Vision based UAV Navigation through Narrow Passages

This research paper presents a novel approach for navigating a micro UAV (Unmanned Aerial Vehicle) through narrow passages using only its onboard camera feed and a PID control system. The proposed method uses edge detection and homography techniques to extract the key features of the passage from the camera feed and then employs a tuned PID controller to guide the UAV through and out of the passage while avoiding collisions with the walls. To evaluate the effectiveness of the proposed approach, a series of experiments were conducted using a micro-UAV navigating in and out of a custom-built test environment (constrained rectangular box). The results demonstrate that the system is able to successfully guide the UAV through the passages while avoiding collisions with the walls.Comment: Currently under review in IEEE CASE 202

Control Barrier Function-based Predictive Control for Close Proximity operation of UAVs inside a Tunnel

This paper introduces a method for effectively controlling the movement of an Unmanned Aerial Vehicle (UAV) within a tunnel. The primary challenge of this problem lies in the UAV's exposure to nonlinear distance-dependent torques and forces generated by the tunnel walls, along with the need to operate safely within a defined region while in close proximity to these walls. To address this problem, the paper proposes the implementation of a Model Predictive Control (MPC) framework with constraints based on Control Barrier Function (CBF). The paper approaches the issue in two distinct ways; first, by maintaining a safe distance from the tunnel walls to avoid the effects of both the walls and ceiling, and second, by minimizing the distance from the walls to effectively manage the nonlinear forces associated with close proximity tasks. Finally, the paper demonstrates the effectiveness of its approach through testing on simulation for various close proximity trajectories with the realistic model of aerodynamic disturbances due to the proximity of the ceiling and boundary walls.Comment: Conference on Automation Science and Engineering (CASE) 202

Real-time UAV Complex Missions Leveraging Self-Adaptive Controller with Elastic Structure

The expectation of unmanned air vehicles (UAVs) pushes the operation environment to narrow spaces, where the systems may fly very close to an object and perform an interaction. This phase brings the variation in UAV dynamics: thrust and drag coefficient of the propellers might change under different proximity. At the same time, UAVs may need to operate under external disturbances to follow time-based trajectories. Under these challenging conditions, a standard controller approach may not handle all missions with a fixed structure, where there may be a need to adjust its parameters for each different case. With these motivations, practical implementation and evaluation of an autonomous controller applied to a quadrotor UAV are proposed in this work. A self-adaptive controller based on a composite control scheme where a combination of sliding mode control (SMC) and evolving neuro-fuzzy control is used. The parameter vector of the neuro-fuzzy controller is updated adaptively based on the sliding surface of the SMC. The autonomous controller possesses a new elastic structure, where the number of fuzzy rules keeps growing or get pruned based on bias and variance balance. The interaction of the UAV is experimentally evaluated in real time considering the ground effect, ceiling effect and flight through a strong fan-generated wind while following time-based trajectories.Comment: 18 page

Predictive Barrier Lyapunov Function Based Control for Safe Trajectory Tracking of an Aerial Manipulator

This paper proposes a novel controller framework that provides trajectory tracking for an Aerial Manipulator (AM) while ensuring the safe operation of the system under unknown bounded disturbances. The AM considered here is a 2-DOF (degrees-of-freedom) manipulator rigidly attached to a UAV. Our proposed controller structure follows the conventional inner loop PID control for attitude dynamics and an outer loop controller for tracking a reference trajectory. The outer loop control is based on the Model Predictive Control (MPC) with constraints derived using the Barrier Lyapunov Function (BLF) for the safe operation of the AM. BLF-based constraints are proposed for two objectives, viz. 1) To avoid the AM from colliding with static obstacles like a rectangular wall, and 2) To maintain the end effector of the manipulator within the desired workspace. The proposed BLF ensures that the above-mentioned objectives are satisfied even in the presence of unknown bounded disturbances. The capabilities of the proposed controller are demonstrated through high-fidelity non-linear simulations with parameters derived from a real laboratory scale AM. We compare the performance of our controller with other state-of-the-art MPC controllers for AM.Comment: European Control Conference '2

Design and Experimental Validation of a Robust Output Feedback Control for the Coupled Dynamics of a Micro Air Vehicle

This paper addresses the design and experimental validation of a linear robust static output feedback controller for a 150 mm span fixed wing micro air vehicle (MAV). Severe coupling between longitudinal and lateral dynamics of the MAV lead to the design of a multivariable controller for the combined dynamics. The control design problem is posed in the framework of static output feedback (SOF) due to the inexpensive computational requirements for implementation. The multiobjective control design problem including stability requirements, closed loop damping ratio requirements and H norm minimization is solved using the hybrid technique of linear matrix inequalities (LMI) and genetic algorithm (GA). The design is carried out in the discrete time domain, facilitating in direct implementation of the multivariable controller in the onboard autopilot hardware. The robustness of the resulting closed loop system under parametric uncertainties is evaluated using structured singular value analysis. The effectiveness of the proposed controller is demonstrated through outdoor flight trial of the micro air vehicle with a customized lightweight autopilot hardware

75-mm Wingspan Fixed-Wing Nano Air Vehicle With a Novel Aircraft Configuration

The development of a fixed-wing nano air vehicle that fits inside a cube of 75 mm is described in this paper. A novel aircraft configuration that satisfies the static and dynamic stability and the mission performance requirements is developed. A performance index is formulated to identify a suitable airfoil as there does not exist a single airfoil that achieves the mission required specifications. Eppler-61 is identified as the suitable airfoil since the value of its performance index is maximum among other airfoils selected for the analysis. The static stability of the nano air vehicle is analyzed using the aerodynamic characteristics obtained from the wind tunnel tests. The outcomes of this analysis indicate that the vehicle is statically stable. The analysis also indicates significant aerodynamic cross-coupling between longitudinal and lateral aerodynamic coefficients. The dynamic stability analysis indicates that the nano air vehicle is dynamically stable. Furthermore, the dynamic stability of the vehicle is validated by flight test results

Effect of propeller-induced flow on the performance of biplane micro air vehicle dynamics

This paper presents the analysis of propeller-induced flow effects on the dynamics of a fixed wing biplane micro air vehicle. The analysis is based on wind tunnel tests and mathematical modeling. This analysis plays a pivotal role because the propeller-induced flow has significant effects on the dynamics of fixed wing micro air vehicle due to submergence of a large portion of the wing in propeller slipstream. Although the effect of the propeller-induced flow on the various aerodynamic parameter is reported in the literature; however, its effects on overall forces, moments and vehicle dynamics are not quantified so far. In this paper, propeller-induced flow effects are modeled as a function of motor rotation speed and mathematical analysis is performed to quantify their effects. The wind tunnel test is conducted at different propeller speeds on a biplane micro air vehicle ``Skylark'', having wingspan and chord length of 150 mm and 140 mm, respectively. Analysis of results shows that the propeller slipstream increases the overall lift, drag, side force, range, and endurance significantly. Propeller flow also contributes to the rolling moment and the pitching moment, while it has negligible effects on the yawing moment. It is shown that the trim angle of attack is lower when the propeller flow is considered in computing the trim conditions