Journal articles: '6DOF method'

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Talley, Michael A., and Shahram Sarkani. "A New Simulation Method Providing Shock Mount Selection Assurance." Shock and Vibration 10, no. 4 (2003): 231–67. http://dx.doi.org/10.1155/2003/756142.

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This paper presents the development and assessment of a practical and efficient process for assessing and/or designing shock isolation systems. This process combines practical methods for determining relative displacements and accelerations (e.g. shock response spectrum analysis) with a new, efficient, easy to use, 6 degree of freedom (6DOF) simulation method known as Shock Isolation Mount Predictions & Loading Estimates (SIMPLE). SIMPLE is also a tool that can easily account for uncertainties in isolated systems and their environments. The implementation of 6DOF rigid body theory in SIMPLE is validated by comparing simulation results with other analytical methods. This paper also summarizes assessments and designs for 60 different mounting systems using SIMPLE. In addition, experimental results from shock tests are compared with pre-test SIMPLE sensitivity simulations and with results of post-test model calibrations. These comparisons show the validity of: 1) using 6DOF analysis; 2) using statically derived load-deflection data for simulations; and 3) assessing and designing isolated systems using uncertainties in model parameters.

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Eppenga, Roeland, Koert Kuhlmann, Theo Ruers, and Jasper Nijkamp. "Accuracy assessment of target tracking using two 5-degrees-of-freedom wireless transponders." International Journal of Computer Assisted Radiology and Surgery 15, no. 2 (November 14, 2019): 369–77. http://dx.doi.org/10.1007/s11548-019-02088-9.

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Abstract Purpose Surgical navigation systems are generally only applied for targets in rigid areas. For non-rigid areas, real-time tumor tracking can be included to compensate for anatomical changes. The only clinically cleared system using a wireless electromagnetic tracking technique is the Calypso® System (Varian Medical Systems Inc., USA), designed for radiotherapy. It is limited to tracking maximally three wireless 5-degrees-of-freedom (DOF) transponders, all used for tumor tracking. For surgical navigation, a surgical tool has to be tracked as well. In this study, we evaluated whether accurate 6DOF tumor tracking is possible using only two 5DOF transponders, leaving one transponder to track a tool. Methods Two methods were defined to derive 6DOF information out of two 5DOF transponders. The first method uses the vector information of both transponders (TTV), and the second method combines the vector information of one transponder with the distance vector between the transponders (OTV). The accuracy of tracking a rotating object was assessed for each method mimicking clinically relevant and worst-case configurations. Accuracy was compared to using all three transponders to derive 6DOF (Default method). An optical tracking system was used as a reference for accuracy. Results The TTV method performed best and was as accurate as the Default method for almost all transponder configurations (median errors < 0.5°, 95% confidence interval < 3°). Only when the angle between the transponders was less than 2°, the TTV method was inaccurate and the OTV method may be preferred. The accuracy of both methods was independent of the angle of rotation, and only the OTV method was sensitive to the plane of rotation. Conclusion These results indicate that accurate 6DOF tumor tracking is possible using only two 5DOF transponders. This encourages further development of a wireless EM surgical navigation approach using a readily available clinical system.

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Chen, Kai, Fuqiang Shen, Jun Zhou, and Xiaofeng Wu. "Simulation Platform for SINS/GPS Integrated Navigation System of Hypersonic Vehicles Based on Flight Mechanics." Sensors 20, no. 18 (September 21, 2020): 5418. http://dx.doi.org/10.3390/s20185418.

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In this study, a simulation platform for an integrated navigation algorithm for hypersonic vehicles based on flight mechanics is designed. In addition, the generation method of inertial measurement unit data and satellite receiver data is introduced. First, the interface relationship between a high-precision six-degree-of-freedom (6DoF) model and the simulation platform in the launch-centered Earth-fixed frame is introduced. Three-axis theoretical specific force and angular velocity are output by the 6DoF model. Accelerometer and gyroscope error models are added, and integral processing of the specific force and angular velocity is performed to obtain velocity increment of the accelerometer and the angular increment of the gyroscope. These data are quantified to obtain the accelerometer and gyroscope pulses. The satellite’s pseudo-range and pseudo-range rate as well as its position and velocity are obtained from the theoretical position, velocity, the attitude of the hypersonic vehicle’s 6DoF model output, and the global positioning system (GPS) satellite broadcast ephemeris. The simulation data can be used for the verification of the loose and tight coupling integrated navigation algorithms. The simulation test verifies the accuracy of the designed method.

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Wu, Yan, Li Hui Cheng, Guo Feng Fan, and Cai Dong Wang. "Inverse Kinematics Solution and Optimization of 6DOF Handling Robot." Applied Mechanics and Materials 635-637 (September 2014): 1355–59. http://dx.doi.org/10.4028/www.scientific.net/amm.635-637.1355.

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The kinematics equation of the handling robot with six free degrees has multiple sets inverse solution, and the robot system only can choose one optimized solutions to drive the robot to work. The kinematics model of the robot is established by D-H method, and the inverse solution is derived by an algebraic method. The best flexibility principle was introduced to determine a set of optimal solutions from 8 sets of feasible solutions. The correctness of robot inverse solution method is verified through a set of calculation examples.

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AGUIAR, LILIANA, CARLOS ANDRADE, MARCO BRANCO, RITA SANTOS-ROCHA, FILOMENA VIEIRA, and ANTÓNIO VELOSO. "GLOBAL OPTIMIZATION METHOD APPLIED TO THE KINEMATICS OF GAIT IN PREGNANT WOMEN." Journal of Mechanics in Medicine and Biology 16, no. 06 (September 2016): 1650084. http://dx.doi.org/10.1142/s0219519416500846.

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Morphological changes are associated to pregnancy, such as weight gain and increased volume of the trunk. The soft tissue artifact can also increase with these characteristics and affect the real joint kinematics. The main objective of this study was to understand the effect of using three different constraining sets in the lower limb joints, in the amount of soft tissue artifact (STA) of pregnant women, in order to obtain the most appropriated joint set to be used in gait and in this population. The ankle, knee and hip joints were modeled respectively with the following characteristics: (1) Universal–revolute–spherical (URS), (2) spherical–revolute–spherical (SRS) and (3) spherical–spherical–spherical (SSS). The six degrees of freedom (6DOF) model was used as the basis for comparison and considered the one with the highest error associated to the STA. In pregnant women, the URS model seems to affect more the kinematic variables when compared with the 6DOF model. Assuming that the kinematic error associated with pregnant women is increased due to the STA, the URS model may be affecting more the angular kinematics of the knee joint. SSS model seems to be more appropriated to analyze gait in second trimester pregnant women.

