DE102014113118B4 - Sensor network for an aircraft - Google Patents

Abstract

A sensor network (100) in an aircraft (200), comprising: a sensor (120) which is arranged on or in the aircraft; at least two access devices (110A, 11OB, 110C, 110D, 110E, 110F), which are spatially arranged at different locations in the aircraft (200); wherein the at least two access devices are designed to send data to the sensor and data from the To receive the sensor; wherein the at least two access devices are designed to send the data simultaneously in the event of a data transmission to the sensor; wherein the at least two access devices (110A, 11OB, 110C, 110D, 110E, 110F) via a connection network (105) are coupled to one another and are designed to be synchronized with one another via the connection set, so that a transmission process of the at least two access devices can be synchronized

Description

Field of invention

The invention relates to a sensor network, in particular a sensor network for an aircraft, and an aircraft with such a sensor network.

Technical background

A sensor network usually consists of at least one sensor or a plurality of sensors and at least one remote station (can also be referred to as an access device or access point, AP) or a plurality of such remote stations which send messages or data to the sensors (downlink, downlink) and receive messages or data from the sensors (uplink, uplink).

Messages can be lost or not arrive at the intended recipient due to changing properties of a transmission link, in particular in the case of a wireless transmission channel, which applies to both the downlink and the uplink. Lost messages usually require retransmission, which costs time and channel capacity.

Spatially distributed (spaced apart) access devices can receive messages that are sent by sensors according to the so-called broadcast principle (one transmitter sends, any number of receivers can receive). This provides redundancy since more than one access device can receive a message sent by a sensor. This provides redundancy for a transmission on the uplink (from a sensor to the access devices) and a sent message can be processed further as long as it is received by at least one access device.

On the downlink (data transmission from the access devices to the sensors), redundancy is usually provided by sending messages from several access devices one after the other.

Messages from several APs to the sensors are sent one after the other. Each AP successively sends the signal sequences (beacons) required for synchronization in the time slots provided for this purpose. For k APs, k time slots are therefore reserved for synchronization signal sequences (B). Messages to the sensors or actuators (e.g. lighting control) are also sent by each access point in the reserved time slots, so m downlink messages (downlink messages, D) require m x k time slots.

the end EP 2 293 625 A1 or DE 10 2009 009 189 A1 For example, sensor networks for aircraft, for example, are known which have several sensors and which communicate with one another via wireless communication.

Summary of the invention

It can be seen as an object of the invention to reduce the time required for redundancy on a downlink of a sensor network.

This object is achieved with the subject matter of the independent claims. Developments of the invention emerge from the dependent claims and from the following description.

According to one aspect of the invention, a sensor network is specified which has a sensor and at least two access devices. The at least two access devices are designed to send data to the sensor and to receive data from the sensor and, in particular, to send the data simultaneously in the case of data transmission to the sensor.

The sensor network can in particular have more than one sensor or a plurality of sensors with any number of sensors. The sensor network can also have a plurality of access devices with any number of access devices.

The access devices are designed to send data simultaneously during a data transmission on the downlink. This means that the data sent by the access devices are superimposed. In the case of data transmission by means of electromagnetic waves, the electromagnetic waves which are sent out by the individual access devices are superimposed.

If a sensor or an access device is spatially arranged in such a way that direct data transmission is not possible between a dedicated sensor and a dedicated access device, for example due to transmission obstacles in a wireless transmission path, then successful data transmission to the dedicated sensor can still take place because a second access device transmits the same data that can reach the dedicated sensor.

The plurality of access devices can in particular be designed to carry out data transmission on the downlink with the same modulation and signal coding.

The sensor or the plurality of sensors is designed in particular to detect a physical parameter and convert it into a measurement signal which is further processed by the sensor network, for example by transmitting the measurement signal to a control device in order to be fed to a regulating or control circuit.

According to one embodiment of the invention, the at least two access devices are designed to send identical data in the event of a data transmission to the sensor.

