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A new method for enabling a quadrotor micro air vehicle (MAV) to navigate unknown environments using reinforcement learning (RL) and model predictive control (MPC) is developed. An efficient implementation of MPC provides vehicle control and obstacle avoidance. RL is used to guide the MAV through complex environments where dead-end corridors may be encountered and backtracking is necessary. All of the presented algorithms were deployed on embedded hardware using automatic code generation from Simulink. Results are given for flight tests, demonstrating that the algorithms perform well with modest computing requirements and robust navigation. [ABSTRACT FROM AUTHOR]

Featured Application: Micro air vehicles. During insect flight, a feathering motion of the wing's controls vortex shedding for lift enhancement. In this study, in order to control the flow around a wing flapping with simplified sinusoidal motion, plasma actuators were introduced to simplify the complex feathering motion. In a wind tunnel, a smoke-wire method was enacted to visualize the flow fields around an oscillating plate with an attack angle of 4° in a uniform flow for the baseline and controlled cases. The actuator placed around the leading edge was found to suppress the flow separation on the top surface. Numerical simulations were performed to investigate the control effects on the fluctuating lift, where the control effects by the intermittently driven actuator were also predicted. The actuator installed on the top surface throughout the up-stroke motion was found to suppress vortex shedding from the trailing edge, which resulted in an 11% lift enhancement compared to the baseline case. In regard to the effects of the installation position, it was found that the actuator placed on the top surface was effective, compared to the cases for installation on the bottom surface or both surfaces. [ABSTRACT FROM AUTHOR]

In this study, experimental investigation is performed into modification to aerodynamic characteristics by distortion and vibration of planar wings with various Young's modulus as well as flow fields around them. Motions of the wings are captured with a high-speed camera. Flows around them are evaluated with phase locked PIV technique. As a result, bending vibration of the wings is observed almost all over the angles of attack while twisting is observed around the angles giving maximum lift force. The twisting vibration causes larger aerodynamic forces and delay in the stall. It is found that amplitude of the twisting determines magnitude of variations in aerodynamic forces. Flow field measurement shows the twisting vibration generates periodic vortices shedding from the leading and trailing edges. They reduce the separation bubble on the wing, in particular, around the middle span in spite of localization of the twisting in the vicinity of the wing tip. [ABSTRACT FROM AUTHOR]

The present paper aims to investigate numerically small amplitude oscillation of NACA 0012 airfoil at Re=1000. The airfoil is sinusoidally pitching around the quarter chord point with 1° pitch amplitude about a mean angle of attack. The computations are performed for mean angles of attack ranging from 0° to 60° and for pitching frequencies of 1Hz and 4 Hz. The effect of the mean angle of attack and pitching frequency on the instantaneous forces as well as the vortex structure is investigated in comparison with the non-oscillatory conditions. It was shown that airfoil oscillations at the investigated conditions change the amplitude of oscillation of the aerodynamic loads. The instantaneous drag coefficient is always positive for pitching airfoil at 1 Hz. In the meantime, there are time intervals where instantaneous drag coefficient becomes negative for pitching motion at 4Hz for mean angles of attack from 3° to 36°. [ABSTRACT FROM AUTHOR]

The work presented in this paper is part of a project called ARChEaN (Aerodynamic of Rotors in Confined ENvironment) whose objective is to study the interactions of a micro drone rotor with its surroundings in the case of flight in enclosed environments such as those encountered, for example, in archeological exploration of caves. To do so the influence of the environment (walls, ground, ceiling, etc) on the rotor's aerodynamic performance as well as on the flow field between the rotor and the surroundings is studied. This paper focuses on two different configurations, flight near the ground and flight near a corner (wall and ground), and the results are analyzed and compared to a general free flight case (i.e. far away from any obstacle). In order to carry out this analysis both numerical and experimental approaches are conducted. The objective is to validate the numerical model with the results obtained experimentally and to benefit from the advantages of both approaches in terms of flow analysis. This research work will provide knowledge on how to operate these systems as to minimize the possible negative environment disturbances, reduce power consumption and predict the micro drone's behaviour during enclosed flights. [ABSTRACT FROM AUTHOR]

