Altitude Control Research Articles

Dynamic coverage performance of wind-assisted balloons mesh based on Voronoi partition and energy constraint

Efficiently navigating a fleet of several thousand high-altitude balloons to provide communication network and information system to the entire Earth is a promising technology. Here we proposed the use of balloons with altitude control system to coverage the entire Earth by exploiting the natural time-varying wind field. The energy constraints are deduced based on the energy collecting-consuming model and the energy management strategy of the wind-assisted balloon. The Voronoi partition is introduced to optimize the configuration. Then a dynamic coverage algorithm for multi-balloons system is developed. Three schemes of 1500 balloons in two launch sites are simulated to show the effectiveness of the algorithm. The results demonstrate that Voronoi partition with energy constraints is an effective solution to spread the wind-assisted balloons out over the entire Earth within a short time and then maintain the optimal dynamic coverage configuration for quite a long time. This can serve as a guideline for the design and flight test of the serviceable wind-assisted balloons coverage mesh.

Synthesized Landing Strategy for Quadcopter to Land Precisely on a Vertically Moving Apron

Quadcopter unmanned aerial vehicles have become increasingly popular for various real-world applications, and a significant body of literature exists regarding the improvement of their flight capabilities to render them fully autonomous. The precise landing onto moving platforms, such as ship decks, is one of the remaining challenges that is largely unresolved. The reason why this operation poses a considerable challenge is because landing performance is considerably degraded by the ground effect or external disturbances. In this paper, we propose a synthesized landing algorithm that allows a quadcopter to land precisely on a vertically moving pad. Firstly, we introduce a disturbance observer-based altitude controller that allows the vehicle to perform robust altitude flight in the presence of external disturbances and the ground effect, strictly proving the system’s stability using Lyapunov’s theory. Secondly, we derive an apron state estimator to provide information on the landing target’s relative position. Additionally, we propose a landing planner to ensure that the landing task is completed in a safe and reliable manner. Finally, the proposed algorithms are implemented in an actual quadcopter, and we demonstrate the effectiveness and applicability of our method through real flight experiments.

HYBRID MULTI-AGENT METHOD FOR OPTIMIZATION OF FUZZY COMPUTER SYSTEMS

Recently, intelligent computer systems based on fuzzy logic and soft computing are used quite effectively to solve a wide range of complex applied problems in various fields of human activity. One of the promising areas of modern research in the field of artificial intelligence is the creation and testing of bioinspired multi-agent and evolutionary methods for the synthesis and optimization of fuzzy automatic control systems (ACS) and decision support systems (DSS). This paper is devoted to the development and research of a multi-agent method of parametric optimization of fuzzy systems (FS) based on hybrid improved grey wolf algorithms. The proposed method allows optimizing the parameters of fuzzy computer systems more efficiently, compared to the basic and improved grey wolf methods. This method uses group hunting and dimensional learning-based hunting strategies, as well as local search strategies based on algorithms of gradient descent and extended Kalman filter, which significantly reduces computational costs and increases the rate of convergence to optimal solutions when optimizing parameters of complex fuzzy systems. To study the effectiveness of the developed hybrid multi-agent method in this work, the synthesis and parametric optimization of the fuzzy flight control system for the unmanned aerial vehicle (UAV) is carried out. In particular, the optimization of the vectors of normalizing coefficients, adjustable parameters of linguistic terms (LT), and weight coefficients of the rule's consequences of the rule base (RB) for the altitude controller of the fuzzy ACS for the UAV is performed. The obtained results of the comparative analysis confirm the significant advantages of the developed hybrid multi-agent method of parametric optimization, as well as the feasibility of its application for the synthesis of different types of ACSs and DSSs based on fuzzy logic.

In-Ground-Effect Model Based Adaptive Altitude Control of Rotorcraft Unmanned Aerial Vehicles

In-Ground-Effect Model Based Adaptive Altitude Control of Rotorcraft Unmanned Aerial Vehicles

Orica and Origin to partner on Hunter Valley hydrogen hub

The exploration of space tends to move on alternate and renewable energy with a limiting mission budget. Therefore, considerable attention has been paid to utilizing solar sail as propellant-less propulsion, which takes advantage of reflecting solar photons by large size membrane sail. This chapter describes the historical development of solar sailing technology, including its advantages and applications. A set of operating principles within the area of transfer trajectory, non-Keplerian orbit generation, altitude, and structural control dynamics is then presented, along with a description of performance measurement. A survey of the current status of the art in CubeSat solar sail and a summary of completed and planned missions, such as NanoSail and NEA Scout projects, are also discussed. Finally, ongoing challenges in orbital dynamics and material technologies are proposed, along with possible technology trends and innovative concepts to develop next-generation solar sailing missions.

