Reliable engineering
takes many forms

Safe flight cover for the inspection of aerial electric lines

16 October 2014by admin
by S. Antunes¹‘²‘³, K. Bousson¹‘²
Universiade da Beira Interior¹, LAETA-UBI/AERO.G², Albatroz Engenharia³


A supervision control based on flight and essential external sensors data is proposed in this paper for quadrotor overhead power line inspections. The first requisite in design of airborne systems is the safety of people and involving assets. Air vehicles involved in overhead power line inspections, manned or unmanned, requires the use of precise and robust systems, and with a constant supervision of mission. These flight requirements due to the fact that missions are develop, in most of cases, in hostile environments and always in reduced levels of altitude and speed. Variables such as: distance from the vehicle to the line; distance from the vehicle to the ground and instantaneous speed of flight, allied to the flight envelope of the vehicle, become safer missions and added comfort to the pilot on decisions as where and under conditions should operate to a successful mission. The pilots are aware of the specific flight envelope of the vehicle to operate, however, during the course of flight, the commitment of the crew to get better possible inspection evidences could let them infringe the safety limits specified in flight envelope.

The proposed work aims to improve the safety of overhead power line inspection, and similar tasks, automatically sensing flight conditions and create a system of analyzing the parameters that lead to the vehicle near the boundaries of the envelope flight safety. Observing these variables the system is able to send advice signals to the inspectors for them have the time to inform the pilot and get the proper safety precautions. In case of autonomous systems, the problem include the supervised control in order to monitor the critical variables and verify how they influence the behavior of the air vehicle; and the use of Kalman filter control to preview dynamic attitude of quadrotor and control the aircraft in order to avoid that skirt of safe flight envelope. In the final phase of this project, the plan is to provide integration solutions on PLMI (Power Line Maintenance System), taken into account the use of autonomous vehicles, the objective being to reach solutions that aim to give more emphasis to security.

The use of semi-quantitative method of zones (red, orange, yellow and green), possibly combined with more detailed quantitative should be communicated with the crews, directly to the inspector which then transmits the information to the pilot, and in turn, they acts upon the control of the vehicle. The research concludes with the design and implementation of automatic controllers for quadrotors, based on supervised learning from the previous stages.

The classification of dangerous maneuvers inherent to inspection are necessary to create methodologies that culminate in our goal of designing means for control, monitor and supervise inspection of the overhead flights missions serving up or autonomous unmanned aerial means. For a specific mission, the condition of monitoring of high voltage towers and their components was considered for this work using a quadrotor.

The literature gives us the characteristic quadrotor equations, to describe the flight attitude of our vehicle (with some considerations), however, the safe flight envelope from manufacturers are not known. In general, some parameters are acknowledged, as maximum and minimum of operational velocity or altitude, and better conditions for a favourable flight.

To illustrate the safe flight envelope, was initially considered two variables of flight, altitude and speed – aircraft performance variables. In the case of the quadrotor the velocity depends of pitch angle, so that can increase or decrease speed. To represent the limits of aircraft performance, is considered quadrotor equations and calculated maximums and minimums for each altitude fixed point-by-point.

In result of this work, using supervision and robust methods of control in real time of flight, the system have ability to follow a target and input corrective signals maintain safe flight distances, speeds and acquire inspection data that is intended to store. The proposed control scheme was implemented on our developed flight envelope control for unmanned quadrotor. Experimental results have demonstrated clear improvements over overhead power line inspection missions, being more secure the approach to the inspection target object.