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Tips & Trends

February 1, 2017

Q.series interface with the Moog Aerospace Test Controller

Introduction

The amount of data generated in an aircraft structural test program is growing. The density of load introduction points (actuators) and sensors (strain gages, thermocouples, LVDTs) on a test article is increasing progressively and model validation requires higher data sample rates to capture more detail. Risks and costs involved in aircraft validation and certification are huge. Pressure for quick entry-into-service is high. To minimize the impact of in-service aircraft retrofitting, the ability to generate test results quicker is crucial to the success of a test program.

Gantner Instruments has developed an Ethernet communication interface that transfers data from the Moog Aerospace Test Controller to the Q.series measurement system. Controller signals such as command, feedback, control error and flight spectrum information are continuously send to the Q.series measurement system for online storage, monitoring and analysis. This reduces the burden of post-test data analysis.

Q.series measurement system

The innovative Q.series system has been designed for today’s most demanding testing environments. High speed, high accuracy and reliability characterize the Q.series system. The Q.series is highly scalable and comes with a wide availability of measurement modules, benefiting test system architecture options and test lab capacity. Each measurement module has been optimized to provide the best price-performance-ratio available on the market.

The Ethernet communication interface with the Moog Aerospace Test Controller is handled by a plugin that runs on the Q.series’ real-time controller, called the Q.station. The Q.station firmware features a plugin management system to support easy deployment and maintenance of custom communication protocols.

For installation and connection details, please refer to the applicable Q.series product manual.

All manuals are available for download.

Moog Aerospace Test Controller

The Moog Aerospace Test Controller is a digital servo controller designed for static and fatigue testing of aircraft structural components. Its unique architecture and control loop design allows for synchronized closed-loop control of up to 500 servo actuators. Test setup, operation, and monitoring is done through the Aerospace Test Suite software.

Ethernet communication interface

The communication interface between the Aerospace Test Controller and the Q.series system uses a bi-directional Ethernet communication protocol, which allows for easy configuration and operation. The protocol consists of three different interfaces:

  1. Controller data that is send from the Moog Aerospace Test Controller to the Q.series system
  2. “Handshaking” interface to send commands and statuses from and to the Test Controller
  3. Measurement data that is send from the Q.series system to the Moog Test Controller

For each control channel the following signals are send to the Q.series system:

  • Force command
  • Force A feedback (load cell bridge A)
  • Force B feedback (load cell bridge B)
  • Position feedback
  • Servo valve current
  • Force control error
  • Position control error

In addition, for each Aerospace Test Controller a set of Shared Memory channels (virtual calculation channels) are send to the Q.series system. The number of Shared Memory channels depends on the controller configuration; minimum 64 channels, maximum 1280 channels.

The Aerospace Test Controller buffers the data, which is then polled by the Q.series system at fixed intervals. The Aerospace Test Controller buffers its data at either 100, 200, or 500 Hz.

Both systems are time synchronized using a networking protocol for clock synchronization. Typically, the NTP server is installed on one of the workstations. Both the Aerospace Test Controller and the Q.series system slave to the NTP server. For more information about configuring the Q.series’ NTP client, please refer to Chapter 6 of the Q.station manual.

The Q.series system, Moog Aerospace Test Controller, and workstation(s) should all be in the same network range. To connect the Aerospace Test Controller to the Q.series system standard Ethernet cables and a 1 Gb/s Ethernet switch are used. Connect the Office Network port on the Aerospace Test Controller to the switch. On the Q.station the Ethernet TCP/IP port should be used.

A Moog Plugin Configuration Tool is provided with the Q.series system to configure the settings of the plugin, i.e. IP addresses, channel selection and time sync alarm.

Usually it is not needed that all Test Controller channels are recorded. To minimize data overhead, a search filter can be added to quickly select a subset of Test Controller channels for recording.

Fully configurable data loggers

The Q.series allows up to 20 unique data loggers. Each data logger can be configured for continuous, triggered or event-based data recording. Each logger can be setup to record a different data set with a different logging rates. For example, one logger can be configured for continuous data recording to a network locations. In parallel, a high-speed data logger can be set up with a pre- and post-trigger time in case an unexpected event occurs.

File name, size, destination, and protection level are fully configurable for each data logger. Each logger can write data to a different location, either the internal flash memory, an SD-Card, SATA hard drive, USB flash drive or any connected network drive.

For more information about recording data using the data logger, please refer to the Q.station manual.

User Benefits

Reduce sensor wiring and cost; all controller data is transferred over a single Ethernet cable. There is no need for extra wiring of sensors, like load cells, to both the control and measurement system.

Distributed system architecture; the Q.series system can be distributed around the test article, resulting in significantly shorter transducer cables between measurement modules and thousands of strain gages.

Connect multiple Moog tests to one Q.station; the Moog Aerospace Test Controller can run up to 5 tests in parallel. Each test has its own data port. All data ports can be connected to one Q.station, saving cost on additional measurement hardware.

On-line monitoring and analysis of test data; ability to monitor and analyze the control and measurement data always and immediately inform the user and/or stress analysist when deviations occur.

Assured data availability; the Q.series system has 3 levels of redundancy for assured data availability. Measurement data can be broadcasted in parallel to an online database as well as to an FTP backup server. Both data ports are continuously monitored. If a broadcast fails, the Q.series system will automatically start logging data to its local disk.

Build-in time sync monitoring; the Q.series provides a unique functionality that allows monitoring the clock time difference between the Moog Aerospace Test Controller and the Q.series system. In case the clock time difference is outside a pre-defined threshold an alarm is generated to inform the operator. This avoids unacceptable data skew or jitter.

For more information please contact s.ploegman@​gantner-instruments.com