DE102008032786A1 - Device for determining position of vehicle, is mobile along course in direction of motion, and has optical position mark reader for line-wise scanning from position marks - Google Patents

Abstract

The device is mobile along course (3) in a direction of motion (K), and has an optical position mark reader (4) for line-wise scanning from position marks (5), which are arranged along the course in fixed orientation. The position mark reader has units (6) for multiple scanning of individual position marks in multiple lines at a distance from each other. An independent claim is included for a method for determining position of vehicle.

Description

The The present invention relates to an apparatus and a method for determining a position of a vehicle. The vehicle is along a web in a direction of movement movable and has a Optical position marker reader for linear scanning of position marks on. The position marks are along the path in a fixed orientation arranged.

A similar device is from the document DE 199 10 933 B4 for positioning a vehicle on a stationary object. In this case, the vehicle is moved along a predetermined path to the object. On the arranged in sections of the web objects encoded marks are attached. First, a reference travel along the track is performed for the absolute determination of the positioning of the vehicle with respect to the existing coding marks, wherein the coding marks are detected in two stages consisting of a coarse positioning and a fine positioning in order to use this reference data to determine the distance of a position of the vehicle and to determine the location of a target.

Of the Disadvantage of this positioning device is that here the position a plurality of individual items, which coding marks have to be determined, so that after each change Referencing of number and position of items of the vehicle will be necessary to an absolute location to detect the items having coding marks. Another disadvantage of this positioning device proves itself in that for the known device barcode reader are provided as optical sensors on the vehicle, a polygonal rotating mirror to multisampling, the barcodes on a single Scanned scanning line multiple times. Such a barcode reader on a vehicle has the disadvantage that in case of errors or contamination of the barcode misinformation is transmitted on the scan line.

From the pamphlets US 5,286,961 . US 5,975,418 and US 2003/0090805 A1 For example, stationary bar code readers, as are commonplace for ticket desks, which allow multiple scans of intersecting scan lines to detect bar code passages past the stationary bar code reader. Such stationary barcode readers have a high number of cost-intensive components and are used to find and decrypt a barcode in a given area. Such stationary barcode readers have the disadvantage that they are unsuitable for mobile use on a vehicle, especially since they have a highly complex structure, are accordingly expensive and require a vibration-free stable ground.

Other positioning devices and positioning methods are in the documents EP 0 039 921 A1 . DE 38 25 097 A1 and EP 0 116 636 A1 described. These known systems have the following disadvantages.

The achievable accuracy of positioning is determined by the length the position marks or their elements limited to the web, since the code elements in a track along a guideway the train are lined up and in the known methods sequentially must be scanned. The packing density can be the code elements on the web do not have a limited Be increased measure, because the spatial Resolution method of the scanning means of the position marker reader is limited. The length of the position marks can therefore not be reduced below a certain minimum value, so that the position resolution is limited.

Further is to complete coverage of a long driveway with sufficient longitudinal resolution a large one Number of positioning marks required and thus, if the code within the positioning marks along the Driveway along the train should not be repeated, one accordingly large scanning width, for example, a barcode required. However, an increasing scanning width of a barcode can be omitted not just the length of the individual positioning marks but above all, the effort and the cost of the Position mark readers increase significantly. It also goes with longer Position marks a lower resolution of Positionsbe mood so that a realization of driveways and railways of several kilometers, the z. B. desired in modern industrial production lines or necessary, with sufficient resolution difficult. This problem is exacerbated considerably if there is redundant information on the position markers should be to the reliability of the system, z. B. its Resistance to contamination or damage to parts improve the code carrier and thereby reduce the risk failures or possibly serious misalignments to reduce.

One Another disadvantage of the known systems is that a Position determination when the vehicle is not always possible is. Those systems which work with transmitted light, are also mechanically complex and prone against deformations of the position marks.

A basic requirement and Aufga benstellung consists in such systems for determining the position is to provide a current position information as soon as possible and in real time at an output of the system or the device. In systems with high dynamics, which have fast start-up and deceleration ramps, significant systematic measurement uncertainties also arise. It should also be noted that in industrial systems often sampling rates of up to one millisecond are to be used, so that overall it is desirable to provide the measurement information by the position marker reader faster and / or at a higher rate and still achieve a reliable position determination ,

When An object of the invention can therefore be considered a device to provide and provide a method which is a more reliable Enable position resolution and narrower routes allow and beyond an improved robustness against partially soiled or damaged Ensure position marks. In addition, should with simple means the measurement accuracy of the position determination for Systems with high dynamics can be increased.

