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In this article, we present a preliminary analysis of a heavy-lift airship carrying a payload through a cable-driven parallel robot. With unlimited access to isolated locations around the globe, heavy-lift airship enables affordable and safe delivery of heavy cargo thanks to its vertical takeoff and landing capabilities. By considering the airship...
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This paper proposes an online Neural Network self-tuned Inverse Dynamic Controller (IDC) for high-speed and smooth trajectory tracking control of a 3-DoF Delta robot. The foregoing approaches provides a suitable controller for a wide range of nonlinear paths and reduce the end-effector oscillations at high speed. To this end, a compact and accurate...
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... Recently, underactuated airship, mostly due to the absence of side direction actuation, has many applications for commercial and military applications. Airships can be used for land communications (mobile signals, home internet, global positioning system, ... etc.), geography and environmental systems, aerial navigation, sea navigation, climate prediction, linking with satellites, remote sensing, crop monitoring, ... etc [5][6][7][8]. ...
A non-linear mathematical model of underactuated airship is derived in this paper based on Euler-Newton approach. The model is linearized with small disturbance theory, producing a linear time varying (LTV) model. The LTV model is verified by comparing its output response with the result of the nonlinear model for a given input signal. The verified LTV model is used in designing the LQT controller. The controller is designed to minimize the error between the output and required states response with acceptable control signals using a weighted cost function. Two LQT controllers are presented in this work based on two different costates transformations used in solving the differential Riccati equation (DRE). The first proposed assumption of costates transformation has a good tracking performance, but it is sensitive to the change of trajectory profile, whereas the second one overcomes this problem due to considering the trajectory dynamics. Therefore, the first assumption is performed across the whole trajectory tracking except for parts of trajectory profile changes where the second assumption is applied. The hybrid LQT controller is used and tested on circular, helical, and bowed trajectories. The simulation assured that the introduced hybrid controller results in improving airship performance.
... Equation (27) can be obtained from the identity of the left and right sides of P x,LWR 1 6 in equations (15) and (16). Bring in equation (19) and angle values θ θ , 3 4 , and θ 5 to obtain θ 1 and θ 2 , as shown in equations (28) and (29). ...
... For the fusion device, it can be divided into two parts i.e., CASK and CFETR parts [28]. The solution of the dynamic ant colony algorithm can be used to build a mathematical model of the positive kinematics of the robot of the transport arm, and the solution of the collision-free planning can be obtained by studying the mathematical model of the positive kinematics of the transport arm with and without collision with the geometrically constrained mathematical model at each detection section [29]. However, it is very complicated to find the intersection point or intersection line directly using the geometric equations of both. ...
Factors like rising work costs and the imminent transformation and upgrading of manufacturing industries are driving the rapid development of the industrial robotics market. In this study, by analyzing the structure of the transport arm and China Fusion Engineering Test Reactor and performing mathematical modeling, a feasible solution for the robot can be obtained using the dynamic ant colony optimization algorithm and grayscale values. However, for multiple degree of freedom robots, due to a large number of joints, the pure use of joint angle restrictions cannot avoid their own mutual interference. The design of the transport arm robot’s own collision algorithm is shown, which focuses on each linkage as a rod wrapped by a cylinder. The experiment shows that the relationship between the integrated center of mass and the whole machine center of mass can get the action area of the whole machine center of mass of the robot, according to which the relationship between the radius of the catch circle and time of the projection area of the whole machine center of mass of the robot in the horizontal plane can be obtained. The maximum outer circle radius r com = 267.977 mm {r}_{\text{com}}=267.977\hspace{.25em}\text{mm} , according to the stability criterion r ssa > r con {r}_{\text{ssa}}\gt {r}_{\text{con}} , can be obtained, so the stability analysis of the gait switching process can be judged to be correct and effective.
... Recently, underactuated airship, mostly due to the absence of side direction actuation, has many applications for commercial and military applications. Airships can be used for land communications (mobile signals, home internet, global positioning system, ... etc.), geography and environmental systems, aerial navigation, sea navigation, climate prediction, linking with satellites, remote sensing, crop monitoring, ... etc [4,5,6,7]. ...
Background: A non-linear mathematical model of underactuated airship is derived in this paper based on Euler-Newton approach. The model is linearized with small disturbance theory, producing a linear time varying (LTV)model. The LTV model is utilized to design a linear quadratic tracking (LQT) controller. Two scenarios of LQT are presented in this work according to assumed costates transformations to compute the LQT control law.
Results: The LTV model is verified by comparing its output response with the result of the nonlinear model for a given input signal. It shows an acceptable error margin. The verified LTV model is used in designing the LQT controller. The controller is designed to minimize the error between the output and required states response with acceptable control signals using a weighted cost function. Two LQT controllers are presented in this work based on two different transformations used in solving the differential Riccati equation (DRE). These controllers are tested by a sample trajectory to deduce the characteristics of each assumption. Finally, a hybrid LQT controller is used and tested on circular, helical, and bowed trajectories.
