Arrangement in a distributed control system for increasing the availability of data and/or control commands

• US 20050030969A1
• Filed: 09/04/2001
• Published: 02/10/2005
• Est. Priority Date: 09/12/2000
• Status: Active Grant

• Current Assignee: Intellectual Ventures Assets 20 LLC (Intellectual Ventures LLC), Kvaser Consultant Aktiebolag
• Original Assignee: Xinshu Management LLC (Intellectual Ventures LLC)
• Inventors: Fredriksson, Lars-Berno
• Granted Patent: US 8,072,877 B2
• Time in Patent Office: Days
• US Class Current: 370/454
• CPC Class Codes: H04Q 2213/13098 Mobile subscriber
• CPC Class Codes: H04Q 2213/13107 Control equipment for a part of the connection, distributed control, co-processing
• CPC Class Codes: H04Q 3/5455 Multi-processor, parallelism, distributed systems
• CPC Class Codes: H04W 72/54 based on quality criteria

Abstract

There is a need for increasing the availability of data and/or control commands in a distributed control system for one or more machines, vehicles and/or processes. The control system comprises or is controlled by a transmitting node (1) or transmitter unit and has two or more receiving nodes (13, 14, 15, 16). The transmitting nodes and receiving nodes are connected to each other via wire [sic] radio links. The receiving nodes are located at a distance from each other and are connected to a few-wire digital link in a wired system for forwarding of the said data and/or control commands to the executing devices. The control [sic] node transmits the said data and/or the control commands in different directions towards the receiving nodes which are arranged at a distance from each other. Receiving nodes with reception that is essentially not subject to interference are arranged to be able to connect to the few-wire link in parallel and simultaneously with a receiver unit or units which have links that are connected to the few-wire link. In another case, only those receiver unit or units are connected that have reception links that are not subject to interference, while the receiver unit of units with links that are subject to interference do not participate in the transmission of the message on the few-wire link.

Claims

1. An arrangement for increasing availability of data and/or control commands (D) in a distributed control system (CAN) for one or more machines (2″

) (also vehicles) and/or processes (2″

), the control system being influenced by or comprising at least one transmitting node (1) or transmitter unit, and also comprising two or more receiving nodes (13, 14, 15, 16), and where the transmitting node or transmitter unit and the receiving nodes can be connected or are connected to each other via wireless links (radio links 5, 6, 7, 8) and where the receiving nodes are located at a distance (A, B) from each other and are connected to a few wire digital (21) link in a wired system for forwarding the said data and/or control commands to executing devices (41) for, for example, functions, measurements, etc, characterized in that the transmitting node or transmitter unit is arranged to send the said data and/or control commands in parallel and simultaneously in different directions (9, 10, 11, 12) towards the receiving nodes, and that in the event of wireless links that are essentially not subject to interference between the transmitting node or transmitter unit and the receiving nodes, the latter are arranged to connect in parallel and simultaneously for parallel and simultaneous transmission of the said data and/or control commands to the few-wire link and thereby to the executing device or devices (41) concerned, and in the event of wireless link or links that are essentially subject to interference between the transmitting node or transmitter unit and the receiving node or nodes concerned, the latter are prevented from making their connections to the few-wire link, whereby the transmission of the said data and/or control commands to the few-wire link and respective executing device in this case is effected by the remaining receiver devices with wireless link or links that are essentially not subject to interference.

2. An arrangement according to claim 1, characterized in that the transmitting node (1) or transmitter unit sends the said data and/or control commands to the receiving nodes (13, 14, 15, 16) on different frequencies.

3. An arrangement according to claim 2, characterized in that data and/or the control commands are incorporated in or form messages (27, 27′

, 27″

, 27′

″

) with system identification (ID, C), data (D) and data length codes and control codes (CRC and CH).

4. An arrangement according to any one of the preceding claims, characterized in that the distributed system (CAN) consists of or comprises a system of the control area system type where the receiving nodes (13, 14, 15, 16) are synchronized with each other or coordinated with the connection or arbitration functions of the few-wire link (21), with the result that they simultaneously obtain access to the few-wire link via messages received from the transmitting node or transmitter unit that are essentially or completely not subject to interference and that in the event of absent coordinated connections on account of messages (27) from the transmitting node (1) or transmitter unit essentially subject to interference or absent, they obtain information from the few-wire link concerning cancelling further attempts to connect to the few-wire link after the receiving node or receiving nodes with link or links that are essentially not subject to interference have completed the transmission of the message on the few-wire link.

