Small Unmanned Vehicles Research Articles

Research on Photovoltaic Power Generation Characteristics of Small Ocean Observation Unmanned Surface Vehicles

Under the action of waves, a small unmanned surface vehicle (USV) will experience continuous oscillation, significantly impacting its photovoltaic power generation system. This paper proposes a USV photovoltaic power generation simulation model, and the efficiency of photovoltaic MPPT control under wave action is studied. A simulation model for solar irradiance on solar panels of USV under wave action is established based on CFD and solar irradiation models. The dynamic changes in irradiance of USV solar panels under typical wave conditions are analyzed. The MPPT efficiency of USV photovoltaic power generation devices under continuously changing irradiance conditions is studied on this basis. The simulation research results indicate that waves and solar altitude angles significantly impact the instantaneous irradiation energy of USV photovoltaic devices. However, the impact of waves on the average irradiance is relatively tiny. The sustained oscillation of irradiance poses certain requirements for the Maximum Power Point Tracking (MPPT) control frequency of USV photovoltaic systems; a disturbance control frequency of no less than 50 Hz is proposed.

Drone direction estimation: phase method with two-channel direction finder

This scientific article presents a block diagram of a two-channel radio direction finder that effectively uses the phase method to determine the direction of the signal source. The main attention is paid to the mathematical model of the formation of the cardioid radiation pattern of biconical antennas, which have unique directivity characteristics. These features significantly affect the accuracy and reliability of the bearing determination process. The developed algorithm aims to accurately determine the direction of motion of an unmanned aerial vehicle, especially in the context of a two-channel radio receiver and a five-element antenna system. This antenna system provides unique capabilities for increased resolution and directional accuracy. The article also touches on the issue of software implementation of the developed algorithm, which is aimed at increasing the number of generated bearing estimates in conditions of limited time for observing an unmanned aerial vehicle. Thus, the proposed method is of interest in the field of precision direction finding in the context of small unmanned vehicles.

Principles of adaptive control of roll stability of reconfigurable chassis with planetary-wheeled propulsion system

BACKGROUND: Roll stability control is a relevant issue in transport platforms’ design in general. Well-known methods of roll stability control are used in development of vehicles of various types. However, these methods can not always be applied in design of small unmanned platforms, so development of special solutions is needed. AIM: Justification of feasibility of application of anti-roll balancing mechanisms in small unmanned vehicles. METHODS: The study is based on the analysis of technical solutions implemented in the design of platforms with extreme off-road capabilities and space rovers. Well-known methods of fundamentals of vehicle dynamics are the main tools of the study. RESULTS: The options of roll stability control system for small unmanned platforms are described. The conclusions regarding feasibility of different options of balancing mechanisms for addressing the issue of counteraction of stability losing and overturning are made. CONCLUSIONS: The discussed principles of roll stability control could be implemented in special small unmanned vehicles with any type of propulsion system. The further research in this field considers building of mathematical models capable of evaluating the required kinematics and power properties of the system of adaptive roll stability control, as well as testing using the mockup of a moving platform.

Unmanned surface vehicle navigation through generative adversarial imitation learning

In the artificial intelligent and big data technology era, the marine industry among others is inevitably developing in this direction, aiming at becoming autonomous and completing tasks without relying on human involvement while providing safety. The technology of small unmanned surface vehicles (USVs) is relatively mature but with a large development potential and wide research interest expecting significant benefits such as safety and high efficiency in shipping and transportation systems. This article addresses these issues and utilizes an imitation learning algorithm to resolve autonomous navigation for USVs even in complex environmental conditions. We formulate the trajectory modeling as a data-driven imitation learning problem where we employ a state of the art imitation learning algorithm. Experiments are performed in a particular simulated environment tailored to match the specific weather conditions of the local area. The simulation results show the potential of the proposed imitation learning scheme to create advanced intelligent agents for USVs under real-world environmental settings, and USV actuation constraints that allow to predict trajectories with high accuracy and safety.In addition, we evaluated the method’s robustness in generating successful trajectories under environmental conditions that differed from those encountered during training, thereby promoting knowledge reusing without the need for retraining.

