Position-determining system

Abstract

A position-determining system (100) for determining the absolute position of a lift car (120) that can be moved along at least one guide rail (110) has a code mark pattern (130) and a code reader (140). A bit sequence (132) of the code mark pattern (130) has a fixed number p of subsequent identical bits (143) only.

Description

[0001] Positioning system

[0002] Description

[0003] The invention relates to a position determination system, its use and a method for determining the absolute position of an elevator car that can be moved along at least one guide rail.

[0004] Devices for determining the absolute position of an elevator car are known in the art. In addition to the elevator car, stationary code mark patterns and corresponding code reading devices attached to the elevator car are used.

[0005] WO 03 / 011733 A1, for example, discloses an elevator system with an absolute length measuring system for determining the car position of an elevator car movable along at least one guide rail, with a code mark pattern of a pseudorandom coding attached to the guide rail in the direction of travel. In the absolute code mark pattern, any n consecutive code marks represent a code word. The absolute code mark pattern is represented as a single-track code mark pattern of an n-digit pseudorandom sequence in Manchester coding with code marks of equal length. This has the disadvantage that two code bits are required to encode one information bit, since in Manchester coding, the state of a payload bit is represented by the change of the logical state (0 to 1 or 1 to 0) from one code bit to the next.Of the four possible sequences of two logical states (00, 01, 10, and 11), only two (01, 10) are used for payload bits by Manchester coding. Thus, the maximum information density of a code mark pattern encoded in this way is only half that of a simple binary coding. This increases the time required to determine the absolute car position, which is detrimental to the determination speed and / or resolution.

[0006] Summary of the invention

[0007] The object of the present invention is to reliably, quickly, and precisely determine the absolute position of an elevator car traveling along at least one guide rail. For this purpose, a suitable position determination system, its use, and a method are to be specified.

[0008] This problem is solved by the subject matter of the independent claims. Advantageous developments of the subject matter of the independent claims are characterized in the subclaims.

[0009] Accordingly, a position determination system is provided which has a code mark pattern fixedly mounted parallel to the direction of travel next to the elevator car and a code reading device, wherein the code mark pattern is formed as a bit sequence of N consecutive code marks, each representing a bit of the code mark pattern.

[0010] Furthermore, the code reading device comprises a sensor mounted on the elevator car and an evaluation unit, wherein the sensor is configured to scan a sequence of the code marks of the code mark pattern and to generate code mark signals from the code marks of the sequence, wherein the code mark signals represent the respective bits of the scanned code marks.

[0011] The evaluation unit is configured to receive the code mark signals from the sensor, to obtain a code word with n consecutive bits of the scanned code marks from the received code mark signals, and to determine the absolute car position from the obtained code word. The bit sequence of the code mark pattern has at most a specified number p of consecutive identical bits, where 2 <p<n.

[0012] During operation, the sensor of the code reading device, which is attached to the elevator car and thus moves with it, scans a sequence of code marks from the stationary code mark pattern. Scanning can occur both while the elevator car is moving and when it is stationary.

[0013] Consecutive code marks are understood to be the code marks each representing a bit of the code mark pattern, which are also referred to as code word encoding code marks. Although it is not intended, it is also not excluded that further code marks which do not represent such bits can be inserted between these code word encoding code marks. Such code marks are referred to as non-code word encoding code marks. The statement that consecutive code marks are used to determine the code word therefore refers to the code word encoding code marks and does not fundamentally exclude non-code word encoding code marks inserted between them, which play no role in the invention. Herein, the terms "code marks", "consecutive", "bit(s) of the code mark pattern", "bit(s) of the code word" refer (only) to code word encoding code marks, unless otherwise stated.The totality of codeword-encoding and non-codeword-encoding code marks is referred to as “physical code marks”.

[0014] Preferably, all physical code marks are codeword-encoding code marks. Preferably, the (codeword-encoding) code marks of a code word, each representing one bit of the code mark pattern, follow one another directly, i.e., without any further physical (e.g., non-codeword-encoding) code marks in between.

[0015] The scanned sequence of code marks particularly preferably consists of a continuous sequence of directly consecutive individual code marks, whereby all code marks of the respective sequence are scanned by the sensor and code mark signals are preferably generated from all code marks. Whenever "consecutive" elements are specified, it is preferred that the respective elements follow one another directly. Thus, the code mark pattern preferably consists of directly consecutive code word encoding code marks. With regard to the bits of the bit sequence, "consecutive" means the direct succession of the bits (without other bits in between), since non-code word encoding code marks do not contribute to the bit sequence. The bit sequence therefore has at most a specified number p of directly consecutive identical bits.

