Papers by Luke Soe Thura Win
Unmanned Systems, Sep 17, 2019
In this paper, we explore a novel multi-mode hybrid Unmanned Aerial Vehicle (UAV). We combine a t... more In this paper, we explore a novel multi-mode hybrid Unmanned Aerial Vehicle (UAV). We combine a tailless fixed-wing with a dual-wing monocopter such that the craft’s propulsion systems and aerodynamic surfaces are fully utilized in both a horizontal cruising mode and a vertical hovering mode. This maximizes the structural efficiency across the flight envelope, thereby reducing drag and unused mass while airborne in either flight mode. This UAV is also designed such that the transition between the two flight modes can be executed in mid-air, using only its existing flight actuators and sensors — there are no transition specific actuators. Using two prototypes, the foundational design and control of the system is established; the first explores the hovering mode characteristics of the unique dual-wing monocopter configuration, while the second explores the full multi-mode capabilities of the combined platform. In addition to analytical simulations, the prototypes are experimentally evaluated and assessed to demonstrate the feasibility, viability and potential of this multi-mode aerial robot design.
IEEE robotics and automation letters, Apr 1, 2021
In this work, a collaborative co-evolution approach is adopted to solve a joint physical design a... more In this work, a collaborative co-evolution approach is adopted to solve a joint physical design and feedback control optimization problem of a nature-inspired Unmanned Aerial Vehicle (UAV). Unlike traditional multirotors and fixed-wing aircraft, lift is achieved by spinning its entire body with attached aerofoils around a central axis and positional control is attained through regulation of 2 sets of independent aerodynamic surfaces and thrusters. The collaborative co-evolution process consists of 2 ‘species,’ the first consisting of the mechanical design variables and the second consisting of Proportional-Integral-Derivative (PID) and central pattern generator (CPG) controller variables. Each species have their own respective individual Evolutionary Algorithm (EA) solvers, Covariance Matrix Adaptation-Evolutionary Strategy (CMA-ES) and Parameter Exploring Policy Gradients (PEPG). In each optimization iteration, the parameters of one species is combined with representatives with the highest fitness from the other species and fed into a shared model for fitness evaluation, with each species taking turns to send a representative. Detailed performance comparison in trajectory tracking and power consumption between the proposed jointly optimized system against a design-only optimized, control-only optimized and unoptimized baseline were conducted. It was found that configurations with optimized designs would draw on average 18% less power than the non-optimized designs, and configurations with optimized controllers reduce error by 56% on average. The best performing configuration is the one with jointly optimized mechanical design and controller which outperforms all other configurations individually and collectively.
Bioinspiration & Biomimetics, Nov 1, 2021
The monocopter is a type of micro aerial vehicle largely inspired from the flight of botanical sa... more The monocopter is a type of micro aerial vehicle largely inspired from the flight of botanical samaras (Acer palmatum). A large section of its fuselage forms the single wing where all its useful aerodynamic forces are generated, making it achieve a highly efficient mode of flight. However, compared to a multi-rotor of similar weight, monocopters can be large and cumbersome for transport, mainly due to their large and rigid wing structure. In this work, a monocopter with a foldable, semi-rigid wing is proposed and its resulting flight performance is studied. The wing is non-rigid when not in flight and relies on centrifugal forces to become straightened during flight. The wing construction uses a special technique for its lightweight and semi-rigid design, and together with a purpose-designed autopilot board, the entire craft can be folded into a compact pocketable form factor, decreasing its footprint by 69%. Furthermore, the proposed craft accomplishes a controllable flight in 5 degrees of freedom by using only one thrust unit. It achieves altitude control by regulating the force generated from the thrust unit throughout multiple rotations. Lateral control is achieved by pulsing the thrust unit at specific instances during each cycle of rotation. A closed-loop feedback control is achieved using a motion-captured camera system, where a hybrid proportional stabilizer controller and proportional-integral position controller are applied. Waypoint tracking, trajectory tracking and flight time tests were performed and analyzed. Overall, the vehicle weighs 69 g, achieves a maximum lateral speed of about 2.37 m s−1, an average power draw of 9.78 W and a flight time of 16 min with its semi-rigid wing.
