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At TASC we have a very strong application-oriented research expertise as indicated by the Technological Readiness Level (TRL) range of our (past and current) projects, which cover:

From TRL 3 (i.e. using high-fidelity, nonlinear simulators developed by industry or of an industrial-standard):
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To TRL 6/8 (i.e. flight tests in piloted and remotely operated vehicles):
  • 2009 Advanced fault detection scheme in DLR's ATTAS manned aircraft
  • 2016 Advanced robust controller in JAXA's MuPAL-alpha manned aircraft
  • 2018 Robust controller in NDUT's small solid rocket
  • 2019 Advanced robust controller in DLR's EAGLE autonomous VTOL demonstrator

Below you can find more details on our flight test experience:

2009  Flight testing of advanced fault detection scheme in DLR's ATTAS manned aircraft
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Fig. 1. DLR Advanced Technologies Testing Aircraft (ATTAS)
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Fig. 2. DLR ATTAS configuration
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Fig. 3. Actuator saturation as an "effective" fault unknown input
This work was performed at Deimos Space S.L.

In collaboration with DLR-Braunschweig, we had the opportunity to verify and validate a fault diagnosis algorithm designed using H-infinity optimization in their Advanced Technologies Testing Aircraft (ATTAS), see Figs 1 and 2.

The robust FDI scheme was designed to detect and isolate actuator rate saturation in the lateral/directional actuators. The effects of this critical non-linearity were modeled as an equivalent "effective fault", see Fig. 3, which then could be detected and isolated by our FDI scheme, some results are given below in Fig. 4.

​The incremental V&V activities went from verification in a high-fidelity, nonlinear model of ATTAS, to validation in DLR's piloted flight simulator, the use of real flight data, and subsequently flight testing (this later results were not published).

Publication:

Kerr, M.L., Marcos, Peñín, L.F., Brieger, O., Postlethwaite, I., Turner, M., “
Piloted Assessment of a Fault Diagnosis Algorithm on the ATTAS Aircraft,” AIAA GNC Conference, Chicago, USA, August 2009
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Fig 4. Strong and Small fault cases results (see publication for details)

2016  Flight testing of advanced controller in JAXA's MuPAL-alpha manned aircraft
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Fig. 5 JAXA Multi-Purpose Aviation Laboratory-α (MuPAL-α)
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Fig 6. JAXA MuPALα in Aircraft-In-The-Loop (AIL) configuration
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Fig 7. Ground-track flight campaign 1 (Dec'16): day 1 and 2
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Fig. 8 Flight test results (1st Day): 360 degrees steady-turns at 20 degrees bank angle and 110 knots airspeed
This work was performed at the University of Bristol.

In collaboration with JAXA-Chofu (Tokyo), and as part of the joint EU-H2020 & Japan-NEDO project VISION, we had the opportunity to verify and validate up to flight testing a series of advanced robust controllers as well as fault tolerant controllers (FTC) in JAXA's Multi-Purpose Aviation Laboratory-α (MuPAL-α)​, see Fig. 5. 

The following is a list of the designs performed and their V&V testing, either flight testing (FC-1) or Aircraft-In-the-Loop (AIL-#) --a type of Iron Bird validation with the full aircraft parked on the hangar, see Fig. 6:

  1. ​Dec 2016 (FC-1): flight test of a robust model-matching structured H-infinity
  2. May 2018 (AIL-1): Aircraft-In-the-Loop testing with faults of the above controller
  3. Jan 2019 (AIL-2): robust structured H-inf Y* & C* control laws
  4. Apr 2019 (AIL-3): robust structured H-inf active-FTC Y* control laws
  5. Jun 2019 (AIL-4): all above where LTI point-designs, in this last campaign the focus was on scheduling designs covering from traditional manual ad-hoc approaches to self-scheduling and up to linear-parameter-varying (LPV):
​                  5.a  Manually scheduled non-structured H-inf active-FTC Y*
​                  5.b  Manually scheduled structured H-inf active-FTC Y* 
                  5.c  Self-scheduled structured H-inf active-FTC Y*
                  5.d  LPV active-
FTC Y* 

The ground tracks for the two days of the Dec'16 flight campaign (FC-1) and the results are shown on Fig 7 and 8 respectively. And example of the design interconnections are given in Fig. 9 below (left for a passive-FTC Y* controller and right for an active-FTC version).

Publications:

Marcos, A., Sato, M., “
Flight Testing of an Structured H-infinity Controller: An EU-Japan Collaborative Experience,” 1st IEEE Conference on Control Technology and Applications (2017 CCTA), Hawai'i, US, August 2017

Marcos, A., Sato, M., “
Robust Model-Matching Controller Design Using Matlab hinfstruct Command,” The 4th Multi-Symposium on Control Systems (SICE-MSCS17), Okayama, Japan, March 2017

Waitman, S., Marcos, A., Sato, M., “
Design and Hardware-In-the-Loop validation of a Fault-Tolerant Y* flight control law,” 4th International Conference on Control and Fault-Tolerant Systems (SYSTOL19), Casablanca, Morocco, September 2019

Takase, R., Marcos, A., Sato, M., Suzuki, S., “
Hardware-In-The-Loop Evaluation of a Robust C* Control Law on MuPAL-a Research Aircraft,” 21st IFAC World Congress, Berlin, Germany, July 2020​​
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Fig 9. Design interconnections: robust (passive-FTC) [left] and active-FTC [right] Y* controllers

2018  Flight testing of advanced controller in NDUT's small solid test rocket
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Fig 10. NDUT small solid rocket: launch [left] and recovery [right]
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Fig 11. Enhanced Disturbance Rejection control design interconnection.
This work was performed at the University of Bristol.

In collaboration with NDUT, after a one-year visit by Mr. Li Tong during his PhD, on his return to NDUT and as a conclusion of the collaboration, an enhanced disturbance rejection controller design obtained using H-infinity optimization was tested in NDUT's small solid test rocket --a type of sounding rocket for experimental testing (see the launch and recovery for our flight test in Fig. 10 and the design interconnection in Fig. 11).  

The incremental V&V activities included nonlinear model simulations, hardware-in-the-loop (HIL) testing and a flight test, see results below in Fig. 12.
 
Publication:

Tong, L., Marcos, A., Zhang, S., "
Enhanced disturbance rejection control based test rocket control system design and validation,” ISA Transactions, January 2019, vol.84, pp.31-42
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Fig 12. Flight test results (see more details in above publication)

2019  Flight testing of advanced controllers in DLR's EAGLE autonomous VTOL demonstrator
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Fig 13. DLR's EAGLE(Environment for Autonomous GNC Landing Experiments).
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Fig 14. DLR EAGLE testing platform
This work was performed at the University of Bristol.

In collaboration with DLR-Bremen, and as part of an ESA-funded PhD, in the last phase of the PhD we successfully flight tested an advanced controller in DLR's EAGLE (Environment for Autonomous GNC Landing Experiments), see Fig. 13 and 14. A preliminary load-relief estimator and compensator was also implemented and flight tested.

The robust controller was designed using structured H-infinity, and followed our work on thrust-vector-control (TVC) for the VEGA launcher. The tests successfully showed the capability of the robust controller to maintain position of EAGLE despite strong wind perturbations (up to 6 m/s, see results in Fig. 15).

Publication:

Simplício, P., Marcos, A., Bennani, S.,
 “New Control Functionalities for Launcher Load Relief in Ascent and Descent Flight,” 8th European Conference for Aeronautics and Space Science (EUCASS 2019), Madrid, SP, July 2019 
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Fig 15. Flight test results for robust controller

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