An Overview of Drones, Unmanned Vehicles, and More
Unmanned vehicles are growing in popularity, especially unmanned aerial vehicles, self-driving cars, and various types of private consumer drones. But what are drones, exactly, and how do they operate and navigate?
First Things First: What is a Drone/UAV/UAS?
Drones, UAVs, UAS, and RPAS… what’s the difference? In short, not much. For the purposes of this article, the term “drone” will be used interchangeably with these common abbreviations, as it’s a general catchall term referring to unmanned aircraft without an onboard pilot. UAV stands for “Unmanned Aerial Vehicle,” UAS for “Unmanned Aircraft Systems,” and RPAS for “Remotely-Piloted Aircraft Systems”. All RPAS operate with remote control as the name suggests. UAVs and UASs feature remote control options or autonomous navigation options.
Initially unique to military applications, drones are equally common in the civilian market after years of development.
This is the result of a combination of factors, including:
- More efficient and specialized manufacturing procedures (for example, 3D printing);
- The miniaturization of powerful electronic components;
- Improved power consumption and/or battery life; and
- Lower price points and cost of entry.
In fact, access to drone technology is now so prevalent that it’s entirely common for the average consumer to buy a UAV, practice flying it, and mount cameras on it for video or photography of the environment. Drone racing continues to grow in popularity, presenting another consumer-level hobby application.
No longer confined to military use, drone applications have exploded in the last few years.
A few examples include:
- Industrial inspection: Drones are frequently used to inspect solar parks, wind parks, power lines, engines, plants, and industrial parks. They’re also common in on- and offshore oil, gas and power plants and utilities. A natural fit for bridge and structure inspections,visual structure assessment, monitoring, and surveying all offer drones further applicable uses.
- Monitoring: Drones are employed for condition-analysis and target-analysis when documenting construction sites. They also play a role in structural monitoring, sound barrier and wall monitoring, excavation documentation, and plant and wildlife preservation and conservation. Drones also get frequent use in first-responder activities in various crisis regions.
- Surveying: Because of their mobility, drones are a good fit for orthographic surveying. They can easily photograph objects and ground to generate point clouds, volume calculations, digital height, and accurate 3D models.
- Aerial images and photography: Perhaps the best-known civilian application, UAVs and drones are frequently used in advertising photography, product photography, real estate photography, landscape photography, the generation of 360° spherical panoramas, Point-of-Interest (POI) imaging, and Circle-of-Interest (COI) imaging.
- Aerial video and videography: Closely related to aerial photography, drones get wide use in image, advertising, and product spots. Drones see a lot of use shooting music videos, sports events, and extreme sports footage.
- And (possibly) coming to your neighborhood soon: Burrito delivery!
How Do Drones Navigate?
For drones that lack automation, control always rests with the pilot or operator. On lower-cost drones, the pilot uses visual tracking to determine position and orientation. In some cases, this is handled from the ground, based on the pilot’s relative position. For drones outfitted with onboard cameras, visual data is relayed to the pilot’s screen.
More advanced drones use GPS/GNSS receivers to allow for smarter navigation features, including:
- Position hold, which lets the drone maintain a fixed location at a set altitude;
- Return-to-home navigation, wherein a drone returns automatically to the press of a button based on its take-off location; and
- Autonomous flight, where the flight path is set based on GPS/GNSS waypoints which the drone will follow using autopilot functions.
Satellite Navigation 101
All too often, GPS is mistakenly used as a generic term referring to any sort of satellite navigation system. The proper term, Global Navigation Satellite System (GNSS), encompasses several satellite constellations.
GNSS comprises several satellite constellations, including the US-owned and operated Global Positioning System (GPS), Russia’s GLONASS constellation, Europe’s Galileo, and the China-backed BeiDou. By timing information received from orbiting satellites, a GNSS receiver can calculate positions on the earth’s surface.
With access to satellite navigation technology comes the ability to compute position and navigate a drone in real time.
When operating a UAV via GNSS satellites in a valley or a city, natural and man-made structures and buildings may block satellite signals. Other autonomous vehicles share this limitation. A common method of overcoming this challenge combines satellite navigation measurements with inertial navigation.
These Inertial Measurement Units (IMU) comprise a set of gyroscopes and accelerometers; in some cases, they also include Micro Electrochemical Sensors (MEMS). The IMU provides the drone with data on linear acceleration across three axes, as well as measurements of pitch, roll, and yaw.
The onboard flight controller, which is the brain of the drone, uses these measurements to provide navigational information and smooth flight capabilities. This data is relayed to the operator, who can use it to manoeuvre the drone and to ensure safe operations in flight.
It’s important to note that inertial sensors do gradually accumulate errors over time. In an integrated satellite/inertial navigation solution, a data fusion algorithm picks the most accurate estimate of position. The Kalman Filter is the most common fusion algorithm in use, and it tracks both the inertial measurements and satellite system position estimates over time.
The popularity of drones has seen exponential growth in the past few years. It’s never been easier to own or operate a drone privately, and increasing adoption rates push development and help discover new uses and applications.
As manufacturing procedures, component miniaturization, and technological advances make it easier to produce high-quality drones at lower costs, drones will likely become ubiquitous and commonplace in daily life. These exciting machines rely on internal navigation systems that work in conjunction with satellite systems and pilot control, but drone automation is a fascinating field with tremendous application potential.