DE102020212641A1 - Non-contact transport device with position detection device and method for position detection - Google Patents

Abstract

A transport device is disclosed which is designed to transport a plurality of payloads simultaneously, with each payload being assigned at least one transport body (mover) which can be moved and positioned in a floating manner over a surface of a stator. The movement and positioning takes place with regard to all six degrees of freedom. An optical position detection device is provided.

Description

The invention relates to a non-contact transport device according to the preamble of patent claim 1 and a method for its operation. In particular, the invention is suitable for industrial applications in assembly technology, the biological, chemical, pharmaceutical and food industries, as well as in the manufacture of solar cells/displays, medical technology, laboratory automation and logistics. The use of the transport device in the semiconductor industry is particularly preferred.

Within the scope of technical production, objects or payloads such as materials, workpieces, tools or products often have to be transported or positioned. For this purpose, both contacting and non-contact conveying devices are known, which are used, for example, in mechanical and plant engineering, for example for transporting objects or payloads in packaging machines, for positioning machine elements or for aligning tools as precisely as possible on the workpiece, for example for laser processing, or in the semiconductor industry for coating, exposure or structuring of substrates in wafer cluster or stepper systems. Systems for levitation of objects can be used.

A challenge in magnetic levitation is to create a structure that levitates stably in a magnetic field. Another challenge is to automatically position and/or move the levitating structure in all six degrees of freedom (three each in translation and rotation) according to a target, also known as full magnetic levitation.

the DE 10 2016 224 951 A1 enables controlled transport and positioning of a transport body carrying a payload relative to a stator. One of the two elements, usually the stator, has a large number of at least partially movably arranged actuating magnets, the respective position and/or orientation of which relative to this element can be specified in a controlled manner via actuating elements. The other of the two elements, usually the transport body, has at least two stationary magnets which are immovably connected to this element and are magnetically coupled to the actuating magnets. The transport device is set up to transport the transport body relative to the stator by controlled positioning and/or orientation of the actuating magnets.

This enables complete magnetic levitation of the transport body in six degrees of freedom, i.e. in three translational and three rotational degrees of freedom relative to the stator. This has the advantage that the transport of the transport body can be carried out more flexibly.

Furthermore, the DE 10 2016 224 951 A1 the advantage that the levitation and/or the forward movement of the transport body relative to the stator is made possible by a corresponding positioning and/or orientation of the actuating magnets by means of the respective actuating elements. As a result, there is no need to provide a complex arrangement and control of magnetic coils. This not only reduces the complexity of the transport device and thus the production costs, but also allows the use of permanent magnets, which can often provide a much higher flux density than magnetic coils that can be used for such purposes. This in turn can allow for a greater lifting height or a larger gap between the stator and the transport body, which can result in a greater freedom of movement for movements in the Z direction and/or in the pitch and roll angle range. Furthermore, this offers the advantage that even an interruption in the supply of electrical energy does not necessarily have to lead to a malfunction or even cause damage. In particular, an interruption in the power supply does not lead to a loss of the magnetic field or the magnetic coupling between the stator and the transport body. For example, in the event of an interruption in the power supply, the coupling forces between the actuating magnets and the stationary magnets can increase as soon as the position and/or the orientation of the actuating magnets gives way to the attractive force of the stationary magnets, whereupon the transport body is pulled onto the stator and is thus secured against uncontrolled falling . The magnetic coupling between the stator and the transport body can cause both a levitation of the transport body, ie a lift above the stator, and a movement of the transport body relative to the stator, ie carriage, without the need for further contacting or contactless systems . This enables contactless transport, so that the transport device can also be used in environments with increased cleanliness requirements. For example, the transport body can be conveyed in the environment with the increased cleanliness requirement, while the stator is arranged outside in an environment with lower cleanliness requirements. Separating elements can run through a gap between the stator and the transport body in order to separate the different cleanliness areas. Thus, the open is suitable disclosed conveying device also for use in biological, chemical and/or pharmaceutical processes, as well as, for example, in gas-tight, liquid-tight and/or encapsulated areas.

The positioning and path accuracy of the transport body is given by a position determination unit. In this context, an optical sensor is mentioned.

The positioning and path accuracy is limited by the performance characteristics of the position determination unit: the more precisely the measured position values of the transport body match the true position, the higher its positioning accuracy. The higher the measuring frequency and the lower the latency of the position determination unit, the lower the dead time of the position controller, which means that the path precision of the transport body also increases.

Accordingly, the invention is based on the object of creating a transport device for payloads and a method for operating such a transport device, in which the optical position determination unit enables accelerated and improved position determination of the transport bodies.

This object is achieved with regard to the transport device by the combination of features of patent claim 1 and with regard to the method by the combination of features of patent claim 12.

Further advantageous refinements of the invention are described in the dependent patent claims.

The claimed transport device is designed for transporting a plurality of payloads simultaneously, with each payload being assigned a transport body (mover) which can be moved and positioned in a floating manner over a surface of a stator. The challenge of automatically positioning and/or moving the fully levitating transport body of the transport device in all six degrees of freedom (three each in translation and rotation) according to a target specification is solved with a control loop, with the controlled variable being the position of the transport body. For this purpose, an optical position detection device is provided which, according to the invention, has at least one camera module and a flat (e.g. less than 1 mm thick) two-dimensional code arrangement.

The position determination according to the invention takes place in several, preferably all, degrees of freedom, ie in six dimensions for the completely levitating transport body, with high frequency and accuracy. The control circuit uses the determined position to track the actual position of the transport body to a specified target position.

The present invention thus describes a transport device with an integrated position determination unit that combines high accuracy with a high measurement frequency and low latency, thereby enabling complete levitation with high positioning accuracy and path precision. The good signal-to-noise ratio of the position determination unit leads to high stability of the position control and reduces the energy requirement of the drives, especially the stator. The low latency of the position determination unit reduces the dead time of the position control and thus enables a quick reaction to external disturbing forces and moments, which are corrected particularly quickly, so that each transport body has a high positional rigidity under the dynamic influence of disturbing forces and moments.

In addition, the position-determining unit according to the invention is characterized by a simple and inexpensive structure that can be integrated into the transport body and into the stator in a particularly space-saving manner. Due to the possibility of arranging the subassemblies of the position determination unit at different locations in the transport device, this can be adapted to different applications in a particularly advantageous manner.

No material connection is required between the transport body and the stator, so that the complete levitation and the freedom of movement of the transport body are not restricted.