In In a first aspect, this object is achieved by the device the features of claim 1 solved.

In In another aspect, this object is achieved by the method the features of claim 8 solved.

preferred and advantageous embodiments of the invention Device and preferred embodiments of the invention Method are the subject of the dependent claims.

The Device of the above type is further developed by a vehicle, which is movable along a path in a direction of movement is and line-wise with an optical position tag reader Scanning of position marks is equipped. These position marks are arranged along the path in a fixed orientation, wherein the Position mark reader Means for multiple sampling of individual position marks in a plurality of spaced-apart lines.

With the multiple scanning of individual position marks by the means of the position marker reader in a plurality of spaced apart Lines is associated with the advantage that of the spaced lines, which the position mark in their areal extent scans linearly, only one of these plurality of sampled lines must have the full coded content, to determine a correct position determination for the vehicle. The rest of the area may be damaged and / or damaged be covered by dirt. The probability of being damaged and / or badly contaminated position marks still assign unambiguously can be compared with conventional devices and a method for determining a position of a vehicle clearly increases and thus the reliability the position determination increases.

The Method of the above type is according to the invention by further developed that for determining a position of a vehicle by means of an optical position marker reader along a path subsequent process steps are performed. First become position marks on the web along the direction of movement fixed to the vehicle. Further, an optical position mark reader becomes on the vehicle in a predetermined angular relationship with the position marks attached to the railway. When moving the vehicle or in stationary mode The vehicle then becomes a plurality of spaced-apart lines on individual position marks for multiple scanning of individual position marks generated. The sampling signal sequences of the multiple sampling formed thereby are under exclusive consideration the Abtastsignalfolgen that a predetermined in multiple agreement enable complete position statement, evaluated. With this method is advantageously excluded that damaged or soiled position marks to incorrect position determinations lead, as a plurality of line-shaped from each other spaced scan tracks over the pattern of a cursor be placed.

In a preferred embodiment of the invention the landmarks have one-dimensional barcodes aligned in this way are that they give an angle to the set orientation of the web have, so that the plurality of spaced lines cross the one-dimensional barcode bars. For this purpose, the position marker reader a light source for illuminating the position markers and a movable one Mirror system for deflecting a light beam of the light source in different scanning angles on a single position marker on. In addition, the position marker reader has a Receiver for receiving sampling signals.

The movable mirror system preferably has at least one faceted mirror rotatable about an axis of rotation, the facets of which are arranged to generate the plurality of spaced apart lines on a single cursor at different angles to the axis of rotation. By the rotational movement of the faceted mirror then automatically results in a plurality of spaced scan lines, which are distributed over the surface of the positioning mark to be scanned.

Around to further improve the reliability of the position statement the device has a time measuring device and a data processing device on. The data processing device can speed and acceleration of the vehicle with the help of the identification of the Calculate the vehicle's registered position marks. With such a time measurement and extrapolation to the speed of the vehicle or to the acceleration of the vehicle can completely Unreadable position marks bridged in an advantageous manner be, if at least between two evaluated position marks one Time tracking with speed determination performed could be. The method according to the invention, which is an incident light method, may in particular also a position information for a stationary vehicle deliver.

to further improve the reliability of the determination a distance the vehicle has known since a last Position mark has completed, can be an additional or additional measurement method for the vehicle become.

For this According to the invention, an acceleration sensor used. A first significant advantage can now be seen therein be that a significant increase in measurement accuracy in dynamic Systems through the use of one of the position marks independent Acceleration sensor is achieved.

About that In addition, the device according to the invention is opposite the devices of the prior art uncomplicated and the method according to the invention is trouble-free feasible.

When Position markers can basically all graphically representable coding and marking types are used, whose structure is arranged at an angle to the web orientation is, as is the case with barcodes in an advantageous manner.

In order to a detected relative position to a particular position mark basically clearly a specific actual position of the Vehicle can be assigned, it is further preferred if the used position marks are different, ie by means of a pulse counting device are clearly distinguished can.

For the detection and evaluation of the bar codes with the help of light beams It is useful if the distance between each Barcodes at least as big as the smallest in the Barcodes occurring structure, so at least as large as a minimum information unit, in particular at least as large as a bit of the barcode. Basically, that of the vehicle in a period of a previous position date traveled distance up to a query time by integration of the accelerometer in this period recorded measured data taking into account the speed of the Vehicle at the beginning of the period. For Consistency tests, for example, the distance traveled also based on different known past Positions are determined.

at A simple variant is the current position of the vehicle as the sum of the last position date and the distance traveled since then and determined based on measurement data of the acceleration sensor Distance determined.

