Optimum Altitude of Quadrotor in Underground Mining Autonomous Navigation
Lukman Alabede, Mostafa Hassanalian · 2024
The utilization of Unmanned Aerial Vehicles (UAVs), more especially quadrotors, in underground mining operations poses challenges because these vehicles must maneuver in close proximity to various surfaces, exposing them to external forces and aerodynamic interactions. The nature of UAV navigation in such restricted environments is examined in this research, where flying at lower altitudes is hampered by ground effects, which may reduce operational efficiency, and flying at higher altitudes increases the risk of colliding with the mine ceiling because of ceiling effects. The ground effects of helicopters have been researched in great detail, but most of the research has been done using the Cheeseman and Bennett models as a reference, whose work may not be directly applicable to multi-rotors because of the unique aerodynamic features that fixed propellers running at varying speeds present. This divergence highlights the need for a detailed analysis of multirotor-specific aerodynamics. Understanding UAV operation in restricted spaces requires a new field of research on ceiling effects, mainly unexplored in traditional helicopter dynamics. In underground mining, this study offers a thorough experimental framework to verify the theoretical models of UAV interaction with surfaces. An Arduino microprocessor and a stepper motor drive a brushless motor with a 10 cm diameter propeller in the experimental setup to mimic the effects of being close to the walls, ceiling, and ground. The setup mimics the ventilation system of the mine and employs acrylic materials to replicate surfaces. It also includes a fan to investigate the effect of the fan on UAV performance at different speeds. The distance from the propeller to the surface (z), stepper motor acceleration in three dimensions, motor amperage draw, and thrust in and out of ground effect are necessary measurements to graph thrust ratios against altitude ratios and determine the best altitude model. Through integrating a thorough investigation of both ceiling and ground effects with the pragmatic difficulties presented by small areas and ventilation systems, this work aims to close a sizable gap in the existing knowledge of UAV dynamics. To thoroughly evaluate the ideal operating conditions for UAVs in underground mines, a multi-phase experimental validation procedure was conducted, which includes individual and combined interactions with the ceiling, ground, and walls. This process strives to improve the accuracy of the ideal altitude model through curve fitting and vibration removal while offering practical recommendations for enhancing UAV operational efficiency and safety in these challenging conditions. The results of this study have the potential to guide the creation of safer and more efficient UAV operating techniques for the mining industry as well as other sectors where UAVs are used in comparable restricted environments. This study also clarifies the methodology and expected contributions in the context of developing quadrotor as a unique form of unmanned aerial vehicle (UAV) technology specifically for underground mining operations, with an emphasis on safety and aerodynamic efficiency optimization will be established. Using UAVs, especially quadrotors, in underground mining operations presents various potential and complex problems. Despite the extra turbulence produced by mine ventilation systems and the aerodynamic disturbances brought on by their proximity to objects like the mine's ceiling, floor, and walls, these vehicles must maneuver through confined spaces, avoid obstructions, and maintain stability and efficiency. The underlying hypothesis of this research study is that there is an ideal altitude for a quadrotor operating in underground mines. This altitude maximizes aerodynamic efficiency and operational safety by balancing the dangers associated with ground effect, ceiling effect, and interactions with walls and mine ventilation systems. The purpose of the testbed is to replicate the intricate aerodynamic circumstances that quadrotors face in underground mines. It is a well-designed system consisting of a brushless motor with vertically positioned propeller blades on a platform controlled by a stepper motor. The propeller's position about simulated mine surfaces may be precisely adjusted thanks to an Arduino microcontroller. The acrylic material used in this configuration ensures uniform and repeatable aerodynamic qualities. An essential part of the experimental setup is the dynamometer, which measures the motor-propeller system's thrust, torque, and other pertinent mechanical and aerodynamic properties under various situations. These circumstances include being close to artificial walls, ceilings, and ground surfaces and being exposed to airflow from a fan that mimics the effect of mine ventilation systems operating at various velocities and pressures. The objective is to create a reliable model that forecasts the ideal operating altitude for quadrotors in deep mines, considering this environment's particular difficulties. The research aims to comprehend the fundamental aerodynamic forces that affect UAV performance in restricted places rather than only determining the ideal altitude. This involves investigating how well-suited and constrained current aerodynamic theories are for quadrotor drones functioning close to surfaces, such as those drawn from helicopter dynamics. This research shows that the ideal altitude for underground mine quadrotor operation is above four diameters of the propeller blade away from the ground and one from the ceiling. Also, the wall effects pitch the propeller blade downward at an angle depending on the velocity and pressure of the ventilation system. Additionally, the results of the experiments show that the impact of a ventilation system on the quadrotor is significant, causing vibration and generating dust, which will affect the quality of the data generated. Therefore, avoiding the ventilation shaft as much as possible while flying a drone during autonomous navigation would be advisable, which might improve the effectiveness and safety of UAV-assisted mining operations. This entails enhancing autonomous navigation system dependability, lowering the possibility of UAV mishaps that can put mine workers in danger, and maximizing UAV performance on jobs like surveying, inspecting, and monitoring in the demanding environment of underground mines. Finally, this study addresses the theoretical and practical difficulties associated with conducting operations in underground mines and offers an advanced investigation of UAV interactions inside these environments. It is anticipated that the results of this study will make a substantial contribution to the field of unmanned aerial vehicles, opening up new avenues for creative applications and practical advancements in a range of commercial and academic settings.