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Yu, Zhaolong, Yugao Shen, Jørgen Amdahl, and Marilena Greco. "Implementation of Linear Potential-Flow Theory in the 6DOF Coupled Simulation of Ship Collision and Grounding Accidents." Journal of Ship Research 60, no. 03 (September 1, 2016): 119–14. http://dx.doi.org/10.5957/jsr.2016.60.3.119.

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Ship collisions and groundings are highly nonlinear and transient, coupled dynamic processes involving large structural deformations and fluid structure interactions. It has long been difficult to include all effects in one simulation. By taking advantage of the user-defined load subroutine and the user common variable, this article implements a model of hydrodynamic loads based on linear potential-flow theory into the nonlinear finite element code LS-DYNA, facilitating a fully coupled six degrees of freedom (6DOF) dynamic simulation of ship collision and grounding accidents. Potential-flow theory both with and without considering the forward speed effect is implemented for studying the speed influence. With the proposed model, transient effects of the fluid, global ship motions, impact forces, and structural damage can all be predicted with high accuracy. To the authors' knowledge, this is the first time the fully coupled 6DOF collision and grounding simulations are carried out with linear hydrodynamic loads for transient conditions but without simplification of collision forces. The proposed method is applied to calculations of an offshore supply vessel colliding with a rigid plate and with a submersible platform. The results are compared with a decoupled method and discussed with emphasis on the influence of different initial velocities. The proposed method is capable of predicting both the 6DOF ship motions and structural damage simultaneously with good efficiency and accuracy; hence, it will be a very promising tool in the application to ship collision and grounding analysis.

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Xi, Ke, and Chao Yan. "CFD Transonic Trajectory Predictions of Three-Store Ripple Release Using Chimera Method." Applied Mechanics and Materials 513-517 (February 2014): 4490–93. http://dx.doi.org/10.4028/www.scientific.net/amm.513-517.4490.

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The complicated unsteady flows with moving boundary were simulated numerically by coupling solving unsteady compressible Navier-Stokes equations and 6DOF rigid-body dynamics equations. The Chimera grid technology was used to handle the relative motion. The three-store ripple release of the wing-store configuration was simulated using this method. The computational results are in good agreement with data from other literature, showing that the method used has a strong applicability to complex multi-body separation problem.

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Gaeid, Khalaf S., Asaad F. Nashee, Ibrahim A. Ahmed, and Mohammed H. Dekheel. "Robot control and kinematic analysis with 6DoF manipulator using direct kinematic method." Bulletin of Electrical Engineering and Informatics 10, no. 1 (February 1, 2021): 70–78. http://dx.doi.org/10.11591/eei.v10i1.2482.

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The robots pay important role in all parts of our life. Hence, the modeling of the robot is essential to develop the performance specification. Robot model of six degree of freedom (6DoF) manipulator implemented numerically using model-based technique. The kinematic analysis and simulation were studied with Inverse kinematics of the robot manipulator through Denevit and Hartenberg method. Matrix transformation method is used in this work in order to separate joint variables from kinematic equations. The finding of the desired configuration is obtained precisely in all motion trajectory along the end-effector path. MATLAB/SIMULINK with R2018b is used for the implementation of the model-based robot system. Simulation results showed that the robot rinks follow their references smoothly and precisely and ensure the effectiveness of direct kinematic algorithm in the analysis and control of the robotic field.

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Jiang, Yifan, Xiang Huang, and Shuanggao Li. "An on-line compensation method of a metrology-integrated robot system for high-precision assembly." Industrial Robot: An International Journal 43, no. 6 (October 17, 2016): 647–56. http://dx.doi.org/10.1108/ir-03-2016-0091.

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Purpose The purpose of this paper is to propose an on-line iterative compensation method combining with a feed-forward compensation method to enhance the assembly accuracy of a metrology-integrated robot system (MIRS). Design/methodology/approach By the integration of a six degrees of freedom (6DoF) measurement system (T-Mac), the robot’ movement can be tracked with real-time measurement. With the on-line measured data, the proposed iterative compensation for absolute positioning and the feed-forward compensation for relative linear motion are integrated into the assembly process to improve the assembly accuracy. Findings It is found that the MIRS exhibits good performance in both accuracy and efficiency with the application of the proposed compensation method. With the proposed assembly process, a component can be automatically aligned to the target in seconds, and the assembly error can be decreased to 0.021 mm for position and 0.008° for orientation on average. Originality/value This paper presents a 6DoF MIRS for high-precision assembly. Based on the system, a novel on-line compensation method is proposed to enhance the assembly accuracy. In this paper, the assembly accuracy and the corresponding distance parameter are given by a series of experiments as reference for assembly applications.

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Elango, P., and R. Mohan. "Trajectory optimisation of six degree of freedom aircraft using differential flatness." Aeronautical Journal 122, no. 1257 (November 2018): 1788–810. http://dx.doi.org/10.1017/aer.2018.99.

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ABSTRACTThe flatness of a six-degree-of-freedom (6DoF) aircraft model with conventional control surfaces – aileron, flap, rudder and elevator, along with thrust vectoring ability is established in this work. Trajectory optimisation of an aircraft can be cast as an inverse problem where the solution for control inputs that yield desired trajectories for certain states is sought. The solution to the inverse problems for certain systems is made tractable when they exhibit differential flatness. Flatness-based trajectory optimisation has a significant advantage over an equivalent collocation-based method in terms of computational efficiency and viability for real-time implementation. An application for the flatness of 6DoF aircraft is shown in the trajectory optimisation for dynamic soaring, and its connection with an equivalent 3DoF flatness-based implementation is also brought out. The results are compared with that from a collocation-based approach.

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Zheng, Yan, Zhicheng Zhou, and Hai Huang. "A multi-frequency MIMO control method for the 6DOF micro-vibration exciting system." Acta Astronautica 170 (May 2020): 552–69. http://dx.doi.org/10.1016/j.actaastro.2020.02.033.

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Viejo, Diego, and Miguel Cazorla. "A robust and fast method for 6DoF motion estimation from generalized 3D data." Autonomous Robots 36, no. 4 (July 23, 2013): 295–308. http://dx.doi.org/10.1007/s10514-013-9354-z.

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Li, Shutong, Ahmad Ghasemi, Wenfang Xie, and Yanbin Gao. "An Enhanced IBVS Controller of a 6DOF Manipulator Using Hybrid PD-SMC Method." International Journal of Control, Automation and Systems 16, no. 2 (April 2018): 844–55. http://dx.doi.org/10.1007/s12555-016-0720-4.

