UDP Based Wireless Telemetry Network and Data Acquisition System for Rotary Application

Transcription

1 UDP Based Wireless Telemetry Network and Data Acquisition System for Rotary Application Item Type text; Proceedings Authors Imay, Murat; Cranley, Nikki; Atman, Ozgur Publisher International Foundation for Telemetering Journal International Telemetering Conference Proceedings Rights Copyright held by the author; distribution rights International Foundation for Telemetering Download date 08/06/ :35:41 Link to Item

2 UDP BASED WIRELESS TELEMETRY NETWORK AND DATA ACQUISITION SYSTEM FOR ROTARY APPLICATION Murat IMAY, Nikki CRANLEY, Ozgur ATMAN Turkish Aerospace Ind. FTI Department Curtiss-Wright Avionics and Electronics, Acra Business Unit ABSTRACT This paper presents an open system architecture with wireless network centric telemetry and data acquisition over UDP/IP. This networked solution was designed and developed for iron bird and helicopter rotor applications which present a significant challenge for data acquisition and telemetry. Traditionally slip rings were used for data transfer however these result in issues with low bandwidth, electrical noise, installation complexity, and high maintenance costs. This paper describes a networked system using standardized technologies and protocols that was used for data acquisition and recording of parameters such as vibration, strain, and video on DAQ installed on the rotating part. The acquired data was transmitted in real-time via the network-centric wireless telemetry link which was synchronized with a ground-based DAQ used for real time processing of the rotor data. KEYWORDS Wireless Network, UDP/IP, PTP 1588, Slip Rings, Data Acquisition System, GPS. INTRODUCTION The wireless network centric data acquisition and telemetry solution described in this paper was designed and developed for iron bird and helicopter rotor application in order to collect and record parameters coming from rotating and static part sensors with GPS data time stamp. This system comprises three subsystems; a static DAQ sub-system, a mobile DAQ subsystem and the wireless network-centric telemetry interface. The static DAQ sub-system monitors and records static parameters such as the engine, transmission etc. The mobile DAQ sub-system can be used either as a standalone device or integrated with the static sub-system. As a standalone device, it supports a battery and solid state recorder. As an integrated subsystem it can interface with the static sub-system via wireless network centric telemetry in order to measure and transmit parameters from the rotating components such as the hub, swash plate and blades. This sub-system is reconfigurable and extendible to support additional channel inputs, or additional data types. In fact, since the solution is realized entirely using open standards-based network technologies, any device with an Ethernet interface can be added to the architecture without any modification. 1

3 The motivation for this work is to replace traditional PCM based telemetry solutionss for slip rings with a fully open system architecture wireless network centric telemetry and reliable data collecting capability. Instrumentationn designerss avoid the difficulties d of slip-ring designs and disadvantage of PCM based data link using this approach.. Difficulties of using slip ring are low bandwidth; electrical noise; installation complexitie s; and highh maintenance and equipment costs. In general, traditional t solutions for acquisition on rotating parts are closed and proprietary, they are expensive andd due to the closed nature n of the technology, it is challenging to integrate equipment from different manufacturer rs without major modification. These factors ultimately determine the success of the project. CONVENTIONAL APPROACHES Figure 1 Slip Ring Slip ring technologies are designed forr rotary applications whereby w current or voltage is transferred from a rotating unit to a stationary one, as shown in i Figure 1.. In a slip ring, it is either the brushes or the rings are stationary whilst the other component rotates. Thesee brushes or rings can generate electrical noise between the stationaryy and rotating contacts which results in distorted data. Other disadvantagesof such systems s include: installation complexities; high maintenance costs duee to size; limited number of rotations and a limited / fixed number of channels, all of which can significantly affect the cost of the system. PCM data link solution is an alternative solution to transfer data from rotating parts to static parts instead of using slipring. PCM technology is old, expensive, and proprietary but it is a mature and proven solution. However, as previously mentioned, PCM based systems are challenging with regards integration in multi-vendor systems. 2

4 NEW MEASUREMENT APPROACH ANDD SOLUTION Figure 2 System Architecture An open system architecture using wireless network centric technologies can solve many of the problems associated with mechanical slip rings and conventional telemetry technologies such as PCM. The main advantage of Ethernet based wireless telemetry t over the PCM-based solution is its open system architecture, cost effectiveness, and ease of installation and integration. Any device that supports an Ethernet interface can be b easily and seamlessly added to the architecturee without modification n. Such an open system and open standards based solution enables an almost plug and play capability for data acquisitionn systems. Standard wirelesss networking technologies such as IEEE G WLAN have an RF line rate of 54Mbps and an effective throughput capability of ~26Mbps which is more than adequate capacity for high speed data orr high definition video. Figure 2 shows the system architecture which comprises a rotating part andd a static part. Both are connected to the switch box, however there is a wireless link connecting the rotating part to the switch box. Data is acquired at these two different locations and merged based on the GPS time to make one complete and total mission. Both DAUs D are synchronized using IEEE1588 PTP time protocol providedd by the switch boxx which has embedded 1588 Grandmaster capability. This enables thee system to have high resolution r time tags associated with every measurement and enables synchronization between the mobile data acquisition system on the rotating part and the static data acquisition system. 3

5 Figure 3 Mobile Data Acquisition System This system, shown in Figure 3, can be used as a stand-alone mobile m dataa acquisition system with its own battery, transmitter, built-in solid state recording, and a signal conditional modules which can be reconfigured to handle additional channel inputs, or to accommodate acquisition from other data types. Moreover, the mobile data acquisition system cann be integrated and synchronized with the static data acquisition system via the network switchh box. SYSTEM COMPONENT Switch Box In any networked system the switch is a key component that allows data to be transmitted to and from sub-systems in the network, inn this instance the static sub-system and the rotating sub-system. The switch box comprises a number of ports to which static DAQ sub-system and wirelesss network centric bridge can be connected using point-to-point full-duplex Ethernet links. By far, the most important task of the switch is to reliably and quickly forward packets to their destination. The switch box used in this system was the NET/SWI/004 from Acra. This switch was chosen not only for its high performance, reliability, andd its unique live at power up capability, but it also had an embedded IEEE grandmaster that wass used to synchronize all devices within the system architecture. Transmitter The systems transmitter operates licensee free ISM frequency bands of GHz and supportss a range of up to 16km with a PHY rate of 54Mbps.The achievable ranges are dependent on the antenna solution. 4

6 Antennas An omni directional antenna is used onn the rotating part in order o to provide a 360 degree coverage with 20 watts of power. Vertical dipole antennas were selected and oriented in such a way to cover all the radio signals coming from the rotating part, as illustrated in Figures 4 and 5. Figure 4 Transmitter Antenna Pattern Figure 5 Receiver Antenna Pattern Real Time Data Monitoring Figure 6 IADS Real-Time Analysis Software 5

7 The IADS software from Symvionics, shown in Figure 7, was used for monitoring and analysis of data in real-time. This software afforded significant time-saving and effort during the test. The test bench can be also stopped automatically in a real time using this software in case of any threshold and overload situation of sensors defined in the test configuration. CONCLUSION This paper presented the design, development and real application of a UDP based wireless network centric data acquisition system for rotary application. This solution was been successfully deployed many times during the test campaign. Not only has this been successful in terms of the reliability, real-timeliness and fidelity of the acquired data but also it has demonstrated the significant advantages of open standards based architectures in terms of installation, flexibility, cost-saving and maintenance. 6