PETREL, a winged hybrid-driven underwater glider is a novel and practical marine survey platform which combines the features of legacy underwater glider and conventional AUV （autonomous underwater vehicle）. It can b...PETREL, a winged hybrid-driven underwater glider is a novel and practical marine survey platform which combines the features of legacy underwater glider and conventional AUV （autonomous underwater vehicle）. It can be treated as a multi-rigid-body system with a floating base and a particular hydrodynamic profile. In this paper, theorems on linear and angular momentum are used to establish the dynamic equations of motion of each rigid body and the effect of translational and rotational motion of internal masses on the attitude control are taken into consideration. In addition, due to the unique external shape with fixed wings and deflectable rudders and the dual-drive operation in thrust and glide modes, the approaches of building dynamic model of conventional AUV and hydrodynamic model of submarine are introduced, and the tailored dynamic equations of the hybrid glider are formulated. Moreover, the behaviors of motion in glide and thrust operation are analyzed based on the simulation and the feasibility of the dynamic model is validated by data from lake field trials.展开更多
Underwater gliders are recent innovative types of autonomous underwater vehicles （AUVs） used in ocean exploration and observation. They adjust their buoyancy to dive and to return to the ocean surface. During the ch...Underwater gliders are recent innovative types of autonomous underwater vehicles （AUVs） used in ocean exploration and observation. They adjust their buoyancy to dive and to return to the ocean surface. During the change of altitude, they use the hydrodynamic forces developed by their wings to move forward. Their flights are controlled by changing the position of their centers of gravity and their buoyancy to adjust their trim and heel angles. For better flight control, the understanding of the hydrodynamic behavior and the flight mechanics of the underwater glider is necessary. A 6-DOF motion simulator is coupled with an unsteady potential flow model for this purpose. In some specific cases, the numerical study demonstrates that an inappropriate stabilizer dimension can cause counter-steering behavior. The simulator can be used to improve the automatic flight control. It can also be used for the hydrodynamic design optimization of the devices.展开更多
A conceptual design of bionic Autonomous Underwater Glider(AUG)is introduced,with a pair of flapping wings.The immersed boundary method is employed and Navier-Stokes equations are solved to investigate the propulsive ...A conceptual design of bionic Autonomous Underwater Glider(AUG)is introduced,with a pair of flapping wings.The immersed boundary method is employed and Navier-Stokes equations are solved to investigate the propulsive performance of the bionic AUG with Aspect Ratios(ARs)of the flapping wings varying from 0.36 to 5.The propulsive efficiency of the whole AUG is newly defined,in contrast to the definition of single flapping wing.The numerical results show that the thrust of flapping wings increases due to the wing-fuselage interaction.The thrust coefficient of the flapping wings increases as the AR increases.The propulsive efficiency of the AUG increases first and then decreases as the AR increases.There is an optimum AR leading to the highest propulsive efficiency,which is different from the result of the single wing case.To balance the advancing speed and gliding endurance,the AR of the flapping wing is recommended to be set as the optimum value of around 0.60.The vortex structures in the wake of the AUG with different ARs are also presented and compared.展开更多
Steering control for an autonomous underwater glider （AUG） is very challenging due to its changing dynamic char- acteristics such as payload and shape. A good choice to solve this problem is online system identifica...Steering control for an autonomous underwater glider （AUG） is very challenging due to its changing dynamic char- acteristics such as payload and shape. A good choice to solve this problem is online system identification via in-field trials to capture current dynamic characteristics for control law reconfiguration. Hence, an online polynomial estimator is designed to update the yaw dynamic model of the AUG, and an adaptive model predictive control （MPC） controller is used to calculate the optimal control command based on updated estimated parameters. The MPC controller uses a quadratic program （QP） to compute the optimal control command based on a user-defined cost function. The cost function has two terms, focusing on output reference tracking and move suppression of input, respectively. Move-suppression performance can, at some level, represent energy-saving performance of the MPC controller. Users can balance these two competitive control performances by tuning weights. We have compared the control performance using the second-order polynomial model to that using the filth-order polynomial model, and found that the tbrmer cannot capture the main characteristics of yaw dynamics and may result in vibration during the flight. Both processor-in-loop （PIL） simulations and in-lake tests are presented to validate our steering control performance.展开更多
