The developed product is an Absolute Angular Encoder, including Signal Conditioning Electronics, suitable for the space environment, characterized by the following features:
- Self compensating configuration of Hall effect probes;
- Rotary Magnetic Design inherently storing angle position (no stand-by current needed to retain position information);
- Purely analogue signal processing (no software);
- Cost effective;
- Accuracy = ± 0.5°.
The INCAS product aims at satisfying these requirements by means of a contact-less sensor. This is the main characteristic that differentiates the INCAS approach with respect to the current used potentiometers, giving a more robust and reliable solution, especially over long life missions. The low cost approach of this product is intended to provide also a convenient alternative to more expensive sensors for this class of performance.
The principle of operation relies in generating a magnetic field which is, thanks to a specific geometry, a function of the angular position only. By means of a feedback loop controlling the output for a common magnetic field to two probes, any common drift or degradation of the magnetic field such as permanent magnet properties, or probes characteristics is automatically self-compensated.
The dedicated electronics is fully redundant and all the parts for the Engineering Model prototype, as well as for the Qualification Model foreseen in the next phase under ARTES 3-4, are ITAR-free.
The activity has been conducted by investigating and characterizing two different hall probe sensors, by completely designing and manufacturing both the mechanical structure and the electronic circuits (fully redundant) and also by a complete performance characterization campaign including vibration, EMC and thermal vacuum.
The criticalities related to the metrological performance of the sensor have been identified and solutions, suggestions and improvements have been identified. They include among others hall probes characterization, magnetic field sensitivity, electronic circuitry influence.
The tests performed showed very promising performance of the sensor with characteristics even beyond the requirements, and together with the criticalities identified will permit its optimization in the following phases of the development. Some of the optimizations identified have been preliminarily tested showing significant improvements in the performance.