Accurate integrated position measurement system for mobile applications in GPS-denied coal mine

The automatic positioning of underground mobile applications plays a crucial role in enabling intelligent coal mining. However, due to the diverse kinematics and dynamics of these applications, various positioning methods have been proposed to match different targets. Nonetheless, the accuracy and applicability of these methods still fall short of meeting the requirements for field applications. Based on the vibration characteristics of underground mobile devices, a multi-sensor fusion positioning system is developed to enhance the accuracy of positioning in long and narrow global positioning system denied (GPS-denied) underground coal mine roadways. The system combines inertial navigation (INS), odometer, and ultra wide band (UWB) technologies through extended Kalman filter (EKF) and unscented Kalman filter (UKF). This approach enables accurate positioning by recognizing target carrier vibrations and facilitating fast conversion between multi-sensor fusion modes. The proposed system is tested on both a small unmanned mine vehicle (UMV) and a large roadheader, demonstrating that UKF enhances stability for roadheaders with strong nonlinear vibrations while EKF is more suitable for flexible UMVs. Detailed results confirm that the proposed system achieves an accuracy level of 0.15 m, meeting most coal mine application requirements.

A Course Controller with Finite-Time Stability for Unmanned Surface Vehicle Thruster System

Aiming at the situation that small unmanned surface vehicle (USV) encounters unknown disturbance during low speed sailing, a course controller with finite time stability is designed. To solve this problem, we construct an undisturbed ideal navigation model which simply meets the stability requirements, and constructs an adaptive sliding mode surface. The control under finite time approach law is also introduced. The model under perturbation can land on the sliding mode surface in finite time and then synchronize with the ideal navigation model. The adaptive control was applied in the implementation of power control for the thruster structure, so as to ensure the tracking of the desired course within the finite time, and satisfy the needs for the stable system performance. Lyapunov direct method is used to strictly prove that the designed controller can ensure the system which converges to the steady state value in a given time period. Simulation results show that the designed adaptive finite-time controller can ensure the stable course tracking of the USV with thruster structure at low speed, and meet the requirements of the course robustness of the USV under dynamic conditions.

Multi-disciplinary engineering design of a high-speed nature-inspired unmanned aquatic vehicle

Recently, small unmanned vehicles have increased their technological importance and practical relevance in private and public interest maritime applications. However, due to this technology's novelty and early stages, complex challenges in engineering design remain unsolved. Therefore, the purpose of this article is to demonstrate the development of an innovative high-speed Unmanned Aquatic Vehicle (UAV) with the inclusion of robust and multi-objective optimization-based methods. This work implemented four robust optimization methods (e.g., efficient low drag generation, theoretical calculation, the production of hydrodynamic forces, and fluid-structure interaction) to design, components, performance, and material optimization. Furthermore, robust computational simulations and mathematical modelling were applied during the engineering design process. The main research findings show that the version of the UAV developed is optimized and able to operate in several working conditions in oceanic applications. Findings also complement previous related studies and offer novel technological alternatives for maritime applications and species detection in complex oceanic conditions. Finally, the aspects of theoretical significance and application value of the research are discussed in the paper.

АНАЛІЗ МОЖЛИВОСТЕЙ БЕЗПІЛОТНИХ ЛЕТАЛЬТНИХ АПАРАТІВПРОВІДНИХ КРАЇН СВІТУ

This work analyzes the capabilities of unmanned aerial vehicles (UAVs) of the leading countries of the world. It was noted that with the appearance of medium and small unmanned lethal vehicles, the tasks of countering them became significantly more relevant. Starting from the mid-2000s, reports began to circulate in the mass media about the danger of using small unmanned aerial vehicles in airport areas, and from the mid-2010s they began to be used to conduct unauthorized surveillance of important military objects, to conduct terrorist attacks. acts and diversions, for the transportation of prohibited goods (weapons, drugs and various contraband). In this work, it is noted that in the leading countries of the world, active scientific development of this direction of research has begun. At the same time, this problem is relatively new, because one of the first works on the use of unmanned aerial vehicles dates back to 2008. And mass scientific publications on their use refer to the years 20616-17. In the modern scientific literature of the leading countries of the world, the main directions of research in these scientific directions of research were introduced. Special terms were developed and implemented in scientific publications. At the initial stage of using UAVs (in the early 2000s), the task of analyzing their capabilities and countering them appeared. The task of countering UAVs was solved exclusively by means of defeating anti-aircraft missile systems of air defense (air defense air defense systems). Currently, military scientists have found out that the direct neutralization of a massive UAV raid by means of anti-aircraft defense systems is economically impractical, due to the unreasonably high cost of anti-aircraft defense means. This leads to the rapid consumption of the combat resource of the air defense system. In this regard, new means of countering UAVs are being widely researched, namely: the use of electronic warfare (ERW), the use of directed energy radiation — laser weapons, as well as the combined use of EW and air defense systems.

