Payload for Contact Inspection Tasks with UAV Systems

Abstract

This paper presents a payload designed to perform semi-autonomous contact inspection tasks without any type of positioning system external to the UAV, such as a global navigation satellite system (GNSS) or motion capture system, making possible inspection in challenging GNSS- denied sites. This payload includes two LiDAR sensors which measure the distance between the UAV and the target structure and their inner orientation angle. The system uses this information to control the approaching of the UAV to the structure and the contact between both, actuating over the pitch and yaw signals. This control is performed using a hybrid automaton with different states that represent all the possible UAV status during the inspection tasks. It uses different control strategies in each state. An ultrasonic gauge has been used as the inspection sensor of the payload to measure the thickness of a metallic sheet. The sensor requires a stable contact in order to collect reliable measurements. Several tests have been performed on the system, reaching accurate results which show it is able to maintain a stable contact with the target structure.

Dry Coupled Ultrasonic Non-Destructive Evaluation Using an Over-Actuated Unmanned Aerial Vehicle

“…Additionally, system ME magnitude is less than the 0.032 mm minimum single measurement resolution for this instrumentation. ME is superior to thin sample measurements reported in literature using commercial, UAV-targeted, instrumentation, which showed consistent errors of 0.6 mm across multiple readings [36]. An asymmetrical error distribution is described by the 5 th and 95 th percentile errors, demonstrating a slight bias towards undersized thickness measurements, which may be attributed to residual V-path effects.…”

“…Jarvis et al use a quadcopter to land a discrete Electro-Magnetic Acoustic Transducer (EMAT) sensor package atop a horizonal steel sheet and pipe section with success rates of 65% and 60%, respectively [35]. Ultrasonic measurement of a vertical metal plate is conducted in [36] using a large supporting outrigger to maintain contact. Updates to this system [37] apply horizontal thrust into the plate via two additional propellers, but do not grant full-actuation.…”

Towards Fully Autonomous UAVs: A Survey

“…Other UAV applications include: solar panel inspection [ 266 , 267 ]; power line and tower inspections [ 268 , 269 ]; water quality monitoring [ 270 ]; magnetic field mapping [ 271 ]; load transportation [ 272 , 273 ]; contact inspection tasks [ 274 ]; road safety and traffic monitoring [ 275 , 276 , 277 ]; aerial photography and cinematography [ 278 ]; entertainment and aerial shows [ 279 , 280 , 281 , 282 ]; firefighting [ 283 , 284 , 285 ].…”

Framework for Structural Health Monitoring of Steel Bridges by Computer Vision

“…The American Association of State Highway and Transportation Officials March 2016 survey found that 17 state Departments of Transportation had studied or used drones, whereas 16 states were either exploring UAV usage, assisting in the development of drone policies, or supporting drone research [27][28][29]. UAVs themselves cannot perform inspections independently, but can be used as a tool for bridge inspectors to view and assess bridge element conditions following the National Bridge Inspection Standard [30][31][32]. We believe that to achieve profits resulting from the automation of the image analysis process, it is also essential to automate the process of data acquisition, which is the drone flight route.…”