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Wu, Tiecheng, Wanzhen Luo, Dapeng Jiang, Rui Deng, and Shuo Huang. "Numerical Study on Wave-Ice Interaction in the Marginal Ice Zone." Journal of Marine Science and Engineering 9, no. 1 (December 22, 2020): 4. http://dx.doi.org/10.3390/jmse9010004.

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The effect of waves on ice sheet is critical in the marginal ice zone (MIZ). Waves break large sea ice into small pieces and cause them to collide with each other. Simultaneously, the interaction between sea ice and waves attenuates these waves. In this study, a numerical research is conducted based on a computational fluid dynamics (CFD) method to investigate the response of single ice floe to wave action. The obtained results demonstrate that the sea ice has a violent six degree of freedom (6DoF) motion in waves. Ice floes with different sizes, thicknesses, and shapes exhibit different 6DoF motions under the action of waves. The heave and surge response amplitude operator (RAO) of the sea ice are related to wavelength. Furthermore, the overwash phenomenon can be observed in the simulation. The obtained results are compared with the model test in the towing tank based on artificial ice, and they agree well with test results.

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Jensen, Mathias Laustsen, Rasoul Mahshid, Greta D’Angelo, Jeppe U. Walther, Malte K. Kiewning, Jon Spangenberg, Hans Nørgaard Hansen, and David Bue Pedersen. "Toolpath Strategies for 5DOF and 6DOF Extrusion-Based Additive Manufacturing." Applied Sciences 9, no. 19 (October 4, 2019): 4168. http://dx.doi.org/10.3390/app9194168.

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This paper introduces two new deposition-strategies for five degrees of freedom (5DOF) and 6DOF extrusion-based additive manufacturing (AM), called the tool path projection- and parent-child-approach, respectively. The tool path projection method can be automated, and allows for the generation of concentric shells layers, which remedy geometrical deviations (known as the stair-case effect) that are typically seen in 3DOF AM processes that potentially require secondary post treatment by machining or grinding of the final part. In the parent-child approach, the designer specifies the manufacturing direction for each distinct feature, thereby helping to remove the need for support material, as well as enabling new features to be dynamically added to the part.

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Kamata, Ryoya, Ryosuke Tamura, Satoshi Niitsu, Hiroshi Kawaharada, and Hiroyuki Hiraoka. "Use of 1DOF Haptic Device for Remote-Controlled 6DOF Assembly." International Journal of Automation Technology 8, no. 3 (May 5, 2014): 452–59. http://dx.doi.org/10.20965/ijat.2014.p0452.

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This paper describes a remote controlled assembly using a haptic device. Most haptic devices have six Degrees Of Freedom (DOFs) for a higher sense of reality. However, for assembly operation, the simultaneous motion of parts with only one or two DOFs is required, and force feedback to operators is used only to maintain contact and detect collisions among parts. This leads to the possibility of assembly operations using a haptic device with a small number of DOFs. In this paper, we propose virtual planes to perform remote control of a 6DOF assembly by way of 1DOF user operations. Virtual planes separate the DOFs for user operation and for automatically generated motions that complement the user operation DOF in each assembly operation. A prototype system was developed with a 6DOF manipulator and camera. The system allows an operator to place virtual planes in any position and orientation using a camera image of the workspace. The experiment results showed the effectiveness of the method for remote controlled assembly without geometry information on the parts.

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Zeng, Ji Guo, Jing Yu Liu, and Qiang Yu. "Design and Development of 6DOF Hydraulic Motion Platform for Vehicle Driving Simulator." Applied Mechanics and Materials 505-506 (January 2014): 315–18. http://dx.doi.org/10.4028/www.scientific.net/amm.505-506.315.

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The high-level driving simulators generally involve motion platform. This paper describes the design and development of a 6DOF hydraulic motion platform for vehicle driving simulator. Firstly, the structure and kinematic model of the platform are introduced. Then, the speed characteristics of the hydraulic cylinders by using different positive and negative voltage are studied. Because the cylinder startup time and hydraulic pump pressure will both affect the platform's final position, so a real-time platform control method according the sensor feedback is described. Finally, commonly used control functions of the platform are listed. The simulator and the motion platform run well by using this control method.

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Hussnain, Z., S. Oude Elberink, and G. Vosselman. "AN AUTOMATIC PROCEDURE FOR MOBILE LASER SCANNING PLATFORM 6DOF TRAJECTORY ADJUSTMENT." ISPRS - International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences XLII-1 (September 26, 2018): 203–9. http://dx.doi.org/10.5194/isprs-archives-xlii-1-203-2018.

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Abstract. In this paper, a method is presented to improve the MLS platform’s trajectory for GNSS denied areas. The method comprises two major steps. The first step is based on a 2D image registration technique described in our previous publication. Internally, this registration technique first performs aerial to aerial image matching, this issues correspondences which enable to compute the 3D tie points by multiview triangulation. Similarly, it registers the rasterized Mobile Laser Scanning Point Cloud (MLSPC) patches with the multiple related aerial image patches. The later registration provides the correspondence between the aerial to aerial tie points and the MLSPC’s 3D points. In the second step, which is described in this paper, a procedure utilizes three kinds of observations to improve the MLS platform’s trajectory. The first type of observation is the set of 3D tie points computed automatically in the previous step (and are already available), the second type of observation is based on IMU readings and the third type of observation is soft-constraint over related pose parameters. In this situation, the 3D tie points are considered accurate and precise observations, since they provide both locally and globally strict constraints, whereas the IMU observations and soft-constraints only provide locally precise constraints. For 6DOF trajectory representation, first, the pose [R, t] parameters are converted to 6 B-spline functions over time. Then for the trajectory adjustment, the coefficients of B-splines are updated from the established observations. We tested our method on an MLS data set acquired at a test area in Rotterdam, and verified the trajectory improvement by evaluation with independently and manually measured GCPs. After the adjustment, the trajectory has achieved the accuracy of RMSE X=9cm, Y=14cm and Z=14cm. Analysing the error in the updated trajectory suggests that our procedure is effective at adjusting the 6DOF trajectory and to regenerate a reliable MLSPC product.

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Jouir, Tasarinan, Reuben Strydom, Thomas M. Stace, and Mandyam V. Srinivasan. "Vision-only egomotion estimation in 6DOF using a sky compass." Robotica 36, no. 10 (July 25, 2018): 1571–89. http://dx.doi.org/10.1017/s0263574718000577.

