HK1108420B - Elevator car positioning determining system - Google Patents

Description

Elevator car position determining system

Technical Field

The present invention relates to a system and method for determining the position of a moving object, and more particularly to a system and method for determining the position of an elevator car.

Background

A technique known as PVT position approximation has been widely used in the industry to determine the position of an elevator car. PVT technology uses a digital shaft encoder, also known as a PVT counter, typically mounted on the main shaft of the crane motor, which can be used to track the displacement and direction of the car between detection points. PVT technology uses machine encoder (also known as primary velocity transducer or PVT) information associated with a bridge plate (vane) mounted at a fixed location in the hoistway. PVT-based approximation systems can have errors due to rope elongation, slippage, etc., and thus determining the car position in the fast zone becomes a particular challenge. The car position can be corrected when a door zone bridge at the end of the express zone is detected. However, the longer the fast zone, the more difficult it is to combine PVT-based position feedback with bridge-plate-based position feedback. To provide a smoother transition, additional bridge plates are installed in the express zone, thereby increasing installation costs.

Elevator safety codes require providing traction elevators with terminal stopping devices such as Normal Terminal Stopping Device (NTSD), Emergency Terminal Speed Limiting Device (ETSLD), Emergency Terminal Stopping Device (ETSD), and final terminal stopping device. ETSLD is used for elevators with a buffer with reduced stroke (stroke buffer), while ETSD is used for elevators with a full stroke buffer. These devices use car position and speed information near the top and bottom of the hoistway to: (1) causing controlled deceleration of the car and stopping at or near the terminal landing (NTSD), or (2) generating an emergency stop by removing power to the drive motor and brake (ETSD and ETSLD and final terminal stop).

The protocol also requires independence between the normal control system, NTSD, and ETSD, as described below. The operation of the ETSLD must be completely independent of the operation of the NTSD. The car speed sensing device of the ETSLD must be independent of the normal speed control system. The ETSD must operate independently of the NTSD and normal speed control system.

The main drawback of the existing systems is the relatively high installation cost caused by the multiple sensors and bridge plates mounted on different tracks (for NTSD, ETSD and door zones) and the additional channels on the machine speed encoder.

Disclosure of Invention

It is therefore an object of the present invention to provide an improved elevator car position determination system and method.

The foregoing objects are achieved by the elevator car position determination system and method of the present invention.

According to the invention, a method of determining the position of a moving object, such as the position of an elevator car in an elevator hoistway, comprises the steps of: mounting the leading sensor and the lagging sensor to the moving object with the leading sensor and the lagging sensor spaced apart by an offset distance; mounting a plurality of spaced apart position indicators along a path of a moving object; sending signals from the lead sensor and the lag sensor indicative of the position of the object to the controller as the sensors pass the spaced position indicators; and filling a discontinuity in the signal collected from one of the sensors with a correction factor established by the position and offset distance sensed by the other sensor.

Preferably, the filling step comprises filling any discontinuity in the signal collected by the leading sensor with the position sensed by the lagging sensor plus the offset distance. More preferably, the filling step comprises filling any gaps in the signal collected by the lagging sensor with the position sensed by the leading sensor minus the offset distance.

Preferably, the installing step includes installing the sensor to an elevator car, and the installing the indicator step includes installing a plurality of spaced smart vanes at spaced landings.

Preferably, the signaling step includes signaling the signal from the lagging sensor as a primary position control signal, and the filling step includes determining car position based on PVT feedback when neither of the two sensors senses one of the smart vanes.

Preferably, the filling step further comprises performing a first position correction when the lead sensor begins reading the bridge plate at the destination floor and performing a second position correction when the lag sensor begins reading the bridge plate at the destination floor.

Preferably, the first position correction comprises applying a correction factor based on a difference between a position feedback signal generated by the leading sensor and a position feedback derived from the PVT, and wherein the second position correction comprises applying a correction factor based on a difference between a position feedback signal generated by the lagging sensor and a position feedback derived from the PVT.

Preferably, the indicator mounting step includes mounting a plurality of smart bridge plates on the rail. More preferably, the indicator mounting step comprises mounting the position indicator to a plurality of door sills to track building settlement.