Integration of laser level survey, photogrammetry and GPR to examine the deterioration of Roman mosaics: A case study of Venus house, Volubilis, Morocco

AbstractVolubilis was founded in the second century B.C. and was one of the largest cities on the fringe of the Roman Empire. In 1997, it was listed as a world cultural heritage site by United Nations Educational, Scientific and Cultural Organization (UNESCO) and is one of the most important archaeological sites of Morocco. Volubilis is renowned for its large number of mosaic floors. Among the major mosaics of Volubilis, and undoubtedly the most remarkable ones given their aesthetic and the variety of themes they hold, are found in the house of Venus. These mosaics have been restored between the 1940s and 1950s, but unfortunately, most of these restorations are past due or nearing their ends. Today, the mosaic floors are becoming unleveled, fractured and separated from their surrounding walls. These deteriorations can be triggered by many factors including inadequate foundation, a clayey soil beneath it sensitive to moisture and the heaving of the thin concrete layer due to the expansion of the soil. The corrosion of the reinforcing bars within these concrete slabs is enabling these deformations as well. The objective of this study is to examine the causes of the mosaics' deterioration by integrating three techniques including a laser level survey, photogrammetry using a small unmanned aircraft vehicles (UAV) and ground‐penetrating radar. The methodology adopted herein can generate documentation that can be used during the preparation and decision making prior to any restoration. The restoration should not only be focused on the visible tesserae on the surface but must also consider the entire layer of the mosaics. These techniques were applied to several mosaics in Volubilis, yet only two mosaics within the house of Venus were selected for this study, and the following findings were accomplished: (1) Void spaces were found beneath the mosaic floors, (2) presence of sinking and heaving of concrete slabs and (3) potential corrosion of rebars. The three methods used in this study were in perfect concurrence in showing how the settling of the concrete slab was directly related to the deteriorations visible on the mosaic surface.

Supercapacitor Control System Based on Fuzzy PID and Active Equalization Technology

In this paper, a supercapacitor control system is designed to improve the motion performance of small unmanned vehicles. The supercapacitor is used as the auxiliary power supply for the chassis of the unmanned vehicle. When working at low power, the lithium battery supplies power to the chassis and charges the supercapacitor. When climbing or accelerating, the supercapacitor is used to assist the power supply to improve the body’s movement ability. The current and voltage values are collected by high-precision sensors and the system charging control is completed by fuzzy PID. It has a good effect on the test, which significantly improves the motion performance of the unmanned vehicle.

Autonomous Navigation Technology for Low-Speed Small Unmanned Vehicle: An Overview

In special locations (scenes) such as campuses and closed parks, small unmanned vehicles have gained more attention and application. Autonomous navigation is one of the key technologies of low-speed small unmanned vehicles. It has become a research hotspot, but there are still many problems, such as perception sensitivity, navigation, and positioning accuracy, motion planning accuracy, and tracking control accuracy. In order to sort out the research status of the key technologies of autonomous navigation for small unmanned vehicles more clearly, this paper firstly reviews the key technologies of autonomous navigation and presents an analysis and summary. Finally, future research trends of small unmanned vehicles with low speed are given.

Autonomous hanging tether management and experimentation for an unmanned air‐surface vehicle team

