LEWIS, Paul (Cranfield Aerospace Ltd, Cranfield UniversityCranfield, Bedfordshire MK43 OAL, GB)
CHARLES, Darrel (Cranfield Aerospace Ltd, Cranfield UniversityCranfield, Bedfordshire MK43 OAL, GB)
LEWIS, Paul (Cranfield Aerospace Ltd, Cranfield UniversityCranfield, Bedfordshire MK43 OAL, GB)
| CLAIMS 1. A vibration logger for logging air carriage vibration, being self- contained and requiring no external power or control connections when fitted to an aircraft for vibration logging, and comprising a case which includes a connector for connection to at least one sensor external to the case and circuitry which is potted within the case and operative to log carriage vibration sensed by at least one sensor when connected to the connector, wherein the circuitry comprises memory for storing vibration data, a processor which processes an output from the at least one sensor and provides for sampling of data in accordance with a predetermined sampling protocol and writing of the sampled data to the memory, and an power source for powering the circuitry. 2. The vibration logger of claim 1, wherein the case is of a construction which can withstand an internal explosive pressure. 3. The vibration logger of claim 1 or 2, wherein the circuitry is fully- potted within the case. 4. The vibration logger of any of claims 1 to 3, wherein the circuitry is mounted on one or more circuit boards, which are subjected to thermal and vibration electronic stress screening processes before potting of the circuitry. 5. The vibration logger of any of claims 1 to 4, wherein the circuitry comprises a plurality of analogue input stages, which each have an input connected to the connector to receive respective ones of analogue outputs from the at least one sensor. 6. The vibration logger of claim 5, wherein each input stage comprises a DC block having an input connected to the connector, an amplifier connected to an output of the DC block, and an anti-alias filter connected to an output of the amplifier for restricting the bandwidth of the received analogue signal. 7. The vibration logger of claim 5 or 6, wherein the circuitry further comprises a plurality of ADCs which each have an input connected to an output of a respective one of the input stages, and a plurality of digital filters which each have an input connected to an output of a respective one of the ADCs and act to filter the received digital signals from the ADCs and an output connected to the processor. 8. The vibration logger of any of claims 1 to 7, wherein the circuitry further comprises a memory control device having a first port connected to the memory, a second port connected to the processor for enabling writing of sampled data to the memory and a third port for enabling reading of logged data from the memory and programming of the processor. 9. The vibration logger of any of claims 1 to 8, wherein the circuitry further comprises a controller which is connected to a start/stop switch, and, through operation of the start/stop switch, enables operation of other components of the circuitry. 10. The vibration logger of any of claims 1 to 9, wherein the power source comprises a rechargeable battery. 11. The vibration logger of claim 10, wherein the circuitry further comprises a battery management controller for managing the battery. 12. The vibration logger of any of claims 1 to 11, wherein the vibration logger is configured to record data continuously over a sampling period to capture benign and severe vibration events. 13. The vibration logger of any of claims 1 to 12, wherein the vibration logger captures and records wideband vibration data having a frequency bandwidth of 2 to 2000 Hz. 14. The vibration logger of any of claims 1 to 13, wherein the vibration logger has a sampling rate of at least 6000 samples per second. 15. The vibration logger of any of claims 1 to 14, wherein the vibration logger captures data for at least 2 hours. 16. The vibration logger of any of claims 1 to 15, further comprising a further connector for connection to a PC and a power supply external to the vibration logger. 17. A vibration logger system for logging air carriage vibration, comprising : the vibration logger of any of claims 1 to 16; and at least one sensor external to the vibration logger and connected to the sensor connector of the vibration logger. 18. The system of claim 17, wherein the at least one sensor is a tri-axial accelerometer having three outputs. 19. The system of claim 17 or 18, further comprising : a PC, preferably a laptop, which has applications for programming the vibration logger with a predetermined sampling protocol, downloading logged data and analysing the logged data. 20. The system of any of claims 17 to 19, further comprising : a power supply external to the vibration logger for powering the vibration logger when removed from the aircraft and charging the power source within the circuitry of the vibration logger. 21. A vibration logger assembly, comprising : an aircraft component; the vibration logger of any of claims 1 to 16 mounted to the aircraft component; and at least one sensor attached externally of the vibration logger to the aircraft component and connected to the sensor connector of the vibration logger. 22. The assembly of claim 21, wherein the aircraft component is an air countermeasure magazine having a plurality of flare cavities and the vibration logger is loaded into one of the flare cavities. 