Preferably, the method further comprises implementing normal end stop means (NTSD) using said object position representative signal from said lead sensor and a velocity signal derived from said lead sensor object position representative signal, and implementing emergency end stop means (ETSD) using said object position representative signal from said lag sensor and a velocity signal derived from said lag sensor object position representative signal. More preferably, the method further comprises alternately activating said sensors, such as said leading sensor and said lagging sensor, as a function of direction of travel. According to the present invention, a position determination system for a moving object includes a leading sensor and a lagging sensor mounted to the moving object with the leading sensor and the lagging sensor spaced apart by an offset distance. The system further comprises: a plurality of spaced apart position indicators mounted along the path of the moving object; means for receiving signals from the leading sensor and the lagging sensor indicative of the position of the moving object as the sensor passes the spaced position indicators; and means for filling in a discontinuity in the signal collected from one of the sensors with a correction factor established by the position and offset distance sensed by the other sensor. In another aspect of the invention, the system may include means for filling in discontinuities in the signals collected by the two sensors using correction factors derived from the PVT signals.

Preferably, the padding means comprises means for padding any discontinuity in the signal collected by the leading sensor with the position sensed by the lagging sensor plus the offset distance, and means for padding any discontinuity in the signal collected by the lagging sensor with the position sensed by the leading sensor minus the offset distance.

Preferably, the moving object is an elevator car, and the indicator is a plurality of spaced smart vanes installed at spaced landings.

Preferably, said signal collection means includes means for taking the signal from said lagging sensor as the primary position control signal and said shimming means includes means for determining car position based on PVT feedback when neither of said two sensors senses one of said smart vanes.

More preferably, the filling device further comprises means for performing a first position correction when the leading sensor starts reading the bridge at the destination floor, and means for performing a second position correction when the lagging sensor starts reading the bridge at the destination floor.

Preferably, said first position correction enforcement device comprises means for applying a correction factor based on a difference between a position feedback signal generated by said lead sensor and a position feedback derived from said PVT, and wherein said second position correction enforcement device comprises means for applying a correction factor based on a difference between a position feedback signal generated by said lag sensor and a position feedback derived from said PVT.

Other details, other objects, and advantages of the elevator car position determination system of the present invention are set forth in the following detailed description and the accompanying drawings in which like reference numerals refer to like elements.

Drawings

Fig. 1 is a schematic view of an elevator car position determining system according to the present invention;

fig. 2 shows sensor feedback for a dual sensor configuration, where at least one sensor reads elevator car position information at any time;

FIG. 3 illustrates the sensor feedback of FIG. 2 including the resultant position in the discontinuity;

FIG. 4 shows sensor feedback for an alternative embodiment of a dual sensor configuration;

FIG. 5 shows the sensor feedback of FIG. 4 including the resultant position in the discontinuity; and

fig. 6 shows an alternative embodiment of an elevator car position determining system.

Detailed Description

Referring now to the drawings, fig. 1 illustrates an elevator car position determination system 10. System 10 includes an elevator car 12 that moves in an elevator hoistway 14. Car 12 has a first sensor 16 mounted on its top and a second sensor 18 mounted on its bottom. The sensors 16 and 18 are offset from each other by a distance D. Depending on the movement of the car 12, one of the sensors 16 and 18 will be the leading sensor (the first sensor in the direction of movement) and the other will be the lagging sensor (the second sensor in the direction of movement). Although the sensors 16 and 18 are described as being mounted to the top and bottom of the car, they could be mounted in other locations if desired, so long as they are aligned with and offset from each other by a certain distance.

The sensors 16 and 18 are each in communication with a controller 20. The controller 20 may be any suitable processor known in the art.

The system 10 also includes a plurality of spaced apart position indicators 22. Each position indicator 22 may be mounted to a landing door strut (door strut)24 or a doorsill, if desired, by a plurality of mounting brackets (mounting brackets) 26. One advantage of mounting the position indicator to a landing door pillar or sill is that the position of the indicator 22 can change as the building settles, thereby always providing a true indication of the landing position. Alternatively, the position indicator 22 may be mounted on a guide rail of the elevator car.

The position indicator 22 may comprise any suitable position indicator or smart bridge known in the art. For example, the position indicator 22 may be comprised of discrete portions of a coded perforated tape. In this case, sensors 16 and 18 may include optical sensors that convert the perforation pattern in indicator 22 into unique absolute positions.

