Rotational Data Acquisition for Rotorcraft Wind Tunnel Models

Abstract

The paper introduces a modular rotating data acquisition system (DAQ) setup of a wind tunnel model for rotorcraft research. A rotorcraft wind tunnel model has the requirement to acquire data in the rotational as well as in the fixed model part. These tasks are handled by two separate DAQ systems, both sampling their data independently at up to 50k/s per channel. The rotating DAQ is using a microcontroller based real-time frontend in combination with a Linux based embedded system serving highlevel-interfaces like the Reduced Media Independent Interface (RMII) or USB. For piloting and monitoring during wind tunnel testing an Ethernet data link is used through a Wi-Fi (Dual-Band 802.11ac) connection. The safe model operation and scientific data analysis needs a low latency online data synchronization and merging from different measurement systems. A synchronization concept based on time stamping with the Network Time Protocol (NTP) and an analog 1/rev reference signal is described.