Rotary Propeller Research Articles

Синтез адаптивной робастной системы управления трикоптером с поворотными винтами в условиях неопределенных аэродинамических коэффициентов, частично неопределенной матрицы входа, влияния внешних возмущений и ограничения входных воздействий

In this article, an adaptive robust control system for a tricopter equipped with three rotary propellers is developed and studied under the following conditions: a) uncertain aerodynamic coefficients; b) partially uncertain input matrix; c) influence of unknown external disturbances; and d) input constraints. When constructing a complete nonlinear mathematical model of the dynamics of a tricopter with rotary propellers in the form of Lagrange-Euler equations, the input constraints are taken into account. The synthesis of an adaptive robust control system for a tricopter with rotary propellers is carried out on the basis of the modified computed torque control (Li–Slotine method) and the function approximation technique to eliminate the influence of uncertainty. Unknown external disturbances are compensated by a smooth sliding mode control using an adaptive estimate of the upper bound of the sum of external disturbances and approximation errors of uncertain functions in the mathematical model. To compensate for the negative effects of input constraints, an auxiliary dynamic system is constructed, the state variables of which are used to synthesize the control law. The robustness of the adaptive system and the desired tracking accuracy of the reference signals are proven using the Lyapunov function method. Simulation results using MatLab/Simulink are presented to illustrate the effectiveness of the proposed control law.

Синтез нелинейной и адаптивно-робастной систем со скользящими режимами в управлении динамикой трикоптера с поворотными винтами при действии неизвестных внешних возмущений

The article develops a complete nonlinear mathematical model of tricopter dynamics with rotary propellers in the form of Lagrange-Euler equations and two systems of nonlinear and adaptive-robust control with sliding modes, operable under the action of unknown external disturbances. The nonlinear control system with sliding modes and constant controller parameters is synthesized based on the Lyapunov function method. The adaptive-robust system is developed on the basis of the Lyapunov function method with a smooth sliding mode control and using an adaptive estimate of the upper bound of external disturbances. The performance of the proposed control systems under the action of unknown external disturbances and variations in aerodynamic coefficients is investigated. A comparative study of the constructed control systems is conducted in the MatLab/Simulink software environment.

Numerical investigation of the effect of rotary propeller type turbulator on the energy and exergy efficiencies of a concentrating photovoltaic/thermal hybrid collector

By combining photovoltaic panels that are able to convert solar energy into electricity with solar collectors that are able to convert solar energy into heat, photovoltaic/thermal hybrid collectors (PTHCs) are invented. In these systems, solar energy is simultaneously converted into electricity and heat, and they have a better performance than separate photovoltaic panels and solar collectors. For this reason, improving the performance of these systems has always been the focus of researchers. The present numerical research is devoted to the investigation of the effect of using a rotary propeller type turbulator in a concentrating PTHC (CPTHC) on the energy and exergy features of the collector. The results are compared with the data belonging to the cases without a turbulator and with a stationary turbulator. The effect of Reynolds number (Re) and rotational speed of the turbulator (ω) on the results is investigated. Water is considered as the working fluid of the CPTHC, and its flow is carried out in a turbulent regime. Among the three investigated cases, the best and worst performance belonged to the CPTHCs with a rotary turbulator and without a turbulator, respectively. The results showed that the rise of ω from 0 to 10000 rpm results in a growth in the thermal energy efficiency, total energy efficiency and thermal exergy efficiency by 75.47%–90.17%, 115.80%–130.78% and 0.75%–0.87%, respectively. Additionally, it was explored that the rise of ω entails an ascending-descending trend in the useful electrical power, first law electrical efficiency, second law electrical efficiency and second law total efficiency of the CPTHC, and the maximum value of these parameters occurs at ω = 5000 rpm. The highest total energy efficiency, which was equal to 130.78%, belonged to the case of Re = 20000 and ω = 10000 rpm, while the highest exergy efficiency was equal to 17.24% and belonged to the case of Re = 20000 and ω = 5000 rpm.

