Yaw Motion Research Articles

Analysis of Available Yawing Moment of an Autonomous Underwater Vehicle Model in Simulation Frame

Research endeavors on the design and control techniques of Autonomous Underwater Vehicles (AUVs) have been going on for a long time. In the present study, the yaw motion of a small submerged underwater vehicle is investigated and visualized as a direct result of changes in the rudder tilt angle and forward velocity. The numerical analysis is performed in ANSYS-Fluent software. The turbulent flow field has been modeled using Shear Stress Transport (SST) k-ω model. A grid independence test has been conducted to ensure the validity of the findings. The forces on the rudder and the available yaw moment have been obtained for different combinations of the AUV’s rudder tilt angle and forward velocity. The trend has intuitively been consistent and agreed with the basic concept of hydrodynamics

Cross-Coupled Dynamics and MPA-Optimized Robust MIMO Control for a Compact Unmanned Underwater Vehicle

A compact, 3-degrees-of-freedom (DoF), low-cost, remotely operated unmanned underwater vehicle (UUV), or MicroROV, is custom-designed, developed, instrumented, and interfaced with a PC for real-time data acquisition and control. The nonlinear equations of motion (EoM) are developed for the under-actuated, open-frame, cross-coupled MicroROV utilizing the Newton-Euler approach. The cross-coupling between heave and yaw motion, an important dynamic of a class of compact ROVs that is barely reported, is investigated here. This work is thus motivated towards developing an understanding of the physics of the highly coupled compact ROV and towards developing model-based stabilizing controllers. The linearized EoM aids in developing high-fidelity experimental data-driven transfer function models. The coupled heave-yaw transfer function model is improved to an auto-regressive moving average with exogenous input (ARMAX) model structure. The acquired models facilitate the use of the multi-parameter root-locus (MPRL) technique to design baseline controllers for a cross-coupled multi-input, multi-output (MIMO) MicroROV. The controller gains are further optimized by employing an innovative Marine Predator Algorithm (MPA). The robustness of the designed controllers is gauged using gain and phase margins. In addition, the real-time controllers were deployed on an onboard embedded system utilizing Simulink′s automatic C++ code generation capabilities. Finally, pool tests of the MicroROV demonstrate the efficacy of the proposed control strategy.

Modeling and nonlinear dynamic analysis of angular velocity system of 2-DOF aerial manipulator

This paper establishes the dynamic model of the angular velocity system of the 2-DOF (degree of freedom) aerial manipulator, describes the coupling relationship between the quadrotor aircraft and the manipulator, and provides the rotational speed relationship of each propeller during open-loop control. On this basis, the dynamic parameters, the nonlinear dynamics under static and dynamic conditions, and the Casimir energy of the system are studied in four parts. In the part of system dynamics parameters, the influence of manipulator configurations and postures on system moment of inertia, yaw motion, and lifting motion are analyzed, and their influence on gyroscopic effect is discussed. In the nonlinear dynamics of the system under static conditions, this paper analyzes the nonlinear dynamics of a typical aerial manipulator by the nonlinear dynamics methods. It reveals for the first time that the angular velocity of the system can produce dynamic behaviors such as sinks, chaotic oscillations, and period-doubling oscillations. The system is a non-autonomous system when it is under dynamic conditions. In this part, this paper considers the dynamic behaviors of the aerial manipulator in three situations: grasping operation, presence of external interference, and presence of time-varying yaw control quantity. It can be seen from the analysis that the dynamic conditions make the nonlinear dynamic behaviors of the system more complicated, which is worthy of further study. In the energy analysis, the Casimir energy of the three cases in this paper is calculated respectively when the sink, chaotic oscillation, and periodic oscillation are generated, and their mean, variance, and standard deviation are calculated. When the system is a sink, the three indexes are the smallest, the energy consumption is the least, and it is easier to control.

