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2005 Vol. 31, No. 07

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Mechanism design and control method of reconfigurable tracked robot
Wang Tianmiao, Zou Dan, Chen Diansheng
2005, 31(07): 705-708.
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The reconfigurable tracked robot was developed for all-terrain recon. Based on the unique characters of reconfigurable robot, modular mechanical and electrical structure and control method were discussed. The tracked robot was composed of four basic locomotion modules, three connecting rods and two rotational articulations. By the different configurations of all the modules, the mechanical reconfiguration of the tracked vehicle was realized. The distributed control system was adopted. Based on the ARM(advanced RISC microprocessor) real time embedded control system, the reconfiguration was realized when the mechanical structure of the robot was reconfigured. The tracked robot was validated that it has the excellent adaptable ability in complex terrain and has easy and simple reconfigurable performance when it executed recon in the building interior simulating the real task.
Trial voyage of SPC-II fish robot
Liang Jianhong, Zou Dan, Wang Song, Wang Ye
2005, 31(07): 709-713.
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The SPC-II fish robot prototype is an experimental platform which validates the stability, high efficiency and maneuverability by utilizing the caudal fin propulsion mechanism. SPC-II doesn't simply mimic the shape of certainkind of real fish, but takes the swimming stability as the primary factor of undersea bionic vehicle design that is taken into consideration. It overcome the swing of fish body effectively ,which makes tail fin propulsion break away from disturbance and reduce the sailing resistance. The SPC-II, about 1.2 m long, utilizes an entirely rigid pressure hull with batteries, GPS(global position system), compass and two-joint servomotors installed inside. SPC-II can swim freely at a fixed depth within 5 m under water. Its maximum speed is 2.8 kn and its power consumption is less than 250 W.The line sailing velocity and turning maneuverability were tested. The test under the badly circumstance of long distance was taken. The comparisons with experimental platform home and broad show that he SPC-II fish has its own advantages in the terms of its shape and sailing velocity.
Conceptual design of compliant leveling mechanism
Yu Zhiwei, Yu Jingjun, Sun Minglei, Zong Guang
2005, 31(07): 714-717.
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In the process of aligning two wafers, leveling them is a very important means to ensure a high aligning precision. A practical and compliant leveling mechanism to smooth away the faults existing in present leveling mechanisms was proposed in the course of microfabrication. This mechanism has the advantages of the high leveling precision, the short leveling time, the compact mechanical configuration, the simple movement control unit, etc. The leveling principle and its corresponding conceptual design were discussed. In the section of conceptual design, the mechanical configuration and the structure of the key parts (flexure hinge) used in the leveling mechanism were introduced, and restriction conditions were established as well for calculating main design parameters from the following three aspects: the original-dimension restriction, the deformative-dimension restriction and the stress restriction. The elasticity of the key part was calculated employing the energy method, and thesimulation of the elasticity using commercial finite element analysis software ANSYS8.0 was carried out, which verifies the former theoretical calculated result. Some key problems to be solved in the design were put forward.
Mechanism and kinematics analysis of climbing robot for complex curved surfaces
Xu Zhenxiang, Liu Rong, Heng Jin, Shi Long
2005, 31(07): 718-721.
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A robot mechanism for complex curved surface with rail was proposed in order to enable the robot to move fast on the complex curved surface. An idea of modularity mechanism designing based on function separate was applied because of the environment with complex constraint. The robot functions consist of scramble and pose adjusting and moving fast along rail, which are realized by two different mechanisms respectively. Scramble and pose adjusting is implemented by quadruped mechanism and moving fast along rail is implemented by wheel-rail mechanism. The movement of scramble and pose adjusting was analyzed, and the analytic equation about control variables of relative joints was obtained for sphere surface. The changing of the relative joints in other different curved surfaces was analyzed in quality. The theory analysis result and the design example show the robot mechanism can adapt different complex curved surface with rails and the control is easy.
Motion mapping in master-slave grasp for dexterous hands
Li Jiting, Zhang Yuru
2005, 31(07): 722-725.
