Drone Inspection Introduction
Drones started out as toy for hobby enthusiasts, but have evolved to become sophisticated commercial aircraft that are now on the cutting edge of technology suitable for drone inspection applications. The use of drones in the commercial markets have been driven by advances in key components such as sensors, radio controlled devices, and the miniaturization of computer processors. Drones are, in some respects, still in the infancy of their technological evolution, but are seeing increasing use in the industrial sector.
Remotely controlled drones are potential platforms for using advanced sensors for drone inspection of industrial systems. However, the market penetration of drones in the industrial space has been rather slow. Using drone inspection solutions provides the following benefits:
- Inspection of areas difficult to reach
- Preventative maintenance planning
- Access to areas that pose health and safety risks to humans
- Fast response times
- Quick on-site deployment of inspection systems
- Reduced downtime
Along with using standard high-resolution cameras, infrared thermography can be incorporated in drone inspection for sub-surface examinations. The drone can monitor the structural health of certain areas by detecting surfaces that are warmer than its surroundings. Defect areas tend to stop the flow of heat and will appear hotter.
This article examines several key areas where drone inspection would prove highly beneficial and cost effective.
Drone Wind Turbine Inspection
Fossil fuels are non-renewable energy sources that have a finite availability. Over time, this resource will become too expensive and environmentally damaging to retrieve. Many countries are investing in renewable energy sources such as hydro, solar and wind energy. Over the past few years, there has been a large increase in the use of wind turbines, driving the need for safe and cost-effective methods of inspection.
Wind turbines are very large in size, and are usually located in remote areas, making them difficult to access. Legacy inspection methods usually involve cherry pickers, hydraulic cranes, service platforms, and rope decent. Each of these methods come with their own set of risks and challenges. The use of heavy equipment, or rope climbing is time consuming, costly, and potentially dangerous.
The use of drones offers many advantages over manual inspection methods.
Wind turbine inspection teams have the potential to inspect twice as many turbines per day by using drones that follow a predetermined path. Manual inspections of turbines currently take place at a rate of two to five turbines per day. Using drones, this can be increased to ten to twelve turbine inspections per day.
There are cost savings benefits to using drones for turbine inspections. Currently manual inspections can cost up to a few thousand dollars per turbine. Using a semi-automated drone inspection process with the pilot in the loop can reduce the per turbine inspection costs by up to 80%.
Drones can deliver much better data than what can be obtained by manual inspection methods. Drones can fly up to the optimal inspection distance from the turbine blade, and can circle around to cover the entire surface area. This data can be used to build a three-dimensional dynamic model of the turbine providing a level of detail that is impossible through manual inspection methods.
There are also current plans to automate the entire turbine inspection process, minimizing the need for specialized training to operate the drones. Soon drones will take off, capture high-resolution images of all sides of the turbine blade, and land back at its hanger within 15 minutes. The turbine blades would not even bee need to be stopped, thereby reducing down time.
Drone Pipeline Inspection
Pipelines, and their related support equipment, are typically located in remote or offshore areas making them difficult to reach. Any equipment failure, accidents, attacks or damage to this critical infrastructure can lead to revenue loss, as well as environmental damage. Furthermore, such events could also lead to a disruption in the international oil and gas transportation system.
The main purpose behind monitoring oil and gas pipelines is for safety reasons. Recently, there has been increased international regulatory pressure on the oil industry to improve the operational safety and integrity of pipelines. Improving pipeline security is now a matter of global importance.
To minimize the risk of leakage, and spills, periodic checks need to be conducted to monitor its physical state and operational capabilities. Pipeline monitoring involves establishing nominal operating points, and monitoring for any changes that go outside the expected range. Due to the potential for large environmental damage, early detection of leaks or spills is crucial.
Visual inspection is the traditional method of inspecting pipelines. This is usually conducted by foot patrols, or using light aircraft or helicopters. Inspection activities that require human involvement are usually very costly. Automated methods involving the use of a network of high sensitivity sensors can be used to measure pressure, acoustics, and temperature. However, such sensors can be damaged and provide incomplete or inaccurate information.
Using small UAVs for pipeline inspection along with conventional methods can contribute to ensuring pipeline security and safety, as well as ensuring production continuity. A variety of different sensors can be used to configure the UAV for the particular monitoring task at hand. Typical tasks include pipeline inspection, and detection of hydrocarbon leaks. Both passive and active sensors can be used to provide additional information for monitoring tasks.
