Fully-Actuated Aerial Manipulator for Infrastructure Contact Inspection: Design, Modeling, Localization, and Control

Abstract

This paper presents the design, modeling and control of a fully actuated aerial robot for infrastructure contact inspection as well as its localization system. Health assessment of transport infrastructure involves measurements with sensors in contact with the bridge and tunnel surfaces and the installation of monitoring sensing devices at specific points. The design of the aerial robot presented in the paper includes a 3DoF lightweight arm with a sensorized passive joint which can measure the contact force to regulate the force applied with the sensor on the structure. The aerial platform has been designed with tilted propellers to be fully actuated, achieving independent attitude and position control. It also mounts a “docking gear” to establish full contact with the infrastructure during the inspection, minimizing the measurement errors derived from the motion of the aerial platform and allowing full contact with the surface regardless of its condition (smooth, rough, ...). The localization system of the aerial robot uses multi-sensor fusion of the measurements of a topographic laser sensor on the ground and a tracking camera and inertial sensors on-board the aerial robot, to be able to fly under the bridge deck or close to the bridge pillars where GNSS satellite signals are not available. The paper also presents the modeling and control of the aerial robot. Validation experiments of the localization system and the control system, and with the aerial robot inspecting a real bridge are also included.

Localization System for Lightweight Unmanned Aerial Vehicles in Inspection Tasks

“…As it was proposed in [ 25 ], we set a global reference frame linked to the infrastructure, provided by the robotic total station, and a set of local reference frames , which depend on the UAV initial position and orientation, and which are associated with the state estimation algorithm of each camera i . We call alignment the procedure to express camera-based position and velocity estimations in the global reference frame, by applying the translation and orientation of with respect to .…”

“…We partially addressed some of these drawbacks in our previous work [ 25 ], where we performed localization for an inspection UAV, combining measurements from a robotic total station and an Intel RealSense T265 camera. This camera comes with an internal processor, where an embedded visual SLAM algorithm [ 26 ] can be run.…”

“…In this paper, we present a novel localization system for UAVs oriented to perform inspection operations in civil infrastructures. We improve our previous work [ 25 ] by combining measurements from multiple onboard cameras and a robotic total station, as well as devising a new method for online camera recalibration. We have achieved a localization system that is capable of providing a high-frequency and reliable full-state estimation in a time-persistent reference frame, fusing information from heterogeneous sources.…”

Installation of Clip-Type Bird Flight Diverters on High-Voltage Power Lines with Aerial Manipulation Robot: Prototype and Testbed Experimentation

“…Physical interaction with the environment generates force reactions to the UAV and causes deviation of the system from a stable hover. Some of the applications of UAVs in IM with interaction with the environment are ultrasonic contact inspection [10], pipe inspection in refineries [11], aerial manipulator system [12], bridge inspection [13], tank thickness measurement [14], and the UAV with a parallel manipulator [15]. Kocer et al presented contact-based autonomous inspection using UAVs equipped with ultrasonic sensors [10].…”

“…Joint compliance was proposed in the manipulator design to facilitate force interaction with the environment. Sanchez-Cuevas et al used a tilted hexacopter design for UAV and an ultrasonic sensor placed on an add-on for bridge inspection [13]. Danko et al employed a parallel manipulator for holding the sensor in UAV contact inspection [15].…”