Flexible Boom Research Articles

Stress stiffening effects in flexible Earth observation satellites with spinning appendage

Modern satellites often adopt innovative configurations to meet the escalating requirements of space operations. This study specifically focuses on one such configuration, exemplified by an Earth observation spacecraft equipped with a large rotating payload connected to the main bus through a flexible boom. The rotational motion of the payload is designed to extend the scanned area, resulting in a substantial reduction in the time required to complete a set of measurements, thus enhancing the overall performance. However, this configuration introduces greater complexity both in the analysis of the dynamical behavior and in the design of the control architecture. When dealing with flexible structures subject to rotational motion, as in this scenario, the stiffening effect resulting from inertial loads—particularly the centrifugal action—becomes crucial. In this study, we derive the dynamic equations of the multibody flexible spacecraft using Kane's formulation, which provides a streamlined set of ordinary differential equations by simplifying their derivation. Treating the link as an elastic beam, flexibility is incorporated through a modal decomposition approach that considers nonlinear elastic dynamics, ensuring the inclusion of stress stiffening in the dynamical model. Stress stiffening emerges as a fundamental effect in spinning space structures, where the contribution of the centrifugal force is significant. Incorrect predictions and structural instability for high spinning rates are observed when this effect is neglected. Furthermore, the error associated with overlooking this physical phenomenon is found to be dependent on the spinning rate. We identify kinematical conditions that render this effect negligible in relation to the fundamental deformation frequencies of the space system. Several numerical results are presented and discussed.

Partial stabilization of an orbiting satellite model with a flexible attachment

We consider a mathematical model of an orbiting satellite comprising a perfectly rigid carrier body and a flexible boom operating under the influence of the orbital moment of the gravity gradient. This model is represented by a nonlinear control system which includes ordinary differential equations governing the carrier body’s angular velocity and attitude quaternion coupled with the Euler – Bernoulli equations that describe the vibration of the flexible component. We propose an explicit feedback design aimed at guaranteeing the partial stability of the closed-loop system in an appropriate Hilbert space.

Fast luffing control of flexible boom of mobile elevated work platform with uncertain control input gain

In this paper, the dynamic model between input electric signal of hydraulic valve and boom luffing angle is established, and luffing control of flexible boom of mobile elevated work platform (MEWP) is studied. The control input gain for the luffing motion of the MEWP is extremely difficult to solve and varies with boom length, work platform load, and luffing angle. For the variable control input gain, all low-order state quantities, rigid-flexible coupling quantity, and control input are included as the “total disturbance” to be observed. Based on the third-order linear tracking differentiator and the first-order ordinary differential linear equation, an active disturbance rejection controller without control input gain is proposed. With the bandwidth-based parameter settings, the controller only needs to adjust two parameters. As a comparison, this paper analyzes in detail the proposed controllers, the fixed input gain active disturbance rejection controller and the PID controller in terms of tracking error, overshoot, setting time, tracking stability, and robustness.

Novel Magnetically Driven Superhydrophobic Sponges Coated with Asphaltene/Kaolin Nanoparticles for Effective Oil Spill Cleanup.

Fast and effective cleanup of oil spills remains a global challenge. A modified commercial sponge with superhydrophobicity, strong absorption capacity, outstanding magnetic response, and fire resistance were fabricated by a facile and inexpensive route of dip-coated melamine sponge carbonization. The low-cost petroleum asphaltene and kaolin nanoparticles were used as the dip-coating reagent. High absorption capacity of the fabricated sponges allowed rapid and continuous removal of oil contaminants. Taking advantage of the good refractory property, the sponges can be used in burning conditions and directly reused after burning out of the absorbed oil. Reusability tests showed that the modified sponges still maintained high absorption capacity (>85%) after six regeneration and reuse cycles. These characteristics make the fabricated sponge a promising aid to promote effective in situ burning cleanup of oil spills, contributing as a magnetic oil collector and a fire-resistant flexible boom. An example usage scenario of the sponges applied to in situ burning cleanup of oil spills is described.