Alternatively, the position indicators 22 may be comprised of intelligent vanes, such as coded track sections, wherein each section is located at one of the landings. Each encoded track portion may comprise a series of marks spaced apart from each other by a desired distance, such as 0.25 m. The code track portions may be spaced apart by a distance that is less than the distance D between the sensors 16 and 18. In systems employing encoded track sections, the sensors 16 and 18 may be cameras. The encoded track sections may be encoded with numbers, each number indicating a position in the hoistway. These numbers may represent any value that enables the elevator control to determine the exact position of the car in the hoistway in a unique, non-repetitive manner. The controller 20 may be programmed in any suitable manner known in the art to acquire the information received from the sensors 16 and 18 and generate an elevator car position signal. A position reference system using coded track sections as described herein is shown in us patent 6435315, which is incorporated herein by reference.

Alternatively, the position indicator 22 may be a smart bridge formed from a plurality of spaced magnetic strips, wherein each magnetic strip has an absolute position track and an incremental position track. The absolute position track on each magnetic strip may include a plurality of differently sized magnets arranged in a single, distinct and non-repeating pattern. For example, there may be alternating small and large magnets forming different patterns. The incremental position tracks on each magnetic strip may include a plurality of equally spaced magnets. The sensors 16 and 18 in such systems may be magnetic sensors that provide their outputs to the controller 20. Each sensor 16 and 18 may comprise any suitable magnetoresistive sensor and/or hall effect sensor array (such as a magnetoresistive sensor manufactured by Siko GmbH) known in the art for detecting and measuring the strength of the magnetic field generated by the magnets forming the pattern in the absolute position track and the magnets forming the incremental position sensor track. As previously described, the spacing between the position indicators 22 is less than the distance D between the sensors 16 and 18. In operation, each sensor 16 and 18 detects a unique magnetic field signature of a particular pattern of absolute position tracks. In this way, the controller knows the position of the car within the hoistway. These sensors also detect the magnetic field generated by the magnets forming the incremental position tracks and thereby determine the speed of the elevator car.

If desired, the system 10' according to the present invention may have a magnetic strip, smart vanes, position indicators 22 mounted to the guide rails 34 instead of the landing door posts or sills as described above. When installed in such a location, the position indicator 22 no longer tracks building settlement. Thus, as shown in fig. 6, a third sensor 50 may be mounted on the car 12, and a sensor target 52 may be fixedly mounted at each landing. The output of the third sensor 50 may be provided to the controller 20.

In a first embodiment of the invention, two sensors 16 and 18 are mounted in-line on car 12. The intelligent bridge plate position indicator 22 is installed as shown in fig. 1. The sensors 16 and 18 and the position indicators 22 are arranged so that at least one sensor reads a portion of at least one position indicator at any one time. Fig. 2 shows position feedback from each of the sensors 16 and 18 provided to the controller 20. As can be seen from fig. 2, when the leading sensor (sensor 1) passes from one position indicator 22 to the next, there is no position feedback signal from the sensor when it is in the gap between the position indicators 22. However, position feedback is provided by the lagging sensor (sensor 2) which is still reading the position indicator. Similarly, when the lagging sensor (sensor 2) passes from one position indicator 22 to the next, there is no position feedback signal from the sensor when it is in the gap between the position indicators 22. However, position feedback is provided by the leading sensor (sensor 1) which is still reading the position indicator.

As shown in fig. 3, the controller 20 is programmed to fill in discontinuities 40 and 42 in the signals of sensor 1 and sensor 2. This is achieved by applying a correction factor derived from the position feedback signal from sensor 2 plus the offset distance in the presence of the signal from sensor 1 and discontinuity 40. In the presence of the signal from sensor 2 and discontinuity 42, this is done by applying a correction factor derived from the position feedback signal from sensor 1 minus the offset distance. The controller 20 may be programmed with any suitable algorithm to be the means to collect signals from the sensors 16 and 18 and the means to fill in discontinuities in the position signals collected from the sensors 16 and 18.

As a result of employing the above methods and systems, the absolute hoistway position of elevator car 12 can be determined at any point in time.

In an alternative embodiment of the invention, the two sensors 16 and 18 are mounted in line on the elevator car, as described above. However, in this case, the position indicators 22 are installed only at the landings and not in the express zones. The position indicator in such a configuration can be shorter, thereby saving installation costs.

In this embodiment, the sensors 16 and 18 may each be offset from the position indicators at various locations in the hoistway and, therefore, may not provide a position signal to the controller 20. The controller 20 can thus be programmed to estimate the position of each sensor (and thus the car) during periods of no signal using PVT (primary velocity transducer) feedback techniques. In this technique, an optical encoder is used. The optical encoder typically produces 1024 pulses per cycle. The controller 20 counts the pulses and estimates the distance traveled and, thus, the position of the elevator car 12 in the hoistway. This is illustrated in fig. 4 and 5, where the PVT correction factors are shown in dashed lines in the figures.

