Applied Mechanics and Materials Vols. 313-314

Abstract: For successful SLAM, landmarks for pose estimation should be continuously observed. Firstly, we proposed the object selection algorithm from 2D images and 3D depth maps without human’s supervision. We used the SIFT algorithm to obtain descriptors of point features inside the object, and the surface segmentation algorithm to obtain separated objects from point clouds of 3D depth maps. Automatically selected objects were tested by the threshold function using repeatability, distinctiveness and saliency whether the objects were suitable or not for reusing and sharing between the robots. Secondly, we suggested the closed-form solution to estimate the 3D pose of robots from the information of selected objects. Furthermore, we provided the effective way to accomplish the tasks using multi-robot by compensating the accumulated navigating errors and re-planning the collision-free motion of the robots using the extended collision map algorithm.

Abstract: One method of dedicated robots task allocation has selected a task to be assigned after comparing the results when tasks are allocated to robots, respectively. Thus, quick and accurate prediction of makespan is important for enhancing the be solved in polynomial time. In this paper, the makespan prediction is mathematically analyzed and a greed algorithm is suggested on the basis of the analysis. The effectiveness of the makespan prediction algorithm was verified by simulation in comparison with the complete enumeration.

Abstract: It proposes an efficient method for kinemics analysis of PUMA560 robot in ADAMS/View in this paper. Comparing with the past, it builds a virtual model of the robot in ADAMS/View. By the way of dynamic simulation, the normal solutions and inverse solutions of the PUMA560 robot are obtained, and this can provide a good study basis for the operability degree and space locus analysis of this kind of mechanics. In addition, a parameterized virtual model of the robot can be build by the ADAMS secondary development technology (APDL), which can accomplish multiple dynamics analysis of the similar kind of mechanics and provide a reliable method for analyzing the effects of mechanical random errors on its motion. This new method needs not to build complex analogue to solve the mechanic, conveniently, shortcut and accurately, and have definite theory meaning and application value in dynamic analysis.

Abstract: For the spraying mobile robot, in order to solve the bad effect of the complex unstructured environment of intensive planting, ground obstacles and spatial disorders coexisting on the path tracking control precision, a sliding mode control method is proposed based on weighted integral gain reaching law to reduce chattering and to improve tracking performance of the system. Moreover, the asymptotical stability of the closed loop system is proved using Lyapunov function. Finally simulation results illustrate the validity and feasibility of the proposed control method.

Abstract: In order to meet theneeds of high-speedpalletizing inlogistics automation industry, a 4 d4-DOF palletizingrobot manipulatorwas designed. Inthis paper,focusing on kinematic analysis, forward kinematics modeland inverse kinematics were introduced in detail.

Abstract: The air-duct cleaning robot (ADCR) is an effective and safe tool for accomplishing terrible cleaning work in an air-duct network. In this paper, a six-dimensional simultaneous localizing and mapping algorithm based on multi-sensor information fusion is proposed to improve the ADCR's autonomous ability in unknown duct environment. By combing an inertial measurement unit (IMU) with a stereo camera and fusing the measurements of sensors with the extended Kalman filter, the uncertainty of measurement caused by noises can be bounded in a low level. Furthermore, the performance of the proposed scheme was proved to be accurate and robust with experiments in an experimental ventilation-duct environment.

Abstract: Delta mechanism with the smooth and flexible movement,reliable structure, is a kind of parallel mechanism.Through inversely solving the Delta mechanism space position is to set up a kind of equivalent relationship and through analysis of the mechanism is to solve the rotating angle of the hinge that is between connecting rods that are equivalents of three parallelograms,and the base platform.Through inverse solution of kinematics before building the whole mechanism,the range of the center in mobile platform can be found intuitively from graphics when it is satisfied with the restriction condition.According to requirements, the optimization of mechanical structure can be achieved.

Abstract: This study presents a brand new concept in contrast to that of the conventional mechanical toy robots on the market. Conventional toy robots rely mainly on a large sole area to reduce wobble during walking. In this study walking stability is realized not by large sole areas but by a cam designed to automatically shift the center of gravity during walking. The biped toy robot proposed is driven by a single motor. As soon as the robot takes a forwards step, the center of gravity is changed by the cam module, and under the action of gravity, the trunk moves automatically to shift the center of gravity. Both walking and shifting the center of gravity is done by one motor. It was a goal of this study to develop a new type of walking toy robot by modifying traditional toy design. Experiment and simulation revealed that the rotation speed of the crank influences the walking of the biped toy robot, and the crank length influences both the length and height of the stride. In addition, counterbalance of the robot while walking is affected by the location of the center of gravity of the trunk and the distance between the feet. It became clear that the stability of the walking robot was determined by many factors, and difficulties may arise if any of these factors is changed.

Abstract: The purpose of this study is to investigate the influence of welding sequence on the risk of burn-through, cold cracking and residual stresses during in-service sleeve repair welding of gas pipelines. Based on ABAQUS software, axisymmetric finite e1ement models were conducted to calculate transient temperature distributions and resulting residual stress field after multi-pass sleeve fillet welding of in-service API 5L-X65 36” Schedule pipes. Influence of welding sequence was investigated by comparing residual stresses and transient deformations for sequential welding; in which welding of the two circumferential pipe/sleeve fillet welds was made in sequence, to the case of performing the two welds at the same time. Sequential welding was found to reduce weld zone distortion and residual stresses due to the sleeve freedom to expand axially while conducting the first fillet weld. The upper limit of heat input was found to generate higher pipe wall peak temperature, but not to the extent of initiating pipe wall melt through.

Abstract: Servo pneumatics is a mechatronic approach that enables accurate control of pneumatic drives which are widely used in automated systems. This technology can provide an alternative for less efficient electromechanical and high cost hydraulic systems. The main problem in the servo pneumatics is the fact that the variables associated with the system such as frictional forces, mass flow rate and pressure in the chambers, varies in nonlinear fashion. The paper presents nonlinear mathematical model for motion of cylinder, pressure in the cylinder chambers and mass flow rate from valve to cylinder are derived from basic gas laws and dynamics of the system. The equation for friction force based on LuGre model is also presented in the paper. Further, a nonlinear state space representation for the servo pneumatic positioning system is obtained. The developed model can be used to simulate the system response, which will help in choice of components used and also in the development of precise controller for the system.