Gait Analysis for a Tiltrotor: The Dynamic Invertible Gait

A conventional feedback-linearization-based controller, when applied to a tiltrotor (eight inputs), results in extensive changes in tilting angles, which are not expected in practice. To solve this problem, we introduce the novel concept of “UAV gait” to restrict the tilting angles. The gait plan was initially used to solve the control problems in quadruped (four-legged) robots. Applying this approach, accompanied by feedback linearization, to a tiltrotor may give rise to the well-known non-invertible problem in the decoupling matrix. In this study, we explored invertible gait in a tiltrotor, and applied feedback linearization to stabilize the attitude and the altitude. The conditions necessary to achieve a full-rank decoupling matrix were deduced and simplified to near-zero roll and zero pitch. This paper proposes several invertible gaits to conduct an attitude–altitude control test. The accepted gaits within the region of interest were visualized. The simulation was conducted in Simulink, MATLAB. The results show promising responses in stabilizing attitude and altitude.

Fuzzy Gain-Scheduling PID for UAV Position and Altitude Controllers.

Unmanned aerial vehicle (UAV) applications have evolved to a wide range of fields in the last decade. One of the main challenges in autonomous tasks is the UAV stability during maneuvers. Thus, attitude and position control play a crucial role in stabilizing the vehicle in the desired orientation and path. Many control techniques have been developed for this. However, proportional integral derivative (PID) controllers are often used due their structure and efficiency. Despite PID’s good performance, different requirements may be present at different mission stages. The main contribution of this research work is the development of a novel strategy based on a fuzzy-gain scheduling mechanism to adjust the PID controller to stabilize both position and altitude. This control strategy must be effective, simple, and robust to uncertainties and external disturbances. The Robot Operating System (ROS) integrates the proposed system and the flight control unit. The obtained results showed that the proposed approach was successfully applied to the trajectory tracking and revealed a good performance compared to conventional PID and in the presence of noises. In the tests, the position controller was only affected when the altitude error was higher, with an error of 2% lower.

Genotyped indigenous Kiwcha adults at high altitude are lighter and shorter than their low altitude counterparts

BackgroundAnthropometric measures have been classically used to understand the impact of environmental factors on the living conditions of individuals and populations. Most reference studies on development and growth in which anthropometric measures were used were carried out in populations that are located at sea level, but there are few studies carried out in high altitude populations.ObjectiveThe objective of this study was to evaluate the anthropometric and body composition in autochthonous Kiwcha permanently living at low and high altitudes.MethodologyA cross-sectional study of anthropometric and body composition between genetically matched lowland Kiwcha from Limoncocha (n = 117), 230 m in the Amazonian basin, and high-altitude Kiwcha from Oyacachi (n = 95), 3800 m in Andean highlands. Student’s t-test was used to analyze the differences between continuous variables, and the chi-square test was performed to check the association or independence of categorical variables. Fisher’s exact test or Spearman’s test was used when the variable had evident asymmetries with histograms prior to the selection of the test.ResultsThis study shows that high altitude men are shorter than their counterparts who live at low altitude, with p = 0.019. About body muscle percentage, women at high altitudes have less body muscle percentage (− 24.8%). In comparison, men at high altitudes have significantly more muscle body mass percentage (+ 13.5%) than their lowland counterparts. Body fat percentage was lower among low altitude women (− 15.5%), and no differences were found among men.ConclusionsThis is the first study to be performed in two genotyped controlled matching populations located at different altitudes to our best knowledge. The anthropometric differences vary according to sex, demonstrating that high altitude populations are, in general, lighter and shorter than their low altitude controls. Men at high altitude have more muscled bodies compared to their lowland counterparts, but their body age was older than their actual age.

Floor and ceiling mirror configurations to study altitude control in honeybees.

