ELEVATOR CAR COMMUNICATION SYSTEM

Abstract

An elevator system (2) comprises an elevator car (4a-d) that is moveable within a hoistway (6a-d). The elevator car (4a-d) comprises a first wireless communication unit (12a-d). A controller (8a-d) is arranged to communicate with the elevator car (4a-d) , the controller (8a-d) comprising a second wireless communication unit (14a-d). The first and second wireless communication units (12a-d, 14a-d) are arranged to exchange elevator operational data using a wireless communication protocol. Each data symbol within a set of data symbols corresponding to the elevator operational data is modulated onto a plurality of orthogonal sub-carriers using an orthogonal frequency division multiplexing modulation scheme. The modulated plurality of orthogonal sub-carriers are transmitted between the first and second wireless communication units (12a-d, 14a-d) over a wireless interface (16a-d).

Claims

1. An elevator system comprising: an elevator car moveable within a hoistway, said elevator car comprising a first wireless communication unit; and a controller arranged to communicate with the elevator car, said controller comprising a second wireless communication unit; wherein the first and second wireless communication units are arranged to exchange elevator operational data using a wireless communication protocol, wherein each data symbol within a set of data symbols corresponding to said elevator operational data is modulated onto a plurality of orthogonal sub-carriers using an orthogonal frequency division multiplexing modulation scheme; and wherein the modulated plurality of orthogonal sub-carriers are transmitted between the first and second wireless communication units over a wireless interface.

2. The elevator system as claimed in claim 1, wherein the first wireless communication unit is located on top of the elevator car.

3. The elevator system as claimed in claim 1, wherein the second wireless communication unit is located within or proximate to the hoistway, optionally wherein the second wireless communication unit is located at the top of the hoistway.

4. The elevator system as claimed in claim 1, wherein the elevator car comprises a car board arranged to generate elevator operational data.

5. The elevator system as claimed in claim 1, wherein the controller generates elevator operational data.

6. The elevator system as claimed in claim 1, comprising a plurality of elevator cars and/or a plurality of hoistways.

7. The elevator system as claimed in claim 1, comprising a plurality of controllers, optionally wherein the plurality of controllers are connected to a group controller arranged to control said plurality of controllers.

8. The elevator system as claimed in claim 1, wherein: a transmitter within the first wireless communication unit and/or a transmitter within the second wireless communication unit has a transmission power of at least 20 dBm, preferably at least 25 dBm, and most preferably at least 27 dBm; and/or a receiver within the first wireless communication unit and/or a receiver within the second wireless communication unit has a sensitivity of at least −80 dBm, for example at least −81 dBm, and preferably has a sensitivity of at least −90 dBm.

9. The elevator system as claimed in claim 1, wherein the modulated sub-carriers carrying the elevator operational data are modulated using at least one modulation scheme from the group consisting of: binary phase-shift keying (BPSK); quadrature phase-shift keying (QPSK); 16-state quadrature amplitude modulation (16-QAM); and 64-state quadrature amplitude modulation (64-QAM).

10. The elevator system as claimed in claim 1, wherein the modulated sub-carriers have a sub-carrier spacing upper bound of 156.25 kHz, and/or wherein a minimal channel bandwidth is between 1.0 MHz and 1.2 MHz.

11. The elevator system as claimed in claim 1, wherein the wireless communication protocol includes a guard interval duration of at least 1.6 μs.

12. The elevator system as claimed in claim 1, wherein the wireless communication protocol conforms to the IEEE 802.11p standard, optionally wherein the wireless communication protocol implements only the PHY and the MAC layers of the IEEE 802.11p standard.

13. A wireless communication system for use in an elevator system comprising an elevator car moveable within a hoistway and a controller arranged to communicate with the elevator car, wherein the wireless communication system comprises: a first wireless communication unit for use with the elevator car; and a second wireless communication unit for use with the controller; wherein the first and second wireless communication units are arranged to exchange elevator operational data using a wireless communication protocol, wherein each data symbol within a set of data symbols corresponding to said elevator operational data is modulated onto a plurality of orthogonal sub-carriers using an orthogonal frequency division multiplexing modulation scheme; and wherein the modulated plurality of orthogonal sub-carriers are transmitted between the first and second wireless communication units over a wireless interface.