This paper presents the design process and experimental results of a brand new flapping and trailing edge control mechanism for a flapping wing micro air vehicle. The flapping mechanism, whose main components are fabricated from string, is suggested and optimized further by a modified pattern search method. The trailing edge control mechanisms for pitching and rolling moments are designed to be attached onto the present flapping mechanism in a modularized fashion. Prototypes of both mechanisms are fabricated and experimentally tested in order to examine the feasibility of the designs. It is expected that the present flapping mechanism will generate enough lift for the total weight of the vehicle. The present control mechanism is found to be able to supply sufficient control moment. [ABSTRACT FROM AUTHOR]

This paper addresses the design and experimental validation of a linear robust static output feedback controller for a 150 mm span fixed wing micro air vehicle (MAV). Severe coupling between longitudinal and lateral dynamics of the MAV lead to the design of a multivariable controller for the combined dynamics. The control design problem is posed in the framework of static output feedback (SOF) due to the inexpensive computational requirements for implementation. The multiobjective control design problem including stability requirements, closed loop damping ratio requirements and H∞ norm minimization is solved using the hybrid technique of linear matrix inequalities (LMI) and genetic algorithm (GA). The design is carried out in the discrete time domain, facilitating in direct implementation of the multivariable controller in the onboard autopilot hardware. The robustness of the resulting closed loop system under parametric uncertainties is evaluated using structured singular value analysis. The effectiveness of the proposed controller is demonstrated through outdoor flight trial of the micro air vehicle with a customized lightweight autopilot hardware. [ABSTRACT FROM AUTHOR]

A wind tunnel tests campaign has been conducted to investigate the aerodynamic flow around a wing morphing to be used in a micro air vehicle. Non-intrusive whole field measurements were obtained by using PIV, in order to compare the velocity and turbulence intensity maps for the modified and the original version of an adaptive wing designed to be used in a micro air vehicle. Four sections and six angles of attack have been tested. Due to the low aspect ratio of the wing and the low Reynold number tested of 6.4 × 104, the influence of the 3D effects has been proved to be important. At high angles of attack, the modified model prevented the detachment of the stream, increased the lift of the wing and reduced the turbulence intensity level on the upper surface of the airfoil and in the wake.

This study investigates the aerodynamic efficiency of a bioinspired flapping wing rotor kinematics which combines an active vertical flapping motion and a passive horizontal rotation induced by aerodynamic thrust. The aerodynamic efficiencies for producing both vertical lift and horizontal thrust of the wing are obtained using a quasi-steady aerodynamic model and two-dimensional (2D) CFD analysis at Reynolds number of 2500. The calculated efficiency data show that both efficiencies (propulsive efficiency-ηp, and efficiency for producing lift-Pf) of the wing are optimized at Strouhal number (St) between 0.1 and 0.5 for a range of wing pitch angles (upstroke angle of attack αu less than 45°); the St for high Pf (St = 0.1 ∼ 0.3) is generally lower than for high ηp (St = 0.2 ∼ 0.5), while the St for equilibrium rotation states lies between the two. Further systematic calculations show that the natural equilibrium of the passive rotating wing automatically converges to high-efficiency states: above 85% of maximum Pf can be obtained for a wide range of prescribed wing kinematics. This study provides insight into the aerodynamic efficiency of biological flyers in cruising flight, as well as practical applications for micro air vehicle design.

Abstract Micro Air Vehicles (MAVs) have the potential to revolutionize our capabilities in gathering information, monitoring situations, and surveillance. They are required to maneuver in and around obstacles as well as negotiate atmospheric disturbances whilst holding accurate trajectories and minimizing rotation which can blur imagery. A study of existing literature on MAV control challenges found that current turbulence mitigation systems and control surface configurations lack the speed of response and control authority required to maintain steady flight in turbulence. Improved control response may come from unconventional designs, bio-inspired systems, or from careful manipulation of the flow mechanics. As such, in this paper, key unsteady aerodynamic parameters are also reviewed and considered prior to deriving potential control solutions that could help MAVs fly well in turbulence. [ABSTRACT FROM AUTHOR]