A methodology to assess the dynamic response and the structural performance of floating photovoltaic systems

This study presents a comprehensive methodology for evaluating floating photovoltaic (FPV) structures, focusing on the impact of wind and wave conditions from hydrodynamic and structural perspectives. The methodology is applied to a Class 1 pontoon-type structure with rigid and hinged configurations. A total of 558 simulations are conducted, considering various environmental actions, configurations, and mooring line chain sections. The results provide essential data on loads and motion time series for subsequent structural analysis. Wind forces primarily influence surge and sway motions, while wave forces dominate other motion components. Comparing the hinged configuration to the rigid one, a significant reduction in maximum yaw motions of 32% to 76% was observed, depending on the mooring chain section employed. This reduction in yaw motions may positively impact the energy yield. However, an inverse trend was observed for pitch motions. Hence, a comprehensive assessment of wave-induced motions is crucial for selecting the optimal FPV configuration. Furthermore, heavier chain sections effectively limited surge, sway, and yaw motions, with variations of up to 75% observed in the hinged configuration when comparing different chain options. Structural analysis highlights the importance of wave characteristics, mooring system configuration, and system flexibility. The findings emphasize the need to consider environmental conditions, structural aspects, and energy efficiency in optimizing FPV configurations.

Design and Fully Coupled Dynamic Response Analysis of a New Floating Offshore Wind Platform

Floating offshore wind platform (FOWP) has become the economically favored option for supporting wind turbines in deep waters. It is urgent to propose new concept designs for FOWPs that can be effectively deployed. Additionally, the extensive use of steel in such platforms significantly escalates costs, necessitating the optimization of steel utilization. Motivated by these challenges, a V-shaped floating semi-submersible platform equipped with NREL 5 MW wind turbine is designed and analyzed based on the potential flow theory and the blade element momentum theory. Fully coupled time-domain simulations are conducted using the F2A program, which couples NREL FAST and ANSYS AQWA via a Dynamic Link Library (DLL), to compare the hydrodynamic performance and stability of the V-shaped floating platform with the original triangle-shaped model of “Fuyao”. Various sea conditions have been considered, including combined wind-wave action and wind-wave-current action at different incidence angles. The results show that the V-shaped floating platform has better economic and hydrodynamic performance (e.g., a reduction of 40.4% and 12.9%, respectively, in pitch and yaw motions, and a 17.4% reduction in maximum mooring tension), but lower stability than its triangle-shaped counterpart.

All-in-One Control Framework for Distributed Drive Electric Buses Path Tracking Subject to Uncertain Crosswind and Varied Passenger Mass

This paper proposes an all-in-one control framework for distributed drive electric buses (DDEBs) that can effectively attenuate the effects of uncertain crosswind and varied passenger mass in path tracking, while minimizing the electricity consumption of battery. To track the desired path and ensure driving stability, a robust tube-based model predictive control method is proposed considering lateral, yaw and roll motions. Simultaneously, for the longitudinal motion, a robust sliding mode control method is designed to achieve accurate tracking of longitudinal velocity. Meanwhile, the uncertain crosswind and varied passenger mass faced by the DDEBs are decoupled into external disturbances and their effects on the system are eliminated in both controllers. Then, to cope with energy optimization problem in path tracking, a torque distribution controller is constructed by formulating the vehicle stability margin, tracking dynamic requirements and energy efficiency as constrained weighted least squares problem. Finally, a Trucksim-Simulink co-simulation is performed, where the simulation results demonstrated that the proposed control framework is robust and effective, and can achieve better energy saving effect compared to the original control methods.