SPH-EBG simulation of oil spill containment by a flexible boom

SPH-EBG simulation of oil spill containment by a flexible boom

Vibration reduction of the rotary crane with flexible boom

Vibration reduction of the rotary crane with flexible boom

The influence of the PID controller settings on the motion of a truck-mounted crane with a flexible boom and friction in joints

The aim of the paper is to analyze the impact of the PID controller settings on the crane positioning accuracy. The PID controller is applied to minimize the load swingings during realization and after the ending of the working motion. In the proposed control system the tangent component of the load oscillations is compared with the assumed (leading) setpoint signal. The obtained controlling error is used to compensate for driving torque applied to the rotary column of crane. The controlled object in the considered control system is a truck-mounted crane. The paper presents a mathematical model of this crane. Dynamics equations are derived using the joint coordinates, homogeneous transformation matrices and the Lagrange equations of the second kind. The flexibility of the boom, supports, rope and drives as well as friction in joints are taken into account in the dynamics model. The Rigid Finite Element Method is applied to model the boom’s flexibility. The friction phenomenon in joints is modeled in the sense of the LuGre friction model. The numerical results obtained for the proposed control system at various controller settings are presented in the paper and discussed.

Solar sail deployment dynamics

The deployment dynamics of a solar sail consisting of four flexible booms and four membrane quadrants are studied. First, previous work on modelling only one membrane quadrant attached to two axially moving beams using time-varying quasi-modal expansion is extended to be applicable to the complete four-quadrant system. This is achieved via “lifting” the quadrant-level matrices into system-level forms by mapping the former’s constituent blocks to the correct partitions in the latter. After the quadrant-to-system conversion of the matrices, the equations of motion from the authors’ previous work readily apply to the complete system. Modal analysis is performed on a constant-length sail to validate the model’s basic foundations against the results obtained by finite element methods in the past literature. Deployment simulation results are presented, numerical parameter studies that show possibility of instability are performed using the system’s eigenvalues, and the stability results are discussed.

Application of Similarity Theory for Dynamic Characteristics Prediction of Crane Flexible Truss Boom

The aim of this study is to explore the similarity relations of dynamic characteristics of crane flexible truss boom. Combining perturbation theory with vibration analysis, a calculation method of the flexible boom natural frequency undergoing large overall rotary motion was proposed. According to the similarity theory, in terms of the geometrically similar truss boom, the similarity relations of their natural frequency and other parameters were derived. Taking the slenderness ratio of the actual product as the reference standard, two groups of scale-down crane truss boom experiments were designed. The results showed that, in aspect of the boom section size and the boom length, by using the similarity relations of the flexible boom, the dynamic characteristics can be predicted well.

Considerations in the design and deployment of flexible booms for a solar sail

The majority of solar sailing missions utilise semi-rigid boom technology but this places limits on the possible size of the sail. Practical large sails may be constructed using flexible booms on a spinning satellite. The dynamics of the deployment of long flexible booms are investigated and limiting parameters discussed. Deployment strategies are proposed utilising active deployment and a means of passive deployment which requires no direct control of the deployment process. Practical insights into the design, testing and use of a flexible boom solar sail deployment mechanism is presented based on small scale experimental testing, discussing aspects such as boom winding and balanced deployment. Three novel deployment mechanism design concepts are developed; two passive mechanisms using rotational damping to retard the boom deployment and one active concept takes advantage of the forces produced by the spinning nature of the satellite to develop a compact deployment mechanism.

Numerical modeling of flexible floating boom using a coupled SPH–FEM model

ABSTRACTA two-dimensional smoothed particle hydrodynamics–finite-element method (SPH-FEM) model is developed to model the movement of flexible floating boom and bending of its skirt under sea environment. The most significant feature of the present model is the introduction of a weakly coupled gird-to-particle interface for bridging the SPH domain of fluid and the FEM domain for resolving the deformation of the flexible boom skirt, which is different from the previous simulation that adopts a rigid module and flexible connector approach of multibody system. The SPH–FEM model is validated against a series of experimental tests of boom motion and skirt deformation. A comprehensive investigation is concentrated on the hydrodynamic characteristics of the floating booms for using different material stiffness and skirt length under the action of combined wave current. It is found that the boom with longer skirt does not necessarily have good containment performances due to its poor hydrodynamic property in terms of heave and roll. Moreover, the flexible floating boom is proved to have better oil containment performance than the rigid one in a wave-dominated environment. It is also found from the FEM solution of the skirt deformation that the maximum principal strain mainly occurs in the vicinity of the floater–skirt joint on the leeside surface of the skirt under the action of combined waves and currents.

