Design of a Small Unmanned Aircraft System for Bridge Inspections

Bridge inspections are an important procedure for maintaining the infrastructure vital to our economy and well-being. The current methodology of utilizing specialized equipment such as snooper trucks and scaffolding to support manned-inspections poses a significant financial cost, disrupts traffic, and is dangerous to the inspectors and public. The advent of unmanned aerial systems (UAS), more commonly called drones, presents a practical solution that promises reduced cost, enhanced safety, and is significantly less intrusive than previous methodologies. Current limitations in the implementation of UAS include the reliance on a skilled operator and/or the requirement for a UAS to operate in a cluttered, GPS-denied environment. A solution to these challenges is presented in this paper by utilizing commercial off-the-shelf (COTS) hardware including laser rangefinders, optical flow sensors, and live video telemetry. Included in the system is the obstacle avoidance equipped drone and a ground station intended to be manned by a pilot and bridge inspector. The proposed custom-fabricated UAS was implemented during eight inspections of Florida Department of Transportation (FDOT) bridges. The UAS was able to navigate under GPS-denied and obstacle-laden bridge decks with position-hold performance comparable to, if not better than, a COTS unit in an unobstructed environment. The position hold capability maintained an altitude of ±12.8 cm with a horizontal hold of ±435 cm. Details of the hardware, algorithm development, and suggestions for future research are discussed in this paper.

[1]  R. Siegwart,et al.  A UAV system for inspection of industrial facilities , 2013, 2013 IEEE Aerospace Conference.

[2]  Anil Rao.  Dynamics of Particles and Rigid Bodies , 2005 .

[3]  Chen-Ming Kuo,et al.  Unmanned Aircraft Systems for Remote Building Inspection and Monitoring , 2012 .

[4]  Emilio Garcia-Fidalgo,et al.  Vessel Inspection: A Micro-Aerial Vehicle-based Approach , 2014, J. Intell. Robotic Syst..

[5]  Zhaozheng Yin,et al.  Develop a UAV Platform for Automated Bridge Inspection , 2015 .

[6]  D. Chun,et al.  Vehicle motion estimation using low-cost optical flow and sensor fusion , 2012, 2012 19th International Conference on Mechatronics and Machine Vision in Practice (M2VIP).

[7]  Carol J. Friedland,et al.  High Resolution Imagery Collection Utilizing Unmanned Aerial Vehicles (UAVs) for Post-Disaster Studies , 2012 .

[8]  Dennis Dalli,et al.  Proof of Concept for Using Unmanned Aerial Vehicles for High Mast Pole and Bridge Inspections , 2015 .

[9]  Hugh Alan Bruck,et al.  Full-field representation of discretely sampled surface deformation for displacement and strain analysis , 1991 .

[10]  Feng Lin,et al.  Homography-based Vision-aided Inertial Navigation of UAVs in Unknown Environments , 2012 .

[11]  Peter Ifju,et al.  Bridge Inspections with Small Unmanned Aircraft Systems: Case Studies , 2019, Journal of Bridge Engineering.

[12]  Carlo Tomasi,et al.  Good features to track , 1994, 1994 Proceedings of IEEE Conference on Computer Vision and Pattern Recognition.

[13]  Steven Mills,et al.  Optical Flow for Heading Estimation of a Quadrotor Helicopter , 2009 .

[14]  Guoqiang Hu,et al.  Adaptive Visual Servo Control , 2009, Encyclopedia of Complexity and Systems Science.

[15]  Christopher Parrish,et al.  Cost-Effective Bridge Safety Inspections Using Unmanned Aircraft Systems (UAS) , 2016 .

[16]  Tarek Hamel,et al.  A UAV for bridge inspection: Visual servoing control law with orientation limits , 2007 .

[17]  R. Siegwart,et al.  Aerial service robots for visual inspection of thermal power plant boiler systems , 2012, 2012 2nd International Conference on Applied Robotics for the Power Industry (CARPI).

[18]  Guido Morgenthal,et al.  Quality Assessment of Unmanned Aerial Vehicle (UAV) Based Visual Inspection of Structures , 2014 .

[19]  Marc Pollefeys,et al.  An open source and open hardware embedded metric optical flow CMOS camera for indoor and outdoor applications , 2013, 2013 IEEE International Conference on Robotics and Automation.

[20]  Cheng-Hsuan Yang,et al.  An Optimized Unmanned Aerial System for Bridge Inspection , 2015 .

[21]  Yanning Zhang,et al.  A Ground-Based Near Infrared Camera Array System for UAV Auto-Landing in GPS-Denied Environment , 2016, Sensors.

[22]  Hubert W. Schreier,et al.  Image Correlation for Shape, Motion and Deformation Measurements: Basic Concepts,Theory and Applications , 2009 .

[23]  Thomas Oommen,et al.  Evaluating the Use of Unmanned Aerial Vehicles for Transportation Purposes , 2015 .

[24]  Heinrich H. Bülthoff,et al.  On-board velocity estimation and closed-loop control of a quadrotor UAV based on optical flow , 2012, 2012 IEEE International Conference on Robotics and Automation.