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Grasp planning is one of the key issues of the dexterous hand research. At present master-slave grasp is a feasible solution. The core problem is to map the human grasp into that of the dexterous hands reasonably. Aiming at the anthropomorphic dexterous hands, the method of mapping human hand motion to the robot hand was investigated. The mapping model of master-slave motion was established in the Cartesian space, and the mapping matrix was formulated and simplified considering the similarity of the kinematics of the human and dexterous hands. Through the linear scalar mapping the human hand fingers can control the corresponding fingertip motions of the robot hand independently. The mapping results were analyzed by the experiments, and the fundamental requirements for mapping were discussed. The experimental results illustrate that the mapped fingertip positions of the dexterous hands are basically within their workspaces thus ensure the master-slave motion feasible, and the motion locus are similar thus ensure the master-slave control simple and intuitive.
Method to avoid dynamic singularity for flexible manipulators
Gao Zhihui
2005, 31(07): 726-729.
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When the natural frequency of the flexible manipulators is equal to the frequency of the mode force and the mode force is stronger, the dynamic singularity will happen. The structure parameter and kinetic parameter of the flexible manipulator are the factors which influence the natural frequency of the flexible manipulator. A method to avoid the dynamic singularity was given on the condition that the predetermined task is not changed. The method is that a mass can be attached to the existed flexible manipulator to change the frequency of the flexible manipulator, so as to avoid the dynamic singularity. A method to plan the mass and the position where the mass attached to the flexible manipulator was given. A space manipulator with three arms ( the last one is flexible) was simulated, and the method was verified to be effective. This method can also used in other mechanism system.
Study on wrist dexterity of minimally invasive surgical robot
Liu Da, Hu Lei
2005, 31(07): 730-734.
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In order to implement robot path planning according to the surgery optimum pose, the wrist dexterity of minimally invasive surgical robot was geometrically investigated. According to the structure and characteristic of minimally invasive surgical robot tools, wrist dexterity was analyzed by using analytic method of tool pose sphere. The impact of predefined pose of tools on the wrist dexterity was studied. It was proved that when the tool axes and the endjoint axes are perpendicular, 2-DOF wrist could meet the dexterity requirementsof minimally invasive surgery. The impact of axis setover of joints on wrist dexterity was studied. It was proved that when the setover along Z axis exists, the end tool could realize poses in all orientation. Based on these principles, the necessary conditions of how 2-DOF wrist becomes dexterous wrist were proposed. According to the conditions, the wrist structure of minimally invasive surgical robot is simplified.
Omnidirectional kinematics analysis on bi-driver spherical robot
Sun Hanxu, Xiao Aiping, Jia Qingxuan, Wang Liangqing
2005, 31(07): 735-739.
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A new type of mobile spherical robots, which are based on a nonholonomic system and takes two motors as impetus sources, was developed. The developed spherical robot has only two input parameters while a sphere rolling on a plane has three degrees of freedom, thus the spherical robot is under actuated. When its IDU(inside drive unit) changes the position of the barycenter of weights by uses two motors as impetus, it can realize any omnidirectional movement and move in a arbitrary direction with zero turning radius. The under-actuated designs can make the structure simpler while making the physical layout more complicated. The omnidirectional movement of the spherical robot varies with different positions and inclinations between the long axis and the vertical line. The architectural feature of this robot were analyzed. Preliminary analysis and research was made on spherical robot kinematics and dynamics by using nonholonomic system dynamics, and based on the concerned knowledge such as Eulerian angle and three-dimensional rotation-group.
Analysis and application of large-deformation flexible hinge
Jia Ming, Bi Shusheng, Yu Jingjun, Xu Yicun
2005, 31(07): 740-743.
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Flexible hinge transfers motion and force by deformation of flexible element, the stiffness of which made by metal material can be calculated on the premise of Hooke’s law. While the stress-strain relation of hyperelastic material is unconformable to Hooke’s law, it must be derived by stress-energy functions. To analysis the stiffness of flexible hinge made by hyperelastic material, a notch flexible hinge was proposed. Approximate formula for stiffness of such hinge was deduced and its scope of application was analyzed. Analysis result comparison between finite element analysis model and approximate formula shows consistency. Flapping flight is ubiquitous in nature and all birds and insects have compliant thoraxes for activating wings to flap. Flexible hinge using in the construction of mechanism offered improvements over rigid hinge on some aspects of large range of motion, long life and saving in power. Application in compliant thorax of micro aero vehicle with flapping wings was realized.