Conclusion: The first assumption of costates transformation has a good tracking performance, but it is sensitive to the change of trajectory profile. Whereas, the second one overcomes this problem due to considering the trajectory dynamics. Therefore, the first assumption is performed across the whole trajectory tracking except for parts of trajectory profile changes where the second assumption is applied.
... First, the differences between these positions (denoted by e c ∈ R ns ) for the cable configurations obtained from the dynamic analysis and the analytical solution are computed. Next, the maximum and average of these differences 1 Although a formal assessment of the stability of the attained equilibrium is not explored in this work, numerical studies such as the one reported in Section 4.4.2.3 suggests otherwise. 2 The final configuration of a cable will be planar provided no external forces are acting perpendicular to the plane containing it, or equivalently, the lateral bending stiffness is negligible. ...
... Furthermore, drag forces are neglected 1 in the present work. 1 A comparison of different models of the unmanned aerial vehicle with multiple rotors was reported by Gill and D'Andrea (2017). As per their observations, the drag forces can be neglected for the low velocities of the vehicle, which is the case in this example. ...
Cable-driven parallel robots manipulate the motions of a moving platform with the help of multiple cables connected to it. These robots possess lower inertias, larger workspaces and higher load-carrying capacities when compared to the conventional parallel manipulators. Accordingly, CDPRs are employed in various fields of applications, including construction, inspection, rescue operations and rehabilitation. Further details of the previous works on various research topics of CDPRs can be found in the book by Pott (2018). In the present work, simulations of the dynamics of CDPRs are performed. The inertia of cable, its stiffness and damping properties associated with deflections in the axial, transverse and lateral directions are included in the dynamic model.
A new approach to improve the computational efficiency of the forward dynamic analyses of the CDPRs is developed. With its help, a novel methodology to solve the forward kinetostatic problems of CDPRs is proposed. Its potential in identifying both
zero-dimensional and higher-dimensional attractors of the robot is explored. Later, this framework is extended to incorporate the effects of actuators. Firstly, the time-varying feeds/retrievals of cables with fixed exit points in Type-I CDPRs are studied. Secondly, the time-varying locations of the exit points with constant lengths of cables in Type-II CDPRs are investigated. Furthermore, the versatility of the proposed dynamic model is illustrated with the help of the FAST manipulator, the CoGiRo robot and a 4-4 CDPR of different classes of redundancy in actuation, i.e., the number of cables used for manipulating the moving platform.
... There are numerous methods for developing the equations of motion for multi-body systems. An example is presented by Abdallah et al. (2019) for an airship with an attached cable-driven payload. The airship was divided into two isolated subsystems and modeled using Kirchhoff equations and the payload motion was considered as a disturbance to the airship. ...
This paper presents pitch control of an uninhabited airship using changes in center of gravity. Changes in center of gravity are achieved by controlling the position of a movable gondola along a rigid keel fixed to the bow of the helium envelope. The longitudinal multi-body dynamic equations of motion were developed using the measured and estimated physical properties and an adaptive PID controller was designed to control the pitch angle. Flight tests on a 4 m long uninhabited airship prototype were conducted to demonstrate the effectiveness of the method.
... Suppressing the payload swinging to limit its effect on the UAV's stability and tracking performance [1] [2] or considering deliberate load swinging to perform specific tasks, e.g., avoiding obstacles by doing aggressive maneuvers [3] or passing through a window [4] are among the topics of interest in previous work. For the control mechanism, using UAV's conventional controls [4], moving the tether point [5], or using the movement of a set of cables [6] have been proposed. Previous work is centered around suppressing the swing angles, assuming constant cable length, point-mass payloads, and hover or low-speed forward flight. ...
Fixed-wing UAVs can be used for slung load transportation for their high-speed flight, large payload capacity, and long endurance and range characteristics. One potential application of interest is UAV-assisted water sampling for inspection and quality assessment. However, the payload swinging motion could negatively affect the UAV's flight performance and stability. To address this challenge, the longitudinal dynamics and control of a baseline fixed-wing UAV with a slung load is studied in this paper. The objective of this work is to achieve payload swinging suppression during the flight while maintaining a specific altitude and flight speed. In the meantime, the water sampling practice requires the UAV to deliberately swing the payload for efficient operation. The longitudinal nonlinear equations of motion are derived for this 4-DOF system using Newton-Euler formulation to capture the effects of the slung load motion on the UAV's flight performance and vice versa. Assumptions include a point-mass payload, rigid cable, and the UAV's center of mass as the tether point. A benchmark control law is developed to solve the payload swing angle control problem. In addition, the effects of different payload masses and cable lengths on the UAV and suspended load dynamics are investigated. Finally, longitudinal flight simulation is carried out to verify the modeling and examine the performance of the swing angle controller. The simulation results suggest limitations on payload mass and cable length for acceptable flight performance and effective control.