Because of The underlying principle of measurement is the one described here Method a precise position information always then when evaluating a position marker from the position marker reader and at least the relative position associated with that cursor of the vehicle is determined based on a predetermined angular relationship.

This allows a further advantageous variant of the invention Method in which the acceleration sensor by comparing determined with the help of the position marks Position data with those position data that are based on obtained from measured data of the acceleration sensor, is calibrated.

Especially the acceleration sensor can be calibrated by comparing the Last position date with the position, which is from the penultimate Position date and between the recording times of the penultimate and the last position date traveled and based the measured data of the acceleration sensor determined route.

Especially The acceleration sensor may be preferred during operation be continuously re-calibrated.

The acceleration data can also be used, for example, to obtain information about the technical condition of the vehicle in question and, in particular, about whether a maintenance phase is to be carried out soon. In an advantageous embodiment According to the method of the invention, an error signal is accordingly emitted if the acceleration of the vehicle over a defined period of time lies within or outside of an also defined maintenance interval.

there the information base can be broadened, albeit accelerations the vehicle transverse to its main direction of motion and orientation measured and logged. expedient For this purpose, a biaxial acceleration sensor is used. for measuring an acceleration of the vehicle in an X and is designed in a Z-direction. As X-direction can be a Main direction of movement of the vehicle are considered and the Z direction is then a direction transverse to the main direction of movement of the vehicle. The biaxial acceleration sensor is accordingly preferred positioned on the vehicle so that the first measuring axis in the direction the main acceleration direction of the vehicle and the second measurement axis oriented in the direction transverse to the main direction of the vehicle.

For example With such a device, a variant of the method is also possible in which an error signal is output when an integral of the Amounts of acceleration of the vehicle across its Main movement direction exceeds a specified limit. This also gives information about the quality of the train, for example of roller rails or of webs with a two-dimensional rolling surface.

For example can for a monorail monorail, for which essentially the position in the direction of travel is determined using a two-axis accelerometer also irregularities of the railway or the rails or possible defects on the vehicle become. The required calculation and evaluation steps of the invention Methods may be preferred using the in the position marker reader arranged data processing device to be executed. After a basically known way to do so Computer program on a computer readable medium, in particular in a ROM of a microcontroller or a programmable Semiconductor devices stored.

The Vehicle whose position is to be determined, may preferably a Monorail monorail, an adjustable stacker crane, part of a crane system or part of others, opposite one given area, in particular in a predetermined Angular relationship, movable devices, be.

Further Advantages and features of the present invention will be described below with reference to the attached figures.

Here in shows:

1 a schematic diagram of a device according to an embodiment of the invention;

2 a schematic perspective view of a rotating mirror;

3 : a schematic view of a measurement situation of position marks a web and

4 : A schematic view of the courses of the location coordinate, the speed and the acceleration for a vehicle whose position is determined by an embodiment of the method according to the invention.

1 shows a schematic diagram of a device 1 according to an embodiment of the invention. The device 1 serves to determine a position 17 of a vehicle 2 that along a pathway 3 in a direction of movement K is movable. This vehicle has an optical position tag reader 4 on, the line by line position marks 5 which are along the train 3 are arranged in a fixed orientation, scans. In this case, the position marker reader 4 medium 6 for multiple sampling of individual position marks 5 in a plurality of mutually spaced scan lines a ', b', c ', d', e 'and f' on.

In addition one smeared by a mirror system 8th deflected light beam 9 a light source 7 the scan lines a 'to f'. In this embodiment, to generate the spaced scan lines a ', b', c ', d', e ', and f', a hexagonal rotating mirror is used 12 used that around its axis of rotation 11 rotates. The light beam 9 is deflected in the illustration shown by a mirror facet c in the direction of the scan line c '. With the following mirror facets d, e and f becomes the light beam 9 from the scan line c 'starting upwards and in the direction of travel K of the vehicle 2 shifted, the mirror facets to different tilt angles relative to the axis of rotation 11 exhibit. Thus, the mirror facets generate superimposed scanning lines.

As another means 6 points the position marker reader 4 in a common housing 18 a receiver 10 receiving the reflected scanning pulses and by means of a data processing device 14 evaluates. From the position marks 5 Backscattered light passes through the respective mirror facet onto a beam splitter 22 and from there over a mirror 23 on the receiver 10 , The corresponding beam path is denoted by the reference numeral 24 characterized.

In addition, the device 1 a means for time recording. With the help of a suitable time measuring device 13 Both the velocity v and the acceleration k from the pulse train of the sampling pulses of the receiver 10 be extrapolated.

