【作者】 赵春光；

【导师】 赵继；

【作者基本信息】 吉林大学 ， 机械制造及自动化， 2009， 硕士

【摘要】 大型模具制造的自动化技术是航空航天、汽车等制造行业提高生产效率、降低生产成本、加速产业升级的重要保障。模具表面的精整加工是模具制造过程中的重要环节。模具表面精整加工的自动化研究也就成为大型模具制造自动化研究的必要组成部分。本课题组独辟蹊径,提出了一种用微小设备加工大型自由曲面的新思路:把机器人技术与模具表面研抛技术融为一体,利用微小机器人在大型自由曲面上灵活地移动,依据曲面的几何信息和工艺信息自主决策,进行研抛作业。依照这个思路,课题组开发了高机动程度、高可操纵度的轮式微小研抛机器人系统。该机器人可以在大型自由曲面工件上自主定位、自主移动并智能地完成研抛加工工作。本文主要针对微小研抛机器人的研抛加工系统和运动系统,运用理论推导、计算机仿真、运动学和研抛系统试验等方法展开研究。开发了一套完整的柔性研抛系统。该系统集主动柔性与被动柔性于一体,很好地适应了工件曲面形状的变化。针对研抛加工工件表面痕迹形成机制进行了仿真试验,研究确定了机器人相邻研抛轨迹的最佳行距。研抛加工试验结果表明,利用微小研抛机器人对大型自由曲面进行研抛可达到较理想的加工效果。设计了正交试验,研究机器人研抛工艺参数,优化了研抛参数配比。在对微小研抛机器人的运动学研究部分,本文解析了微小研抛机器人的运动学特性,建立了机器人运动学模型。确定了机器人移动作业方案,推导了运动过程中的相关参数,提出了机器人角速度因子k并分析了k与机器人循迹过程精度和稳定性的关系。找出了机器人结构的局限性及解决办法。依照以上运动学研究成果,拟定了机器人运动学控制程序。通过试验,微小研抛机器人的运动学规律、运动方案以及运动程序得到了验证。本文对微小研抛机器人运动学方面的研究成果可以指导机器人在非平整地形上,实现对任意轨迹的跟踪。课题的研究工作得到了国家高技术研究发展计划(863计划)资助项目:大型曲面自主研抛作业微小机器人技术(编号:2006AA04Z214)的资助。更多还原

【Abstract】 The automation for the manufacturing of large-scaled freeform surface has been critical in the field of Aeronautics and Astronautics industry as well as automobile industry, in order to enhance the producing efficiency, cut down the costs, and promote the industry. Finishing processing plays a significant role in the mould’s producing. Such, the research on the automation of finishing processing is necessary.Our group has proposed a totally new idea for the automation of finishing processing: using small equipment to work on large-scaled work pieces. Researches based on this method combine knowledge of robot and polishing together. The small robot polishes on large-scaled surface, moving agilely according to the geometric information of the work piece. In the light of this idea, a small polishing robot has been developed, which has the ability of self-location.This paper, based on the results of former researches, pays more attention on the kinematic and polishing system of the small polishing robot. A method for the robot’s moving with a high efficiency when the target point was set as the navigation mark is proposed and testified by experiments. Also, this paper presents a flexible polishing system. This system combines the positive and passive flexibility with both pneumatic control and a flexible polishing tool. Experiments are designed for the tests of moving ability and polishing ability as well as the most fitted parameters of the robot when polishing .In the research of kinematics system, the configuration of wheels has been fixed firstly: two standard wheels as positive wheels and two casters as passive ones, considering the characters of each kind of wheels, such as Figure 1. Fig. 1 Configuration of wheels on chassisThe motion equations of the robot are deduced through each wheel of the robot and the configuration of the wheels: is provided by the location system; v1 , v2indicate the speed of the two standard wheels. Equation 1 shows the kinematic model of the robot, telling the relations between the robot’s movement and the characters of each wheel.However, the inverse kinematics based on Equation 1 could not meet the need of path-tracking, because the moving efficiency of the robot should be considered as an important factor since the robot’s low moving speed when polishing. For higher efficiency, as the path is already determined, we set the tracing mode of the robot as‘forward→change line→backward→change line→forward…’. So the kinematic model and the inverse kinematic are modified for each section of tracking.The paper provides with the angular velocity factor k to illustrate the relation between angular velocity of the robot and the angle which is between the robot’s gesture angle and target’s azimuth angle in the coordinate system:ω= kΔγ. The analysis of the relation shows that the path-tracking of the robot could be stable when when k belongs to (-1/t,0), shown in Figure 2. Fig. 2 Relation between k and angle-differenceAccording to the tracking modes and the inverse kinematic of the robots, a C++ program is compiled for moving controlling in order to output the parameters of two standard wheels. This program integrates the results in the kinematic research, the method of path-tracking, and the transformation matrix, solving the limitations of the robot.Experiments are designed for the verification of the kinematic model and the program. The position information of the robot when tracking the path was collected at the interval of 200ms. Different kinds of paths-tracking on a plane and a freeform surface prove that the model and the program are correct. Figure 3 shows the result of path-tracking of the robot on the freeform surface. Fig. 3 Path-tracking resultIn the research of polishing system, polishing equipment with flexibility installed with a flexible polishing tool was designed for this robot. This polishing system has a high adaptability on the surface. With the easy-change equipment, this tool shows a processing flexibility.In order for a better polishing traces on the work-piece’s surface as well as a higher polishing efficiency, the distance between two lines of the path should be adjusted of 40mm, as shown in Figure 4. (a) macro-trace (b) micro-trace Fig. 4 Polishing trace of the robot , e=40mmResults of polishing experiments verify the polishing ability of the robot. After polishing, Ra of the work piece has decreased from 1.5μm~1.6μm to 0.2μm~0.4μm.To test the polishing effect, 3-factors, 3-levels orthogonal test is designed including the polishing parameters of the robot, as shown in Table 1.Through the visual analysis and the analysis of variance, results are obtained: the sequence of the significance of all the polishing parameters is: rotation speed > feed rate > pressure; The best result could obtained when the rotation speed=4300rpm, feed rate=3.0mm/s, pressure=20N; rotation speed is very significant for the polishing result, and the feed rate is very significant. As shown in Table 2.更多还原