Module 1.5 - UNSY 605

There are a multitude of sensors necessary for an unmanned system to operate safely and effectively.  However, most of these sensors fall into four groups:  accelerometers, biosensors, image sensors, and motion detectors (EngineersGarage 2012).  Accelerometers are used to determine and control the position and motion of unmanned systems and have been heavily tied to unmanned aerial systems (UAS) in their use and development.  Small UAS to date have had issues with stability and reliability, which has brought many to investigate how to create a more stable system.  Creating a more accurate accelerometer has been pointed to by many as the best way to increase the effectiveness and reliability of small UAS.  One of the main types of accelerometers being improved upon are thermal microelectromechanical (MEMS) accelerometers.  These sensors are popular because there are no moving parts involved; the system senses changes in gas molecules as they pass over an integrated circuit (Echoblue Ltd 2016).  Thermal MEMS have found success in some applications, such as stabilizing on-board cameras for UAS, but in order to be effective in more critical applications they need to be more precise (Echoblue Ltd 2016).  

One research team is attempting to create a more stable and accurate thermal MEMS by adding an out of plane aspect to the device.  Most thermal MEMS operate in a dual axis fashion with detectors placed in the same plane as the micro-heater (Mailly, Nguyen, Latorre, & Nouet 2014).  The team in the article presents a thermal MEMS that would operate as a 3-axis system by adding an out-of-plane detector to allow for the z-axis (Mailly, Nguyen, Latorre, &Nouet 2014).  This addition will allow the sensor to measure how gas stretches or shrinks in the z-direction due to accelerations; an ability that dual axis sensors do not have.  The results of the experiment showed that the addition of the out-of-plane detector increases the overall sensitivity of the sensor, which should make it more accurate.  Implementation of sensors similar to the concept proposed by this team could result in more reliable and effective uses for small UAS in the near future.

References

Echoblue Ltd. (2016).  MEMSIC Identifies and Explains the Sensing Technologies used in Drones.  MEMSIC, Inc News.  Retrieved from http://www.unmannedsystemstechnology.com/2016/04/memsic-identifies-and-explains-the-sensing-technologies-used-in-drones/

EngineersGarage. (2012).  Sensors: Different Types of Sensors.  Retrieved from http://www.engineersgarage.com/articles/sensors

Mailly, F., Nguyen, H. B., Latorre, L., & Nouet, P. (2014). CMOS implementation of a 3-axis thermal convective accelerometer. doi:10.1109/ICSENS.2014.6985292