Through multiple scanning of a surface 19 a single cursor 5 in the position shown here 17 it is possible damage in the area of Abtastmar ken 5 and / or contaminants thereof, since a plurality of pulse trains of scan lines a 'to f' for one and the same position mark 5 can be output, which increases the reliability of the scan and thus the reliability of the location. In addition to the time recording device 13 can the vehicle 2 have another means for detecting the position, the speed and the acceleration. As 1 shows, the vehicle can 2 an independent of the position marker evaluation acceleration sensor 15 have. The acceleration sensor 15 On the one hand, it is possible to detect accelerations in the main movement direction K and, moreover, it can be designed such that it carries out biaxial acceleration measurements and thus additionally detects accelerations in the vertical direction Z. These occur when the vehicle 2 drives on rails that have bumps. Accordingly, limit values for the vertical acceleration in the axial direction Z can be set in order to compensate for the alignment of the rails, on which, for example, the vehicle when these limit values are exceeded 2 drives to perform.

While the rotating mirror 12 according to 1 has a hexagonal cross-section with six facets a to f, shows the rotating mirror 12 of the 2 an octagon in cross section for multiple scanning of a position marker 5 with spaced apart scan lines a 'to h', of eight mirror facets a to h of the rotating mirror 12 to be generated. This mirror 12 rotates about a vertical axis 11 in the vertical direction Z, wherein for generating different scanning angles γ, for example between the beams A 'and B' reflected by the mirror facets a and b, the facet a is opposite the axis of rotation 11 in the direction FA by the angle α tilted and the facet b in the arrow direction FB by the angle β with respect to the axial direction Z of the rotating mirror 12 are tilted. The dashed line B 'is drawn on the web 5 falls when in the in 2 shown situation, the mirror is further rotated by 45 ° and corresponding to the light beam 9 is reflected on the mirror facet b.

3 shows a schematic view of a measurement situation of position marks 5 a train 3 derived from a plurality of parallel scan lines a 'to h' of in 2 sampled octagonal rotary mirror are scanned. For this purpose, the position marks 5 barcodes 16 on, wherein a positional shift of, for example, three units between the respective position marks 5 are shown. Assign the position marks 5 a damage 20 or dirt particles 21 However, due to the multiple scanning along the spaced scan lines a 'to h', they can still be completely identified, since at least one of the scan lines a 'to h' with at least one complete set of code elements despite damage 20 or particles 21 can be detected by the barcode reader of the vehicle, not shown here.

4 shows a schematic view of the courses of the location coordinate s, the speed v and the acceleration k for a vehicle whose position is determined by an embodiment of the method according to the invention. For this, the respective courses of the traveled distance s, the speed v and the associated acceleration k for a decelerated movement are schematically shown in FIG 4 shown. The curve of the actual course of the spatial position is in 4 marked with the reference symbol s1. The curve s2 shown above represents the course extrapolated on the basis of the speed present at the instant t1 4 is immediately apparent that the extrapolated curve s2 at time t, at which the position determination is to be performed, is significantly above the actual course s1. The reason for this is the decelerated motion, which is reflected in a negative acceleration k <0 in the phase immediately before the time t.

With the help of the acceleration sensor 15 as he is in 1 can be shown, the values in the lower diagram in 4 as the said negative acceleration k are detected. On the basis of the acceleration values thus measured and with the aid of the last speed and position, the actual position of the vehicle can now be determined by integration. For example, with an acceleration of 4 m / s ² , which corresponds to a stopping distance of 2 m at a speed of 4 m / s and a cycle time of 20 ms, an improvement over the values extrapolated assuming a fixed speed v of 0, 8 mm.

These improvements become even clearer when, for example, position marks 5 as they are in 1 and 3 be presented on the web 3 are missing or difficult to read, so if the last known location and speed information is relatively long ago. Also for measurement situations in which, for other reasons, the distances between the individual position marks 5 are large, such as over the range of Expansion joints in large production halls, the present invention can be usefully used with integration of an acceleration sensor in the position marker reader.

By The majority of the detection beams can also be a random one Observation of direct reflection, which because of the deteriorated Contrasts is undesirable, avoided. The invention is therefore also suitable for applications in which moves the vehicle to be monitored on a curved path.

With the present method and apparatus described herein a new optical positioning system is provided which with simple means a significant increase in reliability and the measuring accuracy during dynamic movements of the vehicle allows. A preferred use of this device according to the invention for monorail overhead conveyors, stacker cranes, Cranes or parts of other than one given area in a predetermined angular relationship movable devices.