14. A method of operating an elevator system comprising an elevator car moveable within a hoistway and a controller arranged to communicate with the elevator car, wherein the method comprises: providing a first wireless communication unit for use with the elevator car; providing a second wireless communication unit for use with the controller; exchanging elevator operational data using a wireless communication protocol, wherein each data symbol within a set of data symbols corresponding to said elevator operational data is modulated onto a plurality of orthogonal sub-carriers using an orthogonal frequency division multiplexing modulation scheme; and transmitting the modulated plurality of orthogonal sub-carriers between the first and second wireless communication units over a wireless interface.

15. A non-transitory computer-readable medium comprising instructions that, when operated by a processor, cause the processor to carry out a method of operating an elevator system comprising an elevator car moveable within a hoistway and a controller arranged to communicate with the elevator car, wherein the method comprises: providing a first wireless communication unit for use with the elevator car; providing a second wireless communication unit for use with the controller; exchanging elevator operational data using a wireless communication protocol, wherein each data symbol within a set of data symbols corresponding to said elevator operational data is modulated onto a plurality of orthogonal sub-carriers using an orthogonal frequency division multiplexing modulation scheme; and transmitting the modulated plurality of orthogonal sub-carriers between the first and second wireless communication units over a wireless interface.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Certain examples of the present disclosure will now be described with reference to the accompanying drawings, in which:

[0035] FIG. 1 is a schematic drawing of an elevator system having a wireless communication system in accordance with an example of the present disclosure;

[0036] FIG. 2 is a schematic drawing of an alternative elevator system having a wireless communication system in accordance with a further example of the present disclosure; and

[0037] FIG. 3 is a schematic drawing of a further alternative elevator system in accordance with a further example of the present disclosure.

DETAILED DESCRIPTION

[0038] FIG. 1 is a schematic drawing of an elevator system 2 having a wireless communication system in accordance with an example of the present disclosure. In the elevator system 2 shown in FIG. 1, there are four elevator cars 4a-d arranged to move within respective hoistways 6a-d. At the top of each of the hoistways 6a-d is located a respective controller 8a-d.

[0039] Each elevator car 4a-d is provided with a respective car board 10a-d, which is arranged to supply and receive operational data relating to the corresponding elevator car 4a-d. This data may include the operational status of the elevator car 4a-d, any error messages, safety information, and control commands for driving operation of the elevator car 4a-d within the respective hoistway 6a-d. These car boards 10a-d may be single boards that perform all such functions, or there may be multiple ‘sub’ boards having functions divided amongst them, e.g. in practice the car boards 10a-d may each have a control board and a safety board. The car boards 10a-d may be positioned on the top of the respective elevator car 4a-d, or any other desired location on the respective elevator car 4a-d.

[0040] Each car board 10a-d is connected to a respective wireless communication unit 12a-d, which is arranged to communicate with a respective wireless communication unit 14a-d connected to the corresponding controller 8a-d over a wireless communication interface 16a-d using a wireless communication protocol. The wireless communication utilises OFDM modulation in which data symbols are spread across multiple orthogonal sub-carriers. As outlined in more detail below, the wireless communication protocol used in this particular example is compliant with the IEEE 802.11p standard.

[0041] The wireless communication units 12a-d, 14a-d each comprise a CAN2Wireless interface which converts signals on the wired CAN bus to signals for transmission across the wireless interface 16a-d, and vice versa. A CAN bus 18a-dconnects the car-side wireless communication units 12a-d to the respective car boards 10a-d, while a further CAN bus 20a-d connects the controller side wireless communication units 14a-d to the respective controllers 8a-d. The conversion may be carried out by firmware or hardware as appropriate. It will, of course, be appreciated that the use of a CAN bus is merely exemplary, and other types of bus could be used as appropriate.

[0042] The wireless communication units 12a-d, 14a-d advantageously provide bidirectional communication across the wireless interface 16a-d and do not require line-of-sight.

[0043] The controllers 8a-d are connected to a group controller 22 via a group CAN bus 24. This group controller 22 centrally controls operation of each of the hoistway controllers 8a-d.

[0044] As outlined above, communication over the wireless communication interfaces 16a-d is carried out in accordance with the IEEE 802.11p protocol, which is a standard specified for vehicle-to-vehicle and vehicle-to-infrastructure communication (e.g. for use in autonomous vehicle applications).