To investigate altitude control in honeybees, an optical configuration was designed to manipulate or cancel the optic flow. It has been widely accepted that honeybees rely on the optic flow generated by the ground to control their altitude. Here, we create an optical configuration enabling a better understanding of the mechanism of altitude control in honeybees. This optical configuration aims to mimic some of the conditions that honeybees experience over a natural water body. An optical manipulation, based on a pair of opposed horizontal mirrors, was designed to remove any visual information coming from the floor and ceiling. Such an optical manipulation allowed us to get closer to the seminal experiment of Heran & Lindauer 1963. Zeitschrift für vergleichende Physiologie47, 39-55. (doi:10.1007/BF00342890). Our results confirmed that a reduction or an absence of ventral optic flow in honeybees leads to a loss in altitude, and eventually a collision with the floor.

Platelets and High-Altitude Exposure: A Meta-Analysis.

Wang, Yuliang, Xuewen Huang, Weibo Yang, and Qingxian Zeng. Platelets and high-altitude exposure: a meta-analysis. High Alt Med Biol. 23:43-56, 2022. Background: How high-altitude hypoxia influences platelets is controversial. We attempted to quantify the impact of high-altitude exposure on platelets through meta-analysis. Methods: We systematically searched electronic databases (PubMed, Embase, Web of Science, VIP, Wanfang, and CNKI) and identified articles reporting an association between platelet count (PC) or platelet indices (platelet distribution width, mean platelet volume [MPV], and plateletcrit) and high-altitude exposure. The mean and standard deviation were extracted, and the standard mean difference (SMD) was estimated using random-effects models. Stata 15.3 was used to analyze statistical data. Results: Thirty-two studies were ultimately included. For acute high-altitude hypoxia (1-14 days), no significant difference was detected, even in patients with acute mountain disease. For the chronic high-altitude hypoxia (≥1 month) group, a significant decrease in PC (SMD [95% confidence interval, CI] = -0.34 [-0.63 to -0.04]) and increase in MPV (SMD [95% CI] = 1.55 [0.60 to 2.49]) were detected compared with those in the control group. Subgroup analysis showed that the tendency was more obvious in the group with longer exposure (≥1 year). Moreover, the PC of the chronic mountain sickness group was less compared with the healthy altitude control group (SMD [95% CI] = -1.82 [-2.74 to -0.91]). Conclusion: A reduced PC and an increased MPV are associated with chronic exposure to high-altitude hypoxia. Moreover, acute high-altitude exposure has no significant influence on platelets.

Mini Drone Linear and Nonlinear Controller System Design and Analyzing

Choosing the mini-drone for a specific payload for designing purposes is one of the most challenging for both cost and design purposes. It is important to develop and analyze the flight control systems of the quadcopter-type Parrot mini drone and how to make the drones more tolerant of adverse weather conditions. The main problem with any quadcopter is that it loses its balance when exposed to any external influence, even if that influence is weak. Where the controller is the most important part of the drone, six plane controllers cover the six degrees of freedom (6dof) in the movement of the drone. In our research, we have improved the height controller in the drone, thus improving the altitude controller by using (PD) and increasing the values of (Kp and Kd) in the altitude controller of the Parrot Mini Drone Mambo to make it more bearable to external influence and to maintain its altitude. We assumed that the aircraft was exposed to bad weather conditions, such as snowfall and dust, which led to an increase in the speed at which the drone fell. We also increased the free fall constant of the object in the simulation design of the drone from (-9.81 m/s2 to -12.81 m/s2) and used Matlab R2021a Simulink to undertake the tuning of the (Kp and Kd) values. This study yielded good results, as illustrated in the results section. Therefore, this research paper suggests adopting the PD controller in the altitude controller and the new values of Kp and Kd to make the drone more tolerant of weather conditions. We tested these results in practice and got good results.

Quadcopter Precision Landing on Moving Targets via Disturbance Observer-Based Controller and Autonomous Landing Planner

Unmanned aerial vehicles, especially quadcopters, play key roles in many real-world applications and the related quadcopter autonomous control algorithms have attracted a great deal of attention. In this paper, we address the vision-based autonomous landing problem of a quadcopter on a ground moving target. Firstly, we propose a disturbance observer-based control algorithm, consisting of a nonlinear disturbance observer and robust altitude and attitude controllers. This algorithm is based on the quadcopter dynamics model, and its stability is strictly proved using Lyapunov’s theory. Secondly, we develop an autonomous landing planner which we test for various landing scenarios to deliver improved reliability and accuracy of the landing mission. These theoretical studies are complemented by a numerical feasibility study, before demonstrating the effectiveness of our approach under actual flight conditions with an experimental quadcopter platform.