[0016] The code mark signals are received by the evaluation unit and interpreted as each of the n consecutive bits of the code word. The n-digit code words encoded in the code mark pattern are each uniquely assigned to a single absolute car position. Preferably, the n-digit code words each represent a unique numerical code (not appearing anywhere else in the code mark pattern). Each n-digit partial bit sequence is therefore contained at most one position in the bit sequence of the code mark pattern. This makes it possible to assign an absolute car position to each of the n-digit code words. Thus, if the code word is known, the corresponding absolute position of the elevator car can be determined based on this assignment.

[0017] Using the majority of the physical code marks, or even all of the code marks, for encoding or decoding individual bits of the code words contained in the code mark pattern increases or even doubles the maximum possible information density per length interval compared to the state of the art, given the same physical code mark length. This allows, for example, a shorter code word length to be selected, enabling the use of a more compact and thus more cost-effective sensor system or the reading of multiple code words with the same sensor reading length, which in turn increases the reliability and robustness of position determination.

[0018] The position determination system is intended for determining the absolute position of an elevator car, in particular a passenger elevator car.

[0019] If the evaluation unit has a memory with the bit sequence of the code mark pattern and is configured to determine the absolute car position by identifying the received code word as a partial bit sequence of the bit sequence, the absolute car position can be determined even faster and in a more direct way.

[0020] If the bit sequence of the code mark pattern is selected such that each partial bit sequence of n bits occurs at most once in it, the uniqueness of the assignment of code words to corresponding absolute car positions is ensured and the determination of the absolute car position is particularly reliable and fast.

[0021] The partial bit sequences are formed using the following steps:

[0022] - An output set of n-digit partial bit sequences is generated,

[0023] - Those partial bit sequences that contain more than p consecutive identical bits are eliminated from the initial set. This ensures that the bit sequence of the code mark pattern contains at most a specified number of p consecutive identical bits. The code mark pattern thus experiences a signal change after every p bits at the latest, thus enabling self-synchronization of the code mark pattern. This ensures that the code reading device receives a suitable reference for synchronizing the code mark pattern.

[0024] If one or each subsequent n-digit partial bit sequence overlaps the preceding n-digit partial bit sequence by n-1 bits, individual code marks can be used to encode multiple code words, thus further increasing the information density of the code mark pattern. This allows the position of the elevator car to be determined particularly quickly and / or with high spatial resolution.

[0025] If the number p of consecutive identical bits is smaller than the number n of positions in the code words and at the same time n is smaller than the number N of code marks in the code mark pattern, it is ensured that a suitable reference is always available at an advantageous distance for the code reading device to be able to determine whether the currently scanned code mark represents the end or the beginning of a code word.

[0026] In a non-limiting example, for illustrative purposes only, particularly preferred ranges for the parameters are given as follows:

[0027] 2 10 < N < 2 16 , preferably 2 12 < N and / or N < 2 14 ;

[0028] 8 < n < 32, preferably 16 < n and / or n < 32;

[0029] 4 < p < 10, preferably 5 < p and / or p < 8.

[0030] If the code marks are either formed by optically detectable markings and the sensor of the code reading device is an optical sensor, or the code marks are formed by magnetic poles and the sensor of the code reading device is a magnetic reading head, or the code marks are formed by different dielectric constants and the sensor of the code reading device is a sensor that detects capacitive effects, sensors that are widely used in technology and are therefore inexpensive can be used, and the positioning system can be specifically adapted to the respective application, e.g. with regard to the degree of contamination to be expected during operation.

[0031] If the code mark pattern is attached to the guide rail or to a belt parallel to the guide rail, preferably a PET belt, a consistent number of code marks is ensured within the distance traveled by the elevator car. This prevents inaccuracies in positioning. Possible belts, including alternatives to a PET belt, are described in US Pat. No. 4,750,592 A and can be, for example, a PET belt, a textile belt, a metal belt, and / or a belt made of another plastic such as polypropylene or a polyester (also different from PET).

