From Model to Prototype: Design and Motor-Flap Propulsion Control of a Twin-Wing Metamorphic UAV

Anja Bosak; Dorian Erić; Ana Milas; Stjepan Bogdan

cs.ROOct 6, 2026

From Model to Prototype: Design and Motor-Flap Propulsion Control of a Twin-Wing Metamorphic UAV

Authors: Anja Bosak, Dorian Erić, Ana Milas, Stjepan Bogdan

Organizations: University of Zagreb, Faculty of Electrical Engineering and Computing, LARICS Laboratory for Robotics and Intelligent Control Systems, Unska 3, 10000 Zagreb, Croatia

Abstract

This paper presents the design and control strategy for MetaMorpher, a metamorphic Unmanned Aerial Vehicle (UAV), capable of both spinning-wing hover and fixed flying-wing cruise flight. Since control of the cruise configuration is comparatively well established in the literature, this paper focuses on control of the MetaMorpher in hover mode, building on the flight dynamics model and conceptual design validated in previous work. The control algorithm is implemented using one of two phase-synchronized strategies: motor propulsion, which pulses motor thrust in synchrony with the vehicle's rotation, or flap propulsion, a novel strategy that pulses the deflection of the wing-mounted elevons. We evaluate both strategies in simulation through different flight experiments. Simulation results confirm the mathematical model and show stable reference tracking, demonstrating flap propulsion as a lightweight, decoupled alternative for hover control. Experimental testing validated the vertical-dynamics propulsion model against the physical prototype, demonstrating very good steady-state agreement across different configurations.

Figures & tables

Fig. 1 : UAV in hover mode configuration during real-world experiments.

Fig. 2 : UAV in cruise mode configuration with marked-down actuator and control surface positions.

Component	Qty.	Unit mass [g]
Flight Controller	1	10
IMU	1	4
Electronic Speed Controller	2	12
BLDC motor	2	33
Propeller	2	3
Battery (3S, 1300 mAh)	1	108

TABLE I : Mass breakdown of MetaMorpher components.

Fig. 3 : Overall schematic diagram of the control, actuation, and UAV model modules. The control module includes altitude, spin, and horizontal position controllers, whose outputs are propagated to motor and flap pulsation. The vehicle model sends the actuator commands through wing kinematics, segment aerodynamics, and force and moment summation to obtain the 6-DOF dynamics, parameterized by wing geometry, aerodynamic coefficients, and gravity [ 5 ] . State feedback closes the loop back to the control module.

Fig. 4 : Comparison of the simulated vertical velocity response and the identified second-order models for the

30^{\circ}

(top) and

40^{\circ}

(bottom) wing configurations.

Fig. 5 : Position response using the phase-synchronized motor pulsation controller for

p_{x,\mathrm{ref}}=0

p_{y,\mathrm{ref}}=1

m, and

p_{z,\mathrm{ref}}=1

Fig. 6 : Waypoint tracking using the phase-synchronized motor pulsation controller. The horizontal trajectory is defined by waypoints $P_{1}$ , $P_{2}$ , and $P_{3}$ , while the altitude reference is varied during the maneuver.

Fig. 7 : Position response using the phase-synchronized flap controller for $p_{x,\mathrm{ref}}=0$ m, $p_{y,\mathrm{ref}}=1$ m, and $p_{z,\mathrm{ref}}=1$ m.

Fig. 8 : Waypoint tracking using the phase-synchronized flap controller. The horizontal trajectory is defined by waypoints $P_{1}$ , $P_{2}$ , and $P_{3}$ , while the altitude reference is varied during the maneuver.

Fig. 9 : Step response of configuration B showing vertical position, vertical velocity, and spin rate for a throttle step from 30% to 70%.

Fig. 10 : Steady-state spin-rate gain versus throttle target for all three configurations, comparing simulation (dashed) against measured hardware response (markers).

Fig. 11 : Measured versus simulated steady-state spin rate for all three configurations, labeled by throttle target. The dashed line indicates ideal agreement.

Fig. 12 : Steady-state gain of vertical velocity with respect to throttle for all three configurations.

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A Multimodal Tiltwing Framework for Bioinspired Aerial Robots

Krispin C. V. Broers, Sophie F. Armanini

Department of Aeronautics, Imperial College London, London, SW7 2AZ, UK

Rotorcraft Aerial Robots Multimodal Model

Open paper AskPDF arXiv

Tailless flapping-wing micro-aerial vehicles (FWMAVs) mimic the impressive flight performance of hummingbirds, utilising unsteady aerodynamic effects. However, existing designs are still limited and purpose-built with a restricted flight envelope and poor endurance. We therefore propose an adaptable tiltwing framework enabling bioinspired aerial robots to switch between hovering flight, high-speed directional flight, and energy-efficient gliding flight. The proposed framework utilises thrust vectoring with a wide actuation range via two fully independent propulsion units, each flapping a single wing, for effective control and enhanced manoeuvrability. For this, we developed a hybrid Scotch-yoke-based flapping mechanism that ensures a symmetric motion profile with a modular design guaranteeing an arbitrarily wide flapping angle to exploit the lift-enhancing clap-and-fling effect. Additionally, we implemented a passive wing-rotation mechanism, which, in combination with our dual-wing thrust-vectoring approach, allows unprecedented wing-design freedom, unlocking potential for precise optimisation. A contactless leading-edge tracking sensor provides accurate feedback on the wing's orientation and, in the gliding mode, enables dihedral-angle control, augmenting the active wing-pitch control. Extensive testing of a propulsion unit was conducted with a six-axis force/torque sensor, demonstrating the flapping mechanism's performance while optimising transmission efficiency and the passive wing-pitch mechanism. At full throttle, the average lift force generated by a single wing, flapping with a 188° amplitude, was 21.1 gf for a small 3.1 g 1S BLDC motor. Additional tests covering the full range of the wide-angle tilting capability showed an effective thrust-vectoring control architecture with a linear and symmetric response curve of the moments generated.

Abstract

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