Sensors used in UAVs

Sensors used in UAVs are mostly categorized into Navigation Sensors and Sensors used for missions. Most of the sensors used for navigations on UAVs comprise of sensors such as Global Navigation Satellite Systems (GNSS) which includes the Global Positioning Systems and the Inertial Navigation System. GPS and INS complement each to the point that they are the preferred sensors for the majority of autopilot systems (Mejias, Lai, & Bruggemann 2015)

Other sensors used for navigations or surveillance include the Electro-Optical (EO) Sensors and Radio- Wave Sensors

Electro Optical (EO) Sensors;

i.                    Visible Spectrum: These are either digital still cameras or machine vision webcams that are used to take pictures or provide a continuous stream of images respectively. This type of sensor cameras is mostly used in aerial photography.

ii.                  Infrared sensors:  Infrared cameras that are sensitive to light at a long wavelength and form images using infrared radiation in the spectrum at wavelengths of 14,000nm.

iii.                Hyperspectral Imaging:  these are sensors that acquire image data simultaneously in multiple adjacent spectral bands. This type of sensor is mostly used for identifying different compositions of materials

Radio- Wave Sensors

Airborne Radio Detection and Ranging (Radar) and Light Detection and Ranging (Lidar) systems are used to determine the range, altitude, direction and speed of objects by measuring signal return time of transmitted controlled radio pulses. Radar sensors such as the Ground Proximity Warning Systems (GPWS) have been widely used in the aviation world. Radars are also recently being used in the automotive industry for collision warning systems. ( Mejias, Lai, & Bruggemann 2015)

Exteroceptors (External) and Proprioceptors(Internal)

Exteroceptors are sensors that allow the robot of unmanned systems to perceive or interact with its environment whole Proprioceptors sensors measure the internal kinematic and dynamic parameters of the unmanned system. Such parameters include the amount of torque exerted by the actuator. Exteroceptors are grouped into contact and non-contact sensors. The contact sensors perceive their environment by touching the objects and shaped in its environment while non-contact sensors obtain information about its environments without physical contact. Such non-contact sensors include pneumatic sensors, ultrasonic sensors, and optical sensors (Gupta, Arora, & Wescott, 2016)

Sensor Review
 https://ieeexplore-ieee-org.ezproxy.libproxy.db.erau.edu/xpls/icp.jsp?arnumber=4772754

For the sensor review, I have selected the journal article that uses the Miniature Strapdown Inertial Navigation System (mini INS) with inertial microelectromechanical systems (MEMS) for control of different UAVs in the autopilot mode. Inertial Navigation System sensors as noted earlier are used for navigation. The Miniature Strapdown Inertial Navigation System (mini INS suit this mission as it is low cost with small overall dimensions and consumes very low power. The sensor can provide the required accuracy of determining the attitude, position, and velocity of the UAV. The use of the inertial system as the main component of the autopilot provides the required flying accuracy with the capability of UAV destination to the desired waypoint at a given time and tracking the predefined path. (Kortunov, Dybska, Proskura, & Kravchuk, 2009)

The disadvantage of using this system in an autonomous mode is hampered since the instability of MEMS sensor characteristics causes fast accumulation of errors in the determination of navigation data. The effective approach to solving this problem is the integration of mini INS with different external measuring devices like GPS navigation, which is considered as the most precise facilities of determination of moving object position, magnetic compass, and air data sensor (Kortunov, Dybska, Proskura, & Kravchuk, 2009)

References

Gupta, A. K., Arora, S. K., & Wescott, J. R. (2016). Industrial automation and robotics: An introduction., 390-401. Retrieved from https://ebookcentral-proquest-com.ezproxy.libproxy.db.erau.edu/lib/erau/reader.action?docID=4895078&query=industrial+automation+and+robotics%C2%A0(Links%20to%20an%20external%20site.)#

Kortunov, V. I., Dybska, I. Y., Proskura, G. A., & Kravchuk, A. S. (2009). Integrated mini INS based on MEMS sensors for UAV control. Retrieved from https://ieeexplore-ieee-org.ezproxy.libproxy.db.erau.edu/xpls/icp.jsp?arnumber=4772754

Mejias, L., Lai, J., & Bruggemann, T. (2015). Sensors for missions Springer, Dordrecht. Retrieved from https://search.credoreference.com/content/entry/sprunmanned/sensors_for_missions/0

Reusable Rocket Launchers

The U.S. military began experimenting with unmanned aircraft as early as World War I. By World War II, the unmanned craft could be controlled by radio signals, usually from another aircraft. Vehicles that could return from a mission and be recovered appeared in the late 1950s. Today, Unmanned Aerial Vehicles (UAVs) perform a wide range of missions and are used by all four branches of the military.  UAVs are used to satisfy requirements for military and commercial markets to include reconnaissance, surveying, wildlife management, Space missions, border control, commercial delivery, and many more missions.

Progress in recent technologies has enabled space drones to be considered as valuable platforms for planetary exploration. Thus, drones and especially Unmanned Aerial Vehicles (UAVs) have had extremely high progress to be applied for planetary science missions.  (Hassanalian, Rice, & Abdelkefi, 2018). There is also the chance of using UAVs and rockets for tourism to Mars. However, whether the mission is for tourism or research, space exploration is very expensive. One of the most expensive parts of launching a UAV into space is the launch vehicle. Most of the launch cost comes from building the rocket, which flies only once. Compare that to a commercial airliner – each new plane costs about the same as Falcon 9, but can fly multiple times per day, and conduct tens of thousands of flights over its lifetime. Following the commercial model, a rapidly reusable space launch vehicle could reduce the cost of traveling to space by a hundredfold. (Post, 2015).

SpaceX has the designed the Falcon 9 rocket and the reusable launcher called the Grasshopper, a 10-story Vertical Takeoff Vertical Landing (VTVL) booster/launcher. While most rockets are designed to burn up on reentry, SpaceX rockets are designed not only to withstand reentry but also to return to the launch pad for a vertical landing.   The Grasshopper VTVL vehicle represents a critical step towards this goal. To date, a fully reusable vehicle has not been successfully developed.  As such, the Grasshopper testing program is incredibly challenging.  Below are videos of our most recent test in which Grasshopper rose 24 stores--or over 260 feet--hovered for approximately 34 seconds and landed safely back on the centermost part of the pad.  Spacex ’s rapidly reusable space launch vehicle could reduce the cost of reaching Earth orbit by a hundredfold(Shanklin, 2013).


SpaceX demonstrated the effectiveness of the reusable launcher by successfully launching an Unmanned Falcon 9 rocket into space. the Falcon 9’s Crewed Dragon capsule separated from the first stage booster which came back to Earth, using its engines to slow for a touchdown on SpaceX’s drone ship in the Atlantic Ocean, ready for inspections and refurbishment before another mission This success has opened a new front in space exploration. The launch of the unmanned crewed rocket opens an opportunity for spaceX and Elon Musk to achieve the aim of sending humans to space on space tourism and setting up a space station on Mars. The US military is looking to incorporate this system of launch into its fleet of space UAVs after full testing.

References

Hassanalian, M., Rice, D., & Abdelkefi, A. (2018). Evolution of space drones for planetary exploration: A review. Progress in Aerospace Sciences, 97, 61-105. doi:10.1016/j.paerosci.2018.01.003

Post, H. (2015). Reusability: The key to making human life multi-planetary. Retrieved from https://www.spacex.com/news/2013/03/31/reusability-key-making-human-life-multi-planetary

Shanklin, E. (2013). Reusability. Retrieved from https://www.spacex.com/reusability-key-making-human-life-multi-planetary