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SUMMARYA novel pure-vision egomotion estimation algorithm is presented, with extensions to Unmanned Aerial Systems (UAS) navigation through visual odometry. Our proposed method computes egomotion in two stages using panoramic images segmented into sky and ground regions. Rotations (in 3DOF) are estimated by using a customised algorithm to measure the motion of the sky image, which is affected only by the rotation of the aircraft, and not by its translation. The rotation estimate is then used to derotate the optic flow field generated by the ground, from which the translation of the aircraft (in 3DOF) is estimated by another customised, iterative algorithm. Segmentation of the rotation and translation estimations allows for a partial relaxation of the planar ground assumption, inherently increasing the robustness of the approach. The translation vectors are scaled using stereo-based height to compute the current UAS position through path integration for closed-loop navigation. Outdoor field tests of our approach in a small quadrotor UAS suggest that the technique is comparable to the performance of existing state-of-the-art vision-based navigation algorithms, whilst also removing all dependence on additional sensors, such as an IMU or global positioning system (GPS).

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Puomio, Otto, Nils Meyer-Kahlen, and Tapio Lokki. "Locating Image Sources from Multiple Spatial Room Impulse Responses." Applied Sciences 11, no. 6 (March 10, 2021): 2485. http://dx.doi.org/10.3390/app11062485.

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Measured spatial room impulse responses have been used to compare acoustic spaces. One way to analyze and render such responses is to apply parametric methods, yet those methods have been bound to single measurement locations. This paper introduces a method that locates image sources from spatial room impulse responses measured at multiple source and receiver positions. The method aligns the measurements to a common coordinate frame and groups stable direction-of-arrival estimates to find image source positions. The performance of the method is validated with three case studies—one small room and two concert halls. The studies show that the method is able to locate the most prominent image sources even in complex spaces, providing new insights into available Spatial Room Impulse Response (SRIR) data and a starting point for six degrees of freedom (6DoF) acoustic rendering.

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Nguyen, Van-Tu, Duc-Thanh Vu, Warn-Gyu Park, and Chul-Min Jung. "Navier–Stokes solver for water entry bodies with moving Chimera grid method in 6DOF motions." Computers & Fluids 140 (November 2016): 19–38. http://dx.doi.org/10.1016/j.compfluid.2016.09.005.

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Montagud, Mario, Cristian Hurtado, Juan Antonio De Rus, and Sergi Fernández. "Subtitling 3D VR Content with Limited 6DoF: Presentation Modes and Guiding Methods." Applied Sciences 11, no. 16 (August 14, 2021): 7472. http://dx.doi.org/10.3390/app11167472.

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All multimedia services must be accessible. Accessibility for multimedia content is typically provided by means of access services, of which subtitling is likely the most widespread approach. To date, numerous recommendations and solutions for subtitling classical 2D audiovisual services have been proposed. Similarly, recent efforts have been devoted to devising adequate subtitling solutions for VR360 video content. This paper, for the first time, extends the existing approaches to address the challenges remaining for efficiently subtitling 3D Virtual Reality (VR) content by exploring two key requirements: presentation modes and guiding methods. By leveraging insights from earlier work on VR360 content, this paper proposes novel presentation modes and guiding methods, to not only provide the freedom to explore omnidirectional scenes, but also to address the additional specificities of 3D VR compared to VR360 content: depth, 6 Degrees of Freedom (6DoF), and viewing perspectives. The obtained results prove that always-visible subtitles and a novel proposed comic-style presentation mode are significantly more appropriate than state-of-the-art fixed-positioned subtitles, particularly in terms of immersion, ease and comfort of reading, and identification of speakers, when applied to professional pieces of content with limited displacement of speakers and limited 6DoF (i.e., users are not expected to navigate around the virtual environment). Similarly, even in such limited movement scenarios, the results show that the use of indicators (arrows), as a guiding method, is well received. Overall, the paper provides relevant insights and paves the way for efficiently subtitling 3D VR content.

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Farah, Edris, and Shao Gang Liu. "3D Modeling and Closed-Form Inverse Kinematics Solution for 6dof Surgical Robot." Applied Mechanics and Materials 455 (November 2013): 533–38. http://dx.doi.org/10.4028/www.scientific.net/amm.455.533.

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Since robots began to inter the medical fields, more research efforts and more attention have been given to this kind of robots. In this paper six degrees of freedom surgical robot was studied. The Denavit-Hartenberg parameters of the robot have been computed and 3D model has been built by using open source robotics toolbox. The paper also discussed a closed form solution for the inverse kinematics problem by using inverse kinematic decoupling method.

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Li, Wei, Xiao Liang, Jianguo Lin, Ping Guo, Qiang Ma, Zhenpeng Dong, Jiamin Liu, Zhenhe Song, and Hengqi Wang. "Numerical Simulation of Ship Oil Spill in Arctic Icy Waters." Applied Sciences 10, no. 4 (February 19, 2020): 1394. http://dx.doi.org/10.3390/app10041394.

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This paper presents a three-dimensional numerical simulation model of an oil spill for application in emergency treatment methods under icy water conditions. The combined effects of wind, wave, current and ice implemented in our model correspond to Arctic Ocean conditions. A discrete element method combined with an overset grid was adopted to track the trajectory movements of oil film with medium-density ice floes and simulate the flow field of moving ice of large displacement in six degrees of freedom (6DOF). The probability of oil spill area extensions were estimated by a response surface method (RSM). Results showed reduced risk of pollution in icy water conditions and greater drift action of oil film. Accordingly, the spraying location and quantity of oil-dispersant could be rapidly specified.

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Liu, Qiang, Yu Han, Min Hao Liu, and Shang Fei Tian. "Implementation of Dynamic Simulation System on Six DOF Industrial Robot." Applied Mechanics and Materials 373-375 (August 2013): 206–12. http://dx.doi.org/10.4028/www.scientific.net/amm.373-375.206.

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A dynamic simulation system whose model objects were industrial robot was designed. An advanced and quickly inverse kinematic algorithm was used to solve inverse kinematic equation for 6DOF industrial robot, the time of solve was improved. The method of trajectory planning was developed. The vision simulation for industrial robot was completed by Creator and Vega software. Simulation result shows that the requirement of kinematic control has been achieved and provides an intuitive and convenient tool for research of the kinematic control algorithm for industrial robot.

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Zheng, Feng, Zhang, and Li. "A Method for Simultaneously Measuring 6DOF Geometric Motion Errors of Linear and Rotary Axes Using Lasers." Sensors 19, no. 8 (April 12, 2019): 1764. http://dx.doi.org/10.3390/s19081764.

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A novel method for simultaneously directly measuring six-degrees-of-freedom (6DOF) geometric motion errors of CNC machine tools was proposed, and a corresponding measurement system was developed. This method can not only be applied for measuring a linear axis, but also for a rotary axis. A single-mode fiber was used to separate the measuring unit from the laser source in order to ensure system thermal stability and measurement accuracy. The method has the advantages of high efficiency and good accuracy, and requires no complicated decoupling calculation. The positioning error of the linear axis and radial motion error of the rotary axis are measured by laser interferometry and other 5DOF geometric motion errors by laser collimation. A series of experiments were performed to verify the feasibility and effectiveness of the developed measurement system.