23. A vibration logger kit, comprising : the vibration logger of any of claims 1 to 16; and a set of a plurality of shape adapters, each having a cavity into which the vibration logger is mountable to allow for logging of data in different environments where using a single, common vibration logger, with the different shape adapters having different shapes corresponding to the different environments. 24. The kit of claim 23, wherein the shape adapter comprises a housing into which the vibration logger is mechanically mounted. 25. The kit of claim 24, wherein the housing includes ballast to provide for mass compensation. 26. A shape adapter for use with a vibration logger on an aircraft, the shape adapter comprising a housing having an external shape corresponding to an aircraft environment and a cavity into which the vibration logger is mountable to allow for logging of data in the aircraft environment. 27. The shape adapter of claim 26, wherein the housing includes ballast to provide for mass compensation. 28. A method of logging air carriage vibration, comprising the steps of: providing the vibration logger of any of claims 1 to 16; mounting the vibration logger to a component of an aircraft; attaching at least one sensor to the aircraft component; connecting the at least one sensor to the vibration logger; and operating the vibration logger to record vibration data over a sampling period during a sortie of the aircraft. 29. The method of claim 28, wherein vibration data is recorded continuously over the sampling period to capture benign and severe vibration events. 30. The method of claim 28 or 29, wherein wideband vibration data having a frequency bandwidth of 2 to 2000 Hz is recorded over the sampling period. 31. The method of any of claims 28 to 30, wherein vibration data is recorded at a sampling rate of at least 6000 samples per second. 32. The method of any of claims 28 to 31, wherein vibration data is recorded for at least 2 hours. 33. The method of any of claims 28 to 32, further comprising the steps of: dis-connecting the at least one sensor from the vibration logger; removing the vibration logger from the aircraft component; connecting the vibration logger to a PC; and downloading the recorded vibration data from the vibration logger. 34. The method of claim 33, further comprising the step of: connecting the vibration logger to a power supply external to the vibration logger to power the vibration logger and charge the power source of the circuitry of the vibration logger. 35. The method of any of claims 28 to 34, wherein the at least one sensor is a tri-axial accelerometer having three outputs. 36. A vibration logger substantially as hereinbefore described with reference to the accompanying drawings. 37. A vibration logger system substantially as hereinbefore described with reference to the accompanying drawings. 38. A vibration logger kit substantially as hereinbefore described with reference to the accompanying drawings. 39. A vibration logger assembly substantially as hereinbefore described with reference to the accompanying drawings. 40. A shape adapter substantially as hereinbefore described with reference to the accompanying drawings. 41. A method of logging air carriage vibration substantially as hereinbefore described with reference to the accompanying drawings. |
The present invention relates to a vibration logger for recording air carriage vibration, in particular the vibration of countermeasures when deployed on aircraft, a vibration logger system, kit and assembly comprising the same, and a method of logging air carriage vibration.
Munitions must be capable of remaining safe and serviceable when deployed on aircraft. That capability is demonstrated by laboratory qualification trials, in which the munition is inspected and functioned after having been subjected to a series of applied environments. Those environments include vibration, which is important because the flight carriage environment can consume a large amount of a munition's fatigue life. Following the successful outcome of such trials, the munition type is granted, amongst other things, a safe and serviceable life, including a specified number of hours of air carriage.
An important consideration for the laboratory trials is the vibration severities (amplitude and duration) that the munition should be subjected to. For air countermeasures, deployment on a range of aircraft and involving a large number of different installations is required. The vibration environment associated with each installation can be different, dependent upon the type of aircraft, i.e. fast jet, helicopter, large body, UAS, and the response of the installation to the local vibration environment. Consequently, there are no default vibration test severities available within the appropriate defence standard (DEF STAN 00-35) that can be used to describe the on-platform environment. Indeed, that defence standard states that the vibration qualification of air countermeasures must be based upon vibration data measured during flight on the installation.
The measurement of the required vibration data has traditionally been accomplished with relatively large complex instrumentation systems, involving installations that require use of the aircraft for a minimum of a week. Such installations are time consuming and expensive to fit and cannot be used on all aircraft. Also, whilst effective, those systems include many elements and are more susceptible to failure in use, possibly leading to re-trials with their associated costs.