Improved SPH simulation of spilled oil contained by flexible floating boom under wave–current coupling condition

A multi-phase Smoothed Particle Hydrodynamics (SPH) method is developed to model the failure process of a flexible oil boom. An algorithm is proposed based on the dynamic boundary particles (DBPs) for preventing particle disorders of multi-phase fluid particle movement around solid boundary. The improved multi-phase SPH model is firstly validated by the experimental data of a wedge falling into a two-layer oil–water fluid. Then a numerical wave–current flume is established with a piston-type active absorbing wave generator and a circulating current system. The model reliability is validated against the measured vertical profiles of velocity. Simulation of the flexible floating boom movement is implemented by introducing a Rigid Module and Flexible Connector (RMFC) multi-body system. The model is finally applied to the simulation of movement of a flexible floating boom in containing industrial gear oil under the action of combined waves and currents. Good agreements are obtained between the SPH modeling results and the experimental data in terms of the ambient wave–current field, hydrodynamic responses of the floating body and evolution process of the oil slick for the flexible boom. The hydrodynamic responses and containment performances of the flexible floating boom are also compared with those of the rigid one. It is found from both the experimental and numerical results that two vortices of the water phase exist in the front and rear of the boom skirt and the size of the front vortex decreases with increase of the current velocity while the wake vortex is reversed. It is also found that the skirt of the flexible boom has a larger magnitude of swaying and rolling than the rigid one and the maximum quantity of escaped oil of a flexible boom within one wave cycle is about 5% more than a rigid one under the present test conditions.

Experimental studies on performances of flexible floating oil booms in coupled wave-current flow

Floating oil booms are commonly-adopted facility to collect spilled oil on sea surface, or to protect specific areas against oil slick spreading. In this study, 931 runs of laboratory test were carried out under wave-current coupling conditions to investigate hydrodynamic performances of the flexible floating oil boom. The tests first conducted a comparison on motion responses between the flexible floating boom and the rigid one to indicate the necessity of taking the flexibility of boom into consideration. Then a comprehensive analysis was carried out to investigate the effects of the ambient currents, waves and the boom characteristics of material stiffness, diameter of floater, length of skirt, and B/W (Buoyancy/Weight) ratio on the motion responses of the flexible floating booms. Finally, by taking the water blockage effect in front of the boom into consideration in the definition of boom effectiveness, the effective draft and freeboard were compared between the flexible boom and rigid one under fixed current and wave conditions. The effects of currents, waves, skirt lengths and B/W ratios on the effective draft and effective freeboard are assessed.

Minimum-Time Attitude Control of Deformable Solar Sails with Model Uncertainty

This paper develops a new algorithm for large-angle pitch maneuvers of deformable solar sails in minimum time that avoids overshooting the target angle given a set of model uncertainties. The paper uses a simplified Euler–Bernoulli beam to model the sail’s flexible booms. Model uncertainties include the flexural rigidity of the sail’s booms, the effectiveness of the sail’s reflectivity, and its moment of inertia about the pitch axis. The effect of each of these sources of uncertainty is investigated for a set of three sails of increasing size. The algorithm relies on trajectory-based reachability techniques to obtain a distribution of final states at the end of a large-angle maneuver that depend on the estimated model uncertainties. Using a tunable measure of statistical safety, the algorithm determines the required buffer angle to avoid overshooting the target attitude. Machine learning is used for reducing the parameter uncertainties based on a calibration maneuver. In addition, it is used to obtain a fast-access relationship between the current uncertainty in the model parameters and the required buffer angle.

Modeling and Analysis of Truck Mounted Concrete Pump Boom by Virtual Prototyping

By far there is lack of research on different working conditions between rigid and flexible dynamics of truck mounted concrete pump booms. First a 3D model has been established by using virtual prototyping technology of a 37 m long boom in Pro/Engineering software. Then the rigid body simulation model has been built. Next modal superimposition method is adopted to change the 4 rigid body booms into flexible ones. Kinematics law and dynamic characteristics of 4 common working conditions had been studied then. Next tip displacement and the first boom hydraulic cylinder force of the 4 working conditions between rigid and flexible models have been researched. Furthermore the first natural frequencies of the structure have been calculated. The results show that the frequency of the horizontal condition has the lowest of all and the roof condition has the largest of all. Besides the cylinder forces of the flexible model are larger than the corresponding rigid ones because of the flexible boom vibration. Finally an experiment has been done on a boom test rig which proved that the established simulation model is reasonable and the frequency results are correct. All of these provide design reference to mechanical manipulator as well as reducing product development cost of such mechanism.

