177 Development  of a Magneto- Resistive Angular  Position Sensor  for   Space  Mechanisms  

Robert Hahn*, Tilo Schmidt*, Klaus Seifart*, Bastian Olberts† and Fernando Romera‡ 

Abstract  

Magnetic microsystems in the form of magneto- resistive (MR) sensors are firmly  established in  automobiles and industrial applications. They  are used to measure travel , angle, electrical current, or  magnetic fields. MR technology opens up new sensor possibilities in space applications and can be an enabling technology for optimal per formance, high robustness and long lifetime at reasonable costs. In  some science  missions , the technology is already applied, however , the designs are proprietary and case  specific, for instance in case of the angular sensors used for JPL/NASA’s Mars rover C uriosity [1].    Since 2013 HTS GmbH and Sensitec GmbH have teamed up to develop and qualify a standardized yet  flexible to use MR angular sensor for space mechanisms. Starting with a first ass essment study and  market survey  performed under ESA contract, a very strong industry interest in novel, contactless position  measurement means was found. Currently a detailed and comprehensive development program is being  performed by HTS and Sensitec. The objective of this program is to advance the sensor design up to Engine ering Qualification Model level and to perform qualification testing for a representative space  application.    The paper briefly reviews the basics of magneto- resistive effects and possible sensor applications and  describes the key benefits of MR angular sensors with reference to currently operational industrial and space applications. The key applications and specification are presented and the preliminary  baseline  mechanical and electric al design will be discussed. An outlook on the upcoming development and test  stages  as well as the qualification program will be  provided.  

Introduction  

Magnetic microsystems in the form of magneto- resistive (MR) sensors are firmly established in  automobiles, mobile telephones, medical devices, wind turbines, machine tools or industrial robots: be it  for the measurement of travel , angle or electrical current, or as an electronic compass. Originally  developed for data storage applications, the various MR effects open up new measurement possibilities  for sensors, not only in terrestrial applications, but also in space applications.    MR sensors are robust, reliable, precise and miniaturized. This combination of features is leading to continuous growth in the application field of MR sensors. The extremely low power consumption of MR sensors make them ideal for wireless, autonomous sensor applications. They present completely new possibilities to the devel opers of many different types of mechanisms or instruments to measure angle,  path, electrical currents , or magnetic fields.    The interest in MR technology from the space community is growing, in particular since the successful application of 40 MR angle sensors to control the motion of electric motors on the Mars Rover “Curiosity” as part of the Mars Science Laboratory Mission [ 1]. This was not the first application on Mars –  MR                                                    * HTS Hoch Technologie Systeme GmbH, Coswig, Germany   † Sensitec GmbH, Lahnau, Germany   ‡ European Space Technology Center ESA/ESTEC, Noordwijk, The Netherlands  

Proceedings of the 43rd Aerospace Mechanisms Symposium, NASA Ames Research Center, May 4-6, 2016