QUOTES INCLUDE IN THE DESCRIPTION

This list The documents listed by the applicant have been automated generated and is solely for better information recorded by the reader. The list is not part of the German Patent or utility model application. The DPMA takes over no liability for any errors or omissions.

Cited patent literature

• - DE 19910933 B4 [0002]
• - US 5286961 [0004]
• - US 5975418 [0004]
• US 2003/0090805 A1 [0004]
• EP 0039921 A1 [0005]
• - DE 3825097 A1 [0005]
• EP 0116636 A1 [0005]

Claims (12)

Device for determining a position of a vehicle ( 2 ), which runs along a path ( 3 ) is movable in a direction of movement (K) with an optical position mark reader ( 4 ) for linear scanning of position marks ( 5 ), which along the path ( 3 ) are arranged in a fixed orientation, characterized in that the position mark reader ( 4 ) Medium ( 6 ) for multiple sampling of individual position marks ( 5 ) in a plurality of spaced apart lines (a 'to h'). Device according to claim 1, characterized in that the position marks ( 5 ) one-dimensional barcodes ( 16 ) exhibit. Device according to claim 1 or claim 2, characterized in that the position marker reader ( 4 ) for multiple sampling a light source ( 7 ) for illuminating the position markers ( 5 ), a movable mirror system ( 8th ) for deflecting a light beam ( 9 ) of the light source ( 7 ) at different scanning angles (γ) to a single position mark ( 4 ) and a receiver ( 10 ) for receiving reflected scanning signals. Apparatus according to claim 3, characterized in that the movable mirror system ( 8th ) at least one about a rotation axis ( 11 ) rotatable faceted mirror ( 12 ) whose facets (a to h) for generating the plurality of mutually spaced lines (a 'to h') on individual position marks ( 4 ) are arranged at different angles (α, β) to the axis of rotation. Device according to one of the preceding claims, characterized in that the device ( 1 ) a time measuring device ( 13 ) and a data processing device ( 14 ) for calculating the speed and acceleration of the vehicle ( 2 ) and to calculate an actual position of the vehicle ( 2 ) with respect to the position marks ( 5 ) the train ( 3 ) having. Device according to one of the preceding claims, characterized in that the position mark ( 4 ) has a predetermined area bounded in width and height, wherein the line-by-line scanning of the position marks ( 4 ) largely covers the limited area. Device according to one of the preceding claims, characterized in that the device comprises an acceleration sensor ( 15 ) to one of the position marks ( 4 ) independently detecting acceleration values of the vehicle ( 2 ) having. Method for determining a position of a vehicle ( 2 ) by means of an optical position mark reader ( 4 ) along a path ( 3 ), the method comprising the following steps: fixing position markers ( 5 ) at the railway ( 3 ) along the direction of movement (K) of the vehicle ( 2 ); Arranging the optical position mark reader ( 4 ) on the vehicle ( 2 ) in a predetermined angular relationship to the position marks ( 5 ) the train; Generating a plurality of mutually spaced lines (a 'to h') on individual position marks ( 5 ) for the multiple scanning of individual position marks ( 5 ); Evaluating sample bursts of the multi-sample taking into account only the sample bursts that enable a given multiple-position complete positional statement. Method according to claim 8, characterized in that in the position mark reader ( 4 ) for multiple scanning a light beam ( 9 ) of a light source ( 7 ) via a movable mirror system ( 8th ) for deflecting the light beam ( 9 ) at different scanning angles (γ) to a single position mark ( 5 ) and reflected scanning signals from a receiver ( 10 ) are received and evaluated. Method according to claim 8 or claim 9, characterized in that in the movable mirror system ( 8th ) at least one faceted mirror ( 12 ) about a rotation axis ( 11 ), wherein the facets (a to h) of the rotating mirror ( 12 ) for multiple scanning at different angles (α, β) to the axis of rotation ( 11 ), wherein the arrangement of the mirror facets (a to h) at different angles (α, β) to the scanning angles (γ) takes into account the fixed angular relationship between the vehicle ( 2 ) and train ( 3 ) is adjusted. Method according to one of claims 8 to 10, characterized in that during the movement of the vehicle ( 2 ) a time measurement is carried out, which is determined by means of a computer program by evaluating previous position determinations for a speed determination and / or for an acceleration determination of the vehicle ( 2 ) is correlated, and an actual position determination of the vehicle ( 2 ) with regard to position marks ( 5 ) of the web is carried out. A method according to claim 11, characterized in that a computational interpolation the actual position and / or the speed of the vehicle ( 2 ) considering acceleration measurements from independent of position marks ( 5 ) is carried out.