IEEE - Aerospace and Electronic Systems - February 2022 - 30

Modular and Flexible On-Ground Test Bench for Aircraft Electromechanical Actuators
start of the flight test campaign, allowing for early detection
of integration issues, which implies their early correction,
thus minimizing the impact in terms of time and cost.
With this approach, any issues that may appear during the
flight test campaign have been minimized, although not
eliminated. Anyway, during the flight test campaign, the
benches were used to reproduce any issues that may
appear in flight, and to analyze and propose solutions to
be implemented quickly.
Several tests were carried out on the primary flight conFigure
8.
Power distribution box to protect each set ofEMA and control unit.
control-and-acquisition rack, and all cRIOs are interconnected
to the PC via Ethernet communication.
Each test bench will incorporate a distribution box,
connected to the electrical network, to protect each set
ofEMA and control units using the corresponding remotecontrolled
circuit breaker. Contactors may also be installed
in series with the circuit breakers so as to switch ON/OFF the
EMA and its control unit remotely (see Figure 8).
At signal lines, patch panels (see Figure 9) are provided,
with manual and switching capability, in order to simulate
the corresponding failures within every EMA subsystem
and validate the response in terms ofload withstanding, and
also electrical and hydraulic network influences.
Closed-loop force/torque control algorithms are used
to control each hydraulic actuator on the test benches,
while load cells installed in the actuators are used to provide
feedback for the control algorithms with applied output
forces, so as to assure the realistic simulation of the
loads desired. In addition, RVDT sensors are used in each
test bench to monitor displacements for safety purposes
(e.g., checking continuously large displacements or velocities)
and other purposes. For their part, start, stop, and
emergency stop states are used to safely provide or quit
forces in the equipment.
The main user interface is programmed in a very scalable
way so that additional specifications, test benches,
and duties may be easily inserted, and fast report generation
is also supported.
TESTING ACTIVITIES
The aforementioned benches were used to perform the
verification and validation process for the FTB2 demonstrator
primary flight control system. This process implies
an evolution in terms of the level of integration, from A/C
subsystem testing to A/C system-level testing, and from
A/C system-level testing to A/C multisystem level testing.
Enough level of maturity had been reached prior to the
30
trol system, in which the flexibility of the benches proved
to be the key to ensuring the verification and validation
objectives. It was considered an iterative process, starting
with the lowest level of integration that is integration at an
equipment level (actuator control electronics), integration
at a subsystem level (actuator control electronics + actuator),
integration at a system level (surface driven by a set of
actuators + their corresponding actuator control electronics,
including cross communications between them), and,
finally, multisystem testing by considering integration with
other A/C systems such as hydraulic systems, electrical
systems, cockpit, and displays.
Figures 10 and 11 show experimental results of two
tests that showcase the correct functioning of both aileron
and flap-tab test benches. Figure 10 shows the response of
the aileron test bench rig actuator (measured by the load
cell) to a sinusoidal force input signal. Figure 11 presents
the response of flap-tab test bench rig actuator to a ramp
force input signal. In both tests, it can be seen that the
developed test benches have a good performance.
Several software versions for actuator control electronics
were also considered as part of an incremental
approach to which different functionalities may be added
for each software version, resulting in development (intermediate)
and flight software versions.
The benches' flexibility allows the overall integration
rig to be configured depending on the level of integration
requested, and their capabilities enable testing in manual
Figure 9.
Patching panels box for one EMA control unit testing.
IEEE A&E SYSTEMS MAGAZINE
FEBRUARY 2022
IEEE - Aerospace and Electronic Systems - February 2022

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