AbstractThe mission of an unmanned air vehicle (UAV) tethered to a small unmanned surface vehicle (USV) is considered. As opposed to the majority of existing tethered UAV work, which assumes a taut tether, this paper addresses the challenge of tether management for a slack, hanging tether in a dynamic ocean environment up to sea state 4 on the Douglas scale. A prototype smart reel system for a UAV–USV team was designed and experimentally validated in controlled and uncontrolled dynamic environments. A reference model for tether control based on static catenary cable theory was extended and shown to be valid through the entire operational envelop. A Kalman filter was developed to fuse slow (4 Hz) differential GPS (dGPS) relative position measurements with fast (100 Hz) inertial measurements, to output a 100 Hz estimate of relative position, relative velocity, and inertial sensor bias. A relative velocity‐based gain‐scheduled proportional‐derivative (PD) controller was developed, and demonstrated robustness to heave, pitch, and roll motion of the USV. Experimental testing with a UAV surrogate showed successful decoupling of heave motion from the UAV altitude in a controlled indoor environment. Taut tether control, in contrast, exhibited 12 times more tether tension at the UAV compared to the controller proposed here. The performance of the tuned controller with feedback from the Kalman filter exhibited minimal deviation from static catenary cable theory during the dynamic experiments. Indoor flight testing showed the developed reference model and controller essentially decoupled the dynamic motion of the USV from that of the UAV; the measured deflections of the UAV altitude and position essentially matched that of untethered flight. Outdoor flights validated the effectiveness of the controller in an unknown dynamic environment, for a larger relative position between the UAV and USV, using the dGPS Kalman filter solution to measure relative position. Initial experimental results look promising for continued on‐water testing of hanging‐tether UAV/USV teams.

Design of Small Unmanned Surface Vehicle with Autonomous Navigation System

Maintaining ecosystems is one of the current leading public concerns. Some of the pressing problems that threaten water resources are pollution of water bodies with floating debris, illegal extraction of water resources, wear and tear of underwater communications. Therefore, the creation of special technical solutions is urgent. This paper reports a model-based design of an unmanned surface vehicle (USV), purposed to control and maintain the oxygen level and parameters such as acidity and the water temperature in rivers, lakes, inland waterways, and coastal waters. The developed USV navigation autopilot is described as a system with two inputs and one output. The autopilot selected is an adaptive controller based on the concept of proportional, integral, and derivative (PID). The autopilot is implemented on the STM32 microcontroller and allows precisely maintaining a given course, adjusting the speed and angle of rotation during wind drift and other influences. The new technique for sensor calibration and data acquisition is described. Simulation results are given, showing the performance of the autopilot algorithm in response to variations in the environment. The numerical experiments of the model have presented the result of confirming the sufficient correspondence between prototype characteristics and simulation results. Finally, thorough field trials were performed to verify the reliability and precision of the proposed solutions. The developed unmanned surface vehicle can be used for environmental monitoring (water sampling, hydrography, patrolling water areas). In turn, the solutions obtained will be suitable for the design of other USV of different sizes.

Multi-Sound-Source Localization Using Machine Learning for Small Autonomous Unmanned Vehicles with a Self-Rotating Bi-Microphone Array

While vision-based localization techniques have been widely studied for small autonomous unmanned vehicles (SAUVs), sound-source localization capabilities have not been fully enabled for SAUVs. This paper presents two novel approaches for SAUVs to perform three-dimensional (3D) multi-sound-sources localization (MSSL) using only the inter-channel time difference (ICTD) signal generated by a self-rotating bi-microphone array. The proposed two approaches are based on two machine learning techniques viz., Density-Based Spatial Clustering of Applications with Noise (DBSCAN) and Random Sample Consensus (RANSAC) algorithms, respectively, whose performances were tested and compared in both simulations and experiments. The results show that both approaches are capable of correctly identifying the number of sound sources along with their 3D orientations in a reverberant environment.

Key technologies and combat pattern analysis of autonomous flight sonobuoy

Launched from a sonobuoy tube and capable of autonomous flight, the autonomous sonobuoy frees the traditional sonobuoy from dependence on costly aerial delivery platforms. It can be installed on various small and medium-sized surface ships and unmanned vehicles to support the operational needs of long-distance and rapid situation awareness regarding underwater battlefields. By introducing the development of in-tube launch and sonobuoy technology, this paper proposes the design method of the autonomous sonobuoy and summarizes the key technologies of autonomous sonobuoy cluster operations, including cluster control, intelligent decision-making, network detection and so on. Furthermore, the battle modes of autonomous sonobuoy clusters in wide-area cooperative detection, precise location and effect evaluation are analyzed. The results can provide references for the demand analysis, design and application of autonomous sonobuoy clusters.

