Autonomous Vertical Take-off And Landing Research Articles

Autonomous Aerospace Technologies in Spacesyslab – A Robotic-Based Rendezvous and Docking System

Abstract Autonomous aerospace technology is an innovation activity currently included in NATO’s operation areas having a profound impact on security and defense. SpaceSysLab facility is the new Laboratory from Romania, able to test control algorithms for autonomous missions and to develop hardware (coupling mechanisms, navigation sensors and actuators). This robot-based test lab is used to test, verify and validate the R&D systems. The degree of novelty is expressed by the fact that the SpaceSysLab designed as a SIL+HIL (Software-in-the-Loop+Hard-inthe-Loop) simulator is a combination of hardware and software simulator that can test and verify space robots, autonomous VTOL (Vertical Take-off and Landing) of UAVs on mobile platforms in complex coupling phases. This technology allows hardware/software robotic broadband systems to be controlled by simulating every phase. SpaceSysLab consists of a virtual platform (VP) based on GNC system (guidance, navigation, and control) and an experimental platform (EP) based on a robotic system. This system permits to simulate the meeting and coupling maneuvers of the robots. VP+EP test system is a hybrid simulator, designed to simulate simultaneously the relative dynamics of two motion bodies on relatively short distances in meeting/coupling maneuvers (rendezvous, proximity and docking – RP&D, VTOL).

Local positioning system for autonomous vertical take-off and landing using ultra-wide band measurement ranging system

An autonomous vertical take-off and landing (VTOL) must be supported with an accurate positioning system, especially for autonomous take-off, landing, and other tasks in small area. This paper presents a novel method of small local outdoor positioning system for localizing the area of dropping and landing of autonomous VTOL by utilizing the low-cost precision ultra-wide band (UWB) ranging system. We compared symmetrical single sided-two way ranging (SSS-TWR), symmetrical double sided-two way ranging (SDS-TWR), and asymmetrical double sided-two way ranging (ADS-TWR) methods to get precision ranging measurement on UWB radio module. ADS-TWR was superior to others by resulting in minimum distance error. The ADS-TWR average error was 1.38 % (35.88 cm), SDS-TWR average error was 1.83 % (47.58 cm), and SSS-TWR average error was 2.73 % (70.98 cm). Furthermore, the trilateration method was utilized to obtain the local position of the autonomous VTOL. The trilateration method successfully implemented autonomous VTOL quadcopter positioning in a small local outdoor area (20 m x 30 m). Autonomous VTOL has been able to drop seven payloads in seven areas (2 m x 2 m) and landed in the home position (3 m x 3 m) successfully.

Application of robust H-infinity controller in transition flight modeling of autonomous VTOL convertible Quad Tiltrotor UAV

PurposeThis paper aims to provide a mathematical modeling and design of H-infinity controller for an autonomous vertical take-off and landing (VTOL) Quad Tiltrotor hybrid unmanned aerial vehicles (UAVs). The variation in the aerodynamics and model dynamics of these aerial vehicles due to its tilting rotors are the key issues and challenges, which attracts the attention of many researchers. They carry parametric uncertainties (such as non-linear friction force, backlash, etc.), which drives the designed controller based on the nominal model to instability or performance degradation. The controller needs to take these factors into consideration and still give good stability and performance. Hence, a robust H-infinity controller is proposed that can handle these uncertainties.Design/methodology/approachA unique VTOL Quad Tiltrotor hybrid UAV, which operates in three flight modes, is mathematically modeled using Newton–Euler equations of motion. The contribution of the model is its ability to combine high-speed level flight, VTOL and transition between these two phases. The transition involves the tilting of the proprotors from 90° to 0° and vice-versa in 15° intervals. A robust H-infinity control strategy is proposed, evaluated and analyzed through simulation to control the flight dynamics for different modes of operation.FindingsThe main contribution of this research is the mathematical modeling of three flight modes (vertical takeoff–forward, transition–cruise-back, transition-vertical landing) of operation by controlling the revolutions per minute and tilt angles, which are independent of each other. An autonomous flight control system using a robust H-infinity controller to stabilize the mode of transition is designed for the Quad Tiltrotor UAV in the presence of uncertainties, noise and disturbances using MATLAB/SIMULINK. This paper focused on improving the disturbance rejection properties of the proposed UAV by designing a robust H-infinity controller for position and orientation trajectory regulation in the presence of uncertainty. The simulation results show that the Tiltrotor achieves transition successfully with disturbances, noise and uncertainties being present.Originality/valueA novel VTOL Quad Tiltrotor UAV mathematical model is developed with a special tilting rotor mechanism, which combines both aircraft and helicopter flight modes with the transition taking place in between phases using robust H-infinity controller for attitude, altitude and trajectory regulation in the presence of uncertainty.