Folding-Boom Lorry Crane Dynamic Modeling and Motion Control

Aiming at flexible folding boom of the lorry cranesuppress the beam vibration while track a desired trajectory, the paperdesigns a composite control method based on the singular perturbation theory. The flexible multi-body dynamics equation of the flexible folding arm was established by the Lagrange equations and assumed mode method. The system was decomposed intorigid motion (slowly varying system) and flexible vibration (fastvariable system). Fuzzy PID control was designed to track the flexible arm’s rigid motion trajectory control and the linear quadratic optimal controlwas designed to suppress the elastic vibration. The simulation in Simulink results show that the composite control method can control the folding arm effectively.

Development of flexible telescopic boom model using absolute nodal coordinate formulation sliding joint constraints with LuGre friction

In this investigation, a modeling procedure of a telescopic boom of cranes is developed using the absolute nodal coordinate formulation together with the sliding joint constraints. Since telescopic booms are extracted and retracted under various operating conditions, the overall length of the boom changes dynamically, leading to the time-variant vibration characteristics. For modeling the telescopic structure of booms, a special care needs to be exercised since the location of the sliding contact point moves along the deformable axis of the flexible boom and the solution to a moving boundary problem is required. This issue indeed makes the modeling of the telescopic boom difficult, despite the significant needs for the analysis. It is, therefore, the objective of this investigation to develop a modeling procedure for the flexible telescopic boom by considering the sliding contact condition with the dynamic frictional effect. To this end, the sliding joint constraint developed for the absolute nodal coordinate formulation is employed for describing relative sliding motion between flexible booms, while flexible booms are modeled using the beam element of the absolute nodal coordinate formulation, which allows for modeling the large rotation and deformation of the structure.

742 スライディングジョイントを用いたクレーン用テレスコピックブームの動力学解析

In this investigation, a modeling procedure of a telescopic boom of cranes is developed using the absolute nodal coordinate formulation (ANCF) together with the sliding joint constraints. Since telescopic booms can be extended and retracted under various operating conditions, the overall length of the boom changes dynamically, leading to the time-variant vibration characteristics. For modeling the telescopic structure of booms, a special care needs to be exercised since the location of the sliding contact point moves along the longitudinal deformable axis of the boom and solutions to a moving boundary problem between two flexible bodies in contact are required. This issue indeed makes the modeling of the telescopic boom difficult, despite the significant needs for the analysis. It is, therefore, the objective of this investigation to develop a modeling procedure for the telescopic boom by considering sliding contacts between the deformable bodies. To this end, the sliding joint constraint developed for the absolute nodal coordinate formulation is employed for describing relative sliding motion between flexible booms, while elastic deformation of booms are modeled using the beam element of the absolute nodal coordinate formulation, which allows for modeling large rotation and deformation. Several numerical examples are presented in order to demonstrate the use of the modeling procedure developed in this investigation.

A modal disturbance estimator for vibration suppression in nonlinear flexible structures

This paper presents a control strategy for the suppression of vibration due to unknown disturbance forces in large, nonlinear flexible structures. The control action proposed, based on the modal approach, consists of two contributions. The first is the well-known Independent Modal-Space Control, which increases system damping and improves its behavior close to the resonance frequencies. The second is a disturbance estimator, which calculates the modal components of the external forces acting on the system and compensates for them using actuator forces. The system modal coordinates, required by both logics, are estimated through a modal state observer. The proposed control logic is tested on a flexible boom. The paper reports the numerical and experimental results both for the linear and nonlinear (large motion) boom configuration.

Study on Comparison of Atmospheric and Vacuum Environment of Thermally-Induced Vibration Using Vacuum Chamber

The present paper studies the thermally-induced vibration phenomenon of the flexible space boom structure. In order to simulate the thermally-induced vibration phenomenon of the flexible thin boom structure of the spacecraft with the attached tip mass in space, the thermally-induced vibration including thermal flutter is experimentally investigated at various thermal environments using a heating lamp in vacuum chamber. In this experimental study, fluctuating characteristics, natural frequency and thermal strains of the thermally-induced vibration are parametrically investigated at various thermal environment conditions. Finally the thermally-induced vibration of the flexible boom structure of the orbiting earth satellite in solar radiation environment from the earth eclipse region including umbra and penumbra is simulated using the power control of the heating lamp in the vacuum chamber.