基于轮廓误差的新型混联式汽车电泳涂装输送机构同步协调控制研究

发布时间：2018-09-01 05:59

【摘要】：在现代化的汽车制造业中,涂装是关键工艺,而输送机工作在汽车涂装生产线全过程,其性能的好坏对白车身表面的处理效果有很大影响。目前,先进的汽车电泳涂装输送机,如RoDip输送机和多功能穿梭机,由于采用悬臂梁结构存在着承受大载荷、重载荷能力较差以及柔性化水平不高等缺点。本课题组在国家自然科学基金项目(51375210)资助下,基于混联机构研制了一种新型汽车电泳涂装输送机构,以弥补上述输送设备的不足。本课题组所研制的新型输送机构具有多个主动关节和两边对称的机械结构,各主动关节间存在着耦合作用,因此主动关节间的同步协调性影响着机构的整体性能。对于新型混联式输送机构,当直接采用应用于串联机构的运动学与动力学控制方法时,由于忽略了混联机构包括多条运动支链的结构特点,因而,各支链主动关节间存在同步协调性问题。为保证该输送机构在各种工作环境下能够平稳、可靠运行,有必要提高其各主动关节之间的同步协调性。本文首先定义了各主动关节之间的跟踪误差、同步误差,设计了一种基于主动关节同步误差的同步协调控制器。然而,该同步协调控制器虽然减小了各主动关节的跟踪误差,但跟踪误差的减小并不一定使轮廓误差减小,因而难以保证机构末端的轨迹跟踪精度。在具有多条运动支链的混联机构控制系统中,衡量机构末端轨迹跟踪精度的主要指标是轮廓误差,混联机构系统中其他的误差,最终均反应为轮廓误差,因此为提高机构末端的轨迹跟踪精度,本文进一步提出一种机构末端轮廓误差的估算方法,设计了一种基于轮廓误差的同步协调控制器,该控制器既可减小各主动关节的跟踪误差、同步误差,又可提高机构末端的轨迹跟踪精度。本文首先综述了现有汽车电泳涂装输送设备和混联机构的发展概况以及基于轮廓误差控制的研究现状;接着,针对新型混联式汽车电泳涂装输送机构进行了运动学与动力学分析,并分别对运动学及动力学分析的结果进行MATLAB仿真,仿真结果表明了运动学分析与动力学分析的正确性;同时根据汽车电泳涂装工艺要求和按比例缩小研制的样机参数,确定了输送机构末端执行器的期望运动轨迹,并分析了该机构样机的工作空间,给出了其工作空间示意图;其次,为解决输送机构运行过程中各运动支链间的同步协调问题及样机末端轮廓误差问题,针对其结构特点及运动特点,提出了一种通过相邻主动关节跟踪误差的偏差进行定义的主动关节同步误差,并基于该主动关节同步误差设计一种主动关节同步协调控制器;为进一步提高机构末端的轨迹跟踪精度,进一步提出一种基于机构末端轨迹跟踪估算的轮廓误差,并设计了基于轮廓误差的同步协调控制器,与主动关节同步协调控制器进行MATLAB仿真比较,仿真结果表明,由于进一步减小了机构末端的轮廓误差,该控制算法具有更高的轨迹跟踪精度,从而进一步提高了输送机构的同步协调运动性能;最后,根据输送机构的控制要求,构建了输送机构样机实验平台,并基于该平台完成了输送机构控制实验。实验结果进一步验证了本文所设计的基于轮廓误差控制的器的有效性。
[Abstract]:In the modern automobile manufacturing industry, painting is the key process, and the conveyor works in the whole process of automobile painting production line. Its performance has a great impact on the surface treatment effect of the white body. Under the support of the National Natural Science Foundation of China (51375210), a new type of automotive electrophoretic coating conveyor was developed based on the hybrid mechanism to compensate for the shortcomings of the above conveyor. The new conveyor developed by our research group has many advantages. There is coupling between active joints and two symmetrical mechanical structures, so synchronous coordination between active joints affects the overall performance of the mechanism. For a new type of hybrid transmission mechanism, when the kinematics and dynamics control method is used directly in the series mechanism, it is neglected that the hybrid mechanism includes more than one. In order to ensure the smooth and reliable operation of the conveying mechanism in various working environments, it is necessary to improve the synchronous coordination among the active joints. Firstly, the tracking error, synchronous error and design between the active joints are defined. A synchronous coordination controller based on active joint synchronization error is proposed. However, although the tracking error of active joints is reduced, the reduction of tracking error does not necessarily reduce the contour error, so it is difficult to guarantee the tracking accuracy of the end of the mechanism. In the system, the main index to measure the tracking accuracy of the end trajectory of the mechanism is the contour error. The other errors in the hybrid mechanism system all respond to the contour error eventually. Therefore, in order to improve the tracking accuracy of the end trajectory of the mechanism, a method for estimating the contour error of the end trajectory of the mechanism is proposed, and a method based on the contour error is designed. Synchronous coordinated controller can not only reduce the tracking error and synchronous error of active joints, but also improve the trajectory tracking accuracy of the end of the mechanism. Firstly, this paper summarizes the development of existing automotive electrophoretic coating conveyor and hybrid mechanism, and the research status of contour error control based on it. The kinematics and dynamics analysis of the transport mechanism of automotive electrophoretic coating are carried out, and the results of kinematics and dynamics analysis are simulated by MATLAB. The simulation results show the correctness of kinematics analysis and dynamics analysis. At the same time, the transport is determined according to the requirements of automotive electrophoretic coating process and the parameters of the prototype developed by reducing the proportion. The desired trajectory of the end effector of the mechanism is analyzed, and the workspace of the prototype is analyzed, and the schematic diagram of the workspace is given. Secondly, in order to solve the problem of synchronous coordination among the moving branches and chains in the running process of the conveyor mechanism and the problem of the error of the end contour of the prototype, a passing phase is proposed according to its structure and motion characteristics. Active joint synchronization error is defined by the deviation of tracking error of adjacent active joints, and an active joint synchronization and coordination controller is designed based on the deviation of tracking error of adjacent active joints. Compared with the active joint synchronous coordinating controller, the simulation results show that the control algorithm has higher trajectory tracking accuracy and further improves the synchronous coordinating motion performance of the conveying mechanism because of further reducing the profile error of the end of the mechanism. According to the control requirements of conveyor mechanism, a prototype experimental platform of conveyor mechanism is constructed, and the control experiment of conveyor mechanism is completed based on this platform. The experimental results further verify the effectiveness of the controller based on contour error control designed in this paper.
【学位授予单位】：江苏大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：U468.2;TP273

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