According to a first principle, the camera module is attached in or on the transport body with a computing unit for image evaluation, while the two-dimensional code arrangement is attached in a stationary manner on the stator. The arithmetic unit calculates the position of the camera module relative to the code arrangement from the image information.

In the first principle, the transport body must carry an electrical energy store, preferably an accumulator or a capacitor, to supply energy to the at least one camera module. In a preferred embodiment, this can be charged or exchanged at a charging station or a changing station.

At least one permanent magnet array is arranged in the transport bodies (preferably on the respective floor), which is operatively connected can be brought with and moved by the stator. This means that no power supply is required for the transport bodies with regard to the drive technology. The at least one permanent magnet array can be circular.

In an embodiment according to the first principle, the field of view of a camera module is arranged inside the annular permanent magnet array.

In a transport device that can be configured particularly flexibly, the stator is composed of drive modules.

• • Die Codeanordnungen aller Antriebsmodule ergänzen sich zu einer durchgängigen Fläche, so dass das Code-Raster über die Antriebsmodul-Grenze hinweg fortgeführt wird. Dies setzt voraus, dass alle Antriebsmodule mit unterschiedlichen Codeanordnungen ausgestattet sind.
• • Das Code-Raster ist an den Antriebsmodul-Grenzen unterbrochen. Dies kann beispielsweise konstruktionsbedingt notwendig sein, um die Codeanordnung mit einem umlaufenden Rahmen auf der Oberfläche des Antriebsmoduls zu fixieren.
• • Eine durchgängig gedruckte Codeanordnung liegt über allen Antriebsmodulen des Stators.

In the network of several composite drive modules and in the first principle, the surface of the drive modules is covered with code arrays, so that the camera modules in the transport body can measure your position in multiple dimensions at any position of the working area. There are different variants:

• • The code arrangements of all drive modules complement each other to form a continuous area, so that the code grid is continued beyond the drive module boundary. This assumes that all drive modules are equipped with different code arrangements.
• • The code grid is interrupted at the drive module boundaries. This can be necessary for construction reasons, for example, in order to fix the code arrangement with a surrounding frame on the surface of the drive module.
• • A solid printed code array overlies all drive modules of the stator.

According to a second principle, the camera module with the computing unit for image evaluation is fixed in or on the stator, while the two-dimensional code arrangement is attached to an underside of the transport body. The arithmetic unit calculates the position of the code arrangement relative to the camera module from the image information.

In an embodiment of both principles, the code arrangement comprises circles serving as basic symbols, the centers of which form a two-dimensional periodic grid.

Optionally, the sensor system additionally uses at least one inertial sensor for detecting an acceleration and a yaw rate in three dimensions. From the partially redundant sensor data of the camera modules and the inertial sensor, a computer system uses an algorithm for sensor data fusion to determine an optimal estimate of the position of the transport body in the stationary coordinate system of the stator in several, preferably all six, degrees of freedom.

The computer system can be distributed over a computing unit in the transport body and a computing unit in the stator or drive module. The computing unit in the transport body calculates intermediate results or the result of the 6D position estimate in real time and wirelessly transmits these to the computing unit in the stator or drive module using a modem. This optionally takes over further calculation steps and transmits the actual position of the transport body to the control unit of the stator or the drive module, which uses it as an input variable for the position controller.

In connection with the second principle, it is possible that the transport body does not require an energy supply. This eliminates the need for mobile energy storage and charging stations or changing stations.

Preferably in the transport space is a gas (e.g. protective gas, nitrogen or inert gas) or a gas mixture (e.g. purified air) or a vacuum or an ultra-high vacuum (e.g. up to 10 ^-7 or up to 10 ^-8 bar) or an aseptic area or a ABC-protected area or a liquid (e.g. up to 2 bar).

• Ermittlung einer optimalen Schätzung der Position des Transportkörpers im ortsfesten Koordinatensystem des Stators oder eines seiner Antriebsmodule in mehreren, vorzugsweise allen sechs Freiheitsgraden aus teilweise redundanten Sensordaten der Kameramodule und des Inertialsensors mit Hilfe eines Algorithmus' zur Datenfusionierung der Sensordaten.

The method according to the invention serves to determine the position of a transport body in relation to a stator according to claim , with the step:

• Determination of an optimal estimate of the position of the transport body in the stationary coordinate system of the stator or one of its drive modules in several, preferably all six, degrees of freedom from partially redundant sensor data of the camera modules and the inertial sensor using an algorithm for data fusion of the sensor data.

The present invention thus also describes a method that combines high accuracy with a high measurement frequency and low latency, thereby enabling complete levitation with high positioning accuracy and path precision. The good signal-to-noise ratio of the method leads to high stability of the position control and reduces the energy requirement of the drives, especially the stator. The low latency of the position determination unit reduces the dead time of the position control and thus enables a quick reaction to external disturbing forces and moments, which are corrected particularly quickly, so that each transport body has a high positional rigidity under the dynamic influence of disturbing forces and moments.

An image field of the camera module captures a section of the code arrangement and the computer system first calculates the position of the camera module in relation to the position of the code arrangement from the image information. After that, the position of the affected transport body is determined in relation to the position of the stator.

• • Räumliche Fusionierung der Sensordaten: Durch Koordinatentransformation wird die Positionsinformation vom Bezugspunkt des jeweiligen Sensors hin zu einem gemeinsamen Bezugspunkt im Transportkörper 1 transformiert. Der gemeinsame Bezugspunkt ist beispielsweise der geometrische Mittelpunkt oder der Schwerpunkt des Transportkörpers 1.
• • Zeitliche Fusionierung der Sensordaten: die Sensorsignale oder die daraus berechneten Positionsinformationen werden in Zeitreihen aufgezeichnet. Durch Interpolation oder Extrapolation der Zeitreihen werden alle Sensorsignale auf eine gemeinsame Bezugszeit korrigiert. Die Bezugszeit ist beispielsweise diejenige Zeit, zu der der Positionsregler im Stator bzw. im Antriebsmodul 10 die Sensordaten erhält. In diesem Fall wird von einem latenzfreien Positionswert gesprochen.

The computer system preferably uses the following methods for fusing the sensor signals:

• • Spatial fusion of the sensor data: The position information is transformed from the reference point of the respective sensor to a common reference point in the transport body 1 by means of coordinate transformation. The common reference point is, for example, the geometric center or the center of gravity of the transport body 1.
• • Temporal fusion of the sensor data: the sensor signals or the position information calculated from them are recorded in time series. All sensor signals are corrected to a common reference time by interpolation or extrapolation of the time series. The reference time is, for example, the time at which the position controller in the stator or in the drive module 10 receives the sensor data. In this case we speak of a latency-free position value.

