Quadrotor Flight Control Research Articles

Symmetric actor–critic deep reinforcement learning for cascade quadrotor flight control

Even though deep reinforcement learning (DRL) has been extensively applied to quadrotor flight control to simplify parameter adjustment, it has some drawbacks in terms of control performance, such as instability and asymmetry. To address these problems, we propose an odd symmetric actor to achieve stable and symmetric control performance, and an even critic to stabilize the training process. Concretely, the bias of neural networks is eliminated, and the absolute value operation is adopted to construct the activation function. Furthermore, we devise a cascade architecture, where each module trained with DRL controls a symmetric subsystem of the quadrotor. Comparative simulations have verified the effectiveness of the proposed control scheme, which shows superiority in dealing with high-dimensional, nonlinear subsystems and disadvantage in dealing with low-dimensional, linear subsystems.

Autonomous aerial obstacle avoidance using LiDAR sensor fusion.

The obstacle avoidance problem of unmanned aerial vehicle (UAV) mainly refers to the design of a method that can safely reach the target point from the starting point in an unknown flight environment. In this paper, we mainly propose an obstacle avoidance method composed of three modules: environment perception, algorithm obstacle avoidance and motion control. Our method realizes the function of reasonable and safe obstacle avoidance of UAV in low-altitude complex environments. Firstly, we use the light detection and ranging (LiDAR) sensor to perceive obstacles around the environment. Next, the sensor data is processed by the vector field histogram (VFH) algorithm to output the desired speed of drone flight. Finally, the expected speed value is sent to the quadrotor flight control and realizes autonomous obstacle avoidance flight of the drone. We verify the effectiveness and feasibility of the proposed method in 3D simulation environment.

Perception, Path Planning, and Flight Control for a Drone-Enabled Autonomous Pollination System

The decline of natural pollinators necessitates the development of novel pollination technologies. In this work, we propose a drone-enabled autonomous pollination system (APS) that consists of five primary modules: environment sensing, flower perception, path planning, flight control, and pollination mechanisms. These modules are highly dependent upon each other, with each module relying on inputs from the other modules. In this paper, we focus on approaches to the flower perception, path planning, and flight control modules. First, we briefly introduce a flower perception method from our previous work to create a map of flower locations. With a map of flowers, APS path planning is defined as a variant of the Travelling Salesman Problem (TSP). Two path planning approaches are compared based on mixed-integer programming (MIP) and genetic algorithms (GA), respectively. The GA approach is chosen as the superior approach due to the vast computational savings with negligible loss of optimality. To accurately follow the generated path for pollination, we develop a convex optimization approach to the quadrotor flight control problem (QFCP). This approach solves two convex problems. The first problem is a convexified three degree-of-freedom QFCP. The solution to this problem is used as an initial guess to the second convex problem, which is a linearized six degree-of-freedom QFCP. It is found that changing the objective of the second convex problem to minimize the deviation from the initial guess provides improved physical feasibility and solutions similar to a general-purpose optimizer. The path planning and flight control approaches are then tested within a model predictive control (MPC) framework where significant computational savings and embedded adjustments to uncertainty are observed. Coupling the two modules together provides a simple demonstration of how the entire APS will operate in practice.

INDI-based aggressive quadrotor flight control with position and attitude constraints

Recent studies have significantly contributed to the extensive use of quadrotors for delivery, mapping, and inspection. To further increase the versatility of quadrotors under confined environments, we focus on the precise trajectory tracking problem with position and attitude constraints. In tightly constrained scenarios, any slight error will infect flight security, especially in a large attitude maneuver. We utilize the incremental nonlinear dynamic inversion (INDI) method to precisely linearize the nonlinearities in the system and generalize it to the entire rotation space to reach a globally expressed control law. Meanwhile, the thrust alignment is introduced to improve the robustness against the mismatch between actuator dynamics and rotational dynamics, guaranteeing higher tracking accuracy. Improvements over a conventional geometry tracking controller are demonstrated in experiments where the quadrotor flies through an inclined narrow gap with orientation up to 90°. Flight tests also indicate the high disturbance rejection capabilities with the thrust alignment in gap traverse flight.