Analysis of moving capability of a spherical mobile robot
Zhan Qiang, Jia Chuan, Ma Xiaohui, Chen Ming
2005, 31(07): 744-747.
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The special structure of spherical mobile robots makes them very suitable to be used in harsh environments where human interventions are hard to reach, such as outer planets and fields. When a spherical mobile robot moves in such environments, moving capability is a key to decide whether the robot can successfully finish given tasks. BHQ-1G, a spherical mobile robot, was introduced.The kinematic and dynamic model of the robot were built with geometry method and Lagrange equation. Its moving capability such as moving in straight line, slope climbing, obstacle climbing and turning radius, etc., were analyzed thoroughly. The analysis results not only demonstrate the feasibility of the design and determine some factors that can affect the moving capability of BHQ-1G, but also can be used to do the optimum design and prototype development of the robot.
Analysis of kinematics and dexterity for new surgery robot
Tang Can, Yun Chao
2005, 31(07): 748-752.
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Based on the requirement of clinical application, the structure characteristic of minimally invasive neurosurgery assisted robot was analyzed. Space kinematics model of robot was founded. The fact that reverse solution of the robot has analytic solution was confirmed. The correctness of reverse solution was validated via VC simulation program. Simultaneously some key problem in founding space kinematics model of robot was argued. Three methods of dexterity analysis were presented, and the freedom of robot dexterity was defined, the dexterity of robot wrist was analyzed. With concept of posture sphere, wrist dexterity definition of the five degree-of-freedom robot was proposed; boundary expression of vector tool posture sphere was presented. Analysis method of wrist dexterity was proposed, the distribution of robot dexterity area was determined and provided by MATLAB simulation analysis. With the help of kinematics and dexterity analysis, reliable reference can be supplied for structure design, and the foundation of realization of robot control function would be established.
Reverse driving character of 2-DOF closed chain haptic device
Guo Xin, Guo Weidong, Zhang Yuru
2005, 31(07): 753-756.
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Reverse driving character plays an important role in evaluating the performance of haptic device, and it’s the primary rule in the mechanical design. The problem of 2-DOF haptic device design for improving reverse driving character was investigated. A 2-DOF closed chain haptic device was designed and a physical prototype was produced in the factory; Based on the physical prototype, the 2-DOF haptic device was analyzed with the method of dynamics which was called Lagrabgian equation, the reverse driving character of the haptic device was evaluated by the generalized inertia ellipsoid (GIE) which can be illustrated with graph directly. With the help of changing material of some components, the reverse driving character of the haptic device can be improved, so that an appropriate 2-DOF haptic device can be obtained in the design aftertime.
Manufacturing error analysis of compliant planar 3-DOF micro robot
Chao Daihong, Liu Rong, Wu Yuemin, Shi Long
2005, 31(07): 757-761.
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In the fields of micro/nano positioning application, error analysis is an effective way to enhance the precision of such micromanipulators. Manufacturing imperfections, which are inevitable, are the most important factors influencing the accuracy. Thus, various manufacturing errors were studied by taking a planar 3-DOF(degree of freedom) flexure hinge-based micro robot as a case. By means of formulating static stiffness of the robot, mapping between manufacturing imperfections and end-effector positioning accuracy was obtained. Based on theoretical calculation and finite element method, effects of various machining imperfection types on end-effector positioning accuracy were evaluated. The results show that errors of the radius of the hinges and angular differences of the center line of the hinges are dominant factors resulting in output errors. Conclusions drawn from experiments can instruct the design of compliant parallel mechanisms by distributing various configurable parameters’ manufacturing differences to ensure the output precision of the end effector within required range; they may also be helpful while calibrating this kind of manipulators.
Residual stress simulation and analysis of milling process
Dong Zhaowei, Zhang Yidu, Liu Shengyong
2005, 31(07): 762-765.