Underwater gliders are buoyancy propelled vehicle which make use of buoyancy for vertical movement and wings to propel the glider in forward direction.Autonomous underwater gliders are a patented technology and are ma...Underwater gliders are buoyancy propelled vehicle which make use of buoyancy for vertical movement and wings to propel the glider in forward direction.Autonomous underwater gliders are a patented technology and are manufactured and marketed by corporations.In this study,we validate the experimental lift and drag characteristics of a glider from the literature using Computational fluid dynamics(CFD)approach.This approach is then used for the assessment of the steady state characteristics of a laboratory glider designed at Indian Institute of Technology(IIT)Madras.Flow behaviour and lift and drag force distribution at different angles of attack are studied for Reynolds numbers varying from 10^(5) to 10^(6) for NACA0012 wing configurations.The state variables of the glider are the velocity,gliding angle and angle of attack which are simulated by making use of the hydrodynamic drag and lift coefficients obtained from CFD.The effect of the variable buoyancy is examined in terms of the gliding angle,velocity and angle of attack.Laboratory model of glider is developed from the final design asserted by CFD.This model is used for determination of static and dynamic properties of an underwater glider which were validated against an equivalent CAD model and simulation results obtained from equations of motion of glider in vertical plane respectively.In the literature,only empirical approach has been adopted to estimate the hydrodynamic coefficients of the AUG that are required for its trajectory simulation.In this work,a CFD approach has been proposed to estimate the hydrodynamic coefficients and validated with experimental data.A two-mass variable buoyancy engine has been designed and implemented.The equations of motion for this two-mass engine have been obtained by modifying the single mass version of the equations described in the literature.The objectives of the present study are to understand the glider dynamics adopting a CFD approach,fabricate the glider and its variable buoyancy engine and test its trajectory in water and compare it with numerically obtained trajectory in the vertical plane.展开更多
To develop a bionic maneuverable propulsion system to be applied in a small underwater vehicle, a new conceptual design of the bionic propulsion is applied to the traditional underwater glider. The numerical simulatio...To develop a bionic maneuverable propulsion system to be applied in a small underwater vehicle, a new conceptual design of the bionic propulsion is applied to the traditional underwater glider. The numerical simulation focuses on the autonomous under- water glider （AUG）＇s flapping propulsion at Re = 200 by solving the incompressible viscous Navier-Stokes equations coupled with the immersed boundary method. The systematic analysis of the effect of different motion parameters on the propulsive efficie- ncy of the AUG is carried out, including the hydrofoil＇s heaving amplitude, the pitching amplitude, the phase lag between heaving and pitching and the flapping frequency. The results obtained in this study can provide some physical insights into the propulsive mechanisms in the flapping -based locomotion.展开更多
基金supported by the National Natural Science Foundation of China(Grant Nos. 50835006 and 51005161)the Science & Technology Support Planning Foundation of Tianjin(Grant No. 09ZCKFGX03000)the Natural Science Foundation of Tianjin(Grant No. 09JCZDJC23400)
文摘PETREL, a winged hybrid-driven underwater glider is a novel and practical marine survey platform which combines the features of legacy underwater glider and conventional AUV （autonomous underwater vehicle）. It can be treated as a multi-rigid-body system with a floating base and a particular hydrodynamic profile. In this paper, theorems on linear and angular momentum are used to establish the dynamic equations of motion of each rigid body and the effect of translational and rotational motion of internal masses on the attitude control are taken into consideration. In addition, due to the unique external shape with fixed wings and deflectable rudders and the dual-drive operation in thrust and glide modes, the approaches of building dynamic model of conventional AUV and hydrodynamic model of submarine are introduced, and the tailored dynamic equations of the hybrid glider are formulated. Moreover, the behaviors of motion in glide and thrust operation are analyzed based on the simulation and the feasibility of the dynamic model is validated by data from lake field trials.
文摘Underwater gliders are recent innovative types of autonomous underwater vehicles （AUVs） used in ocean exploration and observation. They adjust their buoyancy to dive and to return to the ocean surface. During the change of altitude, they use the hydrodynamic forces developed by their wings to move forward. Their flights are controlled by changing the position of their centers of gravity and their buoyancy to adjust their trim and heel angles. For better flight control, the understanding of the hydrodynamic behavior and the flight mechanics of the underwater glider is necessary. A 6-DOF motion simulator is coupled with an unsteady potential flow model for this purpose. In some specific cases, the numerical study demonstrates that an inappropriate stabilizer dimension can cause counter-steering behavior. The simulator can be used to improve the automatic flight control. It can also be used for the hydrodynamic design optimization of the devices.
基金Zhejiang Provincial Natural Science Foundation(Nos.LY18A020002 and LQ18E090010)the National Natural Science Foundation of China(Nos.91634103 and 51279184).
