Development of a Flying Robot With a Pantograph-Based Variable Wing Mechanism

We develop a flying robot with a new pantograph-based variable wing mechanism for horizontal-axis rotorcrafts (cyclogyro rotorcrafts). A key feature of the new mechanism is to have a unique trajectory of variable wings that not only change angles of attack but also expand and contract according to wing positions. As a first step, this paper focuses on demonstrating the possibility of the flying robot with this mechanism. After addressing the pantograph-based variable wing mechanism and its features, a simulation model of this mechanism is constructed. Next, we present some comparison results (between the simulation model and experimental data) for a prototype body with the proposed pantograph-based variable wing mechanism. Both simulation and experimental results show that the flying robot with this new mechanism can generate enough lift forces to keep itself in the air. Furthermore, we construct a more precise simulation model by considering rotational motion of each wing. As a result of optimizing design parameters using the precise simulation model, flight performance experimental results demonstrate that the robot with the optimal design parameters can generate not only enough lift forces but a 155 gf payload as well

Geometric Optimisation of Hinge-less Deployment System for an Active Rotorblade

The Green Rotorcraft project (part of Clean Sky JTI) is\ud studying the Gurney flap as a demonstrator of a smart adaptive\ud rotorblade. Deployment systems for the Gurney flap need to\ud sustain large centrifugal loads and vibrations while maintaining\ud precisely the displacement under aerodynamic loading. Designing\ud such a mechanism relies on both the actuation technology\ud and the link which transmits motion to the control surface. Flexible\ud beams and piezoelectric patch actuators have been chosen as\ud components to design this mechanism. Flexible beams are providing\ud an hinge-less robust structure onto which the piezoelectric\ud actuators are bonded. A candidate topology is determined\ud by investigating the compliance of a simple wire structure with\ud beam elements. A parametrized finite element model is then built\ud and optimized for displacement and force through surrogate optimization.\ud The whole process does not requires many finite element\ud analyses and quickly converge to an optimized mechanism

Dynamic compensation of rotating blades imbalance

The purpose of this paper is to research an effect of factors that are creating an imbalance of fan rotating blades and to estimate the possibility of compensation for this parasitic effect. For this purpose the measurement system including hardware and software was developed. Measurements of vibrations and dynamic pressure of rotating two-blades fan, blades profile and lift force parameters at various rotation speed were performed. This paper presents compensation possibilities when mechanical and aerodynamic imbalance occurs

Investigation of Perforated Ducted Propellers to use with a UAV

Unmanned Aerial Vehicle (UAV) is any flying vehicle which is not controlled by actual human pilots sitting in the cockpit but is installed with proper avionics that can either fly autonomously or by using the commands from its base. Some rotorcraft UAVs use a ducted propeller for two main reasons- safety and to increase the thrust produced by the propellers. While ducted rotors can increase the thrust produced, it also adds weight to the UAV. It was therefore hypothesized that by removing part of the duct materials (i.e. adding perforations in the duct) would benefit from both decreased duct weight and increased thrust. However, it is not clear how much trade-off would be between these two factors. Hence, the objective of this study is to explore the relationship between the change of thrust and addition of different numbers or sizes of perforations. Cases with and without duct, and duct with perforations were simulated using a commercial computational fluid dynamic (CFD) software Ansys/Fluent. The physics of the rotating propeller was modeled by a simplified disc with a pressure jump across an infinitesimal volume. Three different RPM speeds of the propellers were simulated by varying the strength of the pressure jump. The results show that the thrust decreases as the duct is added. As perforations are added, the result shows that with more perforations (i.e. more open area on the duct wall), the thrust increases accordingly until the thrust reaches a maximum value without the duct. The result is in contrast to a published experimental data stating that installation of duct can increase thrust. It is speculated that the current duct with a flat wall has caused such difference from the experimental data. Further study is recommended to continue more detailed computational simulation using a duct with cambered airfoil configuration to reduce the aerodynamic losses

Novel Reconfigurable Delta Robot Dual-Functioning as Adaptive Landing Gear and Manipulator

In this work a novel dual-functioning rotorcraft undercarriage is developed. The design is a reconfigurable delta robot which allows for transformation between Adaptive Landing Gear for vertical take-off and landing and 3DOF Aerial Manipulation mode. To reconfigure between operation modes without reaching singularities, a guideline to find a singularity-free geometry is presented. An adaptive landing control was developed and validated on a test-stand. For the 3DOF manipulation of the delta-structure, a third-order smooth trajectory was presented and integrated. The prototype, also depicted in the accompanying video, is then presented in free flight experiments demonstrating the advantages of the dual-functioning system

Measurement system for analysis of autogyro rotor imbalance

This paper presents the measurement system that is designed for measurement and analysis of mechanical and aerodynamic unbalance. These types of unbalance occurs in mechanical systems composed of high radius blades, including rotorcrafts – autogyro. This work presents structure of the measurement system, processing and visualization process of measurement data

Output Feedback Image-Based Visual Servoing of Rotorcrafts

© 2018, Springer Nature B.V. This paper presents an improved output feedback based image-based visual servoing (IBVS) law for rotorcraft unmanned aerial vehicles (RUAVs). The control law enables a RUAV with a minimal set of sensors, i.e. an inertial measurement unit (IMU) and a single downward facing camera, to regulate its position and heading relative to a planar visual target consisting of multiple points. As compared to our previous work, twofold improvement is made. First, the desired value of the image feature of controlling the vertical motion of the RUAV is a function of other image features instead of a constant. This modification helps to keep the visual target stay in the camera’s field of view by indirectly adjusting the height of the vehicle. Second, the proposed approach simplifies our previous output feedback law by reducing the dimension of the observer filter state space while the same asymptotic stability result is kept. Both simulation and experimental results are presented to demonstrate the performance of the proposed controller