Cascade Flight Control of Quadrotors Based on Deep Reinforcement Learning

Numerous algorithms have been proposed for quadrotor flight control. Conventional methods require massive labor of parameter adjustment. Deep reinforcement learning (DRL) methods also need enormous computation and complicated hyperparameter tuning, since most of them regard the quadrotor dynamics as a black box. To overcome the drawbacks of both conventional and learning-based methods, this letter proposes a DRL-based cascade quadrotor flight controller. Under the small-angle restriction, the quadrotor dynamics are decomposed into six subsystems, each containing only one degree of freedom (DOF) for the agent to control. Six agents are sequentially trained to fully control the corresponding DOF without any prior knowledge of quadrotor dynamic parameters. Experiments show that, with a total training time of 17 min, the proposed controller could accomplish the fixed point tracking task with an error lower than 5 mm, rise time lower than 1.5 s, and peak value lower than 1%. The controller could also track time-variant trajectories.

Flight Simulation and Control of a Quadrotor based on MATLAB/Simulink

Nowadays anyone can fly Unmanned Aerial Vehicle (UAV) and land it according to the specified instructions drafted by the manufacturer. However, the controlling phase is growing day by day as one of the crucial roles of UAV. Obtaining control for autonomous landing is the crucial and critical step. So based on various literature surveys and centering into Industry 4.0, this proposed work deals with image flight simulation and control of Quadrotor, which is an important field of Industry 4.0 in future production and business power. This research is eyed on Quadrotor, a type of flying vehicle with four rotor blades wherein the opposite pairs rotate in alternate direction, which is very useful for vertical take-off and landing. The Quadrotor is created by using CATIA software which is best suited for modelling and developing real time application. The model is extracted in MATLAB/SIMULINK in which a variety of blocks are available under the set of control and aerospace blocks. Then, a suitable simulation environment and controller are made. The advantage of making this proposed work in MATLAB is that it has the features of testing, controlling, and maintaining various operations without equipping any mechanical components, and there is no risk for property or lives.

Adaptive Trajectory Control of Quadrotor by Output Feedback based Control via Backstepping Strategy

In this paper, a control method of quadrotor is proposed based on the almost strictly positive real (ASPR) based output feedback control and backstepping strategy in order to realize a robust and accurate automatic flight control. By adding parallel feedforward compensators (PFCs) to the considered flight control system so as to render the augmented ASPR control system, output feedback based control is easily designed and the number of steps in backstepping strategy can be reduced. In addition, in order to attain output tracking to arbitrary trajectory of the quadrotor, the ideal attitude angles are utilized to the input design in the backstepping strategy, and a two-degree-of-freedom control system with adaptive feedforward input is designed. The effectiveness of the proposed method will be verified though experiments of quadrotor flight control.

Robust flight control for a quadrotor under external disturbances based on generic second order sliding mode control

This paper presents a novel robust second order sliding mode control (RSOSMC) for tracking controller of a quadrotor with external disturbances. In addition, in order to perform the position and attitude tracking control of the quadrotor perfectly, the dynamical model of the quadrotor is divided into two subsystems, a subsystem fully actuated and an underactuated subsystem. The algorithm allows for rapid adaptation and stringent robustness of the quadrotor flight control in the presence of perturbations. Moreover, the proposed controller is based on the idea of second order sliding mode approach, which removes chattering in first-order sliding mode controllers. The finite-time stability and convergence of the proposed method are proved via the Lyapunov theory. To demonstrate the effectiveness of the suggested control approach, extensive simulation results are provided.

Quadrotor Flight Control Based on Improved Active Disturbance Rejection Control Technology

This paper proposes a four-rotor attitude control method based on improved active disturbance rejection control. Based on the analysis of the active disturbance rejection controller from the deviation theory, it is found that the extended state observer has problems such as high steady-state error and difficulty in parameter selection. Then, an improved extended state observer was designed structurally, its stability was proved and the error was compared with the traditional extended observer, and the improved auto-disturbance rejection control was applied to the attitude control of the quad-rotor UAV. Finally, the simulation verification of the controller is carried out from various aspects of attitude tracking, height-fixing experiment, external force interference test and wind interference test, and compared with traditional ADRC, the comparison results show that its performance is better than traditional ADRC.