This means that the signal content is not falsified due to the signal superimposition of the signals from various access facilities. Redundancy on the downlink is thus essentially achieved by the fact that identical data, which are encoded / modulated in identical electromagnetic waves, are transmitted through access devices that are spatially arranged at different locations and that interference in the transmission channel between a specific access device and a specific sensor is compensated for, that this particular sensor receives the (identical) signal from another access device.

According to a further embodiment of the invention, the at least two access devices are designed to wirelessly transmit data to and from the sensor.

Especially on wireless transmission routes and especially in closed rooms (such as the interior of an aircraft), signal propagation may be disturbed, which can lead to a signal either not being received by the receiver or not being received completely. As a rule, interference increases as the distance between the transmitter and receiver increases. By providing several access devices, which are spatially spaced from one another so that a room is covered as evenly as possible (the access devices are arranged at the same or essentially the same distance from one another), it is ensured that the sensor can be reached by at least one access device.

The sensor network as described above and in the following can be particularly advantageous if a plurality of spatially distributed sensors exchange data with a plurality of spatially distributed access devices, in particular via a wireless transmission link.

According to a further embodiment of the invention, the sensor network also has an actuator. The at least two access devices are designed to send data to the actuator in such a way that the data are sent to the actuator at the same time during the data transmission.

The sensor network can have one or a plurality of actuators with any number of actuators. An actuator is designed to receive a signal from an access device on the downlink and to carry out a corresponding action, for example by carrying out a movement of a force application unit.

One or more sensors can be coupled to an actuator in such a way that the action of the actuator is monitored by these sensors, for example by detecting a position and / or a direction of movement of the force exertion unit and transmitting it to an access device.

According to a further embodiment of the invention, the at least two access devices are coupled to one another via a connection network, so that a transmission process of the at least two access devices can be synchronized.

In other words, the connection network enables the access devices to be synchronized with one another via a synchronization protocol, so that the data or signals are transmitted on the downlink from different access devices in such a way that they overlap without interference, i.e. that there is no or no significant time offset there are more different access devices between the signals.

The signal transmission on the downlink can take place, for example, so that the duration of a symbol is 16 microseconds. In this example, the access devices can be synchronized with one another in such a way that a maximum time offset between the transmission processes of the access devices is a few hundred nanoseconds (ns) up to a maximum of 1 μs. With such a synchronization accuracy, common error correction mechanisms in the receiving sensor can intercept and correct the effects on the superimposed signal, so that signal detection at the sensor can be guaranteed.

The connection network can also be designed to forward the measurement signals received from the sensors to a central control unit, which uses these measurement signals as the basis for regulation or control algorithms and which can be designed to generate commands to the actuators, which are transmitted to the actuators by means of the access devices.

According to a further embodiment of the invention, at least one access device is coupled to the connection network via a wireless connection.

According to a further embodiment of the invention, at least one access device is coupled to the connection network via a line.

All access devices can be coupled to the connection network via a wireless connection or each via a line. Alternatively, some of the access devices can be coupled to the connection network via a wireless connection and some of the access devices can each be coupled via a line.

According to a further aspect of the invention, an aircraft with a sensor network as described above and below is specified.

Sensors, especially wireless sensors, are used in aircraft to monitor the status of various systems. The sensors transmit data wirelessly to the access devices, which are arranged spatially distributed in the aircraft. By providing several spatially distributed and spaced-apart access devices, the transmission power of the sensors and the access devices can be kept low and the effect of possibly associated, comparatively low transmission ranges and effects of possibly interfering influences on the transmitted signal can be mitigated.

The redundancy on the uplink and downlink in a sensor network can be of relevance in particular for safety-relevant applications in aircraft, since it can increase the operational safety of the sensor network.

According to one embodiment of the invention, the at least two access devices are arranged spatially distributed in the aircraft.

In particular, the access devices can be arranged at a distance from one another in an interior space of the aircraft. The spatially distributed arrangement can, for example, eliminate the influence of the transmission range of an individual access device and, in particular, mitigate the effects of so-called multipath propagation on the transmitted signal.

According to a further embodiment of the invention, the sensor is a temperature sensor, a light sensor, a smoke sensor, a chassis sensor, a structure monitoring sensor or a seat function sensor.

