically conductive wire) in addition to the damping property also simultaneously serves for electrical signal guidance of the two movable plates. Force and / or torque sensor according to claim 11 or 12, characterized in that the at least one spring and / or damping device comprises one of the following components or combinations thereof: coil spring, spring assembly, elastomer, casting resin. Force and / or torque sensor according to one of claims 11 to 13, characterized in that the spring and / or damping devices are arranged substantially rotationally symmetrical. Force and / or moment sensor according to one of claims 11 to 14, characterized in that at least one of the spring and / or damping means comprises at least one elastomer or spring element which is fixedly connected to the first and second plates. Force and / or torque sensor according to one of claims 10 to 15, characterized by at least one stop device which limits the movement of the first plate relative to the second plate. Force sensor according to one of claims 9 to 16, characterized in that the force sensor is adapted to detect only translational movements. Pan / zoom sensor having a first plate and a second plate, wherein the first plate and the second plate are elastically connected to each other and movable relative to each other, characterized by an optoelectronic device for detecting relative movements or relative positions of two objects according to one of claims 1 to 8th. Pan / zoom sensor according to claim 18, wherein the pan / zoom sensor is arranged to detect only translational movements due to its geometric structure. PC keyboard characterized in that it comprises a sensor according to any one of claims 9 to 19.

Images