Robust Altitude Control of a Quadrotor with Self Tuning via Embedded PLC and Dashboard

Robust Altitude Control of a Quadrotor with Self Tuning via Embedded PLC and Dashboard

Dynamic Event-Triggered Hᵢ/H∞ Optimization Approach to Fault Detection for Unmanned Aerial Vehicles

This paper dealt with the problem of dynamic event-triggered fault detection (FD) for unmanned aerial vehicles (UAVs) in the Hi/H∞ optimization criterion. In order to make use of limited communication resources, a dynamic event-triggered mechanism (ETM) was considered to determine whether system information will be transmitted to the ground station. Note that the transmitted data failing to satisfy a predefined triggered condition were discarded directly. As such, FD performance was affected by not only disturbances and faults, but also dynamic event-triggered transmission errors, namely the errors between the data of non-event time and the current actual system. To solve this problem, a new dynamic event-triggered Hi/H∞ optimization approach was presented, whose contribution lied in the complete decoupling of residuals and event transmission errors under dynamic ETM, which can avoid continuous communication and Zeno phenomenon. Firstly, a dynamic ETM was presented to determine communication time. Then, a variable sampling period model of UAV was established based on the dynamic ETM. On this basis, a dynamic event-triggered residual generator was constructed. In the Hi/H∞ optimization criterion, Riccati recursion was used to compute the optimum solution of a dynamic event-triggered FD filter. Moreover, a new residual evaluation method was proposed, whose effectiveness and feasibility were finally verified by the altitude control system of a UAV.

Application of Nonlinear Correction Method for Attitude Control and Landing Oscillations Prevention

The purpose of this work is to demonstrate the application of the nonlinear correction method to prevent attitude oscillations of flying vehicles. This paper investigates the complications of manual control tasks in aeronautics caused by employing the integral component in the control loop. If the actuators of aircraft controlling surfaces reach their rate limits, the aircraft oscillations can appear for both manually and automatically piloted cases. In this paper, the oscillations alleviation problem is solved using the nonlinear correction method. A general methodology for pilot-induced oscillations prevention is described briefly by the example of an aircraft pitch control system. The obtained pilot model parameters are used for altitude control system examination. The nonlinear systems analysis is carried out by calculating the generalized sensitivity function for the control and disturbance input signal. In the second part, the application of the nonlinear correction method to prevent aircraft and satellite oscillations caused by integrator windup. A comparative analysis of the nonlinear correction and the customary anti-windup feedback is carried out. The results obtained demonstrate that a sequential nonlinear corrective device can be efficiently used to suppress pilot-induced and integrator windup oscillations.

Stabilization of unmanned aerial vehicle on trajectory in high wind conditions

Stationary proportional control laws have been synthesized to ensure stable motion of an unmanned aerial vehicle along a trajectory under the action of a storm wind. We give the values of the regulator coefficients for all sections of the trajectory from the starting point to the landing. Shown are the realizations of wind disturbances and the parameters of the controlled motion of the aircraft under their action. We consider the accuracy of altitude control and the error of the coordinates of the landing site.
 The control laws use the values of constant coefficients obtained at five points of the trajectory. Three points are used for the climb phase and one for level flight and one for descent.
 We took into account the wind speed as the sum of the three-dimensional turbulent component, the average horizontal component, considering the vertical shear, and discrete vertical gusts. The parameters of the Dryden shaping filters, as well as the vertical shear, are calculated for an average wind speed at a height of 6 m equal to 23.15 m / s. The speed of discrete upward gusts is 40 m/s, and downward -25 m / s.
 In such conditions, the unmanned aerial vehicle successfully passes the specified trajectory from the launch to the landing. For thirty realizations of flight simulation, the standard deviation of the landing site error from the wind acting was calculated.