Adaptive fixed-time control of autonomous VTOL UAVs for ship landing operations

This paper addresses the fixed-time control problem of autonomous ship landing operations of vertical take-off and landing (VTOL) unmanned aerial vehicles (UAVs) subject to external disturbances. A continuous reference altitude is planned for the UAV by introducing a high order polynomial function and a continuous differentiable switching function. To ensure a safe and precise board landing operation under bad sea condition, a landing constraint condition is designed in terms of rotational motion of the ship. By combining the planar motion of the ship with the reference altitude, the landing mission is converted into the control development for the UAV tracking. By introducing the hierarchical design, an adaptive fixed-time control algorithm is proposed for the UAV such that the trajectory and command attitude tracking are achieved, respectively. It is proved via Lyapunov stability theory that the proposed control algorithm guarantees the fixed-time trajectory tracking of the UAV subject to unknown external disturbances and inertia parameters. Simulation examples verify the proposed strategy.

Dynamic Inversion and Gain-Scheduling Control for an Autonomous Aerial Vehicle with Multiple Flight Stages

Several configurations of unmanned aerial vehicles (UAVs) were proposed to support different applications. One of them is the tailsitter, a fixed-wing aircraft that takes off and lands on its own tail, with the advantage of high endurance from fixed-wing aircraft and not requiring a runway during takeoff and landing as helicopters. However, the flight envelope of these vehicles contains multiple flight stages, each one with its own particularities and requirements, which makes its control more complex and hampers its use as an autonomous vehicle. Therefore, this paper presents an autopilot structure for a new tailsitter UAV, called Autonomous VerticAL takeOff and laNding (AVALON), with focus in the use of dynamic inversion and gain-scheduling control. Moreover, the AVALON’s equations of motion are described and used to reproduce a simulation environment. The results show the feasibility of these control techniques, with a convergence of the aircraft attitude and velocity during all the different flight stages of AVALON’s operation. We also compared its behaviour with PI controllers that calculates the control surfaces deflections with the attitude, and the use of dynamic inversion with gain-scheduling shows smaller errors in most of the flight stages, with the exception of the horizontal and landing stages.

Autonomous reconfigurable hybrid tail-sitter UAV U-Lion

We present in this work the development of a novel hybrid unmanned aircraft platform, U-Lion, which has both vertical take-off and landing (VTOL) and cruising flight capabilities. Our design is in tail-sitter structure with reconfigurable wings, which combines the advantages of a fixed-wing plane and a rotor helicopter effectively. This allows it to transit from vertical take-off to hovering, before flying in cruise mode for efficient long duration flight. The propulsion comes from two coaxial contra-rotating motors fixed on a gimbal mechanism, which can change the direction of the motors for the required thrust. This thrust-vectored propulsion system primarily provides control in the VTOL mode but also enhances flight capabilities in the cruise mode. The hybrid aircraft is equipped with GPS and airspeed sensors, and has an onboard avionic system with advanced flight control algorithms to perform fully autonomous VTOL and cruising flights, in addition to transiting effectively between VTOL and cruising flight modes. The overall design has been successfully verified by actual flight experiments.

AVALON: definition and modeling of a vertical takeoff and landing UAV

Unmanned Aerial Vehicles (UAVs) have been used in numerous applications, like remote sensing, precision agriculture and atmospheric data monitoring. Vertical takeoff and landing (VTOL) is a modality of these aircrafts, which are capable of taking off and landing vertically, like a helicopter. This paper presents the definition and modeling of a fixed- wing VTOL, named AVALON (Autonomous VerticAL takeOff and laNding), which has the advantages of traditional aircrafts with improved performance and can take off and land in small areas. The principles of small UAVs development were followed to achieve a better design and to increase the range of applications for this VTOL. Therefore, we present the design model of AVALON validated in a flight simulator and the results show its validity as a physical option for an UAV platform.

MOTION PLANNING AND OPTIMAL CONTROL OF AN AUTONOMOUS VTOL AIRCRAFT

This study presents a simple algorithm for motion-planning and state-to-state control of a Vertical Take-Off and Landing (VTOL) aircraft. The proposed motion-planning procedure is based on the solution of a linear algebraic equation. The resulting schemes are useful for flight control of an autonomous VTOL aircraft in case the objective is to transfer the system from a given state to a prescribed target. The proposed controller minimizes a selected quadratic index of performance. The solution to the (sub) optimal control problem is simple and reduces to the evaluation of a minimum point of a function of several variables.