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Hsu, Cheng-Hsing, Jun-Liang Chen, Shan-Chi Yuan, and Kuang-Yuan Kung. "CFD Simulations on the Rotor Dynamics of a Horizontal Axis Wind Turbine Activated from Stationary." Applied Mechanics 2, no. 1 (March 5, 2021): 147–58. http://dx.doi.org/10.3390/applmech2010009.

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The adaptive dynamic mesh, user-defined functions, and six degrees of freedom (6DOF) solver provided in ANSYS FLUENT 14 are engaged to simulate the activating processes of the rotor of the Grumman WS33 wind system. The rotor is activated from stationary to steady operation driven by a steady or periodic wind flow and its kinematic properties and power generation during the activating processes. The angular velocity and angular acceleration are calculated directly by the post-processed real-time 6DOF solver without presuming a known rotating speed to the computational grid frame. The maximum angular velocity of the rotor is approximately proportional to the driving wind speed, and its maximal angular acceleration is also closely proportional to the square of the driving wind speed. The evolution curves of the normalized rotor angular velocities and accelerations are almost identical due to the self-similarity properties of the rotor angular velocities and accelerations. The angular velocity of the rotor will reach its steady value. One can use these steady angular velocities to predict the mechanical power generations of the rotor. The momentum analysis theory and the blade element momentum method are applied to predicted power generations and reveal good agreements with experimental data in the low wind speed range.

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Xu, Lai Bin. "Longitudinal Dynamics Response of M-Wing Morphing Aircraft." Advanced Materials Research 538-541 (June 2012): 2627–30. http://dx.doi.org/10.4028/www.scientific.net/amr.538-541.2627.

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A simulation methodology suitable for morphing wing aircraft is presented, accounting for the changes in both inertial and aerodynamic properties. The aerodynamics was generated with vortex lattice method and solved concurrently with 6DOF nonlinear extended equations of motion. Due to the wing morphing, there are 4 additional forces and moments exhibiting in the extended equations of motion. The simulation mythology was applied to M-wing morphing aircraft, and the longitudinal dynamic response was analyzed with the wing morphing symmetrically. The results show that the additional forces and moments influence the flight dynamic considerably

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Yue, Jin, Guang Ren, Xiao Liang, Xiao Wei Qi, and Geng Tian Li. "Motion Modeling and Simulation of High-Speed Unmanned Surface Vehicle." Applied Mechanics and Materials 44-47 (December 2010): 1588–92. http://dx.doi.org/10.4028/www.scientific.net/amm.44-47.1588.

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According to the motion characteristic and the hydrodynamics of high-speed deep-V planings, forces and moments acted on a deep-V planing propelled by a contra-rotating propeller were analyzed, and on the basis of MMG modeling method, a real-time 6DOF mathematical motion model for the high-speed unmanned surface vehicle(USV) was built and the performance was simulated using the Matlab/Simulink software tool. Compared with the actual sea trial data, the results show that the proposed model can better reflect and simulate the maneuverability of the USV under ocean environment.

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Ricardo, Diogo, Júlia Teles, Maria Raquel Raposo, António Prieto Veloso, and Filipa João. "Test-Retest Reliability of a 6DoF Marker Set for Gait Analysis in Cerebral Palsy Children." Applied Sciences 11, no. 14 (July 15, 2021): 6515. http://dx.doi.org/10.3390/app11146515.

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Background: Cerebral palsy (CP) is a complex pathology that describes a group of motor disorders with different presentations and functional levels. Three-dimensional gait analysis is widely used in the assessment of CP children to assist in clinical decision making. Thus, it is crucial to assess the repeatability of gait measurements to evaluate the progress of the rehabilitation process. The purpose of the study is to evaluate test-retest reliability of a six-degree-of-freedom (6DoF) marker set in key points of gait kinematics, kinetics, and time-distance parameters in children with CP. Methods: trials were performed on two different days within a period of 7.5 ± 1.4 day. Motion capture data was collected with 14 infrared, high-speed cameras at a frequency rate of 100 Hz, synchronized in time and space with two force plates. Intraclass correlation coefficients considering the two-way mixed model, and absolute agreement (ICC[A,k]) were calculated for anthropometric, time–distance, kinematic and kinetic parameters of both lower limbs. Results: the majority of gait parameters demonstrated a good ICC, and the lowest values were in the kinematic variables. Conclusions: this study indicates wide-ranging reliability values for lower limb joint angles and joint moments of force during gait, especially for frontal and transverse planes. Although the use of a 6DoF-CAST in CP children was shown to be a feasible method, the gait variation that can be observed between sessions in CP children seems to be related not only to the extrinsic factors but also to their different gait patterns and affected sides.

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Sun, Lu, Hussein Al Osman, and Jochen Lang. "An Augmented Reality Online Assistance Platform for Repair Tasks." ACM Transactions on Multimedia Computing, Communications, and Applications 17, no. 2 (June 2021): 1–23. http://dx.doi.org/10.1145/3429285.

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Our augmented reality online assistance platform enables an expert to specify 6DoF movements of a component and apply the geometrical and physical constraints in real-time. We track the real components on the expert’s side to monitor the operations of an expert. We leverage a remote rendering technique that we proposed previously to relieve the rendering burden of the augmented reality end devices. By conducting a user study, we show that the proposed method outperforms conventional instructional videos and sketches. The answers to the questionnaires show that the proposed method receives higher recommendation than sketching, and, compared to conventional instructional videos, is outstanding in terms of instruction clarity, preference, recommendation, and confidence of task completion. Moreover, as to the overall user experience, the proposed method has an advantage over the video method.

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Bao Nghi, Le Luong, and Bui Cong Thanh. "A 6DOF super element for nonlinear analysis of composite frames with partial interaction and semi-rigid connections." Vietnam Journal of Mechanics 33, no. 1 (March 30, 2011): 13–26. http://dx.doi.org/10.15625/0866-7136/33/1/35.

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This paper presents a displacement-based finite element formulation for nonlinear analysis of steel - concrete composite planar frames subjected to combined action of gravity and lateral loads. A 6DOF super element is proposed for modeling composite beam, allowing for partial interaction between the steel beam and the concrete slab, semi-rigid nature of beam to column composite connection and material nonlinearity. The load control method and the displacement control method are utilized for tracing the structural equilibrium paths, and the direct method is utilized for solving the nonlinear problem. Numerical examples, concerning a two-span continuous composite beam, a portal composite frame and a six-storey composite frame, are performed. The results are compared with experience data or theoretical results from other studies and are discussed for influences of the factors mentioned above on behaviour of composite beams and composite frames.