It is an aim of the present invention to provide an alternative vibration logger which requires only input from a vibration sensor and no external power or control connections when fitted to an aircraft for vibration logging.
In one aspect the present invention provides a vibration logger for logging air carriage vibration, being self-contained and requiring no external power or control connections when fitted to an aircraft for vibration logging, and comprising a case which includes a connector for connection to at least one sensor external to the case and circuitry which is potted within the case and operative to log carriage vibration sensed by at least one sensor when connected to the connector, wherein the circuitry comprises memory for storing vibration data, a processor which processes an output from the at least one sensor and provides for sampling of data in accordance with a predetermined sampling protocol and writing of the sampled data to the memory, and an power source for powering the circuitry.
In one embodiment the case is of a construction which can withstand an internal explosive pressure.
In one embodiment the circuitry is fully-potted within the case.
In one embodiment the circuitry is mounted on one or more circuit boards, which are subjected to thermal and vibration electronic stress screening processes before potting of the circuitry.
In one embodiment the circuitry comprises a plurality of analogue input stages, which each have an input connected to the connector to receive respective ones of analogue outputs from the at least one sensor. In one embodiment each input stage comprises a DC block having an input connected to the connector, an amplifier connected to an output of the DC block, and an anti-alias filter connected to an output of the amplifier for restricting the bandwidth of the received analogue signal.
In one embodiment the circuitry further comprises a plurality of ADCs which each have an input connected to an output of a respective one of the input stages, and a plurality of digital filters which each have an input connected to an output of a respective one of the ADCs and act to filter the received digital signals from the ADCs and an output connected to the processor.
In one embodiment the circuitry further comprises a memory control device having a first port connected to the memory, a second port connected to the processor for enabling writing of sampled data to the memory and a third port for enabling reading of logged data from the memory and programming of the processor.
In one embodiment the circuitry further comprises a controller which is connected to a start/stop switch, and, through operation of the start/stop switch, enables operation of other components of the circuitry.
In one embodiment the power source comprises a rechargeable battery.
In one embodiment the circuitry further comprises a battery management controller for managing the battery.
In one embodiment the vibration logger is configured to record data continuously over a sampling period to capture benign and severe vibration events.
In one embodiment the vibration logger captures and records wideband vibration data having a frequency bandwidth of 2 to 2000 Hz. In one embodiment the vibration logger has a sampling rate of at least 6000 samples per second.
In one embodiment the vibration logger captures data for at least 2 hours.
In one embodiment the vibration logger further comprises a further connector for connection to a PC and a power supply external to the vibration logger.
In another aspect the present invention provides a vibration logger system for logging air carriage vibration, comprising : the above-described vibration logger; and at least one sensor external to the vibration logger and connected to the sensor connector of the vibration logger.
In one embodiment the at least one sensor is a tri-axial accelerometer having three outputs.
In one embodiment the system further comprises: a PC, preferably a laptop, which has applications for programming the vibration logger with a predetermined sampling protocol, downloading logged data and analysing the logged data.
In one embodiment the system further comprises: a power supply external to the vibration logger for powering the vibration logger when removed from the aircraft and charging the power source within the circuitry of the vibration logger.
In a further aspect the present invention provides a vibration logger assembly, comprising : an aircraft component; the above-described vibration logger mounted to the aircraft component; and at least one sensor attached externally of the vibration logger to the aircraft component and connected to the sensor connector of the vibration logger. In one embodiment the aircraft component is an air countermeasure magazine having a plurality of flare cavities and the vibration logger is loaded into one of the flare cavities.
In yet another aspect the present invention provides a vibration logger kit, comprising: the above-described vibration logger; and a set of a plurality of shape adapters, each having a cavity into which the vibration logger is mountable to allow for logging of data in different environments where using a single, common vibration logger, with the different shape adapters having different shapes corresponding to the different environments.
In one embodiment the shape adapter comprises a housing into which the vibration logger is mechanically mounted.
In one embodiment the housing includes ballast to provide for mass compensation.
In still another aspect the present invention provides a shape adapter for use with a vibration logger on an aircraft, the shape adapter comprising a housing having an external shape corresponding to an aircraft environment and a cavity into which the vibration logger is mountable to allow for logging of data in the aircraft environment.
In one embodiment the housing includes ballast to provide for mass compensation.