Robust fault-tolerant flight control of quadrotor against faults in multiple motors

In this article, position and attitude tracking control of the quadrotor subject to complex nonlinearities, input couplings, aerodynamic uncertainties, and external disturbances coupled with faults in multiple motors is investigated. A robustified nonlinear dynamic inversion (NDI)-based fault-tolerant control (FTC) scheme is proposed for the purpose. The proposed scheme is not only robust against aforementioned nonlinearities, disturbances, and uncertainties but also tolerant to unexpected occurrence of faults in multiple motors. The proposed scheme employs uncertainty and disturbance estimator (UDE) technique to robustify the NDI-based controller by providing estimate of the lumped disturbance, thereby enabling rejection of the same. In addition, the UDE also plays the role of fault detection and identification module. The effectiveness and benefits of the proposed design are confirmed through 6-DOF simulations and experimentation on a 3-DOF Hover platform.

Tracking Flight Control of Quadrotor Based on Disturbance Observer

In this paper, a tracking flight control scheme is proposed based on a disturbance observer for a quadrotor with external disturbances. To facilitate the processing of external time-varying disturbances, it is assumed to consist of some harmonic disturbances. Then, a disturbance observer is proposed to estimate the unknown disturbance. By using the output of the disturbance observer, a flight controller of the quadrotor is developed to track the given signals which are generated by the reference model. Finally, the proposed control method is applied to flight control of the quadrotor Quanser Qball 2. The experimental results are presented to demonstrate the effectiveness of the developed control strategy.

An Anti-wind Modeling Method of Quadrotor Aircraft and Cascade Controller Design Based on Improved Extended State Observer

Wind disturbance may significantly reduce the flight control performance of quadrotors when flying. In order to meet high performance flight control requirements, this paper presents a quadrotor anti-wind model (QAWM) and a flight control scheme for quadrotors. The QAWM takes the influence of aerodynamic effects on the propeller, gyroscopic effect and wind disturbance into account. The model can represent more flight states including not only hovering but also flight in windy conditions even maneuver flight. A cascade control scheme with an improved extended state observer (IESO) is adopted to decompose the quadrotor flight control problem into position control loop and attitude control loop. In the attitude control loop, the IESO is used to estimate the unmodeled dynamics, parameter uncertainties and external disturbances, as well as compensate the angular velocity control. In addition, the stability of IESO and the closed loop system are proved. Simulation and experimental results show the effectiveness of the nonlinear quadrotor model and control scheme, and the control scheme can effectively improve the flight performance of quadrotors under wind disturbance even maneuver flight.

Finite-time Adaptive Integral Backstepping Fast Terminal Sliding Mode Control Application on Quadrotor UAV

This paper presents a reliable and novel quadrotor flight control system designed to enhance trajectory tracking performance, robustness and adaptiveness against the uncertain parameters and the external wind disturbance. By combining a recursive control methodology with a robust control algorithm, a finite-time adaptive integral backstepping fast terminal sliding mode control is designed for major control loops related to position tracking and attitude stabilization. To estimate quadrotor mass and inertia moments, only four adaptation laws are developed. To compensate the unknown upper bound on the disturbances, a robust and adaptive switching gain is designed. The designed controller guarantees that all the closed signals are semi-global practical finite-time stability while the tracking error converges to a small neighborhood of the origin. The obtained numerical results and comparison studies show the effectiveness, robustness, adaptiveness and energy efficiency of the proposed flight control system.

Quadrotor UAV flight control via a novel saturation integral backstepping controller

ABSTRACTIn this paper, in order to reduce the influence on quadrotor flight from different external disturbances, a novel nonlinear robust controller is designed and used in the quadrotor system. At first, a nonlinear dynamic model of the quadrotor is formulated mathematically. Then, a quadrotor flight controller is designed with the method of classical backstepping control (CBC) and the nonlinear system using this controller is proved to be asymptotically stabilized by the Lyapunov stability theory when there is no external disturbance. At last, a new nonlinear robust controller established by the introduction of both the saturation function and the integral of error into CBC is designed and named as saturation integral backstepping control (SIBC). The boundedness of the nonlinear system under external disturbances is verified by the uniformly ultimately bounded theorem of the nonvanishing perturbation. The numerical simulations of hovering and trajectory tracking are carried out using MATLAB/SIMULINK taking the external disturbances into consideration. In addition, a series of outdoor flight experiments were completed on the actual experimental equipments of quadrotor UAV under the time-varying disturbance from wind. According to the simulation and flight experiment results, the proposed SIBC strategy shows a superior robustness than CBC and integral backstepping control (IBC) strategy.

