HASTAC High stability Altimeter SysTem for Air data Computers

Transcription

1 HASTAC High stability Altimeter SysTem for Air data Computers André Larsen R&D Director Memscap Sensor Solution SIXTH FRAMEWORK PROGRAMME PRIORITY 4 Aeronautics and Space EC contract no. AST4-CT HASTAC is carried out with financial support from the European Community FP6 Research Area 4 Aeronautics & Space

2 Technology for a better society HASTAC project outcome HASTAC will develop: A uniqe MEMS based sensor with excellent long term stability A hermetic sensor package optimised for aerospace applications An optimised altimeter pressure transducer A new digital ADU Demonstration of the performance in a rotary wing test fligth Project facts Total cost: Funding: Duration: 35 months Start date: 11 Jan 2005 Project web

3 Why Strategic objective To increase the safety in all in-flight situations, particularly low visibility situations, by improving the transducers used in Air Data Computers for aircraft applications. Improved aircraft performance 1. Auto pilot situations in the reduced vertical separation minima legislation of 1000ft (RVSM) 2. Demanding manual flying situations in darkness and low visibility 3. Increased reliability in altitude information for manual and automated Air Traffic Control systems used in transponder applications 4. Aircraft Traffic Collision Avoidance Systems will also benefit from more accurate and reliable altitude information

4 Project consortium Sensor element Long term drift factors Modelling, simulation & design Process development Fabrication & prototypes Test & characterisation Sensor package Theoretical study Design & pilot production Assembly of pilot batch Test & qualifications Transducer Concept & feasibility Design of prototypes Development & optimisation Industrial prototypes Test & certification Air Data Computer Technical specifications Design of hardware & software Pilot batch manufacturing Performance test Safety of flight qualification Aircraft flight test Flight test program Helicopter installation Ground testing Safety of flight qualification Test flight Data analysis

5 WP3 TP4000 This Work Package aim to make a high end transducer for the new SP83 sensor High accuracy and stability better than 0.01%fs/year The program includes optimization of: Excitation method Noise to signal ratio Calibration process Calibration method and technique Activities: DO-254 procedures Qualification and testing Deliverables : Engineering prototype to WP4 Industrial prototype to WP4

6 TP2000 Units Low cost version of TP4000: Single ADC SP82 Faster calibration Easier compensation

7 TP4000 Input to design Increased focus on safety and reliability Dual ADC based on experience with TP2000 and FTA Evaluate methods for calibration Large storage capacity to achieve higher accuracy in compensation method

8 TP4000 Usage of TP2000 experience TP4000 TP2000 Reference, regulator, filter, protection Power Excitation EEPROM SPI External system Sensor TB PB PB PB Pressure Temperature AD7793 Pressure Temperature AD7794

9 TP4000 Difference from TP2000 Additional built in test during power-up: Verify AD7793 by using AD7794 Use AD7793 to verify AD7794 Verify drift in pressure bridge versus temperature bridge Verify sensor excitation In addition: More than double sample rate versus TP2000 Possibility for synchronised pressure and temperature conversion Loss of function probability (MTBF) only ~5% worse than TP2000 Misleading information probability (FTA) ~100% better than TP2000

10 Calibration How it works Procedure: Apply pressures and temperatures Collect ADC data Curve fit to reference Write constants to unit and verify Temperature (left) and pressure (right) versus time for calibration and verification

11 Curve fit methods Data from a representative TP2000 (110767) 260 curve fit methods were compared High order Chebyshev polynomials have most potential Equation ID A B C D E F G H Type Chebyshev P Chebyshev P Chebyshev P Chebyshev P Fourier P Taylor F Taylor F Chebyshev F P=polynomial F=function Deviation (%FS) Max Min

12 TP4000 Calibration procedure Improved curve fit and constants: Chebyshev curve fit T ADC 80 points Write to TP4000 (8.2kB) Measured data: T ADC P ADC P Ref xx coefficients Bilinear interpolation matrix generation P ADC 25 points

13 Matrix size vs max deviation TP TxP=80x25 D<0.005%

14 TP4000 Safety features These features ensure safe operation of the TP4000: Voltage regulator with high, low and reverse polarity protection Regulator low power supply voltage detection Hardware lock input for write protection of EEPROM ESD protection devices These features can be implemented in external system for safety: Error detection on EEPROM communication by CRC Error detection on ADC communication by multiple read Range checks on ADCs and calculated outputs (pressure, temperature) Communication timeout for loss of function detection Verify ADCs against each other Verify sensor excitation Verify drift of sensor bridge (temperature) New from TP2000 to TP4000

15 TP4000 Target Specification Parameter Min / Typical Max Unit Power-supply 6.5* 20 V Current consumption 5* ma Pressure range (absolute) mbar Overpressure 200 % FSO Total pressure error (absolute) ±0.02** % FSO Long term stability (at ambient temperature) ±0.01** % FSO / year Pressure resolution < * % FSO Output noise ±0.001* % FSO Conversion time 25* ms Response time 50* ms Total temperature error < ±1* C Temperature resolution <0.0002* C Calibration temperature range (105***) C Operating temperature range * C * Estimate based on experience from other pressure transducers. ** Estimate based on expected effect of improved calibration procedure and new SP83. *** Larger temperature range possible. This can influence the accuracy.

16 How New generation of silicon MEMS barometric pressure sensors and fully compensated and digitized Transducers (TP4000) Sensor systems with significantly improved altitude accuracy capabilities over time, target is better than 100ppm/year (0.01%/year) Aircraft flight testing will demonstrate the effectiveness of the improvement The new generation of transducers with a new silicon micro sensor (absolute pressure sensing element) as the key component, will also be available for other application areas, such as transponders and cabin pressure control systems.

17 Technology for a better society WP 1 Sensing element MiNaLab facility Clean room area: SINTEF: 800 m 2 University of Oslo: 600 m 2 A full silicon processing line for MEMS and radiation detectors Capacity of wafers/year Located at the campus of University of Oslo 240 MNOK investeted in scientific equipment and laboratory infrastructure WP 1 Sensing element Long term drift factors Modelling, simulation & design Process development Fabrication & prototypes Test & characterisation

18 ADU and Flight test Next generation air data unit development Primarily to integrate HASTAC transducer Electronic interface Software interface Optimise design of interfaces Evaluate performance in lab simulated environment over extended time period Flight test Expose ADU and transducers to representative real life environment Severe vibration environment experienced on helicopters High hours utilisation on emergency services helicopter Monitor transducer performance during evaluation period and beyond