Validation of maneuvering simulations for a KCS at different forward speeds using the 4-DOF MMG method

Ships with a high center of gravity and at relatively fast speed, such as container vessels, may experience significant heel during turning at a rudder angle of 35°. Accurate prediction of the maneuvering motion of such ships requires consideration of roll motion in addition to surge, sway, and yaw motions. This study applies the 4-Degrees of Freedom (4-DOF) Maneuvering Modeling Group (MMG) method, developed by one of the authors, as a practical simulation method that includes the roll-coupling effect, to predict the maneuvering of a Kriso Container Ship (KCS). To validate the accuracy of the maneuvering simulations, the results are compared with those obtained from free-running model tests for turning and zig-zag maneuvers. Furthermore, to capture the effect of speed on maneuvering, the free-running tests are conducted by varying the approach speed of the ship model. The test results reveal that the advance in turning and the overshoot angle in zig-zag maneuvers increase with speed, while the tactical diameter decreases. The simulation results obtained using the 4-DOF MMG method are consistent with the free-running test results with practical accuracy. Therefore, the 4-DOF MMG method proves useful in predicting the maneuvering of ships, such as container ships, at fast speeds.

Simulation of aircraft multi-axis acceleration in a four-axis Human Centrifuge System

High G-accelerations produced during Aircraft Combat Manoeuvres (ACMs) can adversely affect the physiological and psychological conditions of aircrew and deteriorate their performance. Human Centrifuge Systems (HCSs) provide an effective G-acceleration training tool to prepare and increase the G-tolerance of aircrew. Though highly capable HCSs are available, they are yet to be fully optimised to accurately and reliably recreate the G-vectors produced by ACMs. Optimisation steps to achieve this improvement involve the configurational structure, motion capability, and motion control of HCSs. To improve the motion capability and control of HCSs, the relationship between aircraft G-vectors and HCS G-vectors should be profoundly investigated. This work analyses the G-vectors of common ACMs and the corresponding G-vectors as well as kinematics of an active four Degree-of-Freedom (DoF) HCS. The mathematical models of an aircraft and HCS kinematics are developed using rigid body equations of motion through Newton-Euler method. The relationship between aircraft G-vectors and HCS G-vectors is established using inverse kinematics with an optimal solver. The outcomes of this study show that an active four-DoF HCS with gondola roll, pitch, and yaw rotation can replicate the G-vectors of common ACMs with small discrepancies. The largest error between the reference and achieved G-vectors occurred along the local z-axis of the HCS gondola during the transition of roll, pitch, and yaw motions of the gondola to the required angle replicating the G-vectors of the ACMs. The tracing errors are not significant; hence they can be mitigated with an optimal control technique. The presented outcomes will provide an essential step in identifying the optimal design and refined requirements for an HCS to efficiently replicate aircraft G-vectors. The applied methodology is easily adaptable to HCS with different structures and DoFs.

Frequency-Domain Analysis and Joint Torque Vibration Suppression Control on Two-Input-Two-Output Torque Difference Amplification Motor Drive System of Electrified Vehicles

<div>To improve the cornering performance, a torque vectoring differential (TVD) that generates a torque difference between the left and right wheels has been developed. Particularly, the use of multiple electric traction motors can easily achieve this. A TVD with a two-motor-torque difference amplification mechanism (TDA-TVD), which employs a unique alignment of planetary gears, has been studied and it can generate a larger torque difference compared to an individual-wheel-drive (IWD) system in the case of using the equal torque output from the traction motors. However, due to the mechanically complicated driving force transmission system including driveshafts and planetary gears, TDA-TVD is prone to cause torsional vibrations of the driveshaft, and the yaw rate of the vehicle body while differential torque is generated. A previous study derived a dynamic model TDA-TVD and designed a vibration suppression feedforward controller. While the study demonstrated a certain vibration suppression performance, it did not strictly consider the load side characteristics during the yaw motion. In addition, there was no frequency-domain analysis either. On the other hand, this study will analyze TDA-TVD in the frequency domain and propose a novel modeling method to construct vibration suppression controllers that deal with both longitudinal motion and yaw motion simultaneously. First, this article shows a theoretical frequency-domain analysis using matrices and obtains resonance frequencies of TDA-TVD. Second, TDA-TVD is modeled based on a summation-differential mode transformation (SDMT). Third, simulations and experimental evaluations of vibration suppression controls using a real vehicle equipped with the TDA-TVD are demonstrated.</div>