Nonlinear and Adaptive Intelligent Control Techniques for Quadrotor UAV – A Survey

AbstractParametric uncertainties and coupled nonlinear dynamics are inherent in quadrotor configuration and infer adaptive nonlinear approaches to be used for flight control system. Numerous adaptive nonlinear and intelligent control techniques, which have been reported in the literature for designing quadrotor flight controller by various researchers, are investigated in this paper. As a priori, each conventional nonlinear control technique is discussed broadly and then its adaptive/observer based augmentation is conferred along with all possible variants. Among conventional nonlinear control approaches, feedback linearization, backstepping, sliding mode, and model predictive control, are studied. Intelligent control approaches incorporating fuzzy logic and neural networks are also discussed. In addition to adaption based parametric uncertainty handling, various other aspects of each control technique regarding stability, disturbance rejection, response time, asymptotic, exponential and finite time convergence etc., are discussed in sufficient depth. The contribution of this paper is the provision of detailed and in depth discussion on quadrotor nonlinear control approaches to the flight control designers.

Modeling and Adaptive Flight Control for Quadrotor Trajectory Tracking

In the near future, unmanned aerial vehicles are probably going to be included in the airspace. Therefore, air traffic management needs to be enhanced in terms of reliability, safety, and accuracy. The main objective of this paper deals with a quadrotor flight control system that generates the necessary control laws to perform accurately, as well as possible, the reference flight trajectories. In this paper, a new quadrotor flight dynamics is developed, including an adopted wind model component where a study of the minimum phase and observability conditions is performed. Based on an adaptive backstepping control algorithm, a developed flight control system generates nonlinear control laws in an iterative and systematic procedure design. In addition to some simulations in a no-wind situation, the proposed adaptive flight control system is simulated in a windy flight condition. The design of adaptation laws according to some quadrotor parameters is developed, and the global stability of the proposed flight control system is guaranteed using the Lyapunov theory. Numerical simulations are performed for the quadrotor engaged in complex trajectory tracking, and obtained results show the feasibility and effectiveness of the proposed control approach.

Method of quadrotor flight control in the target tracking problem

A problem of control of trajectory motion of a quadrotor vehicle is considered. The choice of the form of required differential equations in the previously proposed method of tracking of a moving target is justified. The workability of the control system in the presence of measurement noise and external perturbations is confirmed by results of experiments with the AR.Drone quadrotor.

OSEK-V: application-specific RTOS instantiation in hardware

The employment of a real-time operating system (RTOS) in an embedded control systems is often an all-or-nothing decision: While the RTOS-abstractions provide for easier software composition and development, the price in terms of event latencies and memory costs are high. Especially in HW/SW codesign settings, system developers try to avoid the employment of a full-blown RTOS as far as possible. In OSEK-V, we mitigate this trade-off by a very aggressive tailoring of the concrete RTOS instance into the hardware. Instead of implementing generic OS components as custom hardware devices, we capture the actually possible application-kernel interactions as a finite-state machine and integrate the tailored RTOS semantics directly into the processor pipeline. In our experimental results with an OSEK-based implementation of a quadrotor flight controller into the Rocket/RISC-V softcore, we thereby can significantly reduce event latencies, interrupt lock times, and memory footprint at moderate costs in terms of FPGA resources.

Research on Flight Control of Quad-rotor Based on Backstepping and Adaptive Control Technology

According to the uncertainty problem in the process of quad-rotor aircraft flight, As close to the actual flight environment, The nonlinear dynamic model of quad-rotor aircraft is established,On the basis of the backstepping, Analyzed the presence of interference control quantity expression and adaptive law.This paper puts forward a technique of backstepping and adaptive control technology,Through Matlab simulation and flight test of the designed adaptive inverse footwork the effectiveness of the proposed controller is verified, The simulation results show that the system has good robustness.

Flight control for a quadrotor of attitude control based on android system and using optimal-tuning design

This paper proposes the research and development of an Android-based mobile platform with a quadrotor control and quadrotor flight controller. The proposed Android-based mobile platform has the following advantages: (1) with Android remote controller has a bidirectional transmission function, which can transmit flight directives to the quadrotor and receive the feedback information to achieve the desired control. Additionally, the Android remote controller is designed on a mobile platform for convenient carrying. (2) The flight controller is designed with Proportional Integral Derivative (PID) Control and Sliding Mode Control methods to obtain optimum operations. Finally, parameters of optimum control are built and implemented by using Genetic and Tabu Search Algorithms. Experimental results are presented to verify the performance and the feasibility of the proposed Android-based mobile platform with a quadrotor control and quadrotor flight controller.