5. An arrangement according to any one of the preceding claims, characterized in that, in the event of its message from the transmitting node or transmitter unit being essentially subject to interference or absent, the respective receiving part is arranged to receive or detect all or parts of the message that was transmitted on the few-wire link (21) from the receiving unit or receiving units with received message or messages that are essentially not subject to interference, and that, in the event of such received part of the message or received message, it is arranged to prevent continued attempts to access the few-wire link (21).

6. An arrangement according to any one of the preceding claims, characterized in that, in the event of a predetermined level of interference in its received message, the respective receiving node is arranged to generate an internal cancellation signal (i2) or cancelling which prevents the connection of the receiving node to the few-wire link (21).

7. An arrangement according to any one of the preceding claims, characterized in that, in the event of interference in their received messages above a predetermined value, the receiving nodes are arranged to effect an arrangement between the receiving nodes which selects the receiver unit that at the time of reception has reception which is the least subject to interference, and that only the receiving node thereby selected obtains access to the few-wire link for transmission of its received message on this link.

8. An arrangement according to any one of the preceding claims, characterized in that the transmitting node consists of or comprises a service unit provided with a computer, and that the receiver units are located in a vehicle (2′

), with the executing devices in the vehicle controlling function executors, for example in the form of door mirrors, driver'"'"'s seat, sunroof, etc.

9. An arrangement according to any one of the preceding claims, characterized in that the transmitting node or transmitter unit is fixed, that is allocated a predetermined geographical position.

10. An arrangement according to any one of claims 1-9, characterized in that the transmitting node or transmitter unit is movable and constitutes a mobile unit for example incorporated in the general communication mobile system (GSM).

11. An arrangement according to any one of the preceding claims, characterized in that the nodes or units in the system are arranged for message forms that exist in association with Bluetooth.

12. An arrangement according to any one of the preceding claims, characterized in that the receiving nodes are synchronized with each other with regard to connection and arbitration functions that occur in conventional control area systems.

13. An arrangement according to any one of the preceding claims, characterized in that the receiver units operate with and are synchronized or coordinated with each other by means of time functions incorporated in the control area system (CAN).

14. An arrangement according to any one of the preceding claims, characterized in that the system has two types of link, wireless links and wired links, where by wired links is meant such links as have wires, leads, etc, and/or optical connections comprising opto links.

15. An arrangement according to any one of the preceding claims, characterized in that the system can operate with two, three or more steps, where in a first step a transmission is carried out from wireless transmitter to wireless receiver and from wireless receiver to wired link and in the case with three steps from wired link to wireless transmitter(s), from wireless transmitter to wireless receiver(s) per channel, and from wireless receiver(s) to wired link.

16. An arrangement according to any one of the preceding claims, characterized in that the wireless transmitters each transmit on a separate channel (channel frequency), where a channel is characterized in that when transmitting each transmitter has access to a part of the available bandwidth in the ether which is exclusive to the system.

17. An arrangement according to claim 16, characterized in that the exclusivity can be an allocated frequency in a time interval, for example as in the known Bluetooth protocol, IEEE 802.11 for jumping frequency or a correlation code (as in IEEE 802.11 Direct Sequence Spread Spectrum).

18. An arrangement according to any one of the preceding claims, characterized in that a transmitter and one or more receivers can operate on one and the same channel during one and the same time interval.

19. An arrangement according to any one of the preceding claims, characterized in that units in the form of g-nodes, that is nodes that are connected both to the respective wireless network and the respective wired network, are arranged to operate as gateways, where they receive a complete message on the wireless links in question and ascertain in a known way that it has been correctly received by means of check code, error-correcting code, etc, after which the message is able to be sent on the wired links concerned.

20. An arrangement according to any one of the preceding claims, characterized in that the respective message has an identity in the respective medium which is unique at least at the time of transmission, which identity can be a bit code or can consist of a particular time slot in a scheduled system or a combination of these functions.

21. An arrangement according to claim 19 and 20, characterized in that the identity is the same or different for media involved, where in the case where they are different, respective g-nodes are arranged to know the association between the identifies.

