Unmanned Aerial Vehicle Propulsion System Research Articles

Nonlinear recurrence analysis of piezo sensor placement for unmanned aerial vehicle motor failure diagnosis

This paper is focused on the diagnostics of multicopter UAV propulsion system, in which the temporary transient states occur during operation in faulty conditions (eg. not all motor phases working properly). As a diagnostic sensor, the piezo strip has been used, which is very sensitive to any vibrations of the multi-rotor frame. The paper concerns the precise location of the sensor for more effective monitoring of the propulsion system state. For this purpose, a nonlinear analysis of the vibration times series was carefully presented. The obtained non-linear time series were studied with the recurrence analysis in short time windows, which were sensitive to changes in Unmanned Aerial Vehicle motor speeds. The tests were carried out with different percentage of the pulse width modulation signal used for the operation of the brushless motor and for different locations of the piezosensor (side and top planes of the multicopter arm). In the article, it was shown that the side location of the piezosensor is more sensitive to changes in the Unmanned Aerial Vehicle propulsion system, which was studied with the Principal Component Analysis method applied for four main recurrence quantifications. The research presented proves the possibility of using nonlinear recurrence analysis for propulsion system diagnostics and helps to determine the optimal sensor location for more effective health monitoring of multicopter motor.

Integrated Design and Flight Validation of Solar-Powered Unmanned Aerial Vehicle (UAV) Structure and Propulsion System

The development of solar-powered unmanned aerial vehicles (UAVs) primarily focuses on enhancing the efficiency of the propulsion system to minimize energy consumption during the conversion of valuable solar energy. However, due to the unique nature of UAV propulsion systems, there is limited cross-reference ability among existing solar-powered UAV systems. This paper proposes an integrated design approach for the propulsion system and UAV structure. Based on this approach, an overall design is conducted for the solar-powered UAV, including initial design goals and performance parameters. Aerodynamic layout design and performance estimation are carried out, and a prototype is fabricated and assembled for flight testing validation. The results demonstrate the significant importance of this approach in improving the efficiency of the solar-powered UAV propulsion system.

Fuzzy-based optimal energy management strategy of series hybrid-electric propulsion system for UAVs

Hybrid-electric propulsion system (HEPS) has gained significant attention in unmanned aerial vehicles (UAVs) due to its potential to significantly reduce fuel consumption and pollutant emissions. Effective energy management strategies are crucial in ensuring the efficient operation of HEPS in UAVs, as they involve multiple power and energy sources. While conventional equivalent consumption minimum strategy (ECMS) is effective in distributing engine and battery output power, it struggles to maintain the battery’s state of charge (SOC) within desired levels in case of engine failure. The present study introduced the fuzzy logic control-equivalent consumption minimum strategy (FLC-ECMS), a fuzzy-based composite energy management strategy that incorporates the robustness and adaptability of fuzzy logic control. Through simulation tests under general aviation cruise flight and cargo transport flight scenarios, the results indicated that hybrid UAV equipped with the HEPS can decrease fuel consumption and CO2 emissions by at least 18.6% and NOx emissions by 10.1% in the first profile and by 23.6% and 11.2% in the second profile, compared to conventional oil-powered UAV. The FLC-ECMS method not only reduces fuel consumption and emissions, but also maintains the battery SOC within permitted range and minimizes the difference between front and back SOC. This study provides new insights into the optimal energy management of HEPS for complex profiles in UAVs, highlighting the significance of UAVs in reducing environmental impacts, and has the potential for broader application in other electric propulsion systems.

TECHNICAL AND ECONOMIC SUBSTANTIATION OF THE AIR LAUNCH AEROSPACE SYSTEM PARAMETERS

The substantiation of the technical and economic parameters of the air launch aerospace system, which consists of a reusable unmanned aerial vehicle and integrated launch vehicle, is given. A combination of a turbofan engine and a ramjet engine is used as the unmanned aerial vehicle propulsion system. The considered vehicle is capable of delivering a payload into low-Earth orbits without the use of a spaceport. We have developed the methodology of the technical and economic substantiation of the parameters of the air launch aerospace system. The results were obtained by searching for the minimum of the objective function, which established the relationship between the technical and economic parameters of the aerospace system. For the objective function solution, the design parameters of the integrated launch vehicle and unmanned aerial vehicle were determined, as well as the limitation of the total acceleration velocity of the aerospace system. The methods used allowed us to determine the velocity constraints provided by the operation of the turbofan engine, ramjet engine, and the three solid propellant motors of integrated launch vehicle stages, as well as maximum dynamic pressure and maximum permissible temperature on the unmanned aerial vehicle surface. We determined the scheme for estimating the cost of launching the spacecraft into Earth orbit by the air launch aerospace system. The result of the substantiation is the determination of the technical and economic parameters of the integrated launch vehicle, unmanned aerial vehicle, and the aerospace system as a whole. The influence of the maximum temperature on the surface of the unmanned aerial vehicle and the specific impulse of the ramjet engine on the parameters of the aerospace system was also evaluated. The substantiation is the first step towards the creation of the Ukrainian aerospace air launch system.

