UAV Navigation in depth: Precision Laboratory Equipment For Testing and Calibration of Air Data System

INTRODUCTION

1.   Air data information is a key issue for use onboard aircraft in order to estimate current altitude and airspeed. Such flight parameters may be measured using a variety of different sensors.

2.   As a developer and manufacturer of professional grade autopilots, UAV Navigation is committed to the highest aviation standards in terms of product performance, accuracy and reliability. UAV Navigation's manufacturing facility is equipped with state-of-the-art calibration and measurement tools and all products which leave the facility must pass exhaustive Quality Control checks.

3.   All UAV Navigation autopilots and Attitude & Heading Reference Systems (AHRS) include an Air Data System (ADS) which provides temperature, static and dynamic (pitot) pressure values. These variables are used by these products as part of the Estimation process to provide calculations of air density, indicated air speed, true air speed and barometric altitude.

4.   Airspeed can be expresssed as a combination of ground speed and relative wind speed, and is measured by comparing the dynamic pressure in the pitot tube (a probe which points directly into the airflow) and the ambient pressure, also known as static pressure. These static pressure ports are normally located in pairs on either side of the fuselage in order to avoid incorrect readings due to sideslip during turns.

5.   In order to provide the most accurate airspeed data, a different dynamic pressure sensor is used in the autopilot or AHRS unit, depending on customer requirements. This sensor is installed at the factory and cannot be changed by the user.

  • Low Speed Pressure (LSP): Speed range between 20 and 250 kts.
  • Normal Speed Pressure (NSP): Speed range between 35 and 250 kts.
  • High Speed Pressure (HSP): Speed range between 45 and 450 kts.

6.   Amongst other test and calibration equipment, UAV Navigation's laboratory is equipped with state-of-the-art MPS43 air data test units manufactured by D. Marchiori (a leading precision air data instrument manufacturer). These units are used to test and calibrate both dynamic and static pressure sensors over their full range of operation.

AIR DATA TEST UNIT FEATURES

7.   Wide Operating Range.   The MPS43 allows for testing across a wide operating pressure range as follows:

  • Altitude range: -2,000 to 65,000 feet ASL.
  • Maximum airspeed: 450 knots.

8.   High Accuracy.   A precision absolute sensor is used for the static (altitude channel) and a precision differential transducer for the Qd/Pt (airspeed channel). Pressure and temperature characterisation is applied to these sensors ensuring high accuracy (±0.1 hPa for static and ±0.17 hPa for Qd) across the full range of operating pressure values. Calibration ensures that the values are temperature compensated.

9.   Equipment Protection.   The test equipment features built-in safeguards which ensure that no damage can be caused either to the sensors under test or to the equipment itself.

10.   ISO 9001 Certification and Quality Assurance.   UAV Navigation is qualified to ISO 9001:2015, based on a core philosophy of continuous improvement. In order to ensure that the Quality standards of the most demanding aerospace customers are met,  the Company has developed strict Acceptance Testing Protocol (ATP) procedures in order to guaranteee that each autopilot or AHRS unit delivered meets the technical specifications declared by UAV Navigation for the particular product. Repeatability is key. All equipment and tools used during manufacture, calibration and ATP comply with UAV Navigation's strict Quality Policy; they are subject to periodic checks and calibrations to ensure their accuracy and effectiveness.

11.   UAV Navigation is committed to producing only the highest quality products that have an enviable reputation throughout the industry for their accuracy, reliability, robustness and Quality Assurance. The Company works hard every day to ensure that it is on the cutting edge of this technology and uses only the most advanced and accurate tools and procedures in its product manufacturing.

 

Figure 1. MPS43 equipment. Photo courtesy of DMA Marchiori s.l.r.