IEEE Transactions on Robotics, Apr 1, 2022
Large scale aerial deployment of miniature sensors in tough environmental conditions requires a d... more Large scale aerial deployment of miniature sensors in tough environmental conditions requires a deployment device that is lightweight, robust, and steerable. We present a novel samarainspired autorotating craft that is capable of two flight modes (autorotating mode and diving mode) with an average glide angle of 28.9 • (1.81 m lateral distance per 1 m loss of altitude) in the former mode. The bidirectional transition between the two modes and directional control is achieved by using only a single actuator. Also, in order to minimize its glide angle, a design optimization methodology is presented for our prototype, diving samara autorotating wing, along with a new cyclic control strategy for directional control of autorotating descent. The dynamic model, simulated in a six degrees-of-freedom environment using the blade element theory, is integrated with genetic algorithm to derive parameters for the wing geometry, flap angle for autorotation, and the proposed cyclic control. The physical prototype autorotates at a descent velocity of 1.43 m/s and rotation speed 4.17 Hz, and is able to transit to diving mode in an average duration of 272 ms to increase its descent velocity by at least 17.6 times. At any point during the dive, it is able to transit back into autorotation in an average duration of 327 ms. Semioutdoor experiments were used to investigate the bidirectional transitions and verify the glide angle (28.9 •), which is much improved from the previous prototype (SAW+, 58.4 •). Lastly, as a demonstration of a real-life deployment scenario and environmental conditions, the prototypes were dropped from a fixed-wing unmanned aerial vehicle at a suburban test site.
2023 IEEE/ASME International Conference on Advanced Intelligent Mechatronics (AIM)
2023 IEEE/ASME International Conference on Advanced Intelligent Mechatronics (AIM)
2023 IEEE/ASME International Conference on Advanced Intelligent Mechatronics (AIM)
IEEE Robotics and Automation Letters
Inspired by maple seeds, the self-rotary winged aerial robots reflect the advantages of both mult... more Inspired by maple seeds, the self-rotary winged aerial robots reflect the advantages of both multi-rotor aircraft and fixedwing robots. However, their self-rotating speed is related to the takeoff weight, which may affect their application and flight stabilization. To provide a practical and feasible solution, this work proposes a passive compliant variable-pitch mechanism on the self-rotary winged aircraft without requiring extra actuators. Depending on the weight of the payload, the pitching angle of the wings can be passively varied to minimize the increase in the rotating speed and enhance attitude stabilization ability. Besides, an adaptive attitude controller is also designed to address the challenges in attitude stabilization, which are caused by parameter uncertainties and the variable pitching angle. To elaborate on the design and fabrication of the prototype, necessary identification experiments are arranged to find the relationship of pitching angle, thrust generation, power draw, and rotating speed. The experimental findings indicate the proposed robot with optimal pitch angles achieves around 56.8% more power loading than using propellers directly, from 4.4 to 6.9 g/w. The combination of the passive compliant mechanism and adaptive controller improves flight performance from 0.16 to 0.08 meters (mean of absolute translational error). Index Terms-Underactuated robots, aerial systems: mechanics, control and applications. I. INTRODUCTION U NMANNED aerial vehicles (UAVs), such as quadcopters, are believed to have great potential in many fields thanks to their maneuverability when interacting with the environment [1]. However, this ability of a single vehicle is limited by the maximal thrust it can produce, which is mainly related to its physical design, such as the size and number of rotors. In recent years, to address this challenge and be capable of heavier payloads, many approaches and strategies have been studied by researchers, such as the development of modular and reconfigurable airframes [2], [3], optimal thrust configuration [4], [5], cooperative tasking with multiple robots [6], etc. Unlike conventional multirotors producing lift via propellers directly, the self-rotary winged aerial robot (Fig. 1) seems to be able to generate extra thrust by making use of its huge
Bioinspiration & Biomimetics
The paper presents a novel rotary wing platform, that is capable of folding and expanding its win... more The paper presents a novel rotary wing platform, that is capable of folding and expanding its wings during flight. Our source of inspiration came from birds’ ability to fold their wings to navigate through small spaces and dive. The design of the rotorcraft is based on the monocopter platform, which is inspired by the flight of Samara seeds. The wings are constructed by applying origami techniques to fold them in flight. Two configurations are presented, featuring active or passive mechanisms for wing-folding depending on specific application requirements. The two configurations can reduce their overall footprint by approximately 39% and 69% while in flight. A cyclic controller is implemented for controlling the translational motion, where the direction is controlled by pulsing the motors at a specific instance during each cycle of rotation. We have presented experimental results to prove the control of our platform in different modes while in flight. The presented platforms enhance...
Advanced Intelligent Systems
Herein, the development of a multimodal, nature‐inspired unmanned aerial vehicle (UAV) that opera... more Herein, the development of a multimodal, nature‐inspired unmanned aerial vehicle (UAV) that operates in three different flight regimes (rotor wing, tailsitter, cruise), unlike typical UAVs which only consist of two, is discussed. The platform uses a nature‐inspired method to achieve efficient hover, yet possesses the flexibility to enter a more agile state via additional tailsitter and cruise modes. Both the mechanical configuration and software/control architecture used to achieve three‐mode capability are documented in detail. A sigmoid blending control is implemented as the transition control strategy, consisting of transition coordinators that adjust the weight of each individual controller on the actuator outputs. To improve the transition sequence based on performance goals such as reduced altitude variation and throttle usage, an optimization routine is performed to obtain the optimized blending parameters. The optimized parameters are then experimentally verified on a physic...