[0032] If the resolution of the absolute cabin position corresponds at least to the length of a code mark, and if the length of a code mark is a maximum of 10 mm, preferably a maximum of 5 mm, particularly preferably a maximum of 2 mm, or even 1 mm, the absolute cabin position can be determined particularly precisely. A resolution at least as high or even higher (i.e., finer) than that corresponding to the length of a code mark can be achieved, for example, by a fine interpolation unit as described in WO 03 / 011733 A1 or by the method described in patent application EP 23173534.1.

[0033] If each of the 8 binary numbers of bit length 3 (or more generally each of the 2 r binary numbers of bit length r with r = 3, 4 or 5) as a partial bit sequence in the bit sequence of the code mark pattern, the information density of the code mark pattern is particularly high, which increases the speed of position determination.

[0034] The object is further achieved according to the invention by a method for determining the absolute position of an elevator car movable along at least one guide rail by means of the position determination system according to one of claims 1 to 11, wherein the method comprises the following steps:

[0035] - the code mark pattern is scanned,

[0036] - code mark signals are generated from a sequence of code marks of the scanned code mark pattern,

[0037] - a code word with n bits is determined from the generated code mark signals, whereby consecutive code marks are used to determine the code word,

[0038] - the corresponding absolute car position is determined from the determined code word, - the determined absolute car position is output.

[0039] Carrying out the individual process steps ensures a fast, precise and reliable determination of the absolute position of the elevator car.

[0040] The object is further achieved according to the invention by using a position-determining system according to one of claims 1 to 11 for determining the absolute position of the elevator car. The use of a position-determining system according to the invention ensures that the absolute position of the elevator car is determined quickly, precisely, and reliably.

[0041] The use of the singular shall not exclude the plural, unless otherwise disclosed.

[0042] Short description of the characters

[0043] Further details and features will become apparent from the following description of a preferred embodiment in conjunction with the figures. The respective features can be implemented individually or in combination with one another. The possibilities for solving the problem are not limited to the embodiment. For example, range specifications always include all intermediate values ​​(not mentioned) and all conceivable subintervals.

[0044] The exemplary embodiment is shown schematically in the figures. Identical reference numerals in the individual figures denote identical or functionally equivalent elements, or elements that correspond to one another in terms of their functions. In detail:

[0045] Fig. 1 is a schematic side view of a position determination system according to the invention for determining the absolute position of an elevator car movable along at least one guide rail; and

[0046] Fig. 2 is a schematic representation of a bit sequence of an exemplary portion of the code mark pattern of the positioning system of Fig. 1 .

[0047] Description of the Figures Fig. 1 shows a position-determining system 100 according to the invention for determining the absolute position of an elevator car 120 movable along at least one guide rail 110 within an elevator shaft 105. The direction of travel of the elevator car 120 is symbolized by a double arrow within the elevator car 120. The position-determining system 100 has an absolute code mark pattern 130 fixedly mounted parallel to the direction of travel next to the elevator car 120 and a code reading device 140. The code reading device 140 itself has a sensor 142 preferably mounted on the elevator car near the code mark pattern 130 and an evaluation unit 144 connected to the sensor 142.

[0048] Multiple sensors 142 per code reading device 140 are also conceivable, wherein the sensors 142 are preferably arranged offset in the direction of travel over a range with a length greater than the length of two code marks 136 at a distance smaller than the length of one code mark 136 on a line which is congruent with the longitudinal axis of the code mark pattern 130, whereby multiple code marks 136 can be scanned simultaneously. This is particularly useful for scanning the code mark pattern 130 when the elevator car 120 is stationary, but also increases the reliability of the scanning process during the travel of the elevator car 120, since individual code marks 136 can be scanned sequentially by multiple sensors 142, and the corresponding code mark signals can be compared with one another.

[0049] Typically, the elevator car 120 is moved up and down within a (concrete) elevator shaft 105 in a building in the direction of gravity. The fixed attachment point of the code mark pattern 130 is located, for example, in the corresponding shaft head. In the elevator shaft 105, the attachment point may shift due to shrinkage / slumping of the building. The code mark pattern 130 is therefore preferably attached to a support that—unlike the elevator shaft 105 itself—does not shrink. Attachment to the guide rail 110 itself or to a belt parallel to the guide rail 110, preferably a PET belt, is conceivable here. The PET belt can be held under tension by appropriate tensioning elements (not shown in Fig. 1) and / or retensioned over time to counteract the effects of the shrinkage described above.

