Using LabVIEW and PXI to Design and Implement a Test Rig for an Electrical Steering System Prototype for Airplane Nose Landing Gear

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"With the PXI platform and NI LabVIEW programming environment, we efficiently developed our test rig control and measuring system. The hardware configuration leaves room to connect more input signals and to expand the system by using new measurement modules. Due to its modular design, we can expand our application by implementing additional functionalities. In addition, the ready-to-use signal analysis functions in LabVIEW will make that implementation process as simple as possible."

- Bogdan Iwiński, VERITECH Sp. z o.o.

The Challenge:
Designing and implementing a test rig for the electrical steering system prototype of passenger airplane nose landing gear based on an AIRBUS A320.

The Solution:
Creating a system based on NI LabVIEW software and PXI hardware using a real-time OS for quick development of the test and control application for the test rig, and ready-to-use LabVIEW functions to quickly develop our algorithm.

Author(s):
Bogdan Iwiński - VERITECH Sp. z o.o.
Rafał Kajka - Instytut Lotnictwa, Pracownia Podwozi Lotniczych

 

Introduction

The aim of the Distributed and Redundant Electromechanical nose wheel Steering System (DRESS) international project was to create a prototype of a passenger aircraft nose landing gear electrical steering system. The Institute of Aviation (IoA) Landing Gear Department scientists designed and manufactured an electrical steering system test rig prototype to simulate actual conditions. They designed the test rig to withstand quick and simple configuration changes due to the prototypical nature of the test object. Such flexibility in configuration changes almost always forces modifications in control and test rig hardware testing.

DRESS Test Rig Control System

IoA engineers designed, developed, and manufactured the DRESS test system. They created the mechanical design and manufacture, as well as requirements for the test rig control system. Veritech, a National Instruments Alliance Partner, developed the test rig control software. DRESS test program assumptions forced test rig flexibility due to both quasistatic and dynamic loads at the level of the nose landing gear wheels. The test rig needed to perform a wide range of tests. Two main tests configuration was defined: dynamic mode simulates high frequency oscillations and low frequency high torque mode simulating mainly ground manoeuvres.  First of them was defined as a Dynamic Control Sub System (DCSS), second as an Antagonistic Torque Control Sub System (ATCSS). Based on two different loading requirements, the system was designed and build using interchangeable hardware and software configurations (Figure 1.).

To simulate conditions during low-speed airplane taxiing, module powered by a hydraulic engine (ATCSS) was build. In this case, low-frequency (up to 4 Hz), large-angle (up to 90o), high-value torque occurs. To simulate  simulate high frequency oscillations, which normally can occur on Nose Landing Gear, an electrically driven module (DCSS) was made. This module unbalances the airplane nose wheels using two discs mounted in place of the original wheels. During dynamic tests, speed of the wheels can reach up to 4,000 rpm for high-value torque with higher frequency, but with limited twist angle (up to 5o).

With this solution, a test rig was created that meets the tests requirements and is compact enough to fit in the destination laboratory. The unique properties of the PXI measurement platform was maximized (for example, strict synchronization between the measurement modules inside PXI chassis) for high-quality, coherent sets of test data.

New version of LabVIEW was used to create an application that divides its threads between two cores of the multicore CPU for better stability and to execute all tasks within the desired time. The application can also detect the current mechanical configuration of the test rig by using proper identification solutions. The main part of our control-testing application maximizes the capabilities of a real-time OS. Real-time OS was used to make designed application more stable, which is crucial from safety and reliability point of view.

Besides application stability, which enhances test rig safety, also was faced a challenge to deliver properly timed, high-quality signals for external measuring systems made by other project participants. Application multithreading and PXI platform synchronization made it possible to deliver signals with as little as a millisecond delay. Scalable signals was generated, which were measured directly by the test rig. We also generated signals resulting from the analysis of multiple measurement inputs, which required proper signal processing optimization and synchronization to achieve proper signal consistency under time constraints.

Conclusion

With the PXI platform and NI LabVIEW programming environment, we efficiently developed our test rig control and measuring system. The hardware configuration leaves room to connect more input signals and to expand the system by using new measurement modules. Due to its modular design, we can expand our application by implementing additional functionalities. In addition, the ready-to-use signal analysis functions in LabVIEW will make that implementation process as simple as possible.

A National Instruments Alliance Partner is a business entity independent from National Instruments and has no agency, partnership, or joint-venture relationship with National Instruments.

For more information on this Case Study, please contact:

Rafał KAJKA

Rafal.KAJKA@ilot.edu.pl
Institute of Aviation Landing Gear Department
Aleja Krakowska 110/114
02-256 Warszawa, Polska
www.ilot.edu.pl

Author Information:
Bogdan Iwiński
VERITECH Sp. z o.o.
ul. 1 Maja 21/3
Ruda Slaska 41-706
Poland
b.iwinski@veritech.pl

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