Flight Transient Estimation of VTOL Aircraft with Propellers

Methodological issues associated with the determination of the vertical take-off and landing aerodynamic parameters equipped with two rotary propellers during take-off and hovering, descent and landing are studied in the proposed article. During the computer simulation process, kinematics parameters diagrams were made, aerodynamic coefficients and propellers thrust components at all stages of aircraft take-off were estimated. That numerical data can be used in a preliminary stage of aerodynamic design for the vertical take-off and landing aircraft and electric drones at the determination of control and equalization elements geometric and kinematic parameters.

Hydrodynamics of Biomimetic Marine Propulsion and Trends in Computational Simulations

The aim of the present paper is to provide the state of the works in the field of hydrodynamics and computational simulations to analyze biomimetic marine propulsors. Over the last years, many researchers postulated that some fish movements are more efficient and maneuverable than traditional rotary propellers, and the most relevant marine propulsors which mimic fishes are shown in the present work. Taking into account the complexity and cost of some experimental setups, numerical models offer an efficient, cheap, and fast alternative tool to analyze biomimetic marine propulsors. Besides, numerical models provide information that cannot be obtained using experimental techniques. Since the literature about trends in computational simulations is still scarce, this paper also recalls the hydrodynamics of the swimming modes occurring in fish and summarizes the more relevant lines of investigation of computational models.

Design and development of the efficient anguilliform swimming robot— MAR

Propulsion of swimming robots at the surface and underwater is largely dominated by rotary propellers due to high thrust, but at the cost of low efficiency. Due to their inherently high speed turning motion, sharp propeller blades and generated noise, they also present a disturbance to maritime ecosystems. Our work presents a bio-inspired approach to efficient and eco-friendly swimming with moderate to high thrust. This paper describes the concept, development and experimental validation of the novel anguilliform robot MAR. With 15 elements making up the 0.5 m long propulsive section and driven by a single, speed-controlled brushless DC motor (BLDC), the robot creates a smooth continuous traveling wave for propulsion. Steering and autonomy are realized by an actuated head with integrated batteries that serves as a front-rudder. Almost neutral buoyancy paired with individually actuated pectoral fins furthermore enable submerged swimming and diving maneuvers. MAR accomplished high thrusts at a moderate power consumption in first performance tests. The achieved maximum velocity and the speed related efficiency (defined as the achieved speed over the power consumption m Ws−1) did not fulfill the expectations in the first tests (in comparison to commercial rotary thrusters), which can be largely attributed to the spatial limitations and an imperfect test setup. Nevertheless, the potential towards highly efficient and high thrust propulsion is visible and will be further investigated in future efforts.

Motor torque measurement of Halobacterium salinarum archaellar suggests a general model for ATP-driven rotary motors

It is unknown how the archaellum—the rotary propeller used by Archaea for motility—works. To further understand the molecular mechanism by which the hexameric ATPase motor protein FlaI drives rotation of the membrane-embedded archaellar motor, we determined motor torque by imposition of various loads on Halobacterium salinarum archaella. Markers of different sizes were attached to single archaella, and their trajectories were quantified using three-dimensional tracking and high-speed recording. We show that rotation slows as the viscous drag of markers increases, but torque remains constant at 160 pN·nm independent of rotation speed. Notably, the estimated work done in a single rotation is twice the expected energy that would come from hydrolysis of six ATP molecules in the hexamer, indicating that more ATP molecules are required for one rotation of archaellum. To reconcile the apparent contradiction, we suggest a new and general model for the mechanism of ATP-driven rotary motors.

The bacterial flagellar motor and the evolution of molecular machines

Understanding how life on earth evolved is an enduringly fascinating and profound question. Relative to our understanding of eukaryotic evolution, however, our understanding of how the molecular machines underpinning life have evolved is poor. The bacterial flagellar motor, which drives a rotary propeller for motility, offers a fascinating case study to explore this further, and is now revealing recurring themes in molecular evolution. This article describes recent discoveries about how flagellar motors have diversified since the first flagellar motor evolved, and what this diversity tells us about molecular evolution.