... The kinematic model of mobile CDPM seeks to determine the relationship between the 6-DOF moving platform twists,χ χ χ p = [η η η p 1 ,ω ω ω p ] T and both the linear velocities of the driving cables,l l l = [l 1 ,l 2 , ...,l n c ] T as well as the linear and angular velocities of the mobile basė χ χ χ a = [η η η a 1 ,ω ω ω a ] T . Then, the suspended platform twistχ χ χ p of the mobile CDPM is defined as follows [11] J J Jχ χ χ p =l l l + J J J 1χ χ χ a (6) χ χ χ p = J J J +l l l + J J J + J J J 1χ χ χ a ...
... We assume that the cables are massless and not extensible. Gathering both force and torque balance equations, we get [11] ...
... Referring to the control law given by (11) and the dynamic model given by (9), the closed loop system will then be M M M G (χ χ χ)e e e χ χ χ + C C C G (χ χ χ,χ χ χ)e e e χ χ χ − D D D G + M M M G (χ χ χ)Λ Λ Λe e e χ χ χ + C C C G (χ χ χ,χ χ χ)Λ Λ Λe e e χ χ χ = 0 (15) Although the dynamic equations of the global system are nonlinear and complex, they have some known properties which are necessary for the controller synthesis and stability analysis ...
... Hence, the heavy lift airship can be modeled as an interconnection of lower order subsystems (i.e the airship and CDPM). In this case, the basic motion of one subsystem is regarded as an external disturbance input for the other one [86]. ...
In the recent years, researchers have become increasingly interested in the development of radically new and sustainable transportation modes for both passengers and cargo. These challenges have led to study in areas of knowledge that were dormant, such as the potential of using lighter than air aircraft for cargo transportation. The focus of this thesis is the development of a control architecture that can be integrated on autonomous heavy lift airship and thereby enables safe cargo exchange process. Besides, the dynamic model of the heavy lift airship must be clarified before designing a controller. This system makes use of a Cable Driven Parallel Manipulator (CDPM), allowing the airship to load and unload cargo while hovering. The heavy lift airship is a multi-body systems in which multiple rigid bodies are joined together. During loading and unloading process, the transferred cargo can oscillate due to airship maneuvers. On the other hand, the pendulum-like behavior of suspended load can alter the flight characteristics of the airship. The thesis contributions are presented in two parts. In the first part, we assume that there is no inertial coupling between the airship and CDPM. Hence, our researches concern only the CDPM tacking into account the base mobility at first and then the cable sagging phenomena. The control design should integrate an optimal tension distribution since cables must remain in tension. In the second part, we address the analysis of the heavy lift airship considering the coupling effect between the suspended payload and the airship. To describe the dynamics coupling, the basic motion of one subsystem is regarded as an external disturbance input for the other one. Hence, the dynamic model of this multi-body system composed of the airship and the CDPM can be modeled as an interconnection of lower order subsystems. We assume that the heavy lift airship is a weakly coupled subsystems. Based on this assumption, we design a decentralized controller, which makes it possible to control the airship and the CDPM independently. Numerical simulation results are presented and stability analysis are provided to confirm the accuracy of our derivations.
Stratospheric airships require a lightweight envelope to contain lighter-than-air buoyancy gas, making the lightweight design and pressure-bearing performance of the envelope structure a key research issue. The stress state at different cross-sectional positions of the airship envelope structure is different, resulting in a low utilization rate of the overall material performance of the envelope structure. This paper proposes a design scheme for reinforcing envelope structures with sliding reinforcing cable to improve the bearing capacity of the composite fabric structure while reducing its weight, ultimately achieving the optimal strength-to-weight ratio. Two types of composite fabric structures (A-airship and B-airship) were subjected to inflatable burst tests, and the strain changes in the envelope gores were analyzed by digital image correlation. Through re-assembly of the broken composite fabric pieces and analysis of their tear textures, crack origination positions, failure causes, and the stress behavior and state at the failure position were identified. An envelope structural model with consideration of the cutting pattern effect was established, allowing the stress distribution of the envelope to be analyzed and the damage positions to be more accurately predicted. Based on the analysis of the ultimate pressure-bearing performance of an airship envelope structure, a novel idea of incorporating coupled tensile-shear stress into the strength criterion was proposed. Through the data in the study and existing references, it is verified that the strength criterion can accurately predict the ultimate pressure-bearing performance of the envelope structure.
This paper discusses modelling of a multibody system consisting of airship, gondola, and a slung payload. Lighter-than-air vehicles undergo inertial forces that are often neglected in heavier-than-air vehicles. These inertial forces are modelled using added mass and added inertia. The dynamics of the multibody system were first modelled using the Udwadia–Kalaba method. Three constraints were derived and enforced. The resulting equation of motion was used to identify the added mass, added inertia, and inertia of the airship through system identification procedure. The proposed system identification method utilizes semidefinite programming with equality and inequality constraints to find any unknown parameters in the mass matrix of the multibody system. Three experiments were carried out to perform the system identification and validate the dynamic model. The identified mass matrix was used to reconstruct the trajectories of the experiments. Using the experimentally obtained mass matrix demonstrated 35%\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$35\%$\end{document} lower error when compared with simulated trajectories using approximated mass matrices.