22. An arrangement according to any one of the preceding claims 17-21, characterized in that the Bluetooth protocol is used in a modified form as a protocol, inasmuch as several slaves are allocated the same time slot for the reception in question, that a field bus message (CAN message in the form of LLC data frame) is arranged for generation in a computer (microcomputer) which is equipped with a radio interface of the Bluetooth type.

23. An arrangement according to any one of the preceding claims 17-22, characterized in that a CAN message is arranged for packaging as data in a Bluetooth message which is sent by the computer (microcomputer) and that reception of this message is carried out in two or more g-nodes.

24. An arrangement according to any one of the preceding claims 17-23, characterized in that the g-nodes that received the CAN message [error-]free according to the Bluetooth protocol'"'"'s error-detection mechanisms are able thereafter to transmit the CAN message on the CAN bus.

25. An arrangement according to any one of the preceding claims 19-24, characterized in that in the case where several g-nodes commence their transmission synchronized to the same frame (Strat of Frame=SOF), simultaneous transmission of the message from the g-nodes takes place bit by bit, which is made possible as the messages are identical.

26. An arrangement according to any one of the preceding claims 19-25, characterized in that in the case where any one or more of the g-nodes can not synchronize with the message that the first g-node transmits, they change over to receiving nodes in accordance with the CAN protocol, which means that the respective g-node concerned will receive a message which is identical to the one the respective g-node was in the process of transmitting on the bus, and that when the respective g-node has ascertained that such is the case, the g-node ceases to send its message in question, which thus means that there is parallel redundancy for signalling from the computer (the microcomputer) to the CAN network.

27. An arrangement according to any one of the preceding claims 19-26, characterized in that in the opposite direction there is serial redundancy where the respective g-nodes are each allocated a time slot for transmission and information about which CAN identifier identifies the CAN message in question which is arranged to be sent to the computer/processor (microcomputer PC), where the respective g-node receives at the same time the message on the CAN bus in accordance with the CAN protocol.

28. An arrangement according to any one of the preceding claims 19-27, characterized in that the respective message which is arranged to be sent to the computer/processor (PC) is arranged for packaging as data in a Bluetooth message and for dispatch in the respective time slot, where the computer (PC) receives one or more identical messages from the CAN system.

29. An arrangement according to any one of the preceding claims 19-28, characterized in that information about which receiver has received the strongest signal is able to be produced, where the radio part or parts of the g-nodes provide a value for the signal strength (signal strength indicator, SSI), for example a measurement value 0-255, that the CAN identifier is divided into at least three fields, where one contains the value 255 minus the SSI value, one field indicates which g-node is sending the message, and one field indicates that it is one (of several) messages from the computer/processor (PC).

30. An arrangement according to any one of the preceding claims 19-29, characterized in that the said SSI value−

255 is applied in the CAN identifier, where the g-node that [has] the highest signal strength gains access to the bus if all the anodes commence signalling at the same time, which information about which g-node has the strongest signal and the relevant value of this is thus indicated in the CAN identifier and is thus available to all nodes which require this information.

31. An arrangement according to any one of the preceding claims, characterized in that the signal strength in combination with indication of bit errors can be used together with other measures, for example change of transmitter, and/or amended propagation diagram from the transmitter or transmitters, etc, which can be relevant in the case when the signal comes via several different signal paths (a so-called multipath situation).

32. An arrangement according to any one of the preceding claims, characterized in that in the case with one or more mobile transmitters, in a first position these can have contact with a first number of receivers, for example two receivers, thereafter with a second number of receivers, for example three receivers, and thereafter again with the first number of receivers, for example the said two receivers, that the transmission reliability is thereby able to be ensured by the P-presentation function, where the SSI-presentation provides an indication of where the mobile transmitter is located.

33. An arrangement according to claim 32, characterized in that the combination of a mobile transmitter and a fixed network can consist of a car that is in a garage, a car that is at a service station, an ignition key (or corresponding unit that can comprise a similar function, for example a mobile phone, identity card, etc) for a vehicle.

34. An arrangement according to any one of the preceding claims, characterized in that a unit that is not yet connected (for example a mobile unit) can listen on a fixed frequency on which time messages will appear and on which the unit that is not yet connected is able to synchronize itself to the network on the messages that are still to be sent to maintain the global time in the system, and that the messages can contain identification data for the system in addition to the said messages.