A seat function sensor can in particular be designed to detect the status of a seat in the aircraft and of systems that are coupled to the seat. The occupancy status, armrest status, belt status and tray status can be recorded for this purpose.

The sensor network as described above and below can be used in particular with various wireless sensor network technologies and offers redundancy on the downlink, in particular when using spatially distributed access devices. The time required for redundancy on the downlink is reduced and, in particular, no channel estimation nor a high time synchronization effort is required.

In other words, the invention can be described as follows: Sensors, in particular wireless sensors, in aircraft can be used for various applications. In the aircraft cabin for the monitoring and control of e.g. temperature, lighting, smoke detectors, window darkening and seat functions such as occupancy, armrests, belt and tray status. Sensors are also needed to monitor systems such as the chassis and structures. Since high reliability can be required for many applications, a redundant infrastructure with spatially distributed access devices (access points, APs) is used, which enables messages to be sent and received from several senders / receivers.

Wireless sensors communicate with a remote station, the access point, which sends messages to the sensors and receives messages from the sensors. Messages can be lost due to the changing characteristics of a wireless channel. These messages have to be retransmitted, which costs time and channel capacity. Spatially distributed redundant APs can receive messages sent by sensors at the same time (the sensors send to all APs according to the broadcast principle).

Uplink messages (Uplink messages, U) from the sensors to the APs (measurement signals from the sensors, e.g. temperature) are sent once by each sensor and received by each AP that is within range of the sensor, resulting in redundancy on the uplink of the wireless Channel without temporal repetitions enabled.

It is an aspect of the present description that downlink messages are sent from the APs to the sensors at the same time. This means that considerably fewer time slots can now be provided for the downlink (downlink, access point to sensor). This saves capacity and therefore enables significantly more sensors to be supported. Signals from all redundant APs reach the sensors.

• APs senden nacheinander: 6 × B + 6 × 100 × D + 100 × U= 706 Zeitschlitze;
• APs senden gleichzeitig: 1 × B + 100 × D + 100 × U = 201 Zeitschlitze;

Example calculation for 6 APs, 100 downlink messages (D) from AP to sensors, 100 uplink messages (U) from sensors to AP and with synchronization signals (B), with one synchronization signal, one downlink and one uplink message each Time slot is set:

• APs send in succession: 6 × B + 6 × 100 × D + 100 × U = 706 time slots;
• APs transmit simultaneously: 1 × B + 100 × D + 100 × U = 201 time slots;

From this example calculation it can be seen that with constant redundancy on the downlink, considerable savings potential in the time slots required for data transmission is made possible.

The simultaneous sending of messages from distributed APs can require their synchronization so that the sent and superimposed signals can still be decoded by the sensors (receivers). The necessary accuracy of the synchronization depends on the signal duration of the physical transmission method, with IEEE802.15.4, for example, this is 16µs long. Signals that reach receivers in multi-path environments are smeared over time (delay spread), which basically has the same effects on the receiver as distributed transmission. As long as the synchronization accuracy remains within the delay spread due to the multipath propagation, no disadvantages are to be expected.

The APs can be synchronized either via cable or wirelessly, which can be achieved, for example, by the fact that the synchronization signals are not always sent at the same time, but one of the APs in turn does not send and listens for synchronization purposes.

Figure list

• 1 eine schematische Darstellung eines Sensornetzwerks gemäß einem Ausführungsbeispiel der Erfindung.
• 2 eine schematische Darstellung eines Luftfahrzeugs mit einem Sensornetzwerk gemäß einem weiteren Ausführungsbeispiel der Erfindung.
• 3 eine schematische Darstellung der Datenübertragung in einem Sensornetzwerk gemäß einem weiteren Ausführungsbeispiel der Erfindung.

Exemplary embodiments of the invention are discussed in greater detail below with reference to the accompanying drawings. Show it:

• 1 a schematic representation of a sensor network according to an embodiment of the invention.
• 2 a schematic representation of an aircraft with a sensor network according to a further embodiment of the invention.
• 3 a schematic representation of the data transmission in a sensor network according to a further embodiment of the invention.

