HK1049141B - Method to obtain shaft information for an elevator controller - Google Patents

Description

The invention relates to a method for generating shaft information from a shaft control of an elevator shaft with a lift cabin which can be driven in the shaft, whereby the shaft information is generated from pictorial patterns.

The patent EP 0 722 903 B1 is a device for generating shaft information of an elevator shaft. In the shaft, a reflector with a code is placed in the area of a stop. The code has two identical tracks. An entry area of a stop where the crossing of door contacts is allowed is half above and half below a level line. A retrofitting area where the crossing of door contacts is allowed in a door of an elevator descending by a rope extension at open doors is half above and half below the level line. The code of the reflectors is calculated and evaluated by a two-way direction measured on the lift shaft. The direction measured by a transmitter is calculated by means of a reflector. The information is recorded on the screen of a reflector unit and the reflector is measured.

A disadvantage of the known device is that the production of patterns requires a code strip arranged in the lift shaft. The code strip must be arranged precisely and without overstretching in the lift shaft. Furthermore, it is not guaranteed that the code strip will not detach itself from the document in whole or in part.

The purpose of the invention, as described in claim 1, is to avoid the disadvantages of the known device and to specify a system and a process by which the generation of shaft information for elevator control can be guaranteed in any case.

The advantages of the invention are mainly that no additional installation is necessary in the elevator shaft. The installation time of the elevator can be significantly shortened. To generate the shaft information, a sensor-equipped evaluation unit located in the elevator shaft is sufficient. The structures in the shaft make it possible to implement a very reliable and cost-effective shaft information system with high resolution. The shaft information system provides an absolute position even when starting the elevator shaft without the need for extraction procedures.

The figures in the attached table give a detailed explanation of the present invention.

It shows: The following table shows the figures: a schematic representation of the system of the invention,Fig. 2 the procedure for determining the incremental or relative position of a section of a shaft structure and the procedure for determining the absolute position of a section covered.

Fig. 1 shows the system for generating shaft information according to the invention. 1 is a guide rail with a guide rail foot 1.1 which is used as shaft equipment and is located in a lift shaft 2. The current direction of travel of the lift cabin is indicated by an arrow P1. At the lift cabin, a CCD linear camera 3 with an optical and a CCD target sensor is located. The CCD target sensor is located in the upper direction of the lift shaft P1 and has, for example, 128 elements. In this arrangement, for example, section 1.1 of the guide rail may be used to guide a loaded lift cabin 1 cm in the direction of loading. For example, the light sensor can be measured in the direction of loading. For example, in section 2 the image can be measured in c. 1 cm. The image can be captured by a CCD camera and the image can be transmitted at a speed of 1000 Hz. The image can be captured by a camera with a guide and the image can be transmitted at a speed of 3 Hz.

A lighting 4 illuminates the section of the guide rail to be detected, converting the light reflected on the section into charges of the image elements of the CCD aiming sensor. To improve the image quality, lighting 4 may be provided by flashing LEDs or halogen lamps. Furthermore, the image quality may be improved by digital filtering and/or certain image processing methods.

For example, instead of the surface structure or surface pattern of the guide rail 1, the surface structure or surface pattern of the wall structure of the lift shaft 2 or the surface structure or surface pattern of structural parts (steel support) of the lift shaft 2 can be captured by the CCD line camera 3.

To calibrate the shaft information system, the elevator shaft 2 is run through; during this calibration run, the surface structure or surface pattern recorded by the CCD line camera 3 is stored in the computer memory together with a position index; to determine the stop position for a floor, the elevator cabin is run to the desired height, the position is recorded by the system and managed as floor value.

To increase safety, two redundant systems may be provided. One system may record the surface structure or surface pattern of one guide rail, the other the surface structure or surface pattern of the other guide rail. Alternatively, both systems may record the surface structure or surface pattern of the same guide rail. The output signals of one system may be used as a training signal for the other system and vice versa. If the surface structure or surface pattern of one guide rail has changed since calibration, the new surface structure or surface pattern may be provided with the position data of the other system.

Figure 1 shows the method for determining the image of the surface structure or surface pattern of the guide rail section of position i+1. The new image with position i+1 is represented by a broken line and overlaps with the image of position i. The image data is transmitted to the non-represented computer with memory. The first software-realised correlator I of the computer is calculated from the image of position i and the new image of position i+1 in a computer-based system.The estimated position of the image with the position i+1 is fed to a second correlator II of the computer implemented in software, which uses the estimated position to locate the relevant database section in which the image obtained during calibration is located. As explained above, the obtained image is provided with a position index. The correlator II compares the new image of position i+1 with the obtained image and determines the absolute position i+1 based on the position index, which is transmitted to the lift control.

Changes in the surface structure or surface pattern of the guide rail 1 during lift operation can be continuously retrieved by the database.

As described above, a CCD line camera 3 with an optic and a CCD aim sensor is provided. A two-dimensional area sensor may also be provided instead of the line sensor. The image elements of the dimension perpendicular to the direction of travel are averaged, creating a one-dimensional brightness profile.