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Zhang, Wen-Qing, Liang-Long Da, De-Yan Tian, Qin-Dong Sun, Wen-Long Wang, and Wen-Jing Chen. "Research on Anti-Interference Nonlinear Adaptive Control Method for Autonomous Underwater Gliders." Mathematical Problems in Engineering 2021 (August 9, 2021): 1–10. http://dx.doi.org/10.1155/2021/9998061.

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In this paper, the characteristics of underactuation are analyzed according to the working principle of underwater glider, a complete 6DOF model of underwater glider is established, and the error equation of 3D path tracking is given. Based on the line-of-sight navigation method in three-dimensional space, the nonlinear adaptive control strategy is designed, and the roll angle control law, pitch angle control law, and depth control law of underwater glider are given. The tracking error of underwater glider is proved to be convergent by Lyapunov stability theorem. Finally, the results of marine experiments verify that the nonlinear controller designed in this paper can overcome the influence of constant current disturbance under certain conditions and has good robustness and good tracking effect under different ocean current sizes and course angles. Of course, one control method cannot be applicable to all sea conditions. When the angle between the size and direction of the ocean current exceeds a certain value, the tracking control of the underwater glider will show obvious divergence. Therefore, the stability range against the interference of the sea current is given in this paper.

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Ortega, Mario, Eugenio Ivorra, Alejandro Juan, Pablo Venegas, Jorge Martínez, and Mariano Alcañiz. "MANTRA: An Effective System Based on Augmented Reality and Infrared Thermography for Industrial Maintenance." Applied Sciences 11, no. 1 (January 3, 2021): 385. http://dx.doi.org/10.3390/app11010385.

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In recent years, the benefits of both Augmented Reality (AR) technology and infrared thermography (IRT) have been demonstrated in the industrial maintenance sector, allowing maintenance operations to be carried out in a safer, faster, and more efficient manner. However, there still exists no solution that optimally combines both technologies. In this work, we propose a new AR system—MANTRA—with specific application to industrial maintenance. The system can automatically align virtual information and temperature on any 3D object, in real time. This is achieved through the joint use of an RGB-D sensor and an IRT camera, leading to high accuracy and robustness. To achieve this objective, a pose estimation method that combines a deep-learning-based object detection method, YOLOV4, together with the template-based LINEMOD pose estimation method, as well as a model-based 6DOF pose tracking technique, was developed. The MANTRA system is validated both quantitatively and qualitatively through a real use-case, demonstrating the effectiveness of the system compared to traditional methods and those using only AR.

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Jin, Lei, Xiaojuan Wang, Mingshu He, and Jingyue Wang. "DRNet: A Depth-Based Regression Network for 6D Object Pose Estimation." Sensors 21, no. 5 (March 1, 2021): 1692. http://dx.doi.org/10.3390/s21051692.

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This paper focuses on 6Dof object pose estimation from a single RGB image. We tackle this challenging problem with a two-stage optimization framework. More specifically, we first introduce a translation estimation module to provide an initial translation based on an estimated depth map. Then, a pose regression module combines the ROI (Region of Interest) and the original image to predict the rotation and refine the translation. Compared with previous end-to-end methods that directly predict rotations and translations, our method can utilize depth information as weak guidance and significantly reduce the searching space for the subsequent module. Furthermore, we design a new loss function function for symmetric objects, an approach that has handled such exceptionally difficult cases in prior works. Experiments show that our model achieves state-of-the-art object pose estimation for the YCB- video dataset (Yale-CMU-Berkeley).

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Hachiuma, Ryo, and Hideo Saito. "Pose Estimation of Primitive-Shaped Objects from a Depth Image Using Superquadric Representation." Applied Sciences 10, no. 16 (August 6, 2020): 5442. http://dx.doi.org/10.3390/app10165442.

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This paper presents a method for estimating the six Degrees of Freedom (6DoF) pose of texture-less primitive-shaped objects from depth images. As the conventional methods for object pose estimation require rich texture or geometric features to the target objects, these methods are not suitable for texture-less and geometrically simple shaped objects. In order to estimate the pose of the primitive-shaped object, the parameters that represent primitive shapes are estimated. However, these methods explicitly limit the number of types of primitive shapes that can be estimated. We employ superquadrics as a primitive shape representation that can represent various types of primitive shapes with only a few parameters. In order to estimate the superquadric parameters of primitive-shaped objects, the point cloud of the object must be segmented from a depth image. It is known that the parameter estimation is sensitive to outliers, which are caused by the miss-segmentation of the depth image. Therefore, we propose a novel estimation method for superquadric parameters that are robust to outliers. In the experiment, we constructed a dataset in which the person grasps and moves the primitive-shaped objects. The experimental results show that our estimation method outperformed three conventional methods and the baseline method.

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Kratochví, Aleš. "A new approach of creating a finite element stick model for flutter analysis." MATEC Web of Conferences 304 (2019): 01015. http://dx.doi.org/10.1051/matecconf/201930401015.

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The article describes a new approach of creating a finite element stick model for the purpose of the aircraft flutter analysis. The control surface properties are merged with a lifting surface element as a special degree of freedom (DOF). The number of DOF for the coordination system is increased from the classical 6DOF to 9DOF. A new beam element and concentrated mass element are present for the purpose of modal and flutter analysis. The advantage of this method lies in reducing the number of model nodes and introduction of a more appropriate arrangement of global mass matrix for eigen-value extraction. Quality of results is not affected. The paper also presents a verification example of a real sports aircraft.

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SAJKOWSKI, Maciej. "Control system design using rapid prototyping method on the examples of voice controlled mobile robot and 6dof parallel manipulator." PRZEGLĄD ELEKTROTECHNICZNY 1, no. 6 (June 5, 2015): 117–21. http://dx.doi.org/10.15199/48.2015.06.23.

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Wang, Xiao, Ming Wu, and Rong Rong Ying. "Numerical Calculation of Hydrodynamic Interference Coefficients between Hull, Rudder and Propeller." Advanced Materials Research 591-593 (November 2012): 1949–53. http://dx.doi.org/10.4028/www.scientific.net/amr.591-593.1949.

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CFD developed rapidly in capability and practicality during past years. A lot of research works on numerical simulation of viscous flow field around ship were widely carried out in past decades. But the research of interference effect among the hull, rudder and propeller was rarely concerned. In this paper, based on an unsteady Reynolds Averaged Navier–Stokes method, the dynamic mesh methods(6DOF) are adopted to simulate straight line and oblique towing test of ship with twin propellers and twin rudders. And based on the simulation results, the interference coefficients, such as effective weak coefficient ωp, rudder’s effective longitudinal velocity uR, effective attack angle αR, rudder force’s modificatory factor αH for shiphandling derivational transverse force and its dimensionless distance to ship’s gravity point, are calculated. The computed results of this paper agree well with the experimental results carried out in the tower tank of ITTC. It shows that the methods on numerical calculation of Interference Coefficients between hull, rudder and propeller is successful.