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In the milling procedure, the distribution of stress inside material is uneven, which makes the work-piece deformed and affects shape and dimension precision. Adopting the analysis of finite element method(FEM) , the elastic-plastic constitutive equation was established with the theory of incremental method of FEM. Based on the end mills milling procedure, the reasonable two-dimension milling model was established, which uses the adaptive meshing criteria. A typical steel work-piece milling procedure was simulated, which gets the total status of residual stress distribution and the status of received force in the milling procedure, which is very significant in engineering.
Sectional model involving two Weibull distributions for CNC lathe failure probability
Chen Diansheng, Wang Tianmiao, Wei Hongxing
2005, 31(07): 766-769.
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To quantificationally analyze failure distribution law of CNC(computerized numerical control) lathes, and to provide the theoretical basis for improving their reliability level, the failure data from 14 CNC lathes over two years were collected, and the failure probability character of CNC lathes was analyzed. Probability and statistics method was introduced, and the sectional model involving two Weibull distributions was established. The analytical method of Weibull plotting paper was applied to estimate the parameters, hereby curve fitting was implemented for the observed values, and the results validated the sectional model. Laplace tendency test method was used to examine the model. The earlier failure period and the random failure period of CNC lathes can be distinguished based on the sectional model and the relevant failure rate curve. It can be calculated that earlier failure period is about 5 months, which is coincident with the consumer feedback that CNC lathe failure occurs frequently at about the first semiannual period with high failure probability. The occurrence of earlier failure period in this series of lathes shows that the early period faults are not totally excluded before leaving factory, so that the reliability level is degraded.
Visual planning and estimating of multi-process routes
Qian Xianzhi, Zheng Lianyu, Wei Li
2005, 31(07): 770-774.
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To meet the requirements of human machine engineering and alternative selection of process routes in CAPP, an approach to visually plan and estimate the multi-process routes based on graphic components and process nets was put forward. According to the elements of process route, common and typical graphic components including operation component, equipment component, feature component and transfer component were built, and these components were represented by four kinds of attributes: identification, display, technology and estimation. Thus, process routes were constructed by dragging graphic components and were presented by process net so that multiple process routes can be planned simultaneously and visually. Dijkstra algorithm was adopt to estimate the performance indexes of the multi-process routes, and to select the optimal process route. An application example for panning the process routes of an aircraft structural part was illustrated. The approach proposed is able to properly present the process planer’s intents and effectively carry out analyses and decision-makings for planning process routes.
Embedded autopilot design of micro-robots
Wang Song, Li Xinjun, Liang Jianhong, Pu Li
2005, 31(07): 775-779.
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The autopilot requirement of different micro-robots was analyzed. A method of autopilot based on advanced RISC microprocessor (ARM) and μCOS-II was put forward. The design process was presented from requirement analysis, function design, system structure, hardware design and software design, to control algorithm, and the autopilot for all-purpose was discussed from each aspect above. The autopilot adopted hiberarchy structure, modular hardware and structured software, and fuzzy control method needless of accurate model, which made it easy to apply to bionic fish robot, tracked mobile robot and micro unmanned vehicle after simple hardware adjustment and software customization. The autopilot was validated that it has the advantage of stabilization and currency through experiments. The autopilot makes up for the shortage of high cost, control difficulty and bad compatibility and maintenance while it was applied to the multiple and isomeric micro-robots swarm.
Locating cross-shaped image feature with subpixel accuracy based on NCCO
Sun Minglei, Li Dazhai, Yu Zhiwei, Zong Guanghua
2005, 31(07): 780-784.
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Normalized cross correlation operator (NCCO) was used for image matching to localize popular cross-shaped features in machine vision. Distribution feature of similarity function around peak zone was found to be four symmetry hyperboloid planes(FSHP). An approach of subpixel localization based on hyperboloid fitting algorithm (HFA) was presented according to the character of FSHP. A coarse pattern position was localized by one-dimension searching in x and y direction respectively to reduce the computational complexity. The discrete NCCO points around the coarse position were fitted to four hyperboloid planes in four quadrants respectively through least square fitting method. The point of four hyperboloid intersection was adopted as subpixel localization position. The HFA was realized on a microscopy vision system of MEMS device micro-assembly work-cell. Experimental results show that the subpixel localization precision of HFA can reach 0.25 pixel. It has greatly decreased computative cost under the comparisons with conicoid fitting algorithm and Gaussian fitting algorithm.