[0050] Preferably, the code marks 136 of the code mark pattern 130 are formed by optically detectable markings, and the sensor 142 of the code reading device 140 is an optical sensor capable of detecting the optical markings. In the preferred embodiment shown in Fig. 1, the code marks 136 are formed by white and black rectangles, with the optical sensor 142 capable of detecting whether a black or white rectangle is currently being scanned. The optical sensor 142 is, for example, an infrared sensor known from common barcode scanners.

[0051] As an alternative to optically detectable markings, the code marks 136 of the code mark pattern 130 can be formed, for example, by magnetic poles, wherein the sensor 142 of the code reading device 140 is a magnetic read head, which, for example, has a Hall sensor or a reed sensor. Likewise, the code marks 136 can be formed by different dielectric constants, wherein the sensor 142 of the code reading device 140 is a sensor that detects capacitive effects. Scanning by the sensor 142 is preferably contactless. For this purpose, the sensor 142 is preferably guided over the code mark pattern 130 at the smallest possible distance, particularly preferably at a distance of less than 1 cm. However, guidance at a greater distance from the code mark pattern 130 is also conceivable.Example physical lengths of the code marks are 1 mm for code marks formed by optically detectable markings, 7 mm for code marks formed by magnetic poles and 8 mm for code marks formed by different dielectric constants.

[0052] A particularly reliable position determination system 100 can be achieved by designing the code reading device 140, including the sensors 142 and the evaluation unit 144, redundantly. In such an embodiment, the sensors 142 of the individual code reading devices are preferably offset in the direction of travel over a range with a length greater than the length of two code marks 136 at a distance less than the length of one code mark 136 on a line that is congruent with the longitudinal axis of the code mark pattern 130.

[0053] In addition to code reading devices, at least one floor sensor (not shown in Fig. 1) can be attached to the elevator car. This sensor is also moved along with the elevator car in the elevator shaft to detect floor markings arranged at floor level in the elevator shaft. The detected floor markings are preferably transferred to an evaluation unit, which evaluates them, and based on the evaluation, sends corresponding signals to a control system of the elevator car. In this way, it can be determined even more reliably whether, for example, it is safe to open the elevator doors or whether the visual and / or optical output of the floor designation needs to be modified and / or triggered accordingly.

[0054] Fig. 2 shows an exemplary 16-digit section of a bit sequence 132 of the code mark pattern 130 of the positioning system 100 from Fig. 1. A partial bit sequence 152 consists of n=6 bits 134, wherein successive partial bit sequences 152 preferably overlap at (n-1)=5 positions, and thus individual bits 134 of the bit sequence 132 can be assigned to several partial bit sequences 152. The bit sequence has at most p=3 consecutive identical bits, so that a change between 0 and 1 or between 1 and 0 occurs after p=3 bits at the latest.

[0055] In the code mark pattern 130 itself, the logical states 1 and 0 of the individual bits 134 of the bit sequence 132 are realized, for example, by optically detectable code marks 136 in the form of white or black markings, wherein the partial bit sequences 152 each represent a code word 150 (not shown in Fig. 2).

[0056] One possible method for generating a bit sequence 132 of a code mark pattern 130 according to the invention can be implemented by stringing random bits together to form a random sequence, with the additional requirements for the bit sequence 132 being ensured by trial and error. An exemplary implementation of this principle can be as follows:

[0057] Random bits are generated in a loop and, starting from a first random bit 134, are concatenated to form a bit sequence 132 for the code mark pattern 130, with newly generated random bits being appended to the existing bit sequence 132. After each appending of a random bit, the (error) conditions (1) and optionally (2) are checked:

[0058] (1) Are the last (p+1) bits 134 of the bit sequence 130 equal? ​​(2) Do the last b bits 134 of the bit sequence 130 already occur elsewhere as a partial bit sequence 152 of the bit sequence 130?

[0059] If one of the two conditions is met, a number of the last bits 134 of the bit sequence 130 are discarded and randomly generated again. The number of last bits 134 to be discarded can be increased if the (error) conditions (1 ) and / or

[0060] (2) be increased gradually.

[0061] The above steps are repeated until a bit sequence 132 has been generated which has a previously defined number N of bits 134.