The speed v of the lift cab can be determined from the difference between position p1 at time t1 and position p2 at time t2. $\text{v = (p2-p1) / (t2-t1)}$

Instead of the CCD line camera 3, a dual sensor system can also be used with two LEDs as light sources and two photo-resistors as brightness detectors. In a moving elevator cabin, this corresponds to one signal being a time-delayed representation of the other signal. The two signals can be compared by correlation methods and the speed of the elevator cabin can be determined by the time delay and distance of the sensors.

In the case of correlation (correlator I or correlator II), a current image is correlated with a reference image. First, a correlation window is extracted and then pixelwise pushed over the reference image. For each window pixel, the difference in pixel grayscale is determined and then their squares are added.

The pixel-wise calculation of correlation values also allows the derivation of a reliability value. At the corresponding point, the correlation values have a minimum, because two quasi-identical images have a distance of approximately zero. For the calculation of a reliability value ZW, the absolute minimum aM, the second best minimum zM and the standard deviation S over the entire correlation length are used. $\text{ZW = (zM-aM) / S}$

A very good reliability value is obtained at lower lift cab speeds, with good incremental correlation (two successive images with overlap) and database correlation (complete map of the track surface in the database).

If the control surface has changed, a good reliability value is obtained at lower lift cab speeds, with good incremental correlation (two consecutive overlapping images) and poor database correlation (incomplete control surface representation in the database).

If the track gauge has not changed, a good reliability value is obtained at higher lift cab speeds, with a poor incremental correlation (two consecutive images with little overlap) and a good database correlation (complete map of the track gauge in the database).

If the track surface has changed, a poor reliability value is obtained at higher lift cab speeds, with poor incremental correlation (two consecutive images with little overlap) and poor database correlation (incomplete map of the track surface in the database).

Fig. 2 shows the process for determining the incremental or relative position of a section captured, e.g. the guide rail. The first correlator I of the computer, implemented in software, calculates an incremental or relative position from the image of position i and the new image of position i+1. In a first step S1, a one-dimensional image with pixels or pixels is extracted or generated from the image data of the CCD line camera 3. The image, also called image vector or brightness vector, is then passed through a high-pass and low-pass filter stage in step S2.The light vector is filtered with a low pass filter to eliminate thermal noise from the CCD linear camera. In step S3, a correlation window or correlation vector of defined length is taken from the processed image vector or brightness vector of position i+1, whereby the correlation window is pushed pixelwise across the image vector of the previous image i in step S4. In step S5, the distance between pixel i+1 and pixel i is calculated per pixel. Next, in step S6, the relative shift between the image of position i and the image of position i+1 is determined. In Fig. 1 the relative position is denoted with an incremental position.The new absolute position, called the estimated position in Fig. 1, is decisive for locating the relevant database section.

Fig. 3 shows the process for determining the absolute position of a section captured, for example the guide rail. The second correlator II of the computer, implemented in software, calculates an absolute position from the image of position i and the new image of position i+1. In a tenth step S10, a one-dimensional image with pixels is extracted or generated from the image data of the CCD line camera 3. The image, also called image vector or brightness vector, is then passed through a high-pass and low-pass filter stage in step S11. By processing the image vector or lightness vector, external shock effects are processed with respect to illumination throughput by means of a high-pass filter.

Claims (8)

1. Method of generating, to serve an elevator control, hoistway information from an elevator hoistway with an elevator car which can travel in an elevator hoistway, the hoistway information being generated from pictorially recognizable patterns and wherein the hoistway information is generated from patterns present in the elevator hoistway, characterized in that the surface structure of components or equipment in the hoistway which serve other functions is used as patterns.
2. Method according to Claim 1, characterized in that from the patterns which are recorded sector by sector images are generated, and a relative position of a current image to a preceding image, and an absolute position of the current image, are determined.
3. Method according to Claim 1 or 2, characterized in that from the overlap of an image of position i+1 with an image of position i a relative position is determined, and with the relative position and absolute position of the image i an estimated position is determined, which serves to locate a sector of an image database, and from a comparison of the located database image with the current image the absolute position of the current image is determined.
4. Method according to Claim 3, characterized in that determination of the position takes place by means of a comparison of the individual pixels of the image, the distance from the current pixel to a previously known pixel serving as criterion for determining the position.
5. Method according to Claim 3 or 4, characterized in that to check the positions a reliability value is determined.
6. Method according to Claims 3 to 5, characterized in that to generate the image database the elevator hoistway is traveled through and the patterns which are recorded are assigned a position index and stored in the image database.
7. Method according to one of the foregoing claims, characterized in that the surface structure of a guiderail arranged in the elevator hoistway, or the walls of the elevator hoistway, is used as a pattern.
8. Method according to one of the foregoing claims, characterized in that at least one system comprising a CCD line camera and a processor with memory records the patterns and determines the positions.