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NUMERICAL SIMULATION OF BATOID LOCOMOTION

Journal of Hydrodynamics 2011年第5期23卷 594-600页

作者： CHEN Wei-shan WU Zhi-jun LIU Jun-kao SHI Sheng-jun ZHOU Yang State Key Laboratory of Robotics and System Harbin Institute of Technology Harbin 150001 China

The hydrodynamics of batoid swimming motions is investigated using the three-dimensional simulation of a self-propelled body in still water. The kinematics of batoid swimming is characterized by large amplitude undulations of the pectoral fins while the middle part of the body remains straight. The majority of the thrust is generated by pectoral fins. Linear and quadratic amplitude variations are used for the pectoral fins in analyzing the locomotion of the batoid. Navier-Stokes equations are used to solve the unsteady fluid flow. A user defined function and a dynamic mesh method are applied to track the batoid locomotion. The mean swimming velocities of 1.6 BL/s and 1.3 BL/s are achieved, respectively, with thrust coefficients of 0.13 in and 0.095 in the dynamical simulation, where BL/s is the body length per second. The maximum propulsive efficiency 19% is achieved when the frequency of the undulation is 2.2 Hz in both amplitude variations.

关键词： batoid fish undulation pectoral fin dynamical simulation

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Analysis and Application of the Singularity Locus of the Stewart Platform

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Chinese Journal of Mechanical Engineering 2011年第1期24卷 133-140页

作者： MA Jianming HUANG Qitao XIONG Haiguo HAN Junwei State Key Laboratory of Robotics and System Harbin Institute of Technology Harbin 150001 China

The direct use of the determinant of Jacobian matrix being equal to zero for the singularity analysis is generally difficult which is due to complexity of the Jacobian matrix of 6-DOF parallel manipulators,especially for Stewart ***,several scholars make their great contribution to the effective solution of this problem,but neither of them find the right *** paper gives a brief analysis of the kinematics of the Stewart platform and derives the Jacobian matrices of the system through the velocity *** the basis of the traditional classification of singularities,the second type of singularity is *** assumption of any three of the six variables of the Stewart platform as constant is made,then the analytical expression of singularity locus equation of the second type singularity which contains another three pose variables is *** singularity locus is represented in the three-dimensional space through the derived *** correctness and validity of the proposed method are verified through ***,the singularity analysis of an electric Stewart platform in its desired workspace and reachable workspace is ***,one can easily identify whether singularity exists in a given workspace of a Stewart platform and determine whether the existed singularity can be avoided through the proposed *** proposed method also provides theoretical principle for the design and application of the Stewart platform and has great significance for the trajectory planning and control.

关键词： parallel manipulator Stewart platform Jacobian matrix singularity locus workspace

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Planar region alignment based ego-motion estimation for mobile robot

Planar region alignment based ego-motion estimation for mobi...

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IEEE International Conference on Mechatronics and Automation

作者： Z. L. Wang B. G. Cai F. Z. Yi Y. Liu J. Zhao State Key Laboratory of Robotics and System Harbin Institute of Technology Harbin China School of Electronic Information and Engineering Beijing Jiaotong University Beijing China

ISBN: (纸本)9781467312752

The ego-motion estimation is a basic task in many operations of a mobile robot. An accurate and robust result of motion estimation can greatly improve the operation. In this paper, we assume the mobile robot with visual observer is moved on flat ground and a constrained camera-robot configuration is used to simplify the camera motion model. Based on the assumption and simplified camera-robot configuration, the 3D camera motion can be separately estimated by planar region alignment between two frames. Firstly, a detected 2D motion between two frames is used to align corresponding planar regions, such an alignment or registration removes the effects of camera rotation, and the resulting residual parallax displacement field between the two region-aligned images is an epipolar field centered at the FOE (Focus-of-Expansion). Then the camera translation can be recovered from the epipolar field. The camera rotation is recovered from the computed 3D translation and the detected 2D motion. The camera motion model is derived and expressed by two parts, the multistage process for ego-motion estimation is introduced. Some experiments with real images demonstrate the robustness of the motion estimation. And the factors which may affect the results are discussed.