[0045] The modulated sub-carriers transmitted over the wireless interface 16a-d have a sub-carrier spacing upper bound of 156.25 kHz, where the minimal channel bandwidth is between 1.0 MHz and 1.2 MHz.

[0046] Following the IEEE 802.11p standard using the modulation code scheme (MCS) 0, this involves the use of BPSK with a forward error correction FEC=½. With this, the system can transmit 3 Mbit/s over a 10 MHz channel Using OFDM modulation, there are 64 channels of 156.25 kHz width, i.e. a bandwidth of 64×156.25 kHz=10 MHz, plus an additional band occupied by the remaining parts of the sub-carrier functions. The efficiency of this modulation is 0.3 bit/Hz.

[0047] When applied to the elevator system 2 of FIG. 1, the data stream to be transmitted may have a data rate of approximately 70 kbit/s. Using the modulation efficiency of 0.3 bit/Hz above, the required bandwidth is 70 kbit/s/0.3 =240 kHz. Adding a further 50% because the 240 kHz relates only to the payload leads to a total bandwidth of at least 360 kHz.

[0048] If a spacing between the sub-carrier is chosen to be equal to 156.25 kHz for transmitting the data, at least 3 data sub-carriers are needed, leading to 3×156.25 kHz=468.75 kHz.

[0049] Moreover, in some arrangements, a number of pilot sub-carriers may be needed for correctly demodulating the received signals. In an arrangement with 4 pilot sub-carriers, the total channel bandwidth is (4+3)×156.25 kHz=1.0938 MHz.

[0050] Thus by applying a IEEE 802.11p ‘like’ communication, in which the bandwidth is reduced from the 10 MHz specified by the standard to 1.1 MHz as calculated above in light of the data throughput requirements (i.e. only 70 kbit/s rather than the 2 Mbit/s provided for by the standard). Thus, to provide a 1.1 MHz channel, the frequency spacing between the sub-carriers shall not exceed 156.25 kHz.

[0051] In an alternative system, the frequency spacing between sub-carriers may instead be 312.5 kHz with a bandwidth of 2 MHz.

[0052] FIG. 2 is a schematic drawing of an alternative elevator system 2′ having a wireless communication system in accordance with a further example of the present disclosure. Many of the components in the system 2′ of FIG. 2 correspond in structure and function to those described with respect to the system 2 of FIG. 1, where like reference numerals indicate like components, appended with a prime symbol (′).

[0053] The connections and functions of the components of this system 2′ correspond to those described previously with reference to FIG. 1, except in that at the controller-side, there is now a single controller 8′ which communicates with the elevator cars 4a′-d′, where no group controller is provided. This controller 8′ is connected to a number of wireless communication units 14a′-d′, which ease communicate with a respective wireless communication unit 12a′-d′ on the elevator cars 4a′-d′.

[0054] While separate wireless communication units 12a′-d′ are provided for each hoistway 6a′ -d′ in the system 2′ of FIG. 2, in other arrangements multiple elevator cars may communicate with the same controller-side wireless communication unit, as shown in FIG. 3.

[0055] FIG. 3 is a schematic drawing of a further alternative elevator system 2″ in accordance with a further example of the present disclosure. As with the system 2′ of FIG. 2, many of the components in the system 2″ of FIG. 3 correspond in structure and function to those described previously, where like reference numerals indicate like components, appended with a double prime symbol (′).

[0056] In the system 2″ of FIG. 3, the wireless communication units 12a″, 12b″ on two of the elevator cars 4a″, 4b″ both communicate with the same controller-side wireless communication unit 14″. Thus in this system 2″, a single controller-side wireless communication unit 14″ services multiple hoistways 6a″, 6b″, thereby advantageously reducing the amount of hardware required.

[0057] Thus it will be appreciated by those skilled in the art that examples of the present disclosure provide an improved elevator system with wireless communication between the elevator car and the controller that is robust against the Doppler shift and multipath effects when compared to conventional approaches, known in the art per se.

[0058] While specific examples of the disclosure have been described in detail, it will be appreciated by those skilled in the art that the examples described in detail are not limiting on the scope of the disclosure.