It is safe to say that unmanned aerial vehicles (UAVs) or drones are changing our lives. From being a new system of personal delivery to providing spectacular aerial photography, the drone has 101 different applications. Drone technology has, to a greater extent, been used in the outdoor environment; however, there are more uses for drones than just aerial photography and logistics. With an experienced operator and the added advantage of anti-collision and sensor systems drones can also be used in an indoor environment to great effect.
Applications that jump to mind are inspections of tunnels, power plants, bridge inspection, indoor inspection and electric infrastruscture inspection. But, a whole raft of industrial areas is applicable - especially where it is dangerous to send a worker, there is limited access or the place to be inspected is high up and not easily accessible by people. The drone can provide a new perspective improving both inspection schedules and safety and also capturing valuable video imagery in elevated areas.
Introduction of the Indoor Drone
Usually, a drone will be built around a powerful high-resolution camera along with a lighting system and the ability to view 360° and from floor to ceiling. The other important aspects are collision avoidance and a navigation system that can work in the absence of GPS (global positioning satellite). GPS is unreliable in an inside environment where steel and concrete will not allow a signal to reach the drone. Various systems are used for anti-collision. The most basic of these is a protective cage, or nest, that surrounds the drone and protects it from collisions with objects and people. Safety around drones is of paramount importance, and it is vital to know the relationship of the drone to the objects around it, and the walls and floor, etc. This can be achieved by using various scanning technology such as sonar, infra-red and stereo-vision capability (3D triangulation from 2D images).
LiDAR and Anti-Collision
One of the most modern systems uses a combination of LiDAR and Time of Flight (ToF). Lidar is a scanning technique that examines the distance to a target by scanning with laser light and measuring the reflected light with a sensor. The difference in laser light return times and reflected wavelengths can provide digital 3-D representations of the target and surroundings. The ToF sensor module can provide distance values from the sensor to the target and surroundings, by determining the round-trip time of a beam of artificial light from a laser or LED.
TeraRanger Tower Evo
The TeraRanger Tower Evo distance sensor from Terabee is a sophisticated multisensory anti-collision system for drones used in an internal setting. The system incorporates a ToF static LiDAR system that allows close up photography but is also sensitive to the close proximity of objects. There are two versions of the TeraRanger Tower Evo depending on the drone application; both can be equipped with 8 or 4 sensors. There is the long-range Tower Evo 60m and the Tower Evo 600Hz. The 60m model provides detection from 0.5 to 60m at a detector refresh rate of 120-240Hz for 8 and 4 sensors respectively. The Tower Evo 600Hz provides a range of 0.75m to 8m at a detector refresh rate of 320-600Hz for 8 and 4 sensors, respectively. Essentially the 600Hz model provides a higher update rate, which is best suited for indoor environments with many obstacles.
TeraRanger Tower Evo
Benefits of the TeraRanger
The TeraRanger Tower Evo detector system has many benefits when installed on drones for internal operations. The ToF system has a high frame rate ranging from 100Hz to 600Hz for higher resolution distance data that allow more rapid detection of obstacles. The detector also has the benefit of allowing a range of 0.5 to 60 meters allowing time for a fast drone to avoid obstacles. The small size low-cost design of these detectors, and the fact that they only weigh 9 grams allows easy integration on pretty much any popular type of drone. The lightweight of the detector also means lower power consumption and less burden on the power cell. Unlike laser based products, IR LED ToF sensor modules are always eye-safe, which is a strong plus from a health and safety perspective.
The TeraRanger in Use
The Tower Evo is a low-cost, versatile, light and modular detector system. Tower Evo integrates perfectly with Ardupilot (APM) software and PixHawk autopilots for added drone capability. The Tower Evo system provides a huge boost for drones used in internal areas allowing them to have enhanced navigation and collision-avoidance and providing the capability to integrate with a huge number of Internet of Things (IoT) monitoring applications. IoT is the integration of Internet connectivity into everyday devices allowing them to be controlled and monitored via the internet. For example, with inspection drones, the user might be at a remote location and the inspection could be fully automated with video footage being relayed back via the internet.
Sources and Further Reading
- Medina A, Gayá F, Pozo F (2006). ‘Compact laser radar and three-dimensional camera’. J. Opt. Soc. Am. A. 23 (4): 800–805.
- L. V. Santana, A. S. Brandao, M. Sarcinelli-Filho, "Navigation and cooperative control using the ar. drone quadrotor", Journal of Intelligent & Robotic Systems, vol. 84, pp. 327-350, 2016.
- J. Garcia-Pulido, G. Pajares, S. Dormido, J. M. de la Cruz, "Recognition of a landing platform for unmanned aerial vehicles by using computer vision-based techniques", Expert Systems with Applications, vol. 76, pp. 152-165, 2017.
- Jose Luis Asensio, Terabee Tower Evo presentation. Terabee Tower Evo Anti-collision for drones
This information has been sourced, reviewed and adapted from materials provided by Terabee.
For more information on this source, please visit Terabee.