Development of AUV MONACA - Hover-Capable Platform for Detailed Observation Under Ice –

The melting of ice and changes in ocean currents in Antarctica must be investigated to understand global climate change. In this regard, the volume changes of sea ice and ice shelves, bathymetry, and ocean currents in the Antarctic Ocean must be measured in three dimensions. Therefore, the use of autonomous underwater vehicles (AUVs), which can directly observe under ice, is being considered. The authors developed an AUV named Mobility Oriented Nadir AntarctiC Adventurer (MONACA) to observe sea ice and the lower region of the ice shelf in the Antarctic Ocean. Herein, we describe MONACA and its basic autonomous navigation methods (altitude control, depth control, and waypoint tracking), as well as report the results of a sea experiment conducted in Shimoda Bay, Japan. During the 5-day sea trial, the MONACA successfully measured bathymetry by tracking 15 waypoints in sequence, switching the control criteria in the -axis direction between 3 m depth and 3 m altitude.

Fractional-order PI plus D controller for second-order integrating plants: Stabilization and tuning method

In this paper, a fractional-order PI plus D (PIλ-D) structure is proposed for second-order integrating plants. A feedback controller is designed to locate the integrating pole(s) to improve the stability region of the controlling system. Then, the explicit formulae are derived to construct the complex root boundary (CRB) for a given plant model with fractional integrator. By stabilizing approach, it is feasible to put the constraint to calculate the optimal controller parameters. Its effectiveness is presented through numerical examples and a hardware experiment on physical integrating system, namely the altitude control of a quadrotor. The results reveal the improved performances with robustness by the new approach.

Stability control of a fixed full-wing layout UAV under manipulation constraints

The fixed full-wing layout unmanned aerial vehicle (UAV) has simple structure and high aerodynamic efficiency, but the special configuration and manipulation characteristics bring challenges to the controller design, which has little related research work. Aiming at the aileronless and rudderless manipulation mode, considering the disturbance and uncertainty, this paper proposes a comprehensive stability controller for the fixed full-wing layout UAV under manipulation constraints. First, adaptive neural network dynamic surface control schemes based on the asymmetric barrier Lyapunov function and auxiliary system are designed for pitch and yaw attitude control. Then, this paper combines the adaptive super-twisting observer, terminal sliding mode control, and double power reaching law to design the airspeed controller and the altitude controller, and further introduces the pitch angle command constraint in the altitude controller. In addition, an improved vector field-based lateral-directional path following control method is designed to realize straight-line and circular orbit path following control. In this paper, the approximation and compensation effects of the radial basis function neural network and robust compensator are fully verified. The design of the pitch angle command constraint specifically considers the characteristics of weak pitch manipulation ability, small available trim airspeed range, and low longitudinal moment of inertia. The developed path following control approach effectively prevents the nonlinear tracking differentiator from generating unreasonable yaw angle commands. Simulation results also show that the proposed controller can enable the fixed full-wing layout UAV to achieve the typical three-dimensional mission flight with high robustness and high precision, and make the fixed full-wing layout UAV remain stable even after suffering stall and manipulation saturation under the action of the gust wind field.

Feedback Altitude Control of a Flying Insect–Computer Hybrid Robot

Unlike biomimetic methods, the insect–computer hybrid is an alternative approach to developing insect-scale robots. Insect–computer hybrid is a technique that transforms a living insect into a controllable robot by embedding it with artificial devices. In this article, a beetle ( <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">Mecynorrhina torquata</i> ) was transformed into a hybrid flying system by mounting an electronic backpack and implanting electrodes on it. Wing trajectories during fictive flight climbing and flight diving were captured to investigate the natural flight-height control of beetles. Compare with the electrically induced wing trajectories via basalar, subalar, and third axillary (3Ax) muscle stimulations, we hypothesized that the basalar muscles are involved in ascending flight, whereas the 3Ax muscles function to reduce the flight-height. By reproducing the electrical stimulations on bilateral muscle pairs during free flights, we found that stimulations of the basalar muscle pair increased vertical accelerations. In contrast, the 3Ax muscle pair's stimulation decreased vertical accelerations gradually as a function of the electrical stimulation frequency. Accordingly, a proportional-derivative feedback controller was proposed to maintain the beetles' flight-height using frequency-dependent electrical pulses on the basalar and 3Ax muscles. In this article, the altitude control of a free-flying beetle was demonstrated for the first time.