Several exemplary embodiments of the conveying device according to the invention and an exemplary embodiment of the method according to the invention are shown in the figures.

• 1 eine erste Variante eines Transportkörpers in einer geschnittenen Seitenansicht und in zwei geschnittenen Draufsichten,
• 2 eine zweite Variante eines Transportkörpers in einer geschnittenen Seitenansicht und in einer geschnittenen Draufsicht,
• 3 einen Schaltplan von elektronischen Komponenten der erfindungsgemäßen Beförderungsvorrichtung mit dem Transportkörper aus 2,
• 4 ein erstes Ausführungsbeispiel der erfindungsgemäßen Beförderungsvorrichtung mit dem Transportkörper aus 1 in einer geschnittenen Seitenansicht,
• 5 ein Antriebsmodul eines Stators eines zweiten Ausführungsbeispiels der erfindungsgemäßen Beförderungsvorrichtung in einer Draufsicht,
• 6 das zweite Ausführungsbeispiel der erfindungsgemäßen Beförderungsvorrichtung mit einem Ausschnitt des Antriebsmoduls aus 5 und mit einer dritten Variante eines Transportkörpers in einer geschnittenen Seitenansicht,
• 7 ein drittes Ausführungsbeispiel der erfindungsgemäßen Beförderungsvorrichtung mit einem Ausschnitt des Antriebsmoduls aus 5 mit einer vierten Variante eines Transportkörpers in einer geschnittenen Seitenansicht,
• 8 eine erste Variante einer Codeanordnung,
• 9 eine zweite Variante einer Codeanordnung,
• 10 eine erste Variante einer Parzelle einer Codeanordnung,
• 11 eine zweite und eine dritte Variante einer Parzelle, jeweils mit Zusatzdaten,
• 12 einen Stator mit sechs Antriebmodulen mit entsprechenden sechs Teilen einer Codeanordnung ohne Unterbrechung des Rasters,
• 13 einen Stator mit sechs Antriebmodulen mit entsprechenden sechs Teilen einer Codeanordnung mit Unterbrechung des Rasters,
• 14 eine perspektivische Darstellung eines Kameramodus mit einem Teil einer Codeanordnung und ein Ausführungsbeispiel des erfindungsgemäßen Verfahrens,
• 15 eine erste Variante eines Kameramodus,
• 16 eine zweite Variante eines Kameramodus, und
• 17 ein Ausführungsbeispiel des erfindungsgemäßen Verfahrens.

Show it

• 1 a first variant of a transport body in a sectional side view and in two sectional top views,
• 2 a second variant of a transport body in a sectional side view and in a sectional plan view,
• 3 a circuit diagram of electronic components of the transport device according to the invention with the transport body 2 ,
• 4 a first embodiment of the transport device according to the invention with the transport body 1 in a cut side view,
• 5 a drive module of a stator of a second embodiment of the transport device according to the invention in a top view,
• 6 the second exemplary embodiment of the transport device according to the invention with a section of the drive module 5 and with a third variant of a transport body in a sectional side view,
• 7 a third exemplary embodiment of the transport device according to the invention with a section of the drive module 5 with a fourth variant of a transport body in a sectional side view,
• 8th a first variant of a code arrangement,
• 9 a second variant of a code arrangement,
• 10 a first variant of a parcel of a code arrangement,
• 11 a second and a third variant of a parcel, each with additional data,
• 12 a stator with six drive modules with corresponding six parts of a code arrangement without grid break,
• 13 a stator with six drive modules with corresponding six parts of a code arrangement with grid break,
• 14 a perspective view of a camera mode with part of a code arrangement and an embodiment of the method according to the invention,
• 15 a first variant of a camera mode,
• 16 a second variant of a camera mode, and
• 17 an embodiment of the method according to the invention.

1 and 2 each show a variant of a transport body 1 (mover) in a sectional side view and in two or one sectional plan view. The transport body 1 has a magnetically active surface on the underside, which faces a stator (in 1 and 2 not shown), and a transport surface at the top designed to accommodate a payload (in 1 and 2 not shown) is used. The transport body 1 also has an array 2 of permanent magnets, preferably in a Halbach arrangement, for introducing the driving forces and moments. The Halbach arrangement causes the side of the permanent magnet array 2 facing the stator to have a strong magnetic field and the side facing the transport surface to have a weak magnetic field. So will ensures that the payload is not exposed to unnecessarily high magnetic fields.

The transport body 1 also has an energy store 5, for example an accumulator or a capacitor, for supplying the components of the position determination unit with electricity and a charging current interface 8 for charging the energy store 5, either by contact (e.g. with galvanic contacts) or contactless by contactless energy transmission ( e.g. inductively using coils or optically using solar cells). The charging current interface 8 can be omitted if the transport body 1 is supplied with energy by regularly replacing the discharged energy store 5 with a charged energy store 5 .

Furthermore, one or more camera modules 4 for measuring the position of the transport body 1 are integrated at the location of the camera module 4 in the transport body 1 . Furthermore, an inertial sensor 7 for detecting the acceleration and rate of rotation of the transport body 1 is integrated in the transport body 1 in six dimensions. Furthermore, a control unit 6 with a computing unit for calculating the position of the transport body from the data of the at least one camera module 4 and the inertial sensor 7 and for cyclically transmitting the position of the transport body to the stator by means of a wireless communication interface is integrated in the transport body 1. The communication interface is preferably based on inductive data transmission and consists of a modulator/demodulator (modem) with at least one connected coil 3 for sending or receiving modulated magnetic alternating fields.

1 shows the transport body 1 with a camera module 4, which detects its own position in six dimensions. It is preferably integrated in the middle of the transport body 1 near the center of gravity of the transport body 1, surrounded by the coil 3 for wireless communication and by the annular permanent magnet array 2.

2 shows the transport body 1 with 4 camera modules 4, which are located at the four corners of the (eg square) transport body 1. On the one hand, this maximizes the base distance between the camera modules 4, which maximizes the accuracy of the angle detection. On the other hand, the center of gravity of the four camera modules 4 is close to the center of gravity of the transport body 1, thereby increasing the accuracy of the transport body position value calculated from the four camera positions.

The camera modules 4 record their individual position in six dimensions. Due to their rigid mechanical arrangement in the transport body, this information is partially redundant. The redundancy can be used to increase the accuracy of the calculated transport body position by averaging over the position determined from a plurality of camera modules 4 . In addition, erroneous measurements of individual camera modules 4 can be recognized and corrected with a diagnostic function, in that the four independently obtained position values are compared and checked for plausibility. If a position value deviates significantly from the others, this is treated as an incorrect measurement and not included in the evaluation.