In still yet another aspect the present invention provides a method of logging air carriage vibration, comprising the steps of: providing the above- described vibration logger; mounting the vibration logger to a component of an aircraft; attaching at least one sensor to the aircraft component; connecting the at least one sensor to the vibration logger; and operating the vibration logger to record vibration data over a sampling period during a sortie of the aircraft.
In one embodiment vibration data is recorded continuously over the sampling period to capture benign and severe vibration events.
In one embodiment wideband vibration data having a frequency bandwidth of 2 to 2000 Hz is recorded over the sampling period.
In one embodiment vibration data is recorded at a sampling rate of at least 6000 samples per second.
In one embodiment vibration data is recorded for at least 2 hours.
In one embodiment the method further comprises the steps of: disconnecting the at least one sensor from the vibration logger; removing the vibration logger from the aircraft component; connecting the vibration logger to a PC; and downloading the recorded vibration data from the vibration logger.
In one embodiment the method further comprises the step of: connecting the vibration logger to a power supply external to the vibration logger to power the vibration logger and charge the power source of the circuitry of the vibration logger.
In one embodiment the at least one sensor is a tri-axial accelerometer having three outputs.
Preferred embodiments of the present invention will now be described hereinbelow by way of example only with reference to the accompanying drawings, in which: Figure 1 illustrates a vibration logger system in accordance with a preferred embodiment of the present invention;
Figure 2 illustrates the vibration logger of the vibration logger system of Figure 1;
Figure 3 schematically represents the circuitry of the vibration logger of Figure 2;
Figure 4 illustrates the vibration logger and sensor of the vibration logger system of Figure 1 where mounted to an air countermeasure magazine; and
Figures 5(a) to (c) illustrate a shape adapter into which the vibration logger of Figure 2 is mounted in accordance with another embodiment of the present invention.
The vibration logger system comprises a vibration logger 1, in this embodiment a self-contained unit which requires no external power or control connections when fitted to an aircraft for vibration logging, at least one sensor 2, in this embodiment a tri-axial accelerometer, here of ICP type, having three outputs, which is connected to the vibration logger 1 and external thereto, a PC 3, typically a laptop to allow for on-site use, which has applications for programming the vibration logger 1 with a predetermined sampling protocol, downloading logged data and analysing the logged data, and an external PSU 4 for powering the vibration logger 1 when removed from the aircraft and charging a re-chargeable battery cell 70 within the vibration logger 1.
By requiring no external power or control connections when fitted to an aircraft for vibration logging, the vibration logger 1 allows data to be gathered with a minimum disruption to the flying programme of the air vehicle. The vibration logger 1 comprises a case 5 which includes a first, management connector 6, in this embodiment a DIN connector, for connection to the PC 3, a second, sensor connector 7 for connection to the at least one sensor 2, and a start/stop switch 9 for starting/stopping the operation of the vibration logger 1.
In this embodiment the case 5 is a Type 118 flare case of square-section aluminium alloy construction, which can withstand an internal explosive pressure.
The vibration logger 1 further comprises circuitry 15 which is potted, in this embodiment fully-potted within the case 5. In this embodiment the potting material is Silcoset (RTM), which is applied with the circuitry in place within the case 5, and with the connectors 6, 7 being protected against the ingress of the potting material.
In this embodiment the circuitry 15 is mounted on one or more circuit boards, which are subjected to severe thermal and vibration electronic stress screening processes before final assembly.
The circuitry 15 comprises a plurality of analogue input stages 21, in this embodiment three input stages 21a, 21b, 21c, which each have an input connected to the sensor connector 7 to receive respective ones of the three analogue outputs from the sensor 2.
In this embodiment each input stage comprises a DC block 23 having an input connected to the sensor connector 7, an amplifier 25, here a variable- gain amplifier, connected to an output of the DC block 23 and an anti-alias filter 27 connected to an output of the amplifier 25 for restricting the bandwidth of the received analogue signal. In this embodiment the amplifier 25 allows for different gains to be set, such that the vibration logger 1 can be optimized to monitor both benign and severe vibration environments.
The circuitry 15 further comprises a plurality of ADCs 31, in this embodiment three ADCs 31a, 31b, 31c, which each have an input connected to an output of a respective one of the input stages 21a, 21b, 21c.
The circuitry 15 further comprises a plurality of digital filters 41, in this embodiment three digital filters 41a, 41b, 41c, which each have an input connected to an output of a respective one of the ADCs 31a, 31b, 31c and act to filter the received digital signals from the ADCs 31a, 31b, 31c.
