In February 2021 another milestone has been reached in the product development journey of SmartSens. Considering the harsh environment SmartSens equipment will be deployed at, we tested our prototypes brutally to ensure operational readiness all through the flight season. One such challenge was a drop test where a Flying Link was dropped 1000 times from various heights between 3 and 10 meters onto a concrete block, with a custom made drop-test-setup. A dedicated software performed self-tests periodically and sent the results to an application. The endurance test simulated extreme impacts that the Flying Link housings shall endure and the high accelerations that the internal parts shall bear in cases, where the parachute doesn’t function correctly and the Flying Link falls freely.
The results were an enlightenment and a huge success to detect possible in-service issues at a very early stage. When we evaluated the data collected by our equipment last summer, we observed some minor drifts in sensor readings over the season that we couldn’t explain. With the extensive testing, we could replicate the phenomenon and track this back to material properties of the force sensors used at the earlier prototypes of SmartSens. Due to the stiff contact surface (i.e. concrete), the drop impacts acted as large compressive loads on the sensor and the sensor slightly deformed causing a drift in calibration. The sensor was still strong enough to hold the take-off loads with a substantial safety margin but the measurement sensitivity was degraded after the drops.
In light of the endurance test results, SmartSens went through a complete design loop with both mechanical and software adaptations and is upgraded with a new sensor material which is, due to its material properties with wider and higher elasticity, much more resistant to the impact forces. With the new material selection, the SmartSens sensor endured to 1000 drop cycles with a maximum height of 10m onto concrete with no observable zero-point drift in force measurements. After the complete endurance test, the sensor passed a full calibration test without any observable drift and a break test where the sensor didn’t break far beyond the design safety limit.
With the upgraded SmartSens design, we are preparing our product for the upcoming flight season!