An inertial sensor 7 in the transport body 1 has a fixed dimensional relationship to the camera modules 4. The inertial sensor 7 is designed in particular to determine six degrees of freedom, i.e. it preferably comprises a combination of at least one 3D acceleration sensor and at least one 3D yaw rate sensor. Alternatively, the inertial sensor 7 can be designed to determine fewer than six degrees of freedom, such as only the translational and/or rotational degrees of freedom.

The inertial sensor 7 and the camera modules 4 make their measurement signals and/or measurement data available to the control unit 6 of the transport body 1, with the control unit 6 determining the position of the transport body by merging the sensor data. In particular, the control unit 6 is designed to determine the position of the transport body on the basis of the measurement data from the inertial sensor 7 in the event of camera modules 4 temporarily failing and/or detection problems.

The control unit 6 transmits according to FIG 3 the calculated transport body position or intermediate values, possibly with additional information, via the wireless communication interface via the gap 26 formed between the floating transport body 1 and the stator to the stator. A wireless inductive data transmission is preferably used. The binary serial data stream is frequency-coded using an FSK modem 6.1 and converted into a variable magnetic field via the coil 3. There is also a coil 24 in the stator, which is inductively coupled to the coil 3 in the transport body 1 due to its spatial arrangement. The signal received by the stator coil 24 is demodulated with an FSK modem 18.1 in the stator and converted into a serial data stream.

As an alternative to inductive data transmission, for example, radio transmission or optical data transmission can be used, with LEDs and photodiodes in the transport body 1 and the stator can be provided, which are used for information transmission.

A possible embodiment of the invention combines the high accuracy of the camera modules 4 with the high measurement frequency of the inertial sensor 7 to form a position determination device with high accuracy and high temporal resolution. For example, the inertial sensor 7 is designed to detect the linear acceleration in three translational degrees of freedom and the angular velocity in three rotational degrees of freedom, with the relative position and/or relative position being able to be determined in particular by mathematical integration of the sensor signals, but without an absolute reference to a scale and/or an optical one Mark. Due to the drift behavior during integration, the measurement error in particular increases over the measurement period. In order to minimize the drift errors, the measurement information from the camera modules 4 can be used to periodically calibrate the transport body position value at the output of the integrator.

Then, in particular, the inertial sensor position value and/or location value can be used in order to increase the temporal resolution of the absolute position value obtained by the camera module 4. For example, if the output frequency of the camera module 4 is 200Hz and the output frequency of the inertial sensor 7 is 2000Hz, the output frequency of the absolute transport body position value can be increased to 2000Hz by combining the relative position and angle changes supplied by the integrator at 2000Hz with the absolute position information of the camera modules 4 .

In 4 is in addition to the transport body 1 from 1 a drive module 10 is shown, with several of these drive modules 10 forming the stator. The shape of the stator is thus very flexible. Expressed in clear terms, a freely configurable stator consists of several drive modules 10 assembled like tiles.

A drive module 10 of the stator has a plurality of movably arranged magnet arrays 15, which are each connected to the drive module 10 via an actuating element or an actuator 16, the actuator 16 being set up to determine a position and/or an orientation of the associated To change magnet arrays 15 relative to the drive module 10 in a controlled manner. For this purpose, the drive module 10 has a control unit 18 which is able to convey the transport bodies 1 by controlled positioning and/or orientation of the actuating magnets of the magnet array 15 by means of the actuators 16 . Furthermore, the drive module 10 has a housing 17 with a cover plate 12 . A cooling unit 19 is provided below the control unit 18 .

• • Eine drahtlose Kommunikationsschnittstelle, beispielsweise auf Basis induktiver Datenübertragung, bestehend aus mindestens einer Spule 14 und einem FSK-Modem 18.1 (vgl. 3), zur Kommunikation mit dem mindestens einen Transportkörper 1. Im Empfangsbetrieb wird das in der Spule 14 induzierte frequenzmodulierte Signal vom FSK-Modem 18.1 demoduliert und in einen seriellen Datenstrom verwandelt, der von einer Recheneinheit eingelesen und ausgewertet wird.
• • Eine Recheneinheit, welche die Kommunikation mit dem Transportkörper 1 steuert und optional Teilaufgaben zur Sensor-Datenfusion übernimmt. Die Funktion der Recheneinheit kann beispielsweise in der Steuerungseinheit 18 des Antriebmoduls 10 integriert sein.
• • Eine zweidimensionale Codeanordnung 13, die von den Kameramodulen 4 gelesen wird, und als Maßverkörperung für das Koordinatensystem 11 dient. Dabei spannt die Codeanordnung 13 ein Koordinatensystem 11 in der X/Y-Ebene des Antriebsmoduls 10 auf. Die Z-Richtung des Koordinatensystems 11 steht senkrecht auf der X/Y-Ebene, so dass X, Y und Z ein rechtshändiges Koordinatensystem 11 bilden.

Furthermore, the following components of the position detection unit are integrated in the stator or in the drive module 10:

• • A wireless communication interface, for example based on inductive data transmission, consisting of at least one coil 14 and an FSK modem 18.1 (cf. 3 ), for communication with the at least one transport body 1. In the receiving mode, the frequency-modulated signal induced in the coil 14 is demodulated by the FSK modem 18.1 and converted into a serial data stream, which is read in and evaluated by a computing unit.
• • A computing unit that controls the communication with the transport body 1 and optionally takes on subtasks for sensor data fusion. The function of the computing unit can be integrated in the control unit 18 of the drive module 10, for example.
• • A two-dimensional code arrangement 13 which is read by the camera modules 4 and serves as a material measure for the coordinate system 11 . The code arrangement 13 spans a coordinate system 11 in the X/Y plane of the drive module 10 . The Z-direction of the coordinate system 11 is perpendicular to the X/Y plane, so that X, Y and Z form a right-handed coordinate system 11.

With a view to 4 the cover plate 12 of the drive module 10 is transparent, so that the light from the illumination LEDs 45 of the camera module 4 penetrates it and the code arrangement 13 is optically detected by the camera modules 4 . Optionally, the cover plate 12 has an optical filter function to protect against extraneous light by absorbing visible light and transmitting infrared light. In this way, the surface of the stator appears to the human observer as a black surface, while an infrared-sensitive camera module 4 can read the code arrangement 13 under infrared LED illumination.