Multirotor Motor Failure Detection with Piezo Sensor

Failure detection of Unmanned Aerial Vehicle (UAV) motors and propulsion systems is the most important step in the implementation of active fault-tolerant control systems. This will increase the reliability of unmanned systems and increase the level of safety, especially in civil and commercial applications. The following paper presents a method of motor failure detection in the multirotor UAV using piezo bars. The results of a real flight, in which the failure of the propulsion system caused the crash of a hybrid VTOL UAV, were presented and analyzed. The conclusions drawn from this flight led to the development of a lightweight, simple and reliable sensor that can detect a failure of the UAV propulsion system. The article presents the outcomes of laboratory tests concerning measurements made with a piezo sensor. An extensive analysis of the obtained results of vibrations recorded on a flying platform arm with a propulsion system is presented, and a methodology for using this type of data to detect failures is proposed. The article presents the possibility of using a piezoelectric sensor to record vibrations on the basis of which it is possible to detect a failure of the UAV propulsion system.

Prospects and Challenges of Propulsion Technologies of Unmanned Aerial Vehicles: A Review

This review paper discussed the different types of propulsion technologies for unmanned aerial vehicles (UAVs). In it, several UAV propulsion systems were investigated, with particular emphasis on internal combustion engine (ICEs)-powered propulsion systems and electrically powered propulsion systems. The characteristics and working principles of these propulsion systems and challenges were discussed in this paper. Also, the methods in which future generations of UAVs can perform better have been discussed particularly with regards to endurance characteristics, power-to-weight ratios, and environmental wise. Similarly, the relevance of future UAV propulsion systems, which is a hybrid of the two major propulsion systems (ICEs and electric systems), giving a yield for high endurance, long-range, and durability, is discussed.

Overview of Propulsion Systems for Unmanned Aerial Vehicles

Unmanned Aerial Vehicle (UAV) propulsion technology is significantly related to the flight performance of UAVs, which has become one of the most important development directions of aviation. It should be noted that UAVs have three types of propulsion systems, namely the fuel, hybrid fuel-electric, and pure electric, respectively. This paper presents and discusses the classification, working principles, characteristics, and critical technologies of these three types of propulsion systems. It is helpful to establish the development framework of the UAV propulsion system and provide the essential information on electric propulsion UAVs. Additionally, future technologies and development, including the high-power density motors, converters, power supplies, are discussed for the electric propulsion UAVs. In the near future, the electric propulsion system would be widely used in UAVs. The high-power density system would become the development trend of electric UAVs. Thus, this review article provides comprehensive views and multiple comparisons of propulsion systems for UAVs.

Variable Pitch Propeller for UAV-Experimental Tests

Growth in application fields of unmanned aerial vehicles (UAVs) and an increase in their total number are followed by higher and higher expectations imposed on improvements in UAV propulsion and energy management systems. Most commercial vertical takeoff and landing (VTOL) UAVs employ a constant pitch propeller that forces a mission execution tradeoff in the majority of cases. An alternative solution, presented here, consists of the use of a variable pitch propeller. The paper summarizes experimental measurements of the propulsion system equipped with an innovative variable pitch rotor. The investigations incorporated characteristics of the rotor for no wind conditions and a new approach to optimize pitch settings in hover flight as a function of UAV weight and energy consumption. As UAV battery capacity is always limited, efficient energy management is the only way to increase UAV mission performance. The study shows that use of a variable pitch propeller can increase the maximal takeoff weight of the aircraft and improve power efficiency in hover, especially if load varies for different missions. The maximal thrust measured was 31% higher with respect to the original blade settings. The coefficient of thrust during hover showed an increase of 2.6% up to 7.5% for various pitch angles with respect to the original fixed propeller.

Application of multi-axis force/torque sensor system for experimental study of small unmanned aerial vehicles propulsion systems – Preliminary results

The experimental evaluation of the performance of small propellers plays important role in the process of multicopter UAV design perfection. This paper presents a small UAV propeller test stand, based on a multi-axis Force/Torque sensor system. The system makes possible to measure the thrust, torque and the pitching moment or lateral force (when in oblique flow) of the tested propeller. The data processing of the experimental results is discussed. Results for static, axial flow and oblique flow conditions are presented. Some conclusions about the measurement methodology are drawn. The results verify that the test bench has good accuracy and is easy for operation.