The circuitry 15 further comprises memory 45, in this embodiment flash, for storing the logged data, and a memory control device 47, in this embodiment an Antioch (RTM) USB control device, having a first port connected to the memory 45, a second port connected to a processor 51 for enabling the writing of data to the memory 45 and a third port connected to the management connector 6 for enabling the reading of logged data from the memory 45 to the PC 3 and the programming of the processor 51.
The circuitry 15 further comprises a processor 51, in this embodiment a NIOS processor, which receives an output from each of the digital filters 41a, 41b, 41c and is connected to a port of the memory control device 47, such as to allow for the sampling of data in accordance with a predetermined sampling protocol and the writing of the sampled data to the memory 45.
In this embodiment the digital filters 41a, 41b, 41c and the processor 51 are implemented in an FPGA 53, here a Cyclone (RTM) FPGA, which includes memory 55 for storing hardware and software code for the operation of the digital filters 41a, 41b, 41c and the processor 51. In this embodiment the processor 51 allows for the setting of long time delays before the vibration logger 1 begins to record data. In this embodiment the vibration logger 1 is configured to record data continuously over a sampling period during a data gathering sortie, which allows benign and severe vibration events to be captured. Capturing benign and severe events enables improved fatigue damage calculations to be performed in determining laboratory test durations.
The circuitry 15 further comprises a controller 61 which is connected to the start/stop switch 9, and, through operation of the start/stop switch 9, enables operation of the higher-power FPGA 53 and the other circuit components.
In this embodiment the controller 61 is implemented in a low-power FPGA 63, here an Igloo (RTM) FPGA. In implementing the controller 61 in the low-power FPGA 63, the stand-by power requirement of the circuitry 15 is minimized.
The circuitry 15 further comprises a battery cell 70, in this embodiment a Li+ cell, a plurality of power supplies 71, in this embodiment a permanent digital power supply 71a, a switched digital power supply 71b, an 8V analogue power supply 71c and a 28V analogue power supply 71c, which are powered by the battery cell 70 and operative to power the circuit components, and a battery management controller 81.
In this embodiment the battery management controller 81 is connected to the battery 70, here a battery cell, the power supplies 71 and the management connector 6 to manage operation of the power supplies 71 both when the vibration logger 1 is not connected to the external PSU 4 and when the vibration logger 1 is connected to the external PSU 4, and manage the charging of the battery 70 when the vibration logger 1 is connected to the external PSU 4, protecting the battery 70 against the effects of overcharging (voltage and current) and short-circuit conditions.
In this embodiment the external PSU 4 is a COTS 6V high-current PSU.
In this embodiment the vibration logger 1 is configured to capture and record wideband vibration data, here having a frequency bandwidth of 2 to 2000 Hz. In this embodiment the vibration logger 1 has a sampling rate of 6000 samples per second.
In this embodiment the vibration logger 1 is configured to capture data for at least 2 hours.
In this embodiment, by having the sensor 2 external to the vibration logger 1, vibration can be measured at any desired location using the one vibration logger 1, as opposed to just that location at which the vibration logger is mounted.
In this embodiment, as illustrated in Figure 4, the vibration logger 1 is loaded into one of the flare cavities 89 in an air countermeasure magazine 91 and the sensor 2 is attached to the air countermeasure magazine 91.
In another embodiment, as illustrated in Figures 5(a) to (c), the data logger system comprises a set of shape adapters 101 into which the vibration logger 1 is mounted to allow for logging of data in different environments where using a single, common approved vibration logger 1, with the different shape adapters 101 having different shapes corresponding to the different environments. This arrangement is particularly advantageous, in providing for versatility, insofar as a common vibration logger 1 can be used for a wide range of applications, which can be non-countermeasure applications. In this embodiment the shape adapter 101 comprises a housing 103, here a cylindrical housing corresponding to a 55 mm flare for an alternative countermeasure installation, into which the vibration logger 1 is mechanically mounted.
The shape adapter 101 is designed to provide the required mass characteristics, and in this embodiment includes ballast 105 for providing mass compensation.
In this embodiment the housing 103 includes at least one supporting disc 107 through which the vibration logger 1 is inserted and which supports the vibration logger 1.
Finally, it will be understood that the present invention has been described in its preferred embodiments and can be modified in many different ways without departing from the scope of the invention as defined by the appended claims.