A cooling unit 19 of the drive module 10 is provided below the control unit 18 .

In 4 a process chamber 20 is shown, which of course can also be omitted. In this exemplary embodiment, the transport bodies 1 are to be moved without contact in the closed process chamber 20, which includes, for example, a vacuum, a specific gas atmosphere, an aseptic area or an NBC-protected area. Here is the transport body 1 inside the process chamber 20, the stator outside. For this purpose, it is advantageous to design code arrangement 13 including cover plate 12 so that it can be separated from the stator, so that code arrangement 13 can be mounted on the inside of process chamber 20 while the stator is outside of process chamber 20 and aligned with code arrangement 13 . In this way, the code arrangement 13 can be read by the camera modules 4 without being covered by the process chamber 20 .

According to one in the 5 and 6 The installation locations of the camera modules 4 and the code arrangement 13 shown in the second principle of the transport device according to the invention are reversed: in the stator there are several camera modules 4 arranged in a grid, while the code arrangement 13 is mounted on the underside of the transport body 1, possibly behind a transparent cover plate. The camera modules 4 detect the code arrangement 13 and use this to determine the position of the transport body 1 at the installation site of the respective camera module 4. The measured values of the inertial sensor 7 in the transport body 1 are transmitted to the stator by means of wireless communication. From the measured values of the inertial sensor 7 and the camera modules 4, the computing unit in the stator calculates the position of the transport body 1 by means of sensor data fusion. Optionally, the position code in the transport body 1 contains a transport body-specific ID, so that a camera module 4 in the stator can identify the transport body 1 at the same time and can localize.

When using particularly fast camera modules 4, the image acquisition rate of which reaches the measuring frequency of the inertial sensor 7, the inertial sensor 7 can be dispensed with since it does not provide any relevant additional information. This results in a considerable simplification of the structure of the transport body according to the variant 7 : there are no more sensors and electronics in the transport body 1, so it can be operated without power and without a data interface. In addition to the inertial sensor 7, the energy store 5, the charging current interface 8, the wireless communication interface and the control unit 6 with a computing unit in the transport body 1 can be omitted.

8th until 13 show different two-dimensional code arrangements 13, which are attached to the surface of the stator or its drive module 10. Each code arrangement 13 can be read by a camera-based sensor module in the transport body 1, with the absolute position of the transport body 1 being able to be determined in up to six degrees of freedom. The code arrangement 13 serves both as a precise material measure of the coordinate system 11 by spanning a two-dimensional scale in the X and Y directions, and for the encoded representation of the position information at each grid point of the code arrangement 13.

The code arrangement 13 comprises basic symbols 32 such as circles, the centers of which form a two-dimensional periodic grid 31 on the surface. The circles represent the digits of a number system with base b. The b digits are represented encoded with at least b different base symbols 32 . Preferably, the base 2 binary system is used, with the digits 0 and 1 being represented by two circles of different radii.

In the examples shown, the smaller circle is associated with the number 0 and the larger circle with the number 1.

In the example off 8th the basic symbols 32 were arranged in a square grid 31 with a constant grid width dX in the X direction and dY in the Y direction, with dX and dY being equal. In particular, the area centroid of the basic symbols 32 lies on the grid points. For clarity, all points in this representation have the same radius. To make the periodic square grid 31 easier to identify, grid lines are drawn in here as an aid.

8th also shows a possible division of basic symbols 32 arranged to form a periodic grid 31 into similar parcels 33. In this exemplary embodiment, the parcels 33 are in the form of areas with twenty-five grid points. Each plot 33 includes five grid points in the X direction and five grid points in the Y direction. In particular, square plots 33 include the same number of grid points in the X direction and in the Y direction. For better recognition, the parcels 33 are marked here with a parcel border as a logical unit.

The grid length is arranged in the direction of the x-axis and the grid width is arranged along the y-axis. A plurality of plots 33 are arranged both along the grid length and along the grid width, with the plurality of plots 33 forming a periodic square plot grid. In particular, all parcels 33 have the same shape and the same size.

A parcel symbol 34 is arranged at the parcel point which is closest to the center point of a parcel 33 . In the variant shown, the parcel symbol 34 is a blank, that is to say by omitting a base symbol 32 educated. Alternatively, the parcel symbol 34 may be located at a different point within a parcel 33, the location of the parcel symbol 34 within a parcel 33 being the same for all parcels 33 of the code assembly 13. The parcel symbol 34 is used in particular to specify and/or define the reading and/or decoding direction of the basic symbols 32 within a parcel 33 .

9 shows another variant with a comparable structure, but with a plot size of forty-nine grid points, arranged in seven rows and seven columns.

10 shows an example of the structure of a parcel 33 from the code arrangement 13 in 9 with 7x7 grid points. In the middle of the parcel 33 is the parcel symbol 34. The two fields 35 identify the X parcel regions in which the sequential code for the position in the X direction is represented. The X parcel regions comprise twenty-four raster points, accordingly they represent a code with a length of twenty-four bits.

To read the code, the base symbols 32 are read column by column from left to right and within each column from top to bottom. The reading order in the X-lot areas is in grid point coordinates (X,Y): (0,6); (0.5); (0.4); (1.6); (1.5); (1.4); (2.6); (2.5); (2.4); (3.6); (3.5); (3.4); (3.2); (3.1); (3.0); (4.2); (4.1); (4.0); (5.2); (5.1); (5.0); (6.2); (6.1); (6.0).

The two fields 36 identify the Y parcel regions in which the sequential code for the Y-direction position is represented. The reading order is the same as for the X plot areas, but rotated 90° counterclockwise, i.e. bottom to top row by row and left to right within each row.

The code from the X parcel areas (X code) is a subsequence with a length of t=24 digits from a total sequence of g digits, where g is much larger than t. The number g is sufficiently large so that the X parcel areas of all parcels 33 that are adjacent in the X direction can be completely filled. In particular g is greater than fifty, in particular greater than one thousand and in particular greater than one million. The contents of the X parcel areas of parcels 33 adjacent in the Y direction are identical. The overall sequence is designed in such a way that each partial sequence of t consecutive basic symbols 32 read forward is contained exactly once in the overall sequence and each partial sequence read backward is not contained in the overall sequence read forward.

The code from the Y parcel areas (Y code) is shown in reverse video, i.e. each digit z is replaced by the digit (b-1-z). For the binary system with b=2, this corresponds to a bitwise inversion. The inverted Y code is a partial sequence with a length of t=24 bits from a total sequence, whereby the same total sequence can be used as for the X code. The inverted Y code also occurs only once in the overall sequence and does not occur in the overall sequence when read backwards. The contents of the Y parcel areas of parcels 33 adjacent in the X direction are identical.