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Yang, Wenjun, Xiaojun Liu, Xiaoting Guo, Wenlong Lu, Zhenjian Yao, and Zili Lei. "A method for simultaneously measuring 6DOF geometric motion errors of a precision rotary stage based on absolute position-distance measurement." Optics and Lasers in Engineering 138 (March 2021): 106420. http://dx.doi.org/10.1016/j.optlaseng.2020.106420.

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Deilamsalehy, Hanieh, and Timothy C. Havens. "Fuzzy adaptive extended Kalman filter for robot 3D pose estimation." International Journal of Intelligent Unmanned Systems 6, no. 2 (April 16, 2018): 50–68. http://dx.doi.org/10.1108/ijius-12-2017-0014.

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Purpose Estimating the pose – position and orientation – of a moving object such as a robot is a necessary task for many applications, e.g., robot navigation control, environment mapping, and medical applications such as robotic surgery. The purpose of this paper is to introduce a novel method to fuse the information from several available sensors in order to improve the estimated pose from any individual sensor and calculate a more accurate pose for the moving platform. Design/methodology/approach Pose estimation is usually done by collecting the data obtained from several sensors mounted on the object/platform and fusing the acquired information. Assuming that the robot is moving in a three-dimensional (3D) world, its location is completely defined by six degrees of freedom (6DOF): three angles and three position coordinates. Some 3D sensors, such as IMUs and cameras, have been widely used for 3D localization. Yet, there are other sensors, like 2D Light Detection And Ranging (LiDAR), which can give a very precise estimation in a 2D plane but they are not employed for 3D estimation since the sensor is unable to obtain the full 6DOF. However, in some applications there is a considerable amount of time in which the robot is almost moving on a plane during the time interval between two sensor readings; e.g., a ground vehicle moving on a flat surface or a drone flying at an almost constant altitude to collect visual data. In this paper a novel method using a “fuzzy inference system” is proposed that employs a 2D LiDAR in a 3D localization algorithm in order to improve the pose estimation accuracy. Findings The method determines the trajectory of the robot and the sensor reliability between two readings and based on this information defines the weight of the 2D sensor in the final fused pose by adjusting “extended Kalman filter” parameters. Simulation and real world experiments show that the pose estimation error can be significantly decreased using the proposed method. Originality/value To the best of the authors’ knowledge this is the first time that a 2D LiDAR has been employed to improve the 3D pose estimation in an unknown environment without any previous knowledge. Simulation and real world experiments show that the pose estimation error can be significantly decreased using the proposed method.

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Okawa, Marina, Takafumi Taketomi, Goshiro Yamamoto, Makoto Fujisawa, Toshiyuki Amano, Jun Miyazaki, and Hirokazu Kato. "A model-based tracking framework for textureless 3D rigid curved objects." Journal on Interactive Systems 3, no. 2 (January 23, 2013): 1. http://dx.doi.org/10.5753/jis.2012.611.

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This paper addresses the problem of tracking texturelessrigid curved objects. A common approach uses polygonalmeshes to represent curved objects inside an edge-based trackingsystem. However, in order to accurately recover their shape,high quality meshes are required, creating a trade-off betweencomputational efficiency and tracking accuracy. To solve thisissue, we suggest the use of quadrics calculated for each patchin the mesh to give local approximations of the object contour.This representation reduces considerably the level of detail of thepolygonal mesh while maintaining tracking accuracy. The noveltyof our research lies in using curves to represent the quadrics’projection in the current viewpoint for distance evaluation insteadof comparing directly the edges from the mesh and detectededges in the video image. In our tracking framework, we alsoinclude a method to calculate the measurable Degrees of Freedom(DoF) of the target object. This is used to recover the poseparameters when the object has less than 6DoF. Experimentalresults compare our approach to the traditional method ofusing sparse and dense meshes. Finally, we present a potentialAugmented Reality application of the proposed method.

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Eryılmaz, Cenk, and V. E. Omurlu. "SQP Optimization of 6dof 3x3 UPU Parallel Robotic System for Singularity Free and Maximized Reachable Workspace." Journal of Robotics 2019 (February 3, 2019): 1–14. http://dx.doi.org/10.1155/2019/3928705.

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The determination of kinematic parameters for a parallel robotic system (PRS) is an important and a critical phase to maximize reachable workspace while avoiding singular configurations. Stewart Platform (SP) mechanism is one of the widely known PRS and it is used to demonstrate the proposed technique. In the related literature, GCI (Global Condition Index) and LCI (Local Condition Index) are the commonly used performance indexes which give a measure about the dexterity of a mechanism. In this work, Sequential Quadratic Programming (SQP) method is used to optimize kinematic parameters of a 6dof 3x3 UPU SP in order to reach maximum workspace satisfying small condition numbers. The radius of mobile and base platforms and the lengths of the legs used in the platform are chosen as kinematic parameters to be optimized in a multiobjective optimization problem. Optimization is performed at different stages and the number of optimized kinematic parameters is increased at each level. In conclusion, optimizing selected kinematic parameters at once by using SQP technique presents the best results for the PRS.

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Sargeant, B., S. Robson, E. Szigeti, P. Richardson, A. El-Nounu, and M. Rafla. "A METHOD TO ACHIEVE LARGE VOLUME, HIGH ACCURACY PHOTOGRAMMETRIC MEASUREMENTS THROUGH THE USE OF AN ACTIVELY DEFORMABLE SENSOR MOUNTING PLATFORM." ISPRS - International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences XLI-B5 (June 15, 2016): 123–29. http://dx.doi.org/10.5194/isprsarchives-xli-b5-123-2016.

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When using any optical measurement system one important factor to consider is the placement of the sensors in relation to the workpiece being measured. When making decisions on sensor placement compromises are necessary in selecting the best placement based on the shape and size of the object of interest and the desired resolution and accuracy. One such compromise is in the distance the sensors are placed from the measurement surface, where a smaller distance gives a higher spatial resolution and local accuracy and a greater distance reduces the number of measurements necessary to cover a large area reducing the build-up of errors between measurements and increasing global accuracy. This paper proposes a photogrammetric approach whereby a number of sensors on a continuously flexible mobile platform are used to obtain local measurements while the position of the sensors is determined by a 6DoF tracking solution and the results combined to give a single set of measurement data within a continuous global coordinate system. The ability of this approach to achieve both high accuracy measurement and give results over a large volume is then tested and areas of weakness to be improved upon are identified.

