Meng Qing-xin

The design of underwater hull-cleaning robot

The research on underwater ship-hull cleaning robot was conducted on the purpose of realizing the automation of cleaning underwater ship hull so that service life of ship will be prolonged and ship speed will raised. Moreover, fuel consumption and the work intensity of divers will be reduced. In this paper, the current situation and the latest technology in China and abroad were analyzed; meanwhile, the typical characteristics of the underwater cleaning robot were introduced. According to the work principle of the underwater cleaning robot, the emphasis was put on the analysis and study of permanent-magnetic absorption, magnetic wheel, airproof and anticorrosion, underwater cleaning equipment and control system. The robot is easy in rotation and simple in control.

The research on bionic crab-liked robot prototype

This paper introduces the whole developing process and main research techniques of the experiment prototype of crab-liked robot. It mainly includes the following parts: the shape analysis of crab, the establishment of robot model, kinematics analysis, the gaits study of eight-legged robot, design of machine framework, control system design and the experiment of the prototype. The bionic machine has eight legs with twenty-four degrees of freedom. As to its control mode, we adopt multi-layers distribution and recursion style that based on DSP. We take the dual-four legs gait as its radical gait. We made the walking experiment of the prototype after the mono-leg test. During the experiment the prototype can go ahead and back, run amuck, turn off and get over obstacles. It provides the theoretic and practical basis for the further research of bionic multi-leg robot.

Research on chaotic character of ship-radiated noise based on phase space reconstruction

The phase space reconstruction is an important method of chaotic time series analysis. In this paper, the method is applied to ship radiated noise obtained through both onshore acquisition system and underwater hydrophones. Utilizing the delay coordinate reconstruction method, the two primary parameters, delay time and embedding dimension are determined. By optimizing these two parameters, the reconstructed attractor is gained with prominent structure of nonlinear dynamics. The largest Lyapunov exponent and correlation dimension of the data have also been obtained, both of which exhibit chaotic behavior. Comparing with those of data acquired via hydrophones, it proves that the phase space reconstruction and chaotic time series analysis method is effective to seismic-acoustic signal processing.

Motor Driving Leg Design for Bionic Crab-like Robot

The paper presents the design of walking leg for bionics crab-like robot, which is driven with micro servo motor. The kinematic characteristics of the bionics machine are analysed for optimized structure parameters, which has been used in the robot design. A three closed loop motor control system structure for joint driver is also given, as well as the multi-joint driving system for walking robot leg.The paper presents the design of walking leg for bionics crab-like robot, which is driven with micro servo motor. The kinematic characteristics of the bionics machine are analysed for optimized structure parameters, which has been used in the robot design. A three closed loop motor control system structure for joint driver is also given, as well as the multi-joint driving system for walking robot leg.

Virtual prototype simulation on underwater hydraulic impingement shovel

The virtual prototype technology is applied to the design of the hydraulic impingement shovel, which is to increase the reliability of the design. The work principle of hydraulic impingement shovel is expatiated, and its dynamic equations are established. The 3D model of virtual prototype is built by PRO/E. Then the couple between the mechanical body of prototype and the hydraulic system is completed by virtue of ADAMS. Finally, the simulation is made on the virtual prototype. The simulation results show that the design of underwater hydraulic impingement shovel is rational. The virtual prototype technology could lay sound foundation of successful manufacturing of physical prototype for the first time and offer highly effective and feasible means for the design and production of underwater equipments.

Recognition of marine acoustic target signals based on wave structure and Support Vector Machine

According to research findings of speech acoustics, the timbre is applied to identify different types of targets. Since the information of timbre is indicated in the wave structure of time series, the feature of wave structure can be extracted to classify various marine acoustic targets. The method of feature extraction based on wave structure is studied. The nine-dimension feature vector is constructed on the basis of signal statistical characteristics, including zero-crossing wavelength, peek-to-peek amplitude, zero-crossing-wavelength difference, wave train areas and so on. And the Support Vector Machine (SVM) is applied as a classifier for two kinds of marine acoustic target signals. The kernel function is set Radial Basis Function (RBF). The penalty factor and parameter of RBF are properly selected by the method of combination of Differential Evolution (DE) and Particle Swarm Optimization (PSO), which helps to obtain better recognition rates than the grid search method.

Design and kinematics analysis of underwater guillotine saw for oil&gas pipe

Oil or gas was transferred to one place by pipeline after exploitation of ocean oil&gas resources. When an old pipeline was leaking, it must be repaired. The guillotine saw is a necessary tool for repairing underwater oil&gas pipes, and is used to cut off damaged offshore pipeline. It was composed of sine cutting mechanism, eccentric cam mechanism and spiral feed mechanism. According to its technique process of cutting pipe, kinematics model of the guillotine saw was proposed. The rotation center of principal axis acted as center of the coordinates, the whole kinematics model was deeply discussed and its simulation analyses were finished, such as movement contrail and cutting state of the tool. Total resultant movement was validated by simulation and underwater experiment. Analytical results showed that there were optimized parameters: cutting velocity v=314 mm/s, feed velocity vj=12.5 mm/min, height of lifting the saw blade in backhaul e=8∼10 mm, and e is determinated by synthetical factors of movement. Synchronously, experiment shows that work of the guillotine saw is reliable under the influence of current in shallow sea. So the kinematics model is applicable for offshore pipeline service. The guillotine saw can offer a service measure of underwater pipe for oil and gas transporting successfully.

Construction of Master Model from 3D Scanned Data Using Recursive Subdivision Scheme

Construction of master model of a product from 3D scanned data has become a more and more important topic in the field of CAD/CAM. By means of the recursive interpolating subdivision scheme on an initial mesh of 3D scanned data, a polygonal master model that consists of smaller planar patches may be directly obtained. The principle of constructing the initial mesh is presented. Recursive subdivision scheme for triangular mesh is introduced. A quadtree data structure is designed to store all the necessary information of interpolation subdivision.