Experimental investigation on wave-induced bending moments of a 6,750-TEU containership in oblique waves

This study aims at the experimental investigation of wave-induced motions and loads of a containership model without forward speed in -120 degree oblique regular waves to study the influence of the wave steepness and provide reference data for future benchmark studies. A mooring system with 4 horizontally arranged spring lines was used to maintain the heading angle of a 1/65 scaled 9-segmented model designed to be as rigid as possible.Focuses were on studying the nonlinear effects due to the wave steepness on the vertical bending moment (VBM) and horizontal bending moment (HBM) near amidships, and 6-DOF motions at the center of gravity (COG) of the model. Several wave series that are distinguished by wave steepness were considered in the experiment accordingly. Each series consists of waves with various periods that were intended to cover the peak of the wave bending moment transfer functions. Through this, the nonlinear wave effects on the responses of the rigid body at various periods were determined. It was confirmed that the steeper wave contributes to the increase in the higher-order harmonic components including slamming events in the bending moments measured. The change in the characteristics of the wave bending moments according to the change in wave steepness was found to be very different from the linear response.A detailed discussion was made on the influence of the mooring system on the asymmetric horizontal bending moment (HBM) and the change in the average yaw motion. Experiments with and without a mooring system under the same wave condition were conducted, and the effect of the mooring system was identified. It was qualitatively confirmed that the mooring system’s restoring moment correlates with the asymmetric HBM and average yaw movement change.

SCALE EFFECT ON THE LINEAR HYDRODYNAMIC COEFFICIENTS OF DARPA SUBOFF

As well known, forces and moments acting on a ship are functions of Froude and Reynolds numbers. As a ship gets larger in size, these two numbers grow, which leads to different flow regimes around the hull. However, the state-of-the-art in maneuvering calculations is to consider the hydrodynamic coefficients as constants for model and full ship scales. For submerged bodies, the Froude number is insignificant due to the distant free water surface; therefore, these forces only depend on the Reynolds number. In this study, we consider the benchmark ‘DARPA’ Suboff form, which is extensively studied in the literature, and investigated the scale effects on the hydrodynamic coefficients with respect to the Reynolds number. Numerical studies are carried out on the bare hull form of the submarine. Captive motions of static drift and pure yaw motions are conducted utilizing the oblique towing and rotating arm tests via RANS-based CFD. Linear hydrodynamic coefficients are expressed with logarithmic equations as functions of the Reynolds number, explicitly showing the dependency on the ship’s model scale.

Integrated design and prototyping of a robotic eye system for ocular and craniofacial trauma simulators

This article presents the development of a prototype robotic eye-motion system for a novel simulator of ocular and craniofacial trauma that was developed for practical skills training of eye surgeons and first responders. The simulator fills a gap in the ophthalmological training domain, specifically between virtual reality-based systems for cataract and retinal repair and part-task trainers without quantitative measurement capabilities. Combining physical anatomical modules, instrument tracking and embedded sensors with a data acquisition/feedback system in a portable bench-top structure, it offers an alternative to animal- and cadaver-based training. The prototype robotic eye system described includes multiple human eye globe motion features: eye pitch and yaw motion, proptosis, and sensing of applied force to detect pressure/load applied to the globe.

Reaction Rod Link in Rear Cab Suspension to Control Cab Dynamics in Tractor-Semitrailer Vehicles