UAV technology is still being developed, and a fully autonomous inspection system is yet to be realized. However, even with current technology levels, UAVs do have the capacity to support, and possibly substitute, traditional foot patrols and aerial surveys. UAV systems have the potential to be highly effective tools for close and repetitive infrastructure inspection. Further advancements in the miniaturization of sensors for hydrocarbon leak detection will further extend the utility of drone pipeline inspection.
Drone Infrastructure Inspection
There are many economic and environmental for routinely inspecting buildings and large facilities for the purpose of safety and continued operation. However, this requires the monotonous, dirty, and sometimes dangerous work of monitoring and inspection. Drones can simplify the inspection work by providing images that can allow experts to figure out what needs to be repaired, allowing efficient allocation of time and resources.
With the advancement of technology, drones are poised to perform infrastructure inspection by providing high resolution images, video, and perform laser scanning remotely. Drones can get into tight places, and provide low altitude data capture that traditional aircraft cannot. With the inclusion of additional sensors, such as a survey grade LIDAR, drones provide a stable and portable platform for precision scanning of large structures like bridges.
An interesting use case is the inspection of railway lines in mountainous and remote regions. Routine railway line inspections are needed to identify and characterize geohazards, assess susceptibility, and contribute to resource planning for mitigation work. In remote regions, the railway line is exposed to hazards such as landslides, and rock falls which are problematic for the safe, and continued operation of the railway.
For bridge inspection, the typical methods involve using an aerial work platform, or an under-bridge inspection vehicle. Ladders and ropes can also be used if the bridge is small enough. The method used depends on the type of bridge, the amount of needed access, and the ability to block lanes of traffic. Despite what option is used, the inspection costs and hazards remain a challenge. Aerial platforms and snoopers are expensive to maintain, and operate. Rope inspection requires specialized training and equipment. Drones for bridge inspection can provide additional information using infrared scanners, and can complete the work with a reduced cost.
Drones for infrastructure inspection have the additional benefit of being able to operate during the day and the night. Also, drones can be outfitted to operate in the rain, and in moderate windy conditions. Drones can also be programmed to regularly fly a pre-specified route, making the inspection process semi-autonomous.
The power industry has taken notice of the development of drone technology and are now exploring ways to utilize drones for power line inspections. Typical manual inspection power line inspection methods involve long distance images using telescopes, and manual visual inspection. Drones provide the option to reduce costs, and increase the safety in power line inspection operations.
Powerline inspection using foot patrols usually involve a two-man team who walk from pylon to pylon to inspect the power lines. Visual inspection is carried out using binoculars, and occasionally with infrared and corona detection cameras. These inspections can be highly effective, but is only accurate for surfaces that be seen from the ground. In remote regions, this can be even more tedious, as the pylons are not easily accessible, and the terrain between the pylons makes movement difficult.
Aerial inspection is possible using fixed or rotor winged aircraft staffed by a team of three people; the pilot, the inspector, and the recorder. The effectiveness of such aerial inspections for detecting damage and defects to the power lines is generally low. Aerial inspection offers obvious advantages. However, the use of manned helicopters is highly costly. It is usually reserved for quick inspections of large networks, or in areas where accessibility by land is challenging.
Robotic drones offer an alternative to manned aerial inspections. Not only is it safer than manned aerial inspections, it can be carried out at a fraction of the cost. Drone still have the same problems of image stabilization, pole tracking, and automatic defect detection. However aerial drone power line inspections would be faster than foot patrols, and would yield the same, or more accurate results than manned helicopter inspections.
Along with inspecting power lines in the visible spectrum, thermal sensors can be used to identify defects in the power lines. Defect areas have high impedance that generate more heat than the surrounding regions, and generate more heat. By utilizing a simultaneous stream from both a thermal and regular video camera, it is possible for the operator to notice a defect area and record video of the problem area.
Drone Inspection Summary
Drones reduce the costs and time for inspection of confined spaces such as storage tanks, and boilers. Equipping the drone with LED panels and cameras provides good image quality for remote visual testing. The ability to quickly deploy the drone inspection system and the ability to inspect an entire area quickly make them ideal for critical inspections. The data provided by the drone creates a foundation for better maintenance planning. This reduces maintenance downtime and costs.
Aerial inspection using drones is a quick and cost effective option that provides high value, ensures more repetitive inspection intervals, increased knowledge of system conditions, and provides early detection of damage. Drone inspection enables access to otherwise inaccessible structures and details. This allows operators to act immediately, as opposed to using alternative historical methods that are more time consuming and costly.