Vision-based positioning system for auto-docking of unmanned surface vehicles (USVs)

This paper presents an independent stereo-vision based positioning system for docking operations. The low-cost system consists of an object detector and different 3D reconstruction techniques. To address the challenge of robust detections in an unstructured and complex outdoor environment, a learning-based object detection model is proposed. The system employs a complementary modular approach that uses data-driven methods, utilizing data wherever required and traditional computer vision methods when the scope and complexity of the environment are reduced. Both, monocular and stereo-vision based methods are investigated for comparison. Furthermore, easily identifiable markers are utilized to obtain reference points, thus simplifying the localization task. A small unmanned surface vehicle (USV) with a LiDAR-based positioning system was exploited to verify that the proposed vision-based positioning system produces accurate measurements under various docking scenarios. Field experiments have proven that the developed system performs well and can supplement the traditional navigation system for safety-critical docking operations.

Geodetic Seafloor Positioning Using an Unmanned Surface Vehicle—Contribution of Direction-of-Arrival Observations

Precise underwater geodetic positioning remains a challenge. Measurements combining surface positioning (GNSS) with underwater acoustic positioning are generally performed from research vessels. Here we tested an alternative approach using a small Unmanned Surface Vehicle (USV) with a compact GNSS/Acoustic experimental set-up, easier to deploy, and more cost-effective. The positioning system included a GNSS receiver directly mounted above an Ultra Short Baseline (USBL) module integrated with an inertial system (INS) to correct for the USV motions. Different acquisition protocols, including box-in circles around transponders and two static positions of the USV, were tested. The experiment conducted in the shallow waters (40 m) of the Bay of Brest, France, provided a data set to derive the coordinates of individual transponders from two-way-travel times, and direction of arrival (DOA) of acoustic rays from the transponders to the USV. Using a least-squares inversion, we show that DOAs improve single transponder positioning both in box-in and static acquisitions. From a series of short positioning sessions (20 min) over 2 days, we achieved a repeatability of ~5 cm in the locations of the transponders. Post-processing of the GNSS data also significantly improved the two-way-travel times residuals compared to the real-time solution.

Disturbance learning controller design for unmanned surface vehicle using LSTM technique of recurrent neural network

In this study, to effectively control small unmanned surface vehicles (USVs) for marine research, characteristics of ocean current were learned using the long short-term memory (LSTM) model algorithm of a recurrent neural network (RNN), and ocean currents were predicted. Using the results, a study on the control of USVs was conducted. A control system model of a small USV equipped with two rear thrusters and a front thruster arranged horizontally was designed. The system was also designed to determine the output of the controller by predicting the speed of the following currents and utilizing this data as a system disturbance by learning data from ocean currents using the LSTM algorithm of a RNN. To measure ocean currents on the sea when a small USV moves, the speed and direction of the ship’s movement were measured using speed, azimuth, and location (latitude and longitude) data from GPS. In addition, the movement speed of the fluid with flow velocity is measured using the installed flow velocity measurement sensor. Additionally, a control system was designed to control the movement of the USV using an artificial neural network-PID (ANN-PID) controller [12]. The ANN-PID controller can manage disturbances by adjusting the control gain. Based on these studies, the control results were analyzed, and the control algorithm was verified through a simulation of the applied control system [8, 9].

Energy balance comparison of small unmanned vehicle equipped with electric and hybrid propulsion system

Article presents comparison of the energetic balance of vehicle powertrain – pure electric vehicle and vehicle equipped with electric hybrid power transmission. Society is more and more often persuaded to buy electric cars as an environmentally friendly solution because they have opinion of ecological vehicles. Electrification in military applications is also widely considered, especially in case of small to medium UGV’s such as wide range of robotic systems introduced to the milatary operations. The article presents the problems of comparing the efficiency and others parameters such as the range of a two presented powertrains. The research was carried out on an small unmanned land platform equipped with a hybrid propulsion system supplied as standard with Diesel power generator and electrically only powered. Energy used for charging of the battery, from tank-to-wheel, was calculated. This also enables to calculate total efficiency of electric and hybrid power transmission. By calculating different capacity of battery and power of generator, it is possible to determine the vehicle range.

Multi-target method for small unmanned vehicles parameters remote determination by microwave radars

This article explores the properties of the multi-target method for small unmanned vehicles parameters remote determination by microwave radars, which allows to expand significantly the range of unambiguously determined speeds of unmanned vehicles. The reasons of occurrence of false targets and their number in the mode of the parameters simultaneous measurement for the set of unmanned vehicles are identified. Using a computer experiment in LabVIEW, the probability of the unmanned vehicles true parameters determination at various ratios of the signal to noise at the input of the radar receiver in multi-target mode was investigated.