Detailed description of exemplary embodiments

1 shows a sensor network 100 with a plurality of sensors 120 and a plurality of actuators 130 which wirelessly connect to a plurality of access facilities 110A , 110B , 110C , 110D , 110E , 110F are coupled to enable data transmission from the access devices to the sensors and actuators and vice versa.

The majority of access facilities 110A , 110B , 110C , 110D , 110E , 110F are wireless or via one line each to the connection network 105 coupled. In the representation of the 1 is this for the sake of clarity only for the access facilities 100C and 100F shown. It should be noted, however, that any access facility 110A , 110B , 110C , 110D , 110E , 110F with the connection network 105 is coupled.

The connection network 105 can in particular be designed to receive data from the sensors and process them further or forward them to a control unit (not shown). Likewise, the connection network can be designed to route data to the access devices, which the actuators 130 cause an action to be taken.

2 shows a schematic representation of an aircraft 200 with a sensor network 100 .

The elements of the sensor network (sensors, actuators, access devices) are spatially distributed in the interior and are arranged, for example, on the structure of the aircraft or on components in a passenger compartment. The structure of the sensor network enables good adaptability to differently designed aircraft and their interior fittings (arrangement of seats or rows of seats, windows, etc.). The use of wireless sensors offers good opportunities to expand the sensor network.

3 shows a schematic representation of the data exchange in a sensor network 100 as described above.

The horizontal arrow t indicates the time. Correspondingly, a time slot is represented in each case by the columns. The actions of the access devices (AP0 to APn) and sensors (S0 to Sn) are shown in the lines. Even if in 3 If no actions by actuators are shown, the same applies for their data transmission as for the data transmission of the sensors.

First of all, all access devices AP (AP0 to APk) send a synchronization signal sequence B (B0 to Bk) at the same time in the same time slot. The APs then send one or more downlink messages (D0,0 to Dk, m), with all APs sending the same downlink message in a time slot. The sensors then individually send an uplink message U (U0 to Uk) to the APs according to the broadcast principle.

In particular, the fact that the downlink messages D are sent simultaneously by all APs, the time required for the data transmission is reduced, but without reducing the redundancy of the data transmission on the downlink.

Claims (9)

Sensor network (100) in an aircraft (200), comprising: a sensor (120) arranged on or in the aircraft; at least two access devices (110A, 11OB, 110C, 110D, 110E, 110F) which are spatially arranged at different locations in the aircraft (200); wherein the at least two access devices are designed to send data to the sensor and to receive data from the sensor; wherein the at least two access devices are designed to send the data simultaneously in the event of a data transmission to the sensor; wherein the at least two access devices (110A, 11OB, 110C, 110D, 110E, 110F) are coupled to one another via a connection network (105) and are designed to be synchronized with one another via the connection set so that a transmission process of the at least two access devices is synchronized can be Sensor network (100) Claim 1 , wherein the at least two access devices (110A, 11OB, 110C, 110D, 110E, 110F) are designed to send identical data in the event of a data transmission to the sensor. Sensor network (100) Claim 1 or 2 , wherein the at least two access devices (110A, 11OB, 110C, 110D, 110E, 110F) are designed to wirelessly transmit data to and from the sensor (120). Sensor network (100) according to one of the Claims 1 until 3 , further comprising an actuator (130); wherein the at least two access devices (110A, 11OB, 110C, 110D, 110E, 110F) are designed to send data to the actuator; wherein the at least two access devices are designed to send the data simultaneously in the event of a data transmission to the actuator. Sensor network (100) according to one of the preceding claims, wherein at least one access device is coupled to the connection network (105) via a wireless connection. Sensor network (100) according to one of the preceding claims, wherein at least one access device is coupled to the connection network (105) via a line. Aircraft (200), with a sensor network (100) according to one of the Claims 1 until 6th . Aircraft (200) according to Claim 7 , wherein the at least two access devices are arranged spatially distributed in the aircraft (200). Aircraft (200) according to Claim 7 or 8th , wherein the sensor (120) is a temperature sensor, a light sensor, a smoke sensor, a chassis sensor, a structure monitoring sensor or a seat function sensor.

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