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Sargeant, B., S. Robson, E. Szigeti, P. Richardson, A. El-Nounu, and M. Rafla. "A METHOD TO ACHIEVE LARGE VOLUME, HIGH ACCURACY PHOTOGRAMMETRIC MEASUREMENTS THROUGH THE USE OF AN ACTIVELY DEFORMABLE SENSOR MOUNTING PLATFORM." ISPRS - International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences XLI-B5 (June 15, 2016): 123–29. http://dx.doi.org/10.5194/isprs-archives-xli-b5-123-2016.

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When using any optical measurement system one important factor to consider is the placement of the sensors in relation to the workpiece being measured. When making decisions on sensor placement compromises are necessary in selecting the best placement based on the shape and size of the object of interest and the desired resolution and accuracy. One such compromise is in the distance the sensors are placed from the measurement surface, where a smaller distance gives a higher spatial resolution and local accuracy and a greater distance reduces the number of measurements necessary to cover a large area reducing the build-up of errors between measurements and increasing global accuracy. This paper proposes a photogrammetric approach whereby a number of sensors on a continuously flexible mobile platform are used to obtain local measurements while the position of the sensors is determined by a 6DoF tracking solution and the results combined to give a single set of measurement data within a continuous global coordinate system. The ability of this approach to achieve both high accuracy measurement and give results over a large volume is then tested and areas of weakness to be improved upon are identified.

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Liu, Jingshu, and Yuan Li. "Visual Servoing with Deep Learning and Data Augmentation for Robotic Manipulation." Journal of Advanced Computational Intelligence and Intelligent Informatics 24, no. 7 (December 20, 2020): 953–62. http://dx.doi.org/10.20965/jaciii.2020.p0953.

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We propose a visual servoing (VS) approach with deep learning to perform precise, robust, and real-time six degrees of freedom (6DOF) control of robotic manipulation to ease the extraction of image features and estimate the nonlinear relationship between the two-dimensional image space and the three-dimensional Cartesian space in traditional VS tasks. Owing to the superior learning capabilities of convolutional neural networks (CNNs), autonomous learning to select and extract image features from images and fitting the nonlinear mapping is achieved. A method for designing and generating a dataset from few or one image, by simulating the motion of an eye-in-hand robotic system is described herein. Therefore, network training requiring a large amount of data and difficult data collection occurring in actual situations can be solved. A dataset is utilized to train our VS convolutional neural network. Subsequently, a two-stream network is designed and the corresponding control approach is presented. This method converges robustly with the experimental results, in that the position error is less than 3 mm and the rotation error is less than 2.5° on average.

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An, Tong, JianHua Wang, YuLong Pan, and HaiShan Chen. "A Low-Order Partial Integrated Guidance and Control Scheme for Diving Hypersonic Vehicles to Impact Ground Maneuver Target." Mathematical Problems in Engineering 2021 (September 7, 2021): 1–12. http://dx.doi.org/10.1155/2021/7407739.

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In this article, a low-order partial integrated guidance and control (PIGC) design method is proposed for diving hypersonic vehicles to impact ground maneuver target. A three-channel analytical model of body rates is deduced based on acceleration components of the hypersonic vehicle. By combining the analytical model of body rates and relative dynamic model between the hypersonic vehicle and target, three-channel commands of body rates are directly generated based on the extended state observer (ESO) technique, sliding mode control approach, and dynamic surface control theory in the guidance subsystem. In the attitude control subsystem, a sliding mode controller is designed to track the commands of body rates and generate commands of control surface fin deflections. By making full use of acceleration information of the hypersonic vehicle measured by the mounted accelerometer, the proposed PIGC design method provides a novel solution to compensate the unknown acceleration of the ground maneuver target. Besides, the order of design model is also reduced, and the design process is simplified. The effectiveness and robustness of the PIGC design method are verified and discussed by 6DOF simulation studies.

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San, Yam Ke, Gordon Chiew, Chin Howe, Vincent Chieng Chen Lee, and Sukanta Roy. "Analysis on Rolling Damping of a Conventional Boat fitted with T-shaped Bilge Keels." MATEC Web of Conferences 202 (2018): 02007. http://dx.doi.org/10.1051/matecconf/201820202007.

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This work presents a numerical study on the effect of T-shaped bilge keels on the roll damping of a conventional boat. A scaled boat model with the same dimensions as that of Irkal et al. [2] was fitted with two T-shaped bilge keels at the edges of the model. Computational Fluid Dynamics method was employed to simulate the roll decay motion of the boat. The motion of the boat is captured using a 6DOF model and the Overset grid approach. Comparison was performed on the damping characteristics of the conventional I-shaped and the T-shaped bilge keels. In addition, the impact of the aspect ratio of the keel bilges on the roll damping of the boat was evaluated. It was found that the bilge keel aspect ratio influences the damping coefficient non-linearly. Sufficiently large aspect ratio, i.e. an aspect ratio greater than 2, is necessary in order to obtain an effective damping on the peak angle.

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ANDO, Takashi. "Obtaining the center of gravity, inertia parameters and finite element approximation models of electromagnetic nonlinearity on 6DOF magnetic levitation system by adaptive control method." Transactions of the JSME (in Japanese) 81, no. 824 (2015): 14–00496. http://dx.doi.org/10.1299/transjsme.14-00496.

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Lu, Yun, Jinbo Wu, Weijia Li, and Yaozhong Wu. "A New Six-DoF Parallel Mechanism for Captive Model Test." Polish Maritime Research 27, no. 3 (September 1, 2020): 4–15. http://dx.doi.org/10.2478/pomr-2020-0041.

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AbstractIn order to obtain the hydrodynamic coefficients that can save cost and meet the accuracy requirements, a new hydrodynamic test platform based on a 6DoF (six degrees of freedom) parallel mechanism is proposed in this paper. The test platform can drive the ship to move in six degrees of freedom. By using this experimental platform, the corresponding hydrodynamic coefficients can be measured. Firstly, the structure of the new device is introduced. The working principle of the model is deduced based on the mathematical model. Then the hydrodynamic coefficients of a test ship model of a KELC tank ship with a scale of 1:150 are measured and 8 typical hydrodynamic coefficients are obtained. Finally, the measured data are compared with the value of a real ship. The deviation is less than 10% which meets the technical requirements of the practical project. The efficiency of measuring the hydrodynamic coefficients of physical models of ships and offshore structures is improved by the device. The method of measuring the hydrodynamic coefficients by using the proposed platform provides a certain reference for predicting the hydrodynamic performance of ships and offshore structures.

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Journal articles on the topic '6DOF method'

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