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Nicola Mimmo

Ricercatore a tempo determinato tipo a) (junior)

Dipartimento di Ingegneria dell'Energia Elettrica e dell'Informazione "Guglielmo Marconi"

Settore scientifico disciplinare: ING-INF/04 AUTOMATICA

Temi di ricerca

Parole chiave: Aersoapce systems; nonlinear control, active fault tolerant control

The  principal  research  theme  is  about  Fault  Tolerant  Control  in  Aerospace  where  a  novel  methodology for Active Fault Tolerant Control Systems (AFTCS) has been developed. The AFTCS  can be also obtained by keeping the already in-place guidance and control (GC) laws and by adding  a loop for feedback of the fault estimate. This ulterior loop contains a Fault Detection and Diagnosis  (FDD) module that  provides  the most update information about the real system's state. It's worth  noting that the design of the proposed FDD scheme and the design of the guidance and control (GC)  scheme can be done independently. These features could significantly reduce the applicability scope  of these approaches since the modification of the validated and certified in-place nominal control  law could be a major concern and especially for aerospace systems. Concerning the FDD procedure,  a  novel  nonlinear  method  based  on  the  Non  Linear  Geometric  Approach  has  been  developed. Thanks to this approach it's possible to obtain a new observable sub-system affected by the fault to  be  estimate  and  decoupled  from  other  faults  and  disturbances  such  as  wind.  The  resulting  fault  estimate is unbiased and the reliability of the overall AFTC system increases.  Motivated by several  literature  publications  particularly  focused  on  aircraft  actuator  oscillatory  faults,  t he  mentioned  technique has been applied at actuator or sensors  multi-faults  scenarios as, for example, in the case  of oscillatory  and  step faults on actuators  and sensors.  Moreover, the potentialities of the depicted  approach  have  been  exploited  to  estimate  an  actual  wind  shear  during  landing  phase.  Moreover,  recent  results  show  how  singular  perturbations  are  particularly  suitable  in  aircraft  applications.  Thanks to this approach it's possible to  detect and isolate a single fault affecting aircraft actuators and  sensors (i.e. redundant multi fault scenario).  The novel Active Fault Tolerant Control is tested  by using high fidelity  simulators of aircraft and spacecraft systems and the performance show the  method's robustness in presence of model-reality mismatches, disturbance effects and measurement  errors.  The  production  of  a  lot  of  publications  about  this  theme  prove  the  effective  work's  prolificacy.

The theoretical research work is completed by its practical counterpart. The two main activity are: - Nonlinear simulation environments;  - Laboratory work on Unmanned Aerial Vehicles 

Nonlinear simulation environments
To understand the effective applicability and the performance of the new AFTC it's necessary to  use valid environments of simulations. Particular attention is paid to the most important aerospace  models.  Aircrafts  and  spacecrafts  have  to  be  modelled  in  their  complete  dynamics,  with  no  assumptions  or  reduction.  Simulation  tests  are  obtained  including  actuators'  dynamic,  input  and  output sensors. They  are modelled with real noises and measurement errors (bias, drift, …).  The  environment disturbances  aren't  left out: wind gusts, wind shears, turbulences for the aircraft and  solar, aerodynamic, magnetic, gravitational disturbance momentum for the satellite.    

Laboratory work on Unmanned Aerial Vehicles 
The  goal is to realize a completely autonomous  ultra-light  aircraft  equipped  to transport  the safety  pilot  and  the  research  avionics.  The  first  phase  of  the  project  has  concerned  on  the  definition,  calibration,  installation,  integration  of  avionics.  The  second  phase  consists  in  the  flight  tests  for  aircraft  model  identification.  In  the  third  phase  navigation,  guidance  and  controls  laws  will  be  developed  and  tested.  The  aircraft  will  be  the  test-rig  for  the  fault  tolerant  control  systems  developed.  The  first  step  of  the  project  has  been  completed  by  obtaining  a  Permit  To  Fly  for  research activities. The second phase of the project is planned to start in the autumn of 2013.