Haptic rendering algorithm based on discrete energy optimization method of preparation of human tooth
Wang Yuhui, Zhang Yuru, Wang Dangxiao
2005, 31(07): 785-788.
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Fidelity and stability are two keys of performance of virtual reality haptic interaction system. In virtual reality haptic interaction system of dental preparation, force acting on dentist who receives training is a key factor of training effect. Volumetric model of human tooth was constructed based on laser scanning data and tetrahedral division of tooth model was implemented. A method to calculate cutting force was proposed by combining empirical formula and experimental data. Optimum haptic rendering algorithm was studied to guaranteeing fidelity and stability of that haptic system. In order to solve the contradiction between fidelity and stability, haptic rendering algorithm based on discrete energy optimization algorithm was proposed. That algorithm processed force series with constant time difference. As a result, optimized cutting force signals between fidelity and stability were obtained. Experimental results show that this algorithm restrains vibration in high frequency of haptic device. Performances of human machine interactive haptic dental training system are improved.
Study on working path of microarrayer
Zhou Qiang, Yu Bao, Bi Shusheng
2005, 31(07): 789-793.
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Microarrayer is the key instrument for biochip fabrication. The working process and system configuration of microarrayer were studied. Special attention was paid to the computation method of the microarrayer working path in biochip fabrication. On the condition of given parameters, such as sample variety, slip quantity, spot matrix module, pin matrix module etc., the working path was divided into two main sub-path, such as z axis pin path, xy axis spotting path. Then the tree classing method was taken to calculate the working path with the given parameters. The method and expressions were presented. The main factors for working path were analyzed. The agreement of the final computation results with the experimental data indicates this method can be used to estimate the working path of microarrayer quickly and effectively at engineering analyses. It has the significance for design of microarrayer and working path plan.
Integration of microsensor for microsurgery robot's end-effector
Hu Yida, Li Dazhai, Yang Yang, Sun Xuguang
2005, 31(07): 794-798.
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In order to enhance the effect of robotic microsurgery, the microsensors were integrated on the robot’s end-effector. On the basis of requirements presented for the integration design, measuring mechanism for the robotic end trephine’s force and cutting depth was studied. Force microsensor and position microsensor were made use of to measure the surgical information of force and depth. The measuring mechanism was practised by means of linear sliding bearing and differential measuring structure. The sensor data board was developed. With the power spectral estimation of sensor data, the two digital filtering methods were proposed to eliminate the interference to the original microsensor signal. They are a filtering method of lowpass-bandstop serial structure suitable for the PC and a shift average filtering arithmetic suitable for the sensor data board. The experimental results show the integration of microsensors for microsurgery robot’s end-effector is qualified for the design requirements, and the robotic end trephine can fulfill the surgical task of corneal cutting accurately.
Algorithm of fast calculate exact contacted position among virtual objects
Chen Xuewen, Liu Jinghua, Chou Wusheng, Wang Tianmiao
2005, 31(07): 799-804.
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In the virtual reality interactive system of the force-feedback or touch-feedback,fast calculating exact contacted position among virtual objects is precondition of these collision detection systems. Because the model of these systems is most polygon model, the collision detection algorithm of hierarchy bounding box was taken to determine whether two objects contact or intersect, if intersected, the two-step algorithm was taken to detect thecontact position. At first, determine whether the intersected triangles are in the same plane or in the other plane; if in the other plane, calculate the intersected line of one triangle T2 and the plane of another triangle T1, then determine which line of the triangle T1 that will intersect the intersected line, and calculate the intersected point, now the final intersected line is received at this case; if in the same plane, determine the relationship of the two triangles, and calculate the intersected point of the lines which are intersected, and do not calculate the intersected point of the lines which are not intersected( thus it conduce to the fastness of the algorithm), the final intersected region or lines is received at this case. Three examples show the effectiveness and robustness of the algorithm.
