Overview
Tower Inspections have always been a challenge. Traditional solutions involving rope-access can be slow, expensive and above all risky, even with trained technicians involved.
Drones are transforming the way these inspections are conducted. By taking off a commercial drone safely from the ground, towers can be inspected an order of magnitude faster, cheaper and safer. But what's the best way to inspect a tower using a drone? Let's take a look.
Starting With the End Goal
As with any other drone mission, we recommend thinking through your inspection workflow starting with the end goal in mind and what you're looking to achieve. Is the goal to create a 3D model of the tower and inspect it in a digital twin environment? Is it to capture parts of the tower most likely to have defects? Each drone mission has its own purpose and it's important to think through the entire operation with the end goal in mind.
For instance, if you're looking to create a 3D model of the tower, we recommend using a drone such as the Phantom 4, because of it's mechanical shutter. A mechanical shutter ensures each picture is taken in one swift action, reducing the changes for motion blur, which can interfere with the 3D modelling in your chosen photogrammetry software.
Operational Challenges
Once you've got a clear idea of what you're aiming for and the equipment you will need, it's time to plan the operation. Every operation will present its unique set of challenges. Over here, we cover 3 main challenges related to tower inspections.
1. Structures Around the Tower
Towers come in different shapes and forms - cell towers, water towers, cooling towers, etc and each one presents a different set of challenges. No matter the structure, it's important to analyze the site around the tower of interest for obstacles, to understand the operating corridor for the drone.
2. Battery Change
Battery changes are a critical component to most drone missions. They are especially important to monitor closely in tower missions. The biggest reason for this being the fact that your drone could have run low on battery on the other side of the tower, and therefore the battery resume flight path needs to account for the 3D tower in the way, which now acts as an obstacle between the battery change point and the mission resume point. See below.
img src Critical to avoid the tower on battery change
Luckily, this is something our flight automation software - Hammer already addresses. Every tower is marked as an obstacle on the map, and the drone will automatically plan its flight path around the tower to ensure maximal safety. See below.
Avoiding Tower Obstacles on Battery Change
3. Line-of-Sight
Another important component of tower missions is to maintain line of sight of the drone at all times. This can be tricky for water towers for example, where the structure is opaque and it's hard to see on the side of the tower. Moving along with the drone can help with this problem. Choosing a flight path that cover one side of the tower at a time is another way to solve this challenge.
Mission Planning
Outside of the operational challenges in tower inspections, it is also important to consider the mission planning challenges that you might encounter while planning your mission. Each mission needs to be carefully planned to ensure the best possible data. Over here we look at some of the mission planning challenges and how to combat them.
1. Low Oblique Angle
A common issue associated with tower missions is poor quality 3D outputs. Most of the times these can be attributed to the presence of horizon / sky in the images. To ensure high quality 3D models, it is important to ensure that images are devoid of any patches of sky or horizon. This can be done by maintaining a low oblique angle on the drone's gimbal. Hammer allows you to set this as one of the associated parameters in the tower mission plan.
Important to maintain a low oblique angle
img credit - ryka uas
2. Positioning the Drone
Google Maps is internally consistent but may include discrepancies up to a few metres from the real world. Therefore, planning a mission solely using Google maps or other global mapping technology is usually not sufficient. We recommend using the drone to mark the tower of interest, mark the flight radius around the tower and the horizontal distance to the tower. Hammer makes this process super easy by allowing you to fly the drone to the tower, tapping a button and applying the measured distance as a parameter for the mission. If you're interested in learning more about this functionality, we recommend visiting the Fly-To-Draw features in Hammer.
3. Width or Height First?
Depending on the type of the target tower, it might be more efficient to fly the width of the tower first (e.g. water tower), or alternatively, it might be more efficient to fly the height of the tower first (e.g. cell tower). Therefore, it's important to have a flight plan on hand that can tackle both of these cases. In Hammer, we allow you simply choose the circles mode for a breadth first scan or the Up Down mode for a height first scan.
Width First or Height First Flight Modes
img credit - ryka uas
Post Processing
Once you've collected the data, we recommend using Hammer Hub to sift through the images and annotate your findings. You can even run your data through AI-based defect detection software to speed up your analysis process. If you'd like to learn more about data processing options, please feel free to get in touch with us at team@hammermissions.com.
Tutorial
To learn how to use Hammer for Tower mapping in Hammer, please visit our tutorial on tower missions in Hammer.
Summary
We hope this guide provided you with an insight into some of the operational challenges while conducting a tower inspection using drones. Every tower inspection is slightly different, so don't be afraid to add your own creativity to the data capture process!
At Hammer, we provide an extremely adaptive flight planning platform for commercial drones, that helps you capture the best data possible for your specific needs. If you'd like to try Hammer, feel free to download the app through the App store or get started with our web platform here.
If you're interested to learn more about our enterprise solutions, including mission collaboration, flight analytics and more please contact us at team@hammermissions.com.
We look forward to hearing from you.
- The Hammer Team