<div>Articulated vehicles form an important part of our society for the transport of goods. Compared to rigid trucks, tractor-trailer combinations can transport huge quantities of load without increasing the axle load. The fifth wheel (FW) acts as a bridge between the tractor and trailer, which can be moved within the range to achieve rated front and rear axle loads. When the FW is moved front, it adversely affects the cab dynamics and cab suspension forces. Compared to the cab pitch and roll, yaw motion increases drastically. The current study tries to address this issue by providing reaction rod links in the rear cab suspension.</div> <div>In this study, a 4×2 tractor with a three-axle semitrailer is considered by keeping the FW at its frontmost position, which is the worst-case scenario for a cab. Three different cases of reaction rod arrangement and its influence on cab dynamics are studied in comparison with a model without reaction rods. To assess this, time signal–based relative pseudo-fatigue damage, power spectral density (PSD), and level crossing plots are analyzed.</div> <div>The outcome shows that cab pitch, roll, and yaw motion reduce by a considerable amount with the presence of a reaction rod. Cab suspension forces will also reduce. The horizontal V-inclination of the reaction rod plays a major role in improving cab yaw motion and reducing the lateral forces. A straight link without any inclination helps in reducing the pitch and roll motion of the cab.</div>

Nonlinear inviscid aerodynamics of a wind turbine rotor in surge, sway, and yaw motions using a free-wake panel method

Abstract. We investigate the aerodynamics of a surging, heaving, and yawing wind turbine with numerical simulations based on a free-wake panel method. We focus on the UNAFLOW (UNsteady Aerodynamics of FLOating Wind turbines) case: a surging wind turbine which was modeled experimentally and with various numerical methods. Good agreement with experimental data is observed for amplitude and phase of the thrust with surge motion. We achieve numerical results of a wind turbine wake that accurately reproduce experimentally verified effects of surging motion. We then extend our simulations beyond the frequency range of the UNAFLOW experiments and reach results that do not follow a quasi-steady response for surge. Finally, simulations are done with the turbine in yaw and heave motion, and the impact of the wake motion on the blade thrust is examined. Our work seeks to contribute a different method to the pool of results for the UNAFLOW case while extending the analysis to conditions that have not been simulated before and providing insights into nonlinear aerodynamic effects of wind turbine motion.

Study on the yaw-based wake steering control considering dynamic flow characteristics for wind farm power improvement

Wake steering is one of the wind farm control strategies that can effectively reduce wake losses and increase power generation. Upstream wind turbines are set with yaw misalignment angles to deflect their wake away from downstream wind turbines, which will alleviate the wake effect. Currently, the yaw misalignment angles of the wind turbines are optimized through CFD or analytical wake models with a fixed inflow wind direction. However, wind turbines operate in rapidly changing wind directions where they cannot immediately track the optimized yaw misalignment angles owing to the slow yaw mechanism as expected. Therefore, a dynamic yaw control method is proposed in this study with the aim of balancing the energy gain and the number of yaw movements. Firstly, in order to improve efficiency, the yaw misalignment set points of wind turbines are optimized with different wind conditions based on the steady wake model. Then, we illustrate the procedure for determining the yaw misalignment angles for dynamic wind conditions. Finally, the performance of the yaw controller under the measured inflow condition is analyzed for the case of two-turbine array. It was found that the optimized yaw misalignment angles based on the steady model are applied to the dynamic control under changing wind direction, where the energy gain does not reach the estimated value using the static optimized control.

Research on the effect of yawing motion on tidal turbine performance based on actuator-line method

An actuator line method (ALM) code is used to investigate the yaw motion of tidal stream turbines, using different induced frequencies, amplitudes and starting angles. The relative velocity in the ALM calculation is corrected by considering the reaction force of the water on the floating tidal turbine. Because the ALM directly converts the flow velocity characteristics on the mesh element into the force characteristics, more small-scale and high-frequency signals appear, compared to Blade-Resolved Method simulations. In the results, the oscillation frequency of power coefficient and thrust coefficient (Cp, Ct) is twice of the yawing motion frequency when the starting yaw angle is 0°. Increasing the yawing amplitude as well as the starting angle both lower the mean values of Cp and Ct whilst the effect of frequency is slight. The turbine's hydrodynamic coefficients are obtained by best-fit model. The yawing amplitude has a moderate effect on the constant hydrodynamic terms.