文摘A conceptual design of bionic Autonomous Underwater Glider(AUG)is introduced,with a pair of flapping wings.The immersed boundary method is employed and Navier-Stokes equations are solved to investigate the propulsive performance of the bionic AUG with Aspect Ratios(ARs)of the flapping wings varying from 0.36 to 5.The propulsive efficiency of the whole AUG is newly defined,in contrast to the definition of single flapping wing.The numerical results show that the thrust of flapping wings increases due to the wing-fuselage interaction.The thrust coefficient of the flapping wings increases as the AR increases.The propulsive efficiency of the AUG increases first and then decreases as the AR increases.There is an optimum AR leading to the highest propulsive efficiency,which is different from the result of the single wing case.To balance the advancing speed and gliding endurance,the AR of the flapping wing is recommended to be set as the optimum value of around 0.60.The vortex structures in the wake of the AUG with different ARs are also presented and compared.
基金supported by Beihang University and Institution of China Academy of Aerospace Aerodynamics
文摘Steering control for an autonomous underwater glider （AUG） is very challenging due to its changing dynamic char- acteristics such as payload and shape. A good choice to solve this problem is online system identification via in-field trials to capture current dynamic characteristics for control law reconfiguration. Hence, an online polynomial estimator is designed to update the yaw dynamic model of the AUG, and an adaptive model predictive control （MPC） controller is used to calculate the optimal control command based on updated estimated parameters. The MPC controller uses a quadratic program （QP） to compute the optimal control command based on a user-defined cost function. The cost function has two terms, focusing on output reference tracking and move suppression of input, respectively. Move-suppression performance can, at some level, represent energy-saving performance of the MPC controller. Users can balance these two competitive control performances by tuning weights. We have compared the control performance using the second-order polynomial model to that using the filth-order polynomial model, and found that the tbrmer cannot capture the main characteristics of yaw dynamics and may result in vibration during the flight. Both processor-in-loop （PIL） simulations and in-lake tests are presented to validate our steering control performance.
基金Authors would like to acknowledge the departmental grant received from Indian Institute of Technology,Chennai towards design and development of this model.
文摘Underwater gliders are buoyancy propelled vehicle which make use of buoyancy for vertical movement and wings to propel the glider in forward direction.Autonomous underwater gliders are a patented technology and are manufactured and marketed by corporations.In this study,we validate the experimental lift and drag characteristics of a glider from the literature using Computational fluid dynamics(CFD)approach.This approach is then used for the assessment of the steady state characteristics of a laboratory glider designed at Indian Institute of Technology(IIT)Madras.Flow behaviour and lift and drag force distribution at different angles of attack are studied for Reynolds numbers varying from 10^(5) to 10^(6) for NACA0012 wing configurations.The state variables of the glider are the velocity,gliding angle and angle of attack which are simulated by making use of the hydrodynamic drag and lift coefficients obtained from CFD.The effect of the variable buoyancy is examined in terms of the gliding angle,velocity and angle of attack.Laboratory model of glider is developed from the final design asserted by CFD.This model is used for determination of static and dynamic properties of an underwater glider which were validated against an equivalent CAD model and simulation results obtained from equations of motion of glider in vertical plane respectively.In the literature,only empirical approach has been adopted to estimate the hydrodynamic coefficients of the AUG that are required for its trajectory simulation.In this work,a CFD approach has been proposed to estimate the hydrodynamic coefficients and validated with experimental data.A two-mass variable buoyancy engine has been designed and implemented.The equations of motion for this two-mass engine have been obtained by modifying the single mass version of the equations described in the literature.The objectives of the present study are to understand the glider dynamics adopting a CFD approach,fabricate the glider and its variable buoyancy engine and test its trajectory in water and compare it with numerically obtained trajectory in the vertical plane.
基金Project supported by the National Natural Science Foun-dation of China(Grant No.51279184)
文摘To develop a bionic maneuverable propulsion system to be applied in a small underwater vehicle, a new conceptual design of the bionic propulsion is applied to the traditional underwater glider. The numerical simulation focuses on the autonomous under- water glider （AUG）＇s flapping propulsion at Re = 200 by solving the incompressible viscous Navier-Stokes equations coupled with the immersed boundary method. The systematic analysis of the effect of different motion parameters on the propulsive efficie- ncy of the AUG is carried out, including the hydrofoil＇s heaving amplitude, the pitching amplitude, the phase lag between heaving and pitching and the flapping frequency. The results obtained in this study can provide some physical insights into the propulsive mechanisms in the flapping -based locomotion.