This paper proposes a wing root control mechanism inspired by the drag-based system of a dragonfly. The previous mechanisms for generating wing rotations have high controllability of the angle of attack, but the structures are either too complex or too simple, and the control of the angle of attack is insufficient. In order to overcome these disadvantages, a wing root control mechanism was designed to improve the control of the angle of attack by controlling the mean angle of attack in a passive rotation mechanism implemented in a simple structure. Links between the proposed mechanism and a spatial four-bar link-based flapping mechanism were optimized for the design, and a prototype was produced by a 3D printer. The kinematics and aerodynamics were measured using the prototype, a high-speed camera, and an F/T sensor. In the measured kinematics, the flapping amplitude was found to be similar to the design value, and the mean angle of attack increased by approximately 30° at a wing root angle of 0°. In the aerodynamic analysis, the drag-based system implemented using the wing root control mechanism reduced the amplitude of the force in the horizontal direction to approximately 0.15 N and 0.1 N in the downstroke and upstroke, respectively, compared with the lift-based system. In addition, at an inclined stroke angle, the force in the horizontal direction increased greatly when the wing root angle was 0° at the inclined stroke angle, while the force in the vertical direction increased greatly at a wing root angle of 30°. This means that the flight mode can be controlled by controlling the wing root angle. As a result, it is shown that the wing root control mechanism can be applied to the MAV (micro air vehicle) to stabilize hovering better than the MAV using a lift-based system and can control the flight mode without changing the posture. [ABSTRACT FROM AUTHOR]

The article presents a research in the field of morphing wings (adaptive wing geometry) developed over a prototype of micro-unmanned air vehicle based on smart materials technology. This morphing wing will optimize the aircraft performance features. Modifying the curvature of the wing, the micro-unmanned air vehicles will adjust its performance in an optimum mode to cruise flight condition as well as in the phases of takeoff and landing. The installation of mechanical elements for control surfaces in small size aircraft means, on some occasions, an extra complexity. In addition, it takes into account an increase in aircraft weight. In this research, the adaptive wing geometry is based on macro-fiber composites, so that its position on the inner surfaces of the wing allows the appropriate modification of the curvature, adapting them to the flight profile. This research will present the conceptual design of the vehicle, computational calculations, experimental results of the wind tunnel testing, validations using non-intrusive techniques (particle image velocimetry) and a theoretical-experimental analysis of the macro-fiber composite effects over the wing. An Arduino board will perform the control parameters of the macro-fiber composite deformation. With these analytical, computational, and experimental results, the most relevant conclusions are presented. [ABSTRACT FROM AUTHOR]

The performance and effectiveness of serpentine dielectric barrier discharge plasma actuators as hingeless high-lift devices on a three-dimensional airplane model were investigated. Attempts were made to design the actuators in the most optimized way, based on the reported results of the latest dielectric barrier discharge optimization efforts. Four actuators were mounted onto four different locations of the wings as the leading-edge slat, spoiler, flap, and leading-edge aileron. Operation of the actuators on one wing increased and/or decreased the lift/drag and generated a gradual rolling moment. The experiments were performed separately for each actuator at three different Reynolds numbers, seven angles of attack, three peak-to-peak voltages, and three wave frequencies. The Reynolds numbers were approximately 8×104, 1.2×105, and 1.6×105. The evaluation based on actuators effects on rolling moment generation was performed, and the results indicate that employing the serpentine dielectric barrier discharge actuators as high-lift devices for low Reynolds number applications is possible, especially as DBD slat and DBD spoiler, and they can have the same effect of a conventional aileron only for normal flight maneuvering, with low power consumption. [ABSTRACT FROM AUTHOR]

We present a novel design of a tailless flapping wing micro air vehicle, which uses four independently driven pairs of flapping wings in order to fly and perform agile maneuvers. The wing pairs are arranged such that differential thrust generates the desired roll and pitch moments, similar to a quadrotor. Moreover, two pairs of wings are tilted clockwise and two pairs of wings anti-clockwise. This allows the micro air vehicle to generate a yaw moment. We have constructed the design and performed multiple flight tests with it, both indoors and outdoors. These tests have shown the vehicle to be capable of agile maneuvers and able to cope with wind gusts. The main advantage is that the proposed design is relatively simple to produce, and yet has the capabilities expected of tailless flapping wing micro air vehicles. [ABSTRACT FROM AUTHOR]