Experimental evaluation of a hybrid electric propulsion system for small UAVs

PurposeThis paper aims to experimentally evaluate the performance of a parallel hybrid propulsion system for use in small unmanned aerial vehicles (UAVs).Design/methodology/approachThe objective is to combine all the individual components of the hybrid electric propulsion system (HEPS) into a modular test bench to characterize the performance of a parallel hybrid propulsion system, and to evaluate a rule-based controller based on the ideal operating line concept for the control of the power plant. Electric motor (EM) designed to supplement the power of the internal combustion engine (ICE) to reduce the overall fuel consumption, with the supervisory controller optimizing ICE torque.FindingsThe EM was able to supplement the power of the ICE to reduce fuel consumption, and proved the capability of acting as a generator to recharge the batteries drawing from ICE power. Furthermore, the controller showed that it is possible to reduce the fuel consumption with a HEPS when compared to its gasoline counterpart by running simulated representative UAV missions. The findings also highlighted the challenges to build and integrate the HEPS in small UAVs.Originality/valueThe modularity of the test bench allows each component to be changed to assess its impact on the performance of the system. This allows for further exploration and improvements of the HEPS in a controlled environment.

Overview of solutions and analysis of the ability to evaluate the performance parameters of unmanned aerial vehicles propulsion systems

The aim of aircraft engines development is the propulsion which is characterized by high power-to-mass ratio. Therefore, the alternative solutions that provide the required power by the low weight propulsion are sought after. The main advantage of these solutions is improvement of environmental and economic properties. This paper presents the overview of solutions and studies conducted for the unmanned aerial vehicles propulsion. For the purposes of studies a test bench was prepared. Its enables the comparison of the propulsion operating parameters taking into account changes in the values of thrust and propulsion power. The summary includes a proposal to improve the environmental indicators of propulsion systems for unmanned aerial vehicles.

Development of Lightweight 200‐W Direct Methanol Fuel Cell System for Unmanned Aerial Vehicle Applications and Flight Demonstration

AbstractA lightweight 200‐W direct methanol fuel cell (DMFC) stack was developed to power a small‐scale unmanned aerial vehicle (UAV). To reduce the weight and volume of the DMFC stack, carbon‐composite bipolar plates were fabricated using natural graphite, phenolic resin, and carbon black. In addition, lightweight end plates, bolts, and nuts were fabricated using polyetheretherketone (PEEK) materials. The lightweight DMFC stack, which was designed for small UAV operating under cruising conditions, consisted of 33 cells, in which membrane‐electrode assemblies (MEAs) with active area of 88 cm2 were stacked with the composite bipolar plates. The DMFC stack was first evaluated under various methanol feed concentrations. It produced a maximum power of 251 W at 13.4 V and 71.3 °C under methanol feed concentration of 2 M. Thereafter, the DMFC stack was integrated with a Li‐polymer battery as an auxiliary power source, and the load‐sharing characteristics of the UAV propulsion system were tested under actual flight mode comprising takeoff, cruising, and landing. The flight test results showed that the lightweight DMFC stack successfully delivered full power for cruise flight, whereas the battery provided the additional power required during takeoff. This work successfully demonstrated that the DMFC technology can be applied to small‐scale UAVs.

Car-Top Test Module as a Low-Cost Alternative to Wind Tunnel Testing of UAV Propulsion Systems

In an effort to assess motor and propeller performance for small unmanned aerial vehicles (UAVs), a car-top test module has been developed. This device allows for characterization of propeller and motor combinations in mean flow without the investment that is inherent with wind tunnel testing. Additionally, propulsion systems can be tested for reliability in real-world environments without risk to an airframe. Measurements of the propeller efficiency, thrust coefficient, power coefficient, and temperature of the motor and the electronic speed controller as initial parameters of interest are reported. Thrust at different advance ratios is compared to data from wind tunnel testing in order to gauge the accuracy of this technique. The module performed well in its intended role, and it is recommended that similar devices be used for time-critical or low-cost applications.

A Study on Transient Performance Characteristics of the Canard Rotor Wing Type Unmanned Aerial Vehicle Propulsion System During Flight Mode Transition

A propulsion system of the CRW (Canard rotor wing) type UAV (unmanned aerial vehicle) was composed of the turbojet engine, exhaust nozzles (including some tip jet nozzles and a main nozzle), and the duct system (including straight ducts, curved ducts, and master valve). The CRW-type UAV has three different flight modes, such as the rotary wing mode for takeoff and landing, the high-speed forward flight mode with the fixed wing, and the transition flight mode between the previously mentioned two flight modes. In order to evaluate transient performance characteristics of the CRW-type UAV propulsion system during flight mode transition, the propulsion system was modeled using SIMULINK®, which is a user-friendly graphical-user-interface-(GUI) type dynamic analysis tool provided by MATLAB, in this study. The transition flight mode between the rotary wing mode and the fixed wing mode was simulated by considering area variation of the master valve and the main exhaust nozzle. In order to verify acceptability of the main turbojet engine model, performance simulation results using SIMULINK were compared to results using the commercial program GSP. Through this simulation, proper operation of the master valve and the variable area main nozzle can be found for safe flight transition. Therefore, performance characteristics were investigated depending on various angle positions of the master valve.