In one possible embodiment of the invention, the overall sequence is designed in such a way that a checksum of a partial sequence is less than half the maximum possible checksum of a partial sequence. In particular, the checksum for any partial sequence selected from the overall sequence is less than half the maximum possible checksum of a partial sequence. For example, the checksum of each subsequence of length t in a number system with base b is less than q=t(b-1)/2.

The partial sequences of the overall sequence encode in particular a coordinate value, for example the X coordinates of the starting position of the reading process. Likewise, a partial sequence of the inverted overall sequence encodes a Y coordinate, for example the position from which the partial sequence is read. The X code and Y code read in a parcel 33 are associated with the X and Y coordinates of a reference point in the parcel 33, for example grid point (3,3) in the center of the parcel 33.

A reading field is any section of the code arrangement 13 the size of a parcel 33. The reading field is not tied to the parcel grid, but to the grid of the basic symbols 32 and parcel symbols. Compared to the parcel grid, it can be offset by any number of grid points in the X and Y directions.

Each reading field contains exactly one parcel symbol 34, t basic symbols 32 from X parcel areas and t basic symbols 32 from Y parcel areas. The position of the parcel grid and thus the position of the X and Y parcel areas in the reading field and the associated reading order can be derived from the position of the parcel symbol 34 . The basic symbols 32 read in accordance with the reading order result in a sequence of digits with t digits which—possibly after inversion—is a subsequence of the overall sequence.

If the orientation of the reading field is unknown, it is initially not known whether it is an X-axis or a Y-axis. This is determined by calculating the checksum of the read code and comparing it with q: the checksum of an X code is less than q, the checksum of a Y code is greater than q. The direction of the coordinate axes of the reading field in relation to the coordinate axes of the code arrangement 13 is clearly derived from the direction of the read codes in relation to the overall sequence (forwards or backwards).

In this way, the position and orientation of a reading field in the coordinate system 11 of the code arrangement 13 can be determined, the position in integer steps of the grid width and the orientation in integer steps of 90°.

In 11 analogously, two variants of parcels 33 with 9 columns and 9 rows are shown. In addition to the parcel areas X (35) and Y (36), which represent the position code for the respective axis of the coordinate system 11, parcel areas (37) are provided for additional data.

In example a, there is an additional data area (37) with 5×5 grid points in the center of parcel 33, with the middle grid point being cut out for parcel symbol 34, so that twenty-four grid points remain, each of which can accommodate a basic symbol 32. In this way, twenty-four bits of additional information can be displayed in each parcel 33, which are read in a fixed order.

Example b shows another code arrangement 13 with four parcel areas for additional data and a total of 40 bits of information content of the additional data per parcel 33.

• • Gemäß 12 ergänzen sich die Codeanordnungen 13 aller Antriebsmodule 10 zu einer durchgängigen Fläche, so dass das Code-Raster über die Antriebsmodul-Grenze hinweg unterbrechungsfrei fortgeführt wird. Dies setzt voraus, dass alle Antriebsmodule 10 mit unterschiedlichen Codeanordnungen 13 ausgestattet sind.
• • Gemäß 13 ist das Code-Raster an den Antriebsmodul-Grenzen unterbrochen, indem die Rasterpunkte in einer oder mehreren Reihen entlang der Antriebsmodul-Grenzen nicht mit Basissymbolen 32 besetzt sind. Dies kann beispielsweise konstruktionsbedingt notwendig sein, um die Codeanordnung 13 mit einem umlaufenden Rahmen auf der Oberfläche des Antriebsmoduls 10 zu fixieren. Dann können die Codeanordnungen 13 gleich sein.
• • Eine durchgängig gedruckte Codeanordnung 13, die über allen Antriebsmodulen 10 des Stators liegt.

In a network of several lined-up drive modules 10 and in the first principle, the surface of the drive modules 10 is covered with code arrangements 13, so that the camera modules 4 in the transport body 1 can measure your position in several dimensions at any position in the work area. There are different variants:

• • According to 12 the code arrangements 13 of all drive modules 10 complement each other to form a continuous surface, so that the code grid is continued without interruption across the drive module boundary. This presupposes that all drive modules 10 are equipped with different code arrangements 13.
• • According to 13 the code grid is interrupted at the drive module boundaries in that the grid points in one or more rows along the drive module boundaries are not occupied by basic symbols 32 . This can be necessary for construction reasons, for example, in order to fix the code arrangement 13 with a surrounding frame on the surface of the drive module 10 . Then the code arrangements 13 can be the same.
• • A solid printed code assembly 13 overlying all drive modules 10 of the stator.

The camera module 4 off 1 and 4 and the camera modules 4 from the 2 and 3 are set up to read the code arrangement 13 without interruption when crossing a drive module boundary. If each drive module 10 is equipped with the same code arrangement 13, each drive module 10 has its own coordinate system 11. The transport body 1 cannot initially access a higher-level stator coordinate system. In order to remedy this deficiency, the transport body 1 is given the opportunity to identify and differentiate between drive modules 10, for example by the drive module 10 sending its ID to the transport body 1, which is located above the drive module 10, by means of contactless communication. The transport body 1 uses this information to read out the offset position of the drive module coordinate system 11 in relation to a global stator coordinate system from a previously defined table and to add it to the local position on the drive module 10 .

14 shows a possible arrangement of a camera module 4 relative to the drive module surface with a code arrangement 13. The code arrangement 13 forms a flat surface, the flat surface forming the XY plane of the Cartesian coordinate system 11 at the same time. The Z axis is perpendicular to the XY plane of the coordinate system 11, with the XYZ axes forming a right-hand system. In this coordinate system 11, the position of the camera module 4 can be specified in the coordinates (x _k , y _k , z _k ), the angular position in the angles (φ1, φ2, φ3). The angles φ1 and φ2 are the tilting angles around the X and Y axes, the tilting angle φ3 is the angle of rotation of the camera module 4 around its optical axis. For example, for ϕ1 = ϕ2 = 0°, the camera looks perpendicular to the code arrangement 13.

The optical axis intersects the code arrangement 13 at a reference point with the coordinates (x′, y′, 0). The vector z' lies on the optical axis, its length corresponds to the distance of the camera module 4 from the reference point. The Cartesian position (x _k , y _k , z _k ) of the camera module 4 results from the vector addition of the coordinates of the reference point and the vector z′.