The stability of small unmanned air systems can be challenged by turbulence during low-altitude flight in cluttered urban environments. This paper explores the benefits of a tandem wing aircraft configuration with the implementation of a pressure-based phase-advanced turbulence sensory system on a small unmanned air system for gust mitigation. The objective was to utilise passive and active methods to minimise gust-induced perturbations. Experimentation in repeatable turbulence within a wind tunnel’s test section was conducted. The experiments focus on the roll axis, which is isolated through a specially designed roll-axis rig. The results show improvement over conventional aircraft. This work is part of a larger research project aimed at enabling safe, stable and steady small unmanned air systems flight in urban environments. [ABSTRACT FROM AUTHOR]

Automation of inspection tasks is crucial for the development of the power industry, where micro air vehicles have shown a great potential. Self-localization in this context remains a key issue and is the main subject of this work. This article presents a methodology to obtain complete three-dimensional local pose estimates in electric tower inspection tasks with micro air vehicles, using an on-board sensor set-up consisting of a two-dimensional light detection and ranging, a barometer sensor and an inertial measurement unit. First, we present a method to track the tower’s cross-sections in the laser scans and give insights on how this can be used to model electric towers. Then, we show how the popular iterative closest point algorithm, that is typically limited to indoor navigation, can be adapted to this scenario and propose two different implementations to retrieve pose information. This is complemented with attitude estimates from the inertial measurement unit measurements, based on a gain-scheduled non-linear observer formulation. An altitude observer to compensate for barometer drift is also presented. Finally, we address velocity estimation with views to feedback position control. Validations based on simulations and experimental data are presented. [ABSTRACT FROM AUTHOR]

Membranous hind wings of the beetles can be folded under the elytra when they are at rest, and rotate and lift the elytra up only when they need to fly. This characteristic provides excellent flying capability and good environment adaptability. Inspired by the beetles, the new type of the bionic folding wing for the flapping wing Micro Air Vehicle (MAV) was designed. This flapping wing can be unfolded to get a sufficient lift in flight, and can be folded off flight to reduce the wing area and risk of the wing damage. The relationship between the internal pressures of the hydraulic system for the bionic wing folding varies and temperature was analyzed, the results show that the pressure within the system tends to increase with temperature, which proves the feasibility of the schematic design in theory. Stress analysis of the bionic wing was conducted, it was shown that stress distributions and deformation of the bionic wing under the positive and negative side loading are basically the same, which demonstrates that the strength of the bionic folding wing meets the requirements and further proves the feasibility of the schematic design. [ABSTRACT FROM AUTHOR]

A novel design of a micro air vehicle with flapping rotary wings was recently proposed. In this paper, the investigation is focused on aerodynamic enhancement of a bore-hole and an elastic cover added onto an intact flapping rotary wing. The aerodynamic force and the pitching motion of the perforated wing are both acquired in experiments. In comparison with an intact wing, a typical perforated wing shows a significant decrement in negative lift and thus a higher mean lift. As a supporting process, the computational fluid dynamics method is then employed to analyze the flow around the wing and the hole, and thereby make clear the underlying physical mechanism. It is found the hole opens due to the cover deflection in a passive manner and produces a secondary starting vortex on the wing lower surface of the cover during upstrokes. Together with the tip vortex around the lateral edges of the cover, the resulting vortex significantly reduces the magnitude of the negative lift, and thus explains the mean-lift enhancement in a flapping cycle. Additionally, the mean-lift enhancement correlates with the geometric parameters of the hole. An increment up to 40% in maximum mean lift is identified for a perforated wing in comparison with an intact wing. These results indicate that a bore-hole design could be a promising approach to enhance the aerodynamic lift of a flapping rotary wing. [ABSTRACT FROM AUTHOR]

Because of its own advantages, micro air vehicles can accomplish reconnaissance / surveillance tasks in low altitude and indoor flight environments, with inertial / satellite integrated navigation system. As a useful supplement to its navigation system, optical flow can assist INS to update position and attitude information in some occasions without GPS assistent. Considering the low calculation precision of optical flow in unconstant illumination condition, optical flow navigation method based on ROF denoising is studied, convex optimization theory and dual principle is discussed, and image decomposition method in the light texture changes is researched on. The obtained texture part is not affected by illumination variations, and used to calculate the movement of field information of the image. Then, the movement information is further calculated for position and attitude of micro air vehichles. The experimental results show that the accuracy of optical flow calculation is improved by decomposing and denoising. [ABSTRACT FROM AUTHOR]