Building a flagellum in biological outer space

Flagella, the rotary propellers on the surface of bacteria, present a paradigm for how cells build and operate complex molecular ‘nanomachines’. Flagella grow at a constant rate to extend several times the length of the cell, and this is achieved by thousands of secreted structural subunits transiting through a central channel in the lengthening flagellum to incorporate into the nascent structure at the distant extending tip. A great mystery has been how flagella can assemble far outside the cell where there is no conventional energy supply to fuel their growth. Recent work published by Evans et al. [Nature (2013) 504: 287-290], has gone some way towards solving this puzzle, presenting a simple and elegant transit mechanism in which growth is powered by the subunits themselves as they link head-to-tail in a chain that is pulled through the length of the growing structure to the tip. This new mechanism answers an old question and may have resonance in other assembly processes.

Swimming Using Surface Acoustic Waves

Microactuation of free standing objects in fluids is currently dominated by the rotary propeller, giving rise to a range of potential applications in the military, aeronautic and biomedical fields. Previously, surface acoustic waves (SAWs) have been shown to be of increasing interest in the field of microfluidics, where the refraction of a SAW into a drop of fluid creates a convective flow, a phenomenon generally known as SAW streaming. We now show how SAWs, generated at microelectronic devices, can be used as an efficient method of propulsion actuated by localised fluid streaming. The direction of the force arising from such streaming is optimal when the devices are maintained at the Rayleigh angle. The technique provides propulsion without any moving parts, and, due to the inherent design of the SAW transducer, enables simple control of the direction of travel.

Guidance and control of a biomimetic autonomous underwater vehicle using body-fin propulsion

Autonomous underwater vehicles (AUVs) with rigid hulls and powered by rotary propellers have problems such as inefficient propulsion, difficulties associated with positioning, limited turning agility and imprecise hovering. Recently, research and development into biomimetic AUVs (BAUVs) have accelerated in order to solve the problems of the propulsion of AUVs by propellers. A testbed BAUV is being developed. A local control law that coordinates body angles by periodically alternating the position of the centre-of-mass in local coordinates is developed. Three parameters are found to suffice to coordinate joint angles in carangiform swimming. A global control law is then developed for solving the waypoint tracking problem. The effectiveness of this method is evaluated using computer simulation. The control performance of the BAUV system with model uncertainties for waypoint tracking under the influence of disturbances is also discussed.

Bacterial Flagellar Microhydrodynamics: Laminar Flow over Complex Flagellar Filaments, Analog Archimedean Screws and Cylinders, and Its Perturbations

The flagellar filament, the bacterial organelle of motility, is the smallest rotary propeller known. It consists of 1), a basal body (part of which is the proton driven rotary motor), 2), a hook (universal joint—allowing for off-axial transmission of rotary motion), and 3), a filament (propeller—a long, rigid, supercoiled helical assembly allowing for the conversion of rotary motion into linear thrust). Helically perturbed (so-called “complex”) filaments have a coarse surface composed of deep grooves and ridges following the three-start helical lines. These surface structures, reminiscent of a turbine or Archimedean screw, originate from symmetry reduction along the six-start helical lines due to dimerization of the flagellin monomers from which the filament self assembles. Using high-resolution electron microscopy and helical image reconstruction methods, we calculated three-dimensional density maps of the complex filament of Rhizobium lupini H13-3 and determined its surface pattern and boundaries. The helical symmetry of the filament allows viewing it as a stack of identical slices spaced axially and rotated by constant increments. Here we use the closed outlines of these slices to explore, in two dimensions, the hydrodynamic effect of the turbine-like boundaries of the flagellar filament. In particular, we try to determine if, and under what conditions, transitions from laminar to turbulent flow (or perturbations of the laminar flow) may occur on or near the surface of the bacterial propeller. To address these questions, we apply the boundary element method in a manner allowing the handling of convoluted boundaries. We tested the method on several simple, well-characterized cylindrical structures before applying it to real, highly convoluted biological surfaces and to simplified mechanical analogs. Our results indicate that under extreme structural and functional conditions, and at low Reynolds numbers, a deviation from laminar flow might occur on the flagellar surface. These transitions, and the conditions enabling them, may affect flagellar polymorphism and the formation and dispersion of flagellar bundles—factors important in the chemotactic response.