Materials Today: Proceedings
Bioinspiration & Biomimetics
The monocopter is a type of micro aerial vehicle largely inspired from the flight of botanical sa... more The monocopter is a type of micro aerial vehicle largely inspired from the flight of botanical samaras (Acer palmatum). A large section of its fuselage forms the single wing where all its useful aerodynamic forces are generated, making it achieve a highly efficient mode of flight. However, compared to a multi-rotor of similar weight, monocopters can be large and cumbersome for transport, mainly due to their large and rigid wing structure. In this work, a monocopter with a foldable, semi-rigid wing is proposed and its resulting flight performance is studied. The wing is non-rigid when not in flight and relies on centrifugal forces to become straightened during flight. The wing construction uses a special technique for its lightweight and semi-rigid design, and together with a purpose-designed autopilot board, the entire craft can be folded into a compact pocketable form factor, decreasing its footprint by 69%. Furthermore, the proposed craft accomplishes a controllable flight in 5 de...
2019 IEEE/ASME International Conference on Advanced Intelligent Mechatronics (AIM)
Borrowing dispersion methodology from its natural cousin ’maple seed’, the Solar Samara Autorotat... more Borrowing dispersion methodology from its natural cousin ’maple seed’, the Solar Samara Autorotating Wings (SSAW) uses autorotation as the means of slowing down the descent rate and uses no propulsion for the entire flight envelope. It carries a limited battery which powers the control flap for regulated descent and on-board sensors for data collection. Integrating solar cells onto its wing extends the service life-span of the concept. The solar cells in SSAW serve multiple purposes: surfaces for aerodynamic lift creation, structural rigidity improvement and energy provision. However, the solar cells present limitations on possible wing and flap configurations due to their functional structure. Considering physical modification constraints, we optimized the configuration of the control flap for the best glide slope and minimum undesired oscillations. SSAW was dynamically modelled and simulated in a 6DOF environment to find the optimal flap configuration using Genetic Algorithm (GA). We verified the functionality of the optimized flap on a vertical test rig and dropped SSAW outdoors for real-life autorotation with flap control. Furthermore, we tested SSAW for its solar functionality of charging the on-board batteries while on data collection mission.
2022 International Conference on Robotics and Automation (ICRA)
2020 IEEE/ASME International Conference on Advanced Intelligent Mechatronics (AIM)
For an aerial craft that autorotates for its flight similar to its biological counterpart, the ma... more For an aerial craft that autorotates for its flight similar to its biological counterpart, the maple seed, it is intuitive to use a flap or an aileron to control its drop trajectory. In this work, we propose the use of a single thruster unit, as an alternative to the flap, for its multi-directional trajectory control. A thrust unit provides a more focused and precise application of aerodynamic force and torque, and its assembly is light enough to be mounted in various configurations on the craft. A concurrent mechanical design and control parameter optimization is carried out using Genetic Algorithm to determine the optimal physical configuration of the thruster and the parameters for square cyclic control. The objective function of this optimization is designed to achieve the best glide slope with minimum undesired oscillations. Simulations are carried out in 6DOF environment to evaluate performance of the optimum configuration compared to less optimal configurations. Real-life experimental drop tests with a physical prototype are carried out via hand launching to verify the glide slope and drop characteristics.
IEEE Transactions on Robotics
Large scale aerial deployment of miniature sensors in tough environmental conditions requires a d... more Large scale aerial deployment of miniature sensors in tough environmental conditions requires a deployment device that is lightweight, robust, and steerable. We present a novel samarainspired autorotating craft that is capable of two flight modes (autorotating mode and diving mode) with an average glide angle of 28.9 • (1.81 m lateral distance per 1 m loss of altitude) in the former mode. The bidirectional transition between the two modes and directional control is achieved by using only a single actuator. Also, in order to minimize its glide angle, a design optimization methodology is presented for our prototype, diving samara autorotating wing, along with a new cyclic control strategy for directional control of autorotating descent. The dynamic model, simulated in a six degrees-of-freedom environment using the blade element theory, is integrated with genetic algorithm to derive parameters for the wing geometry, flap angle for autorotation, and the proposed cyclic control. The physical prototype autorotates at a descent velocity of 1.43 m/s and rotation speed 4.17 Hz, and is able to transit to diving mode in an average duration of 272 ms to increase its descent velocity by at least 17.6 times. At any point during the dive, it is able to transit back into autorotation in an average duration of 327 ms. Semioutdoor experiments were used to investigate the bidirectional transitions and verify the glide angle (28.9 •), which is much improved from the previous prototype (SAW+, 58.4 •). Lastly, as a demonstration of a real-life deployment scenario and environmental conditions, the prototypes were dropped from a fixed-wing unmanned aerial vehicle at a suburban test site.