This paper presents the nonlinear six degrees of freedom dynamic modeling of a fixed wing micro air vehicle. The static derivatives of the micro air vehicle are obtained through the wind tunnel testing. The propeller effects on the lift, drag, pitching moment and side force are quantified through wind tunnel testing. The dynamic derivatives are obtained through empirical relations available in the literature. The trim conditions are computed for a straight and constant altitude flight condition. The linearized longitudinal and lateral state space models are obtained about trim conditions. The variations in short period mode, phugoid mode, Dutch roll mode, roll subsidence mode and spiral mode with respect to different trim operating conditions is presented. A stabilizing static output feedback controller is designed using the obtained model. Successful closed loop flight trials are conducted with the static output feedback controller. [ABSTRACT FROM AUTHOR]

Due to broad applications in military and civil areas, biomimetic micro air vehicle (MAV) has become a research hotspot. The aerodynamics of biomimetic MAV is the foundation in designing a MAV, and relevant aerodynamic theories and designing methods are also gradually enriched with the development of miniature aircraft. This paper reviews the progress in aerodynamics research of biomimetic MAVs in hovering flight. At present, a series of experimental and numerical methods have been matured and widely used. The high lift mechanisms of the biomimetic micro-aircraft, such as clapping-cling effect and delayed stall has been revealed in the hovering state. A considerable progress has been achieved in solving problems on stabilization of leading edge vortex. Various methods have been proposed and become more and more mature for the aerodynamic primary design and the optimization of geometrical, kinematic, and structural parameters of MAV wings. In the future, the high-lift mechanisms of insects, such as butterfly and ladybugs, needs to be further explored. In order to fulfill a bionic hoverable micro-aircraft, more works are required on the design and optimization of bio-inspired wing as well as on the analysis of bionic flight mechanics and control. [ABSTRACT FROM AUTHOR]

Flapping-wing Micro Air Vehicles (FW-MAVs), inspired by small insects, have limitless potential to be capable of performing tasks in urban and indoor environments. Through the process of mimicking insect flight, however, there are a lot of challenges for successful flight of these vehicles, which include their design, fabrication, control, and propulsion. To this end, this paper investigates the wing design and fabrication of an X-wing FW-MAV and analyzes its performance in terms of thrust generation. It was designed and developed using a systematic approach. Two pairs of wings were fabricated with a traditional cut-and-glue method and an advanced vacuum mold method. The FW-MAV is equipped with inexpensive and tiny avionics, such as the smallest Arduino controller board, a remote-control receiver, standard sensors, servos, a motor, and a 1-cell battery. Thrust measurement was conducted to compare the performance of different wings at full throttle. Overall, this FW-MAV produces maximum vertical thrust at a pitch angle of 10 degrees. The wing having stiffeners and manufactured using the vacuum mold produces the highest thrust among the tested wings.

During insect flight, a feathering motion of the wing’s controls vortex shedding for lift enhancement. In this study, in order to control the flow around a wing flapping with simplified sinusoidal motion, plasma actuators were introduced to simplify the complex feathering motion. In a wind tunnel, a smoke-wire method was enacted to visualize the flow fields around an oscillating plate with an attack angle of 4° in a uniform flow for the baseline and controlled cases. The actuator placed around the leading edge was found to suppress the flow separation on the top surface. Numerical simulations were performed to investigate the control effects on the fluctuating lift, where the control effects by the intermittently driven actuator were also predicted. The actuator installed on the top surface throughout the up-stroke motion was found to suppress vortex shedding from the trailing edge, which resulted in an 11% lift enhancement compared to the baseline case. In regard to the effects of the installation position, it was found that the actuator placed on the top surface was effective, compared to the cases for installation on the bottom surface or both surfaces.

This work investigates the design parameters and their consequences in the control of a helicopter rotor combined with a pair of fixed wings. This hybrid vehicle has a light and aerodynamically efficient rotor with a large range of pitch angles to enable both hover and forward flight. Because of the light stiff rotor and heavy wings, the hybrid vehicle exhibits couplings between the roll and pitch axes during hover flight. The rotor-wing interaction depends on a lot of parameters. In this article, we utilize a simplified theoretic model and simulations in order to gain insight in the effect of these parameters on the vehicle dynamics. Finally, a controller is designed that compensates undesired coupling between pitch and roll. [ABSTRACT FROM AUTHOR]

