Papers by Keyword: Position

Abstract: Micro-extrusion process is one of the micro-forming technology for fabrication of micro-parts such as micro-gear shaft for microelectromechanical system (MEMS) and micro pins for electronic parts. This paper presents the friction models effects and geometry effects on curving tendency of micro-extrusion 6063 aluminum alloy pins. Three friction models were considered: (1) Coulomb friction, (2) plastic shear friction, and (3) combined (Coulomb & plastic shear) friction. The finite element simulation was carried out and the results showed that the combined friction model accurately predicted the micro-extrusion results. Then, four tool geometry and position effects were investigated: (1) punch shift length, (2) die angle, (3) die shift length, and (4) bearing length. The finite element simulation was carried out to determine these tool geometry and position effects on the curving tendency of micro-extruded pins. The results showed that punch shift length and die angle did not affect the curving tendency. However, die shift length caused the micro-extruded pins to curve. The increase in bearing length helped straighten the micro-extruded pins.

Abstract: The paper deals with the influence of wood-based thermal insulation in building envelope constructions to the summer comfort of indoor climate thorough their thermal accumulation properties. In this study, the optimum positions of thermal insulation (wood fibre insulation, cork board) were investigated numerically from the maximum decrement factor and the maximum time lag. Thermal mass material of the wall is formed from CLT (cross-laminated timber) with different thicknesses of layers. It depends on the position of the insulation material maintaining the total thickness of wall 240 mm. Totally, there were composed six different configurations of insulation placement with a consequent shift in its position. The calculations of decrement factor and time lag were carried out by computer simulations based on the particular configurations. In terms of decrement factor the most effective location of thermal insulation in two layers more precisely - in the middle of the wall and on the outer surface or on the outer surface and inner surface of the wall.

Abstract: In a manufacturing process it may be necessary to distinguish the parts of various types produced by different machine-tools and placed on a conveyor. Using an artificial vision system represents a possible solution. Images of the parts can be periodically taken using a video camera. It is considered that all parts are positioned with one of the faces which defines its type on the upper side. Thus, parts’ recognition can be solved by recognizing the shapes from the images. In addition, information about position and orientation of parts can be determined using the captured images. All these information are listed in a text file which can be used by a decision algorithm. This algorithm can choose which parts are useful to assemble different objects. An industrial robot can be commanded using a program written in RobotStudio environment’s programming language (RAPID) to pick the needed parts and place them in a storage area.This paper describes a recognition and measurement of position and orientation method of the different parts produced. In addition, details about implementing this method in MATLAB environment using Image Processing Toolbox and geometrical relations are provided gradually.

Abstract: This paper describes an algorithm for computing the position and orientation of 3-D objects by comparing graphs. The graphs are based on feature points of the image. Comparison is performed by a spectral decomposition with obtaining eigenvectors of weighted adjacency matrix of the graph.

Abstract: To estimate influence of velocity on kinematic accuracy for a cross-linked Stewart type Parallel Machine Tool, position and orientation errors of the moving tool platform are researched. Based on rigid body dynamics, inertial and friction forces and moments are considered. Firstly, analytical expression of driving force is derived for each link. Secondly, change of length is derived using Hooke’s Law for each link. Then mapping matrix between change of link length and change of platform position and orientation is derived based on both Euler angle and revolving angle around a spatial axis. Finally, analytical expression of position and orientation errors of the moving platform is derived. Figures of distribution of position and orientation errors in workspace under two velocities are obtained respectively. The results show that, in frequently used workspace, all of the three components of position error are less than 3.5μm. All of them increase with z coordinate of platform center. Position error is influenced slightly by velocity. The difference of position error between two velocities is less than 2%.

Abstract: Existed in the work of wireless positioning error, the need to suppress NLOS (Non line of sight) transmission problem of positioning the bad influence of the NLOS system model is put forward and the novel geometric positioning model, the introduction of appropriate NLOS channels model to suppress NLOS error, and make full use of the propagation characteristics of derived meet MS (Mobile Station) coordinates equation, with two NLOS paths can only calculate the position of MS, and using only a single base Station can complete the MS positioning, overcome the base Station number too little to pinpoint the flaws of the MS. This paper also gives a method of least squares and maximum likelihood algorithm, using the NLOS paths to improve the positioning accuracy. So as to realize the movement of the MS in NLOS environment position tracking. Through the theoretical analysis and computer simulation analysis, the results show that the positioning method in NLOS environment on the effectiveness and accuracy of the MS positioning.

Abstract: The author has designed a visual workbench to realize that the rim can rotate with the workbench. Meanwhile, the linear CCD camera records the rim’s circumference. The paper has explored the measurement method of getting the rim valve hole position using machine vision. The system can calculate the position of rim-hole and control the servo motor by image processing, characteristic recognizing and measuring to locate the position of wheel-hole automatically. And the paper has verified the accuracy of the method by experiments.

Abstract: Position equation of 3-RRC parallel mechanism is established and its position direct and inverse solution is solved. The mechanism rate equation is established and its kinematics analysis is done. The result shows that it is easier to solve the kinematics inverse solution of the parallel mechanism.

Abstract: The armature trigger position of multi-stage electromagnetic coil gun has great influence on the exit velocity of projectile. The energy conversion efficiency of the coil gun can be improved effectively if the armature is triggered in the optimum position. So it is important to detect the projectile position in time. Several typical electrical and optical methods for position detection are summarized in this paper. The advantages and disadvantages of each method are analyzed and evaluated. And a new laser scattering measurement method is proposed. Results show that optical detection method is simple and easy to implement, but it is susceptible to environmental impacts.

Abstract: In this paper a method that allows the generation of complex trajectories using a RRTRRR robotic system (with five rotation modules and a translation module) is presented. The method is based on the decoupling between the positioning function and the orientation function of the tool frame (O_Tx_Ty_Tz_T) attached to the robot gripper. The method permits to determine all the solutions corresponding to the robot coordinates that allow obtaining the movement of the tool frame with imposed position and orientation parameters. Finally, some simulation results are presented in the case when O_T is moving along a parabolic trajectory with an imposed orientation of the tool frame.