[0062] List of reference symbols

[0063] 100 Positioning System

[0064] 105 Elevator shaft

[0065] 110 guide rail

[0066] 120 elevator cars

[0067] 130 code mark patterns

[0068] 132 bit sequence

[0069] 134 bits

[0070] 136 Code mark

[0071] 140 Code reading device

[0072] 142 Sensor

[0073] 144 Evaluation unit

[0074] 150 code words

[0075] 152 partial bit sequence

Claims

Patent claims 1. A position-determining system (100) for determining the absolute position of an elevator car (120) movable along at least one guide rail (110), wherein the position-determining system (100) comprises a code mark pattern (130) fixedly mounted parallel to the direction of travel next to the elevator car (120), and a code reading device (140), wherein the code mark pattern (130) is formed as a bit sequence (132) of N consecutive code marks (136), each representing a bit (134) of the code mark pattern (130); wherein the code reading device (140) comprises a sensor (142) mounted on the elevator car (120) and an evaluation unit (144); wherein the sensor (142) is configured to scan a sequence of the code marks (136) of the code mark pattern (130) and to generate code mark signals from the code marks (136) of the sequence, the code mark signals representing the respective bits (134) of the scanned code marks (136);wherein the evaluation unit (144) is configured to receive the code mark signals from the sensor (142), to obtain a code word (150) with n consecutive bits (134) of the scanned code marks (136) from the received code mark signals, and to determine the absolute car position from the obtained code word (150); wherein the bit sequence (132) of the code mark pattern (130) has at most a specified number p of consecutive identical bits (134), wherein 2 <p<n.; 2. Position determination system (100) according to claim 1, wherein the evaluation unit (144) has a memory with the bit sequence (132) of the code mark pattern (130) and is configured to determine the absolute car position by means of an identification of the received code word (150) as a partial bit sequence (152) of the bit sequence (132).

3. Positioning system (100) according to claim 2, wherein the bit sequence (132) of the code mark pattern (130) is selected such that each sub- Bit sequence (152) of n bits (134) occurs at most once in it.

4. Positioning system (100) according to any one of the preceding claims, wherein the sequence of scanned code marks (136) is a continuous sequence.

5. Positioning system (100) according to any one of the preceding claims, wherein the partial bit sequences (152) are formed by means of the following steps: - An output set of n-digit partial bit sequences (152) is generated; - those partial bit sequences (152) which have more than p directly consecutive identical bits (134) are eliminated from the initial set.

6. Positioning system (100) according to any one of the preceding claims, wherein a subsequent n-digit partial bit sequence (152) overlaps the preceding n-digit partial bit sequence (152) by n-1 bits (134).

7. Positioning system (100) according to any one of the preceding claims, wherein p <n<N.

8. Positioning system (100) according to any one of the preceding claims, wherein at least one of a) to c): a) the code marks (136) are formed by optically detectable markings and the Sensor (142) of the code reading device (140) is an optical sensor; b) the code marks (136) are formed by magnetic poles and the sensor (142) of the code reading device (140) is a magnetic reading head; c) the code marks (136) are formed by different dielectric constants and the sensor (142) of the code reading device (140) is a capacitive effect detecting sensor.

9. Positioning system (100) according to any one of the preceding claims, wherein the code mark pattern (130) is applied to the guide rail (110) or to a belt parallel to the guide rail (110), preferably a PET belt.

10. Positioning system (100) according to any one of the preceding Claims, wherein the resolution of the absolute cabin position is less than or equal to the length of a code mark (136) and the length of a code mark (136) is a maximum of 10 mm, preferably a maximum of 5 mm and particularly preferably a maximum of 1 mm.

11. Positioning system (100) according to any one of the preceding Claims, wherein each of the binary numbers of bit length 3 occurs as a partial bit sequence (152) in the bit sequence (132) of the code mark pattern (130).

12. Method for determining the absolute position of a signal along at least one Guide rail (110) movable elevator car (120) by means of the position determination system (100) according to any one of the preceding claims, wherein the method comprises the following steps: - the code mark pattern (130) is scanned; - code mark signals are generated from a sequence of code marks (136) of the scanned code mark pattern (130); - a code word (150) with n bits (134) is determined from the generated code mark signals; - the corresponding absolute cabin position is determined from the determined code word (150); - the determined absolute cabin position is output.

13. Use of a positioning system (100) according to one of the claims 1 to 11 for determining the absolute position of the elevator car (120).

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