This paper describes the design, controls system development, and hover testing of a 60 -g meso-scale cycloidalrotor based (cyclocopter) micro air vehicle. The cycloidal rotor (cyclorotor) is a revolutionary vertical take-off and landing concept with a horizontal axis of rotation. The twin-cyclocopter utilizes two optimized cyclorotors and a horizontal tail rotor used to counteract the pitching moment generated by the cyclorotors. An innovative lightweight and high strength-to-weight ratio blade design significantly reduced cyclorotor weight and improved aerodynamic efficiency. In addition, increasing the virtual camber and incidence (by increasing chord-to-radius ratio) and using a symmetric pitching schedule with a maximum ± 45° pitching amplitude also improved rotor efficiency. Due to gyroscopic coupling and inherent instability of the cyclocopter, a closed-loop feedback control system was implemented using a custom autopilot weighing 1.5 g. The 60-g meso-scale twin-cyclocopter successfully demonstrated stable, sustained hover. [ABSTRACT FROM AUTHOR]

In general, there are four common Low Reynolds Number wing's designs for fixed wing Micro Air Vehicle (MAV) which known as Rectangular, Zimmerman, Inverse Zimmerman and Ellipse wing. However, each wing design produces diverse performance and in fact the aerodynamic comparison study among the wings is still lack. Thus, the objective of this study is to evaluate the basic aerodynamic performance found on Rectangular, Zimmerman, Inverse Zimmerman and Ellipse wing designs with view to find the optimal wing shape for Micro Air Vehicle (MAV) configuration. Here, each design was analysed based on simulation works. The results show that at stall angle, the Ellipse wing has maximum lift coefficient ( ) recorded at 1.12 which is at least 4.33% higher than the other wing designs. Based on drag coefficient ( ) analysis, the Inverse Zimmerman Wing exhibited the lowest minimum drag value at 0.033 which is 8.45% lower than the other wing's designs. In moment coefficient analysis, the results reveal that the Inverse Zimmerman Wing has produced the steepest curve slope value at -0.36 which is 17.39% higher than the other wings. The aerodynamic efficiency (CL/CD) study has also revealed that Zimmerman Wing recorded the highest CL/CDvalue at 6.80 and at least 1.35% higher than to the other wing. Based on these results, it was concluded that Zimmerman wing has the highest potential to be adopted as MAV wing due to its optimal aerodynamic efficiency. [ABSTRACT FROM AUTHOR]

Delayed stall is the most dominant lift enhancing factor in insect flapping motion. Micro air vehicle operates at Reynolds number 104-105; slightly higher than the insects' Reynolds number (Re). In the present research, thefocus is to investigate "stall-absent"phenomenon at Re representative of the micro air vehicles, the effect of spanwiseflow on the leading edge vortex and also to study the effect of geometry variations on the aerodynamic performance of the wing in unsteady motion. Corrugated dragonfly airfoil with rectangular wing planform is used, however, with wing kinematics restricted to azimuth rotation only. Three-dimensionalfinitevolume method is used, through commercial software Fluent, to numerically solve time-dependent incompressible Navier-Stokes equations. Computed results at Re 34000 and 100,000 reveal the same phenomenon of delayed stall, as observed in the case of insects. Furthermore, the performance of flat plate, profiled and corrugated wing in a sweeping motion at a high angle of attack is also compared. [ABSTRACT FROM AUTHOR]

Recently, flapping wing micro air vehicles have received great attention with the drive to make smaller and smaller devices. This paper describes a theoretical investigation and subsequent practical implementation of a specific type of flight motor structure for this type of micro air vehicle that uses a "click' mechanism to improve mechanical efficiency. Diptera, which may use the mechanism, are the inspiration for this work. It builds on previous research into the "click" mechanism, which has been studied both from the biological and engineering points of view. It is difficult to capture the important fine details using a simple analytical model; hence, a multi-body dynamic software is used to model the device and to aid the design of a large-scale prototype. Force-deflection curves of the structure and the displacement response are obtained numerically and experimentally. The experimental and numerical results compare reasonably well, enabling the model to be used for further development and potential miniaturization of the flight motor structure. In a practical device, asymmetry occurs in the up- and down-stroke. The effects of this asymmetry are compared with previous results from analytical models. It is found that asymmetry offers a marginal improvement. [ABSTRACT FROM AUTHOR]