The camera module 4 is designed to record a section of the code arrangement 13 and store it as an image in the main memory of a processing unit. The computing unit calculates the position and angular position of the camera module 4 from each individual image by means of image evaluation. The camera position (x _k , y _k , z _k ) is transmitted to the control unit in the transport body 1 by means of a data interface, which carries out the data fusion with further sensor data and finally the position of the transport body 1 is calculated.

15 shows an example of the structure of a camera module 4. A camera circuit board 40 is equipped with an image recording sensor, a processing unit and a data interface 43. Above a camera chip is a small camera housing 41, which is also attached to the printed circuit board 40 and serves to shield the camera chip from extraneous light and to attach a wide-angle lens 42.

The LEDs 45 are installed on an annular LED circuit board 44 for illumination to form a ring light which is preferably electrically and mechanically connected to the camera circuit board 40 . Alternatively, it is integrated on the same printed circuit board 40. It is preferably operated as a flashlight, i.e. it only lights up briefly in each measurement cycle for exposure during image recording by the camera chip.

The lens 42 is located in the center of the ring light. The LEDs 45 and the lens 42 are aligned with the code arrangement 13 to be measured. In order to minimize the penetration of direct light reflections into the lens 42, this is surrounded by an opaque sleeve 46. A transparent protective glass 47 forms the closing surface. The protective glass 47 is diffuse in the outer area 47d. The light from the LEDs 45 passes through this area and is scattered on the diffuse glass surface. Due to the diffuse illumination, code arrangements 13 which have a glossy surface can be recorded in the image without disturbing reflections. The protective glass 47 is fully transparent in the circular inner area 47t, so that the beam path can pass through to the lens 42 unhindered.

16 shows a variant of the camera module 4 with a reduced installation height. Here the lens 42 is mounted looking sideways. A 45° deflection mirror 49 in the center of the camera module 4 deflects the beam path downwards so that it leaves the protective glass 47 with the optical axis 48 orthogonally oriented.

17 shows an embodiment of the method for determining the transport body position in six degrees of freedom from the sensor data, which is executed as an algorithm by a computer system. The computer system can include one or more networked computing units that can be spatially distributed on the transport body 1 (camera circuit board 40 with computing unit, control unit 6) and the stator (control unit 18) or other computing units.

The sensor data is recorded periodically, preferably with a fixed output frequency. For example, the inertial sensor 7 supplies the sensor data with an output frequency that differs from the output frequency of the camera modules 4 . Typically, the output frequency of the inertial sensor 7 is greater than that of the camera modules 4 by a factor of 2-100. On the other hand, the camera modules 4 have the property of delivering precise absolute positions. The sensor data are the input data of the position determination method. In addition, all units have access to a common, precise time base (timer) whose temporal resolution is significantly higher than the two output frequencies mentioned.

The data from the inertial sensor 7 (3 DoF acceleration and 3 DoF yaw rate) are provided with a time stamp and, after an offset correction and signal processing, for example with a digital filter, are transmitted to the algorithm for sensor data fusion.

A camera module 4 records a greyscale image of a section of the code arrangement 13 and provides this data with a time stamp. First, the image data are rectified in order to mathematically compensate for distortions caused by the lens 42 that are caused by the imaging. The grid 31 of basic symbols 32 of the code arrangement 13 is then recorded using conventional methods of image processing. The image coordinates of the raster points are precisely determined with sub-pixel accuracy, for example by adapting a mathematically generated variable model of the raster 31 to the measured image data with numerical optimization.

The basic symbols 32 are then detected and classified at the grid points. For example, the area of a base symbol 32 is determined using blob analysis, with the area value serving as a classification criterion.

In the "rough position determination" step, at least one reading field is determined within the identified grid, i.e. any section of the code arrangement 13 the size of a parcel 33. With the method described above, the X code and the Y code in the reading field are read and from this the position and orientation of the reading field in the coordinate system of the code arrangement 13 is determined. As a result, the coordinates x' and y' in integer steps of the grid frequency, and the orientation ϕ3 in integer steps of 90°.

Optionally, several reading fields are evaluated at different positions in one image. This results in a number of position values which, in order to increase reading reliability, are checked against one another in pairs for plausibility by comparing the difference between two read coordinate values with the distance between the reading fields in units of grid points. Implausible position values can thus be identified using a 2-out-of-3 selection and excluded from further processing.

The evaluation of several reading fields can also be necessary in order to determine the transport body position relative to both drive modules 10 at a boundary between two drive modules 10 . In this case, the camera module 4 is designed to capture the code arrangements 13 of both drive modules 10 in an image field, to recognize the border and to evaluate the positions on both sides of the border with reading fields.

The "fine position determination" aims to determine all six camera coordinates with high accuracy. It receives the rough position and the previously determined precise coordinates of the grid points in the camera image as input information. The camera coordinates (x′, y′, z′) and the camera angles (φ1, φ2, φ3) are determined with high accuracy from the grid point coordinates using an imaging model of the camera module 4 and conventional mathematical methods. Optionally, the non-Cartesian coordinate values (x', y', z') are converted into Cartesian camera coordinates (x _k , y _k , z _k ) using the camera angles (ϕ1, ϕ2, ϕ3). The method is used in the same way for all camera modules 4 in a transport body 1 .

The sensor data fusion uses mathematical methods to determine a precise and up-to-date estimate of the transport body position from the measurement data from the inertial sensor 7, the camera modules 4, the time information of all measurements and the current time. For this purpose, the measurement data provided with different time stamps and recorded at different locations of the transport body 1 are spatially and temporally fused.

• • Räumliche Fusionierung der Sensordaten: Durch Koordinatentransformation wird die Positionsinformation vom Bezugspunkt des jeweiligen Sensors hin zu einem gemeinsamen Bezugspunkt im Transportkörper 1 transformiert. Der gemeinsame Bezugspunkt ist beispielsweise der geometrische Mittelpunkt oder der Schwerpunkt des Transportkörpers 1.
• • Zeitliche Fusionierung der Sensordaten: die Sensorsignale oder die daraus berechneten Positionsinformationen werden in Zeitreihen aufgezeichnet. Durch Interpolation oder Extrapolation der Zeitreihen werden alle Sensorsignale auf eine gemeinsame Bezugszeit korrigiert. Die Bezugszeit ist beispielsweise diejenige Zeit, zu der der Positionsregler im Stator bzw. im Antriebsmodul 10 die Sensordaten erhält. In diesem Fall wird von einem latenzfreien Positionswert gesprochen.