Referring now to fig. 4 and 5, the car is assumed to travel upwards for reasons such as the manner in which the sensors are located on the car 12, sensor 16 (sensor 1) leading sensor 18 (sensor 2) and direction of travel in the hoistway position. At the start of the operation, the hysteresis sensor (sensor 2) is designated as the master of the position control. As the car begins to move, the lagging sensor (sensor 2) leaves the position indicator 22 and after a certain time, when both sensors are off the bridge plate, the car position is estimated using the PVT feedback technique described above and by the controller 20. As the car approaches the destination floor, the lead sensor (sensor 1) begins reading the position indicator at that floor. At this time, the sensor 2 is farther from the destination floor (by a distance equal to the distance between the two sensors 16 and 18) than the sensor 1, and the first position correction is performed by the controller 20. This first position correction is the application of a correction factor based on the difference between the position feedback signal generated by the lead sensor (sensor 1) and the position feedback derived from PVT. When the hysteresis sensor (sensor 2) as the main device of the position control starts reading the position indicator at the destination floor, the controller 20 performs the second position correction. The second position correction is the application of a correction factor based on the difference between the position feedback signal generated by the lagging sensor (sensor 2) and the position feedback derived from the PVT.

The method utilizes the spacing between the two sensors 16 and 18 to perform two position corrections. The leading sensor acts as a location look-ahead device allowing early location correction, while the lagging sensor is used for second location correction and leveling of the floor. The method also enables a smoother transition between PVT-based car estimation and car position based on position indicators or smart vanes. This eliminates the need for additional decks in the hoistway.

The system shown herein may be used to implement NTSD and ETSD/ETSLD functions. This is because the sensors 16 and 18 provide all the information needed to implement the NTSD and ETSD/ETSLD functions. In the embodiment shown in fig. 2-5, sensor 16 may be used for NTSD and sensor 18 may be used for ETSD regardless of the direction of travel. Preferably, the length of the coded track portion (smart vanes) in the terminal zone is such that the sensors 16 and 18 can simultaneously read the coded track portion in that zone (when the elevator car is in that zone). In this case, NTSD may be performed with the position generated by sensor 16 and the velocity derived from the position information of sensor 16, and ETSD may be performed using sensor 18 and the velocity derived from the position information of sensor 18. Speed information for NTSD and ETSD may be derived by the controller 20. Table I summarizes the main differences between the prior art and the proposed embodiment of the present invention.

TABLE I

	Normal position and speed control	NTSD	ETSD/ETSLD
				Prior Art	Position:machine encoder (channel A and B) + door zone sensor + door zone bridge plateMachine encoder (channel A and B)	Position:NTSD sensor + NTSD bridge plateMachine encoder (channel A and B)	Position:ETSD/ETSLD sensor + ETSD/ETSLD bridge plateMachine encoder (channel C)
The invention (use the ordinary intelligent bridge plate)	Position:sensor 2Machine encoder (channel A and B)	Position:sensor 1SensingDevice 1	Position:sensor 2Sensor 2

Also, in the embodiments shown in fig. 2-5, the sensors associated with NTSD and ETSD functions (e.g., leading sensors for NTSD and lagging sensors for ETSD) take turns depending on the direction of travel. Thus, depending on the direction of travel, position information for the NTSD function may be determined from the sensor 16 or 18, and the velocity may be derived from the position information generated by the sensor 16 or 18. Depending on the direction of travel, position information for the ETSD function may be determined from the sensors 16 or 18, and the speed may be derived from the position information generated by the sensors 16 or 18. The speeds for NTSD and ETSD may be derived by the controller 20.

The position determination methods shown herein have many advantages, including: the installation cost is greatly saved; dual sensor redundancy, which eliminates the need for separate devices for NTSD, ETSD and separate speed checks; the correction in case of loss of absolute position due to instantaneous power-off of the building is avoided; automatic floor table (floor table) adjustment upon detection of excessive building settlement; and a smoother transition between the various position feedbacks (from PVT-based car position to absolute position based on position indicators).

Although the position determination system of the present invention is described in the context of an elevator system moving through a hoistway, the position determination system may be used in other environments to determine the position of various types of moving objects. For example, the moving object may be a vehicle (e.g., a train, a car, etc. traveling along a track).