Orientation sensing of 3-DOF spherical motor
Kou Jinqiao, Chen Weihai, Yu Shouqian, Wang Jianhua
2005, 31(07): 805-808.
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Noncontact orientation sensing is very important for the close-loop control of a 3-DOF spherical motor. Based on the sensing principle of optical sensor with microprocessor, a sensing principle to sense 3-DOF orientation displacements for spherical motor by utilizing 2-DOF optical sensors was illustrated, anassembly method of optical sensors was proposed, and an algorithm for solving the orientation displacements was presented. The approach is to solve z-axis coordinate according to the sensed x-axis and y-axis coordinate data, as well as the spherical geometry relationship analysis, the orientation matrix describing the spherical motor motion can be given and solved based on the screw theory. A simulation was also studied to verify the effectiveness of proposed approach.
Position and orientation measurement using monocular camera-ultrasonic sensor configuration mounted on robot
Xie Yuwen, Ding Xilun, Liu Ying
2005, 31(07): 809-813.
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A method was proposed for measuring the position and orientation of objects using monocular CCD camera and a ultrasonic sensor. Firstly, in the image coordinate, the undistorted coordinates of the desired point on objects was obtained from one image captured by the CCD camera, from which the orientation of the projection vector (the line connecting the object point and its image) was obtained. Then, by moving the robot, let the z axis of the ultrasonic sensor coincide with the orientation of the projection vector; lastly, the length of the vector was measured using the ultrasonic sensor, and the point coordinates in the camera coordinate system were calculated. The mainly factors that affected the measurement accuracy were analyzed, the influence of mounting parameters of the ultrasonic sensor was discussed and simulations were given. The position and orientation of objects can be measured rapidly and accurately with low computation cost and the avoidance of the image matching in stereo vision.
Kinematic analysis and simulation for modular manipulators based on screw theory
Chen Weihai, Zhou Jie, Yu Shouqian, Wu Xingming
2005, 31(07): 814-818.
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Based on the screw theory, through analyzing the kinematic relationship of modular robots for velocity model and incremental displacement model, an inverse kinematic approach was developed for modular redundant robots. Since it can be assumed that modular robots have any possible DOFs and configurations, will be assembled and disassembled often, and are easily reconfigured because of having the series and standardization components, a simulation system with self-modeling function for modular manipulators was developed. This simulation system consists of module editor, robot builder, graphical teaching pendants, and motion planning pendants. The effectiveness of the proposed approach and simulation system was demonstrated by a 7-DOF modular serial robot with pick and place demonstration.
Accurately locate target points using programmable sonar array
Li Baoguo, Wang Wei, Zhang Yangtian
2005, 31(07): 819-822.
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A novel programmable sonar array for mobile robots environment detecting was presented. Each sonar sensor in the array could be programmed to work as a sound emitter/receiver, or a sound receiver. When one sonar sensor was programmed to be a sound emitter/receiver, the others acted as sound receivers so that the array was always working in a single-emitter-multi-receiver situation during environment detecting. Benefiting from crosstalk, the system could get a group of distance data about the target point after each sound emitting. The redundant information was fused in a geometric interpolation way to estimate the accurate position of the target point. After all the sonar in the array emitted sound signals in turn, position estimates about target points in the area were obtained. The Euclidean distance between the estimates classified different target objects. Experiments show that the sonar array can locate one or more different targets after one detecting cycle, which is more efficient than conventional sonar systems.
UDP based implementation of peer to peer communication
Xu Ying, Luan Sheng
2005, 31(07): 823-827.
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By exploring the temporary UDP(user datagram protocol) port-mapping time window on NAT(network address translation) devices, the principal of using UDP to work through NAT devices was presented. A detection and handshaking server was proposed to solve the detection of dynamically mapped UDP ports. With packet reflecting service implemented at detection and handshaking server, port-mapping characteristics of NAT device and the external mapped UDP ports can be discovered. The procedures of the discovery process and the procedures of completing a peer to peer connection were presented. The implementation can benefit a broad range of applications like voice over IP, real-time video, file-sharing and peer to peer based distributed computing.

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