Numerical analysis of fishtailing motion, buoy kissing and pullback force in a catenary anchor leg mooring (CALM) moored tanker system

The catenary anchor leg mooring (CALM) sys tem is one of the most complex hydrodynamic systems in terms of hydrodynamic theory. This complexity comes from a large amount of interaction between the buoy, its mooring legs, hawsers, and the moored tanker. A dynamic simulation analysis of a CALM moored tanker system is carried out in this research. A double spring hydrodynamic response system model composed of "Anchoring-Buoy" and "Hawser-Tanker" established for the CALM system in the given environmental conditions with the method of time domain coupling simulation, correlation, and comprehensive analysis simulations of the fishtailing motion, buoy kissing, hawser capacity, and pullback force. A numerical analysis shows that without pullback force, fishtailing occurs often. A pullback force of 800 kN in line with the tanker's centerline effectively reduces the yaw motion and preserves a safe distance between the tanker and the buoy, so fishtailing occurs less often, and buoy kissing does not occur. Thus, the pullback force of 800 kN represents astern propulsion and a pullback tug, as it significantly improves the behavior of the moored tanker in relation to the buoy. Therefore, it is recommended that a tug is always present while a tanker is moored to the CALM system.

Dynamic response and impact loads in twin-barge floatover installation

Complex impact loads during the floatover installation will threaten the mating operations. This paper presents the experimental investigation on the impact loads and dynamic response in the twin-barge floatover installation. In the model test, two critical loads transfer scenarios were modeled, including 0% and 100% stages in which the topsides are initially connected and separated from the barges. The near-zero gaps between the topsides and the twin-barge are simulated at two stages with the aim of investigating the collision characteristics. The impact loads on mating units, mooring forces, hawser forces, as well as motions of the twin-barge and the topsides were investigated. It is found that the windward barge motions are much larger than the leeward barge in sway, roll and yaw directions. The larger barge sway and yaw motions occurred at the 100% stage compared with the 0% stage. Statistical results indicate that the 100% stage seems to induce the larger impact loads on mating units than the 0% stage. The lateral impact loads were comparable with the vertical loads, in which the maximum lateral impact loads were even greater than the vertical impact loads. The mooring and hawser lines at the 100% stage are subjected to larger loads.

AUV-aided data collection considering adaptive ocean currents for underwater wireless sensor networks

Autonomous underwater vehicle (AUV)-assisted data collection is an efficient approach to implementing smart ocean. However, the data collection in time-varying ocean currents is plagued by two critical issues: AUV yaw and sensor node movement. We propose an adaptive AUV-assisted data collection strategy for ocean currents to address these issues. First, we consider the energy consumption of an AUV in conjunction with the value of information (VoI) over the sensor nodes and formulate an optimization problem to maximize the VoI-energy ratio. The AUV yaw problem is then solved by deriving the AUV's reachable region in different ocean current environments and the optimal cruising direction to the target nodes. Finally, using the predicted VoI-energy ratio, we sequentially design a distributed path planning algorithm to select the next target node for AUV. The simulation results indicate that the proposed strategy can utilize ocean currents to aid AUV navigation, thereby reducing the AUV's energy consumption and ensuring timely data collection.

6축 및 무한 요(yaw) 운동을 지원하는 공간정위상실 가상훈련 시뮬레이터를 위한 전향성 착각 체험 시나리오

We propose the Coriolis illusion scenario for 6-DoF and infinity yaw motion platforms. The proposed scenario can be applied to a simulator that includes a motion platform supporting 6-axis and infinite yaw motion. During the training, a trainee ascends to 1500 feet after take-off, continues level flight to the direction 145, and then turns to the direction 050 while maintaining a bank of 15 degrees. During the right turn, the motion platform rotates to the right at a speed of 30 degrees per second, and this movement implies the Coriolis illusion to the trainee. When the trainee reaches the 360 direction, a trainer orders the trainee to look his feet quickly. As a result, the trainee experiences abnormal sensations due to the Coriolis illusion. The result section shows the proposed scenario generates the Coriolis illusion to trainees.