关键词： Cameras Robot vision systems Motion estimation Robustness Mobile robots Transmission line matrix methods Computer vision

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A robust multistage ego-motion estimation

A robust multistage ego-motion estimation

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Congress on Image and Signal Processing, CISP

作者： Z. L. Wang B. G. Cai X. L. Du S. Ou J. Zhao State Key Laboratory of Robotics and System Harbin Institute of Technology Harbin China School of Electronic Information and Engineering Beijing Jiaotong University Beijing China

In this paper, we assume the platform with visual observer is moved on flat ground and a constrained camera-platform configuration. The constrained camera-platform is used to simplify the camera motion model. Based on the assumption and simplified camera-platform configuration, the 3D camera motion can be separately estimated by planar region alignment between two frames. Firstly, a detected 2D motion between two frames is used to align corresponding planar regions, such an alignment or registration can removes the effects of camera rotation, and the resulting residual parallax displacement field between the two region-aligned images is an epipolar field centered at the FOE (Focus-of-Expansion). Then the camera translation can be recovered from the epipolar field. The camera rotation is recovered from the computed 3D translation and the detected 2D motion. The camera motion model is derived and represented by two parts, and a multistage ego-motion estimation process is introduced. Some experiments with real images demonstrate the robustness of the proposed motion estimation method.

关键词： Cameras Motion estimation Robustness Transmission line matrix methods Computer vision Robot vision systems Estimation

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Target Tracking Algorithm Using Finite-time Convergence Smooth Second-order Sliding Mode Controller for Mobile Robots

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Chinese Journal of Mechanical Engineering 2011年第3期24卷 414-419页

作者： GE Lianzheng ZHAO Lijun GAO Tong State Key Laboratory of Robotics Technique and System Harbin Institute of Technology Harbin 150001 China

Target tracking control for wheeled mobile robot （WMR） need resolve the problems of kinematics model and tracking ***-order sliding mode control is a valid method used in the nonlinear tracking control system,which can eliminate the chattering of sliding mode *** there lacks the research of robustness and uncertain factors for high-order sliding mode *** address the fast convergence and robustness problems of tracking target,the tracking mathematical model of WMR and the target is *** on the finite-time convergence theory and second order sliding mode method,a nonlinear tracking algorithm is designed which guarantees that WMR can catch the target in finite *** the same time an observer is applied to substitute the uncertain acceleration of the target,then a smooth nonlinear tracking algorithm is *** on Lyapunov stability theory and finite-time convergence,a finite time convergent smooth second order sliding mode controller and a target tracking algorithm are designed by using second order sliding mode *** simulation results verified that WMR can catch up the target quickly and reduce the control discontinuity of the velocity of WMR.

关键词： mobile robots second order sliding mode finite-time convergence observer

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Extraction of coastline in high-resolution remote sensing images based on the active contour model

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Journal of Harbin Institute of Technology(New Series) 2011年第4期18卷 13-18页

作者：邢坤付宜利王树国韩现伟 State Key Laboratory of Robotics and System Harbin Institute of Technology

While executing tasks such as ocean pollution monitoring,maritime rescue,geographic mapping,and automatic navigation utilizing remote sensing images,the coastline feature should be *** methods are not satisfactory to extract coastline in high-resolution panchromatic remote sensing *** contour model,also called snakes,have proven useful for interactive specification of image contours,so it is used as an effective coastlines extraction ***,coastlines are detected by water segmentation and boundary tracking,which are considered initial contours to be optimized through active contour *** better energy functions are developed,the power assist of snakes becomes *** internal energy has been done to reduce problems caused by convergence to local minima,and new external energy can greatly enlarge the capture region around features of *** normalization processing,energies are iterated using greedy algorithm to accelerate convergence *** experimental results encompassed examples in images and demonstrated the capabilities and efficiencies of the improvement.

关键词： remote sensing images coastline extraction active contour model greedy algorithm

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Image sub-pixel recognition method for optical precise adjustment

Image sub-pixel recognition method for optical precise adjus...