The computer system preferably uses the following methods for fusing the sensor signals:

• • Spatial fusion of the sensor data: The position information is transformed from the reference point of the respective sensor to a common reference point in the transport body 1 by means of coordinate transformation. The common reference point is, for example, the geometric center or the center of gravity of the transport body 1.
• • Temporal fusion of the sensor data: the sensor signals or the position information calculated from them are recorded in time series. All sensor signals are corrected to a common reference time by interpolation or extrapolation of the time series. The reference time is, for example, the time at which the position controller in the stator or in the drive module 10 receives the sensor data. In this case we speak of a latency-free position value.

A gravitational compensation subtracts the gravitational acceleration vector from the measured acceleration vector, so that the difference vector only indicates the inertial acceleration. This can be converted into a displacement vector by mathematical integration.

Optionally, the sensor data can be digitally filtered. A Kalman filter or an extended Kalman filter is preferably used, which receives the possibly pre-processed sensor data as input information and from this calculates the optimal estimated value for the transport body position and its variance.

The determined transport body position value is optionally extrapolated in order to compensate for the delay time due to the subsequent data transmission or other events.

Methods for diagnosis and error correction are used along the entire signal processing chain in order to increase the robustness and accuracy of the output transport body coordinates.

An advantageous embodiment consists in the additional use of the camera module 4 as an identification sensor. For this purpose, additional information such as an ID code is embedded in the code arrangement 13, which is read and evaluated by the camera module 4 in addition to the position information.

• • die elektronischen Funktionen aller Komponenten in verschiedener Weise auf einer oder mehreren Leiterplatten integriert werden,
• • eine beliebige Technologie zur drahtlosen Datenübertragung zum Einsatz kommen, insbesondere können außer der beschriebenen induktiven Datenübertragung auch verschiedene Funktechnologien oder optische Übertragungstechnik eingesetzt werden.

The exemplary embodiments described above are not to be understood as limiting. For example:

• • the electronic functions of all components are integrated in different ways on one or more printed circuit boards,
• • any technology for wireless data transmission can be used, in particular, in addition to the described inductive data transmission, different which radio technologies or optical transmission technology are used.

A transport device is disclosed which is designed to transport a plurality of payloads 9 at the same time, with each payload 9 being assigned a transport body 1 (mover) which can be moved and positioned in a floating manner over a surface of a stator. The movement and positioning takes place with regard to all six degrees of freedom. An optical position detection device is provided.

Reference List

1

transport body

2

permanent magnet array (of the transport body)

4

camera module

5

energy storage

6

control unit

6.1

FSK modem (of the transport body)

7

inertial sensor

8th

charging current interface

9

payload

10

drive module (of the stator)

11

coordinate system (of the drive module)

12

cover plate (of the drive module)

13

code arrangement

14

stator coil

15

magnet array (of the actuator)

16

actuator (of the drive mode)

17

housing (of the drive module)

18

control unit (of the drive module)

18.1

FSK modem (of the stator)

19

cooling unit (of the drive module)

20

process chamber

26

gap

31

grid

32

base icon

33

plot

34

parcel icon

35

field

36

field

40

Printed circuit board with computing unit (of the camera module)

41

body (of the camera)

42

lens

43

interface

44

LED circuit board

45

LEDs

46

sleeve

47

protective glass

47d

diffuse area

47t

transparent area

48

optical axis

49

deflection mirror

QUOTES INCLUDED IN DESCRIPTION

This list of the documents cited by the applicant was 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.

Patent Literature Cited

• DE 102016224951 A1 [0004, 0006]

Claims (14)

Transport device for transporting at least one payload (9), each payload (9) being assigned at least one transport body (1) which can be moved while hovering over a surface of a stator with respect to all six degrees of freedom (X, Y, Z, rot_X, rot_Y, rot_Z). and positionable, and with an optical position detection device, characterized in that the position detection device has at least one camera module (4) and a passive and/or currentless flat code arrangement (13), the position of the transport body (1) relative to the stator being determined via the position detection device can be determined at least with respect to several degrees of freedom (X, Y, Z, rot_X, rot_Y, rot_Z). transport device claim 1 , wherein the at least one camera module (4) is arranged in or on the transport body (1), and wherein the flat code arrangement (13) is arranged on the surface of the stator. transport device claim 2 , wherein the transport body (1) for supplying energy to its at least one camera module (4) carries along an electrical energy store (5) which can be charged or exchanged at a charging station or a changing station. transport device claim 2 or 3 , wherein at least one annular permanent magnet array (2) is arranged in the transport body (1), which can be brought into operative connection with the stator and moved by it, wherein a field of view of a camera module (4) inside the annular permanent magnet array (2) is arranged. Conveyor device according to one of the preceding claims, in which the stator is composed of drive modules (10). Transport device according to one of claims 2 until 4 and after claim 5 , wherein the code arrangement (13) is composed of parts, each part being associated with a drive module (10), and the parts being different and complementing one another to form a continuous surface. Transport device according to one of claims 2 until 4 and after claim 5 , wherein the code arrangement (13) is composed of equal parts, each part being associated with a drive module (10). Transport device according to one of claims 2 until 4 and after claim 5 , wherein the code arrangement (13) extends across the drive module over the stator. transport device claim 1 , wherein the at least one camera module (4) is arranged in or on the stator, and wherein the flat code arrangement (13) is arranged on an underside of the transport body (1). Conveyance device according to one of the preceding claims, in which the code arrangement (13) comprises circles serving as basic symbols (32), the centers of which form a two-dimensional periodic grid (31). Conveyance device according to one of the preceding claims, wherein at least one inertial sensor (7) is additionally provided for detecting an acceleration and a yaw rate in three dimensions in each case. Method for determining the position of a transport body (1) relative to a stator claim 11 , with the step: determining an optimal estimate of the position of the transport body (1) in the stationary coordinate system (11) of the stator or one of its drive modules (10) in several, preferably all six degrees of freedom (X, Y, Z, rot_X, rot_Y, rot_Z ) from partially redundant sensor data from the camera modules (4) and the inertial sensor (7) using an algorithm for data fusion of the sensor data. procedure after claim 12 , wherein the data fusion is spatial, and wherein the position information is transformed from the reference point of the respective sensor towards a common reference point in the transport body (1) by coordinate transformation. procedure after claim 12 , wherein the data fusion is temporal, and wherein the sensor signals or the position information calculated therefrom are recorded in time series, and wherein all sensor signals are corrected to a common reference time by interpolation or extrapolation of the time series.

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