The three use cases were analysed by the consortium, and the actual sensor types and models were selected for each use case. The selected elements include ARINC429 bus tapping, COLUMBIA strain gauges, digital accelerometers, analogue accelerometers, thermistors and piezo-electric diaphragms. The sensor operations procedures for the whole data transmission chain were established.
On the hardware side, the architecture of an acquisition PCB meant to be plugged to the wireless communication electronics was proposed. It includes performant ADCs for the acquisition of analogue sensors and the digital high range accelerometer. The PCB was produced and successfully interfaced to the communication board. A housing was created for the sensor node and the tests showed that the sensors can be acquired with the required data rate and accuracy.
The wireless data concentrator (WDC) manages groups of wireless sensors and interconnects them with the avionics over the aircraft wired network. The WDC design was proposed and its implementation realised. It includes a powerful STM32H743 MCU to withstand the high throughput and implement communication over Ethernet. Synchronisation between several WDC's is done by a Precise Time Protocol (PTP) implementation. After integration, synchronisation was evaluated at the whole network scale (wired plus wireless parts): as the synchronisation error on the wireless part of the network is around 12 µs, the total synchronisation error between two sensor nodes is in the order of 15 µs. assuming variability between samples of the same components and environmental effects, and taking some margin, a synchronisation accuracy of 100 µs is achievable. A housing was also realised for the WDC.
The wireless communication protocol was implemented over the u111 real-time operating system which provides best-in-class energy consumption.
A theoretical assessment of inductive power line harvesting from the aircraft main power supply harnesses was performed, revealing that adequate power density can potentially be achieved, to address the power requirements of use case 1 when the duty cycle is low (100 mW). Therefore, the inductive energy harvesting method was selected. A new flux funneling approach was developed and adopted, offering a substantial increase of power density. A first energy harvesting power supply design was developed during the first period and then improved during the second. It was delivered to Airbus for integration into the full SMARTWISE system and tests. The results demonstrate the power supply functionality with power line currents as low as 6 A, 300 Hz. Indicatively, the cold starting time at 10 A, 500 Hz is around 10 minutes. The average power can support the functionality of the SMARTWISE sensor nodes at low sampling rates. Higher power line currents are expected to provide higher power flows, indicatively up to 100 mW at 40 A, 500 Hz.
An architecture was also proposed for the active interrogation of up to 7 piezo-electric sensors, with an 8th one used to generate high voltage excitation signals. An embedded demonstrator based on evaluation kit was realised. Signals from the pizoeelectric sensors were acquired and also the active piezo sensor could be sucessfully driven by the embedded platform. This result was passed on to H2020 GENEX during which the system TRL will be increased.
The project has successfully submitted three peer reviewed publications, including a journal paper. The project was also advertised at the 2023 Paris Air Show and also demonstrated to students.