It is apparent that there has been provided in accordance with the present invention an elevator car position determining system which fully satisfies the objects, means, and advantages set forth hereinbefore. While the invention has been described in terms of specific embodiments, other alternatives, modifications, and variations will become apparent to those skilled in the art upon reading the foregoing description. It is therefore intended to embrace those alternatives, modifications, and variations as fall within the broad scope of the appended claims.

Claims (17)

1. A method for determining the position of a moving object, comprising the steps of:

mounting a leading sensor and a lagging sensor to the moving object with the leading sensor and the lagging sensor spaced apart by an offset distance;

mounting a plurality of spaced apart position indicators along a path of the moving object;

sending signals representative of the position of the object from the leading sensor and the lagging sensor to a controller when the sensors pass the spaced position indicators; and

filling any gaps in the signal collected from another one of the sensors using a correction factor established from the position sensed by one of the sensors and the offset distance.

2. The method of claim 1, wherein the filling step comprises filling any discontinuity in the signal collected by the leading sensor with the position sensed by the lagging sensor plus the offset distance.

3. The method of claim 1, wherein the filling step comprises filling any discontinuity in the signal collected by the lagging sensor with the position sensed by the leading sensor minus the offset distance.

4. The method of claim 1, wherein the installing step includes installing the sensor to an elevator car and the installing an indicator step includes installing a plurality of spaced smart vanes at spaced landings.

5. The method of claim 4, wherein the signaling step comprises sending the signal from the lagging sensor as a primary position control signal, and the padding step comprises determining car position from PVT feedback when neither of the two sensors senses one of the smart vanes.

6. The method of claim 5 wherein the padding step further comprises performing a first position correction when the lead sensor begins reading a bridge plate at a destination floor and performing a second position correction when the lag sensor begins reading a bridge plate at the destination floor.

7. The method of claim 6, wherein the first position correction comprises applying a correction factor based on a difference between a position feedback signal generated by the lead sensor and a position feedback derived from the PVT, and wherein the second position correction comprises applying a correction factor based on a difference between a position feedback signal generated by the lag sensor and a position feedback derived from the PVT.

8. The method of claim 1, wherein the indicator mounting step comprises mounting a plurality of smart vanes on a rail.

9. The method of claim 1, wherein the indicator mounting step comprises mounting the position indicator to a plurality of door sills to track building settlement.

10. The method of claim 1, further comprising implementing a normal end stop device (NTSD) using the object position representative signal from the lead sensor and a velocity signal derived from the object position representative signal from the lead sensor, and implementing an emergency end stop device (ETSD) using the object position representative signal from the lag sensor and a velocity signal derived from the lag sensor object position representative signal.

11. The method of claim 10, further comprising alternately activating the sensors, such as the lead sensor and the lag sensor, as a function of direction of travel.

12. A position determination system for a moving object, comprising:

a lead sensor and a lag sensor mounted to the moving object, the lead sensor being spaced from the lag sensor by an offset distance;

a plurality of spaced apart position indicators along a path of the moving object;

means for receiving signals from said leading sensor and said lagging sensor indicative of the position of said moving object as said sensors pass said position indicators spaced from each other; and

means for filling any discontinuity in the signal collected from another one of the sensors with a correction factor established from the detected position and the offset distance from one of the sensors.

13. The system of claim 12, wherein the padding means comprises means for padding any discontinuity in the signal collected by the leading sensor with the position sensed by the lagging sensor plus the offset distance, and means for padding any discontinuity in the signal collected by the lagging sensor with the position sensed by the leading sensor minus the offset distance.

14. The system of claim 12, wherein the mobile object is an elevator car and the indicator is a plurality of spaced smart bridge plates mounted at spaced landings.

15. The system of claim 12 wherein said signal collection means includes means for taking the signal from said lagging sensor as the primary position control signal and said shimming means includes means for determining car position based on PVT feedback when neither of said two sensors senses one of said smart vanes.

16. The system of claim 15 wherein the shimming device further comprises means for performing a first position correction when the lead sensor begins reading a bridge at a destination floor and means for performing a second position correction when the lag sensor begins reading a bridge at the destination floor.

17. The system of claim 16, wherein the first position correction enforcement device comprises a device that applies a correction factor based on a difference between the lead sensor generated position feedback signal and the PVT derived position feedback, and wherein the second position correction enforcement device comprises a device that applies a correction factor based on a difference between the lag sensor generated position feedback signal and the PVT derived position feedback.