2021 IEEE/ASME International Conference on Advanced Intelligent Mechatronics (AIM)
A monocopter is a single wing, rotating, non-linear platform that has gained popularity recently.... more A monocopter is a single wing, rotating, non-linear platform that has gained popularity recently. The agility and maneuverability of the platform depends largely on the number of actuators, among other parameters. This paper investigates the flight response of a dual motor + flap configuration monocopter, based on variation of the control signal allocated to the motors. Different scenarios are considered where the step response, waypoint tracking and trajectory tracking are compared for the different cases of control allocations considered. The contribution done in this paper is the implementation of Sliding Mode Control (SMC), which is a non-linear controller, on the monocopter platform. The sliding surface design of the SMC is done based on Proportional-Integral-Derivative (PID) terms of the error in states, which are driven by a saturation based signal from the controller. Simulation as well as experimental results processed through MATLAB suggest that a configuration with inner motor controlling the altitude and the outer motor controlling the cyclic motion provides with the least amount of oscillations, whereas, both motors controlling only the altitude result in the high settling time for directional control. The performance response and the root mean square error results also proved that PID-SMC's performance is predominant over other controllers for positional control as well as trajectory tracking by monocopter.
2018 IEEE International Conference on Robotics and Automation (ICRA), 2018
The seeds of Maple trees (Samara) use autorotation as a unique mechanism to disperse their seeds.... more The seeds of Maple trees (Samara) use autorotation as a unique mechanism to disperse their seeds. By exploiting gyroscopic stability of a spinning wing, the Samara is able to cover large horizontal distance despite having no form of propulsion. We applied and adapted this natural ability in our novel concept, the Samara Autorotating Wings (SAW), and extended its stability and direction controllability by generalizing the mechanism to incorporate designs with more than 1 wing. By conceiving cyclic control, the translational motion of autorotation is regulated. A nonlinear model of SAW with $n$ wings is derived and control schemes developed to control the translational position during autorotation. Numerical simulations were performed to investigate the performance of the multi-wing SAW prototypes to track a conical spiral autorotation trajectory. Direct experiments were conducted in a vertical wind-tunnel through a special ball joint that allows z-axis translation and all three rotational degrees of freedom. Finally, free-fall drop tests are used to verify the directional controllability and performance of SAW.
IEEE Robotics and Automation Letters, 2021
In this work, a collaborative co-evolution approach is adopted to solve a joint physical design a... more In this work, a collaborative co-evolution approach is adopted to solve a joint physical design and feedback control optimization problem of a nature-inspired Unmanned Aerial Vehicle (UAV). Unlike traditional multirotors and fixed-wing aircraft, lift is achieved by spinning its entire body with attached aerofoils around a central axis and positional control is attained through regulation of 2 sets of independent aerodynamic surfaces and thrusters. The collaborative co-evolution process consists of 2 ‘species,’ the first consisting of the mechanical design variables and the second consisting of Proportional-Integral-Derivative (PID) and central pattern generator (CPG) controller variables. Each species have their own respective individual Evolutionary Algorithm (EA) solvers, Covariance Matrix Adaptation-Evolutionary Strategy (CMA-ES) and Parameter Exploring Policy Gradients (PEPG). In each optimization iteration, the parameters of one species is combined with representatives with the highest fitness from the other species and fed into a shared model for fitness evaluation, with each species taking turns to send a representative. Detailed performance comparison in trajectory tracking and power consumption between the proposed jointly optimized system against a design-only optimized, control-only optimized and unoptimized baseline were conducted. It was found that configurations with optimized designs would draw on average 18% less power than the non-optimized designs, and configurations with optimized controllers reduce error by 56% on average. The best performing configuration is the one with jointly optimized mechanical design and controller which outperforms all other configurations individually and collectively.
2018 IEEE/ASME International Conference on Advanced Intelligent Mechatronics (AIM), 2018
First presented in 2017, the Transformable HOvering Rotorcraft (THOR) is a structurally efficient... more First presented in 2017, the Transformable HOvering Rotorcraft (THOR) is a structurally efficient hybrid Unmanned Aerial Vehicle (UAV) design that uses a dual servo, dual motor configuration to hover as a nature-inspired monocopter and cruise as a delta shaped fixed-wing. Such a design has potential applications in disaster relief, agriculture and surveillance; scenarios where it is desirable for the UAV to be able to both travel long distances fast and hover for long periods of time. To improve on the 2017 design, we propose the replacement of the existing dual servo system with a high torque, high precision central servo system and a controllable flap on each wing. Through simulation and experimental data, we argue that these would improve the system's flight characteristics while also giving it the ability to fly in a third mode, as a dual motor, dual flap tailsitter UAV.
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Papers by Luke Soe Thura Win