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2012 9th IEEE International Conference on Mechatronics and Automation, ICMA 2012

作者： Ma, Li Zhou, Shasha Ouyang, Hangkong He, Zhengfeng Rong, Weibin Sun, Lining School of Mechatronic Engineering and Automation University of Shanghai Shanghai China State Key Laboratory of Robotics and System Harbin Institute of Technology Harbin Heilongjiang Province China

ISBN: (纸本)9781467312776

Cavity adjustment is a critical step for manufacturing laser gyro. Location relation of the laser facula and the aperture images should be detected to provide control information for the movement of the cavity adjustment mechanism. According to the image features, a sequence image variance method is proposed to segment the laser facula image, and maximum variance between clusters method (Ostu algorithm) is adopted to acquire automatic threshold value to segment the aperture image. Use the edge detection of binary image to obtain pixel edge of the laser facula and the aperture images. And sub-pixel edge point information of the images is given by a parameter fitting method. Centre points coordinates of the laser facula and the aperture are achieved by fitting sub-pixel edge utilizing the least square ellipse fitting method. The experimental results of cavity adjustment verify the validity of image recognition method of the laser facula and the aperture. © 2012 IEEE.

关键词： Binary images

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Working principle and design of a double cylinders type traveling wave ultrasonic motor using composite transducer

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Journal of Harbin Institute of Technology(New Series) 2011年第2期18卷 28-32页

作者：陈维山刘英想刘军考石胜君 State Key Laboratory of Robotics and System Harbin Institute of Technology

A double cylinders type traveling wave ultrasonic motor using composite transducer was *** proposed stator contained two cylinders and one composite transducer,and the transducer located on the outer surfaces of *** composite transducer included two exponential horns located on leading ends,and the horns insected with the cylinders at tip *** degenerated flexural vibration modes spatially and temporally orthogonal to each other were excited in each cylinder by the composite *** this new design,a single transducer could excite two flexural traveling waves in the ***,elliptical motions were achieved at the particles on the *** working principle of the proposed motor was *** cylinder and transducer were designed with *** resonant frequencies of two vibration modals of the stator were tuned to be the same,and the motion trajectories of nodes on the teeth were *** analysis results show that the motion trajectories of teeth are *** results of this paper can guide the development of this new type of ultrasonic motor.

关键词： ultrasonic motor traveling wave double cylinders composite transducer FEM

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Actuating mechanism and design of a T-type linear ultrasonic motor

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Journal of Harbin Institute of Technology(New Series) 2011年第2期18卷 43-46页

作者：刘英想刘军考陈维山石胜君 State Key Laboratory of Robotics and System Harbin Institute of Technology

To take advantage of merits of higher output-power and efficiency of bolt-clamped transducer,a T-type linear ultrasonic motor was proposed in this *** proposed motor contained a horizontal transducer and a vertical *** horizontal transducer included two exponential shape horns,and the vertical transducer contained one exponential shape *** the horns intersected at tip ends where a driving foot was *** longitudinal vibrations of transducers were excited by the stretching vibration of PZT *** vibrations were superimposed in the motor and generated elliptical trajectory at the driving *** actuating mechanism of the proposed motor was *** two working modals of the motor were gained with *** resonant frequencies of two working modals were degenerated by adjusting the structural *** motion trajectory of nodes on the driving foot was gained by transient *** vibration amplitude of node on the driving foot indicates that the proposed motor has potential good output *** results verify the feasibility of the proposed design and provide instructions for the development of the new ultrasonic motor.

关键词： ultrasonic motor linear T-type longitudinal transducer FEM

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A ring type standing wave ultrasonic motor using cantilever type longitudinal transducers

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Journal of Harbin Institute of Technology(New Series) 2011年第1期18卷 52-56页

作者：刘英想刘军考陈维山石胜君 State Key Laboratory of Robotics and System Harbin Institute of Technology

The disadvantages of classic ring type ultrasonic motor were *** obtain large mechanical output power,a ring type standing wave ultrasonic motor using cantilever type longitudinal transducers was *** are four pairs of cantilevers on one side of the ring,and four PZT ceramics are set between each pair of cantilevers.A screw fastened the PZT ceramics and cantilevers together to form a longitudinal *** bending vibration mode of the ring is excited by the stretching vibration of the PZT ***,linear simple harmonic motions are achieved at the particle on the *** the driving force is the frictional force between rotor and *** working principle of the proposed motor was *** ring and the longitudinal transducer were designed with *** sensitive parameters of resonant frequency of the transducer and ring could be gained with modal *** longitudinal vibration modal of transducer and bending vibration modal of ring were degenerated,and the motion trajectories of nodes on the teeth were *** results of this paper could guide the development of this new type of motor.

关键词： ultrasonic motor standing wave ring type vibration characteristic FEM

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