考虑线缆干涉约束的铣削机器人进刀轨迹规划

发布时间：2018-11-24 13:54

【摘要】：工业机器人以其高柔性化等特点在工业制造领域如焊接,搬运,装配,铣削等多个方面得到越来越多的应用。为了实现这些不同的制造功能,机器人末端需要安装不同的末端执行器,如焊枪,激光,喷枪,铣刀等,这些末端执行器的引入势必给机器人末端增加柔性线缆,例如导线,气管,光纤,水管等。这些加工通常涉及复杂的曲线或者曲面轨迹,通常采用的示教编程方式效率低下。离线编程一方面可以克服示教编程生产效率低的缺点;但另一方面,由于末端执行器的引入,容易发生线缆与机械臂挤压、缠绕或者自身过度扭转等情况,从而导致线缆损坏,对作业过程造成严重影响。因此,针对末端执行器可更换的机器人离线编程问题,考虑末端线缆的干涉对机器人轨迹的影响,实现机器人轨迹规划和优化,具有重要的现实意义。本文以末端带线缆的六自由度铣削机器人作为研究对象,以避免机器人在进刀过程发生线缆干涉及自身过度扭转为目标,基于笛卡尔空间规划方法、构建机器人欧拉角插补模型、采用萤火虫算法对进刀轨迹进行优化,本文主要研究内容如下:(1)提出了一种基于笛卡尔空间对线缆移动端轨迹进行圆弧插补的策略,基于柔性线缆的一端固定,另一端则固定在机器人末端执行器上,通过分析机器人进刀过程中线缆两端的位姿而间接分析柔性线缆的实时状态,在减小了冲击与振动的同时还能实现机器人运行平滑且稳定,并且在进刀轨迹中针对线缆末端姿态的欧拉角进行线性插补,使线缆两端姿态差异控制在一定范围内以避免机器人在运行中发生线缆干涉及自身扭转过度等情况。(2)在避免线缆干涉及其自身扭转过度的约束下,为了减小机器人在进刀过程中的抖动并提高工作效率,把进刀轨迹的长度与平滑性作为优化目标,然后建立多目标优化数学模型,采用萤火虫算法在跳转点空间进行搜索并最终得到多目标最优运行轨迹。(3)针对Staubli TX90铣削机器人系统,分别进行了仿真和实物实验,对本文所提出的多目标最优轨迹方法进行验证,通过相关的运动状态分析以及数据对比分析,验证了所提方法的有效性。
[Abstract]:Because of its high flexibility, industrial robot has been widely used in many fields such as welding, handling, assembly, milling and so on. In order to achieve these different manufacturing functions, different end actuators, such as welding torch, laser, spray gun, milling cutter, etc., are required to be installed at the end of the robot. The introduction of these end actuators is bound to add flexible cables, such as wires, to the end of the robot. Trachea, optical fiber, plumbing, etc. These processes usually involve complex curves or surface trajectories, and the teaching programming method is usually inefficient. On the one hand, off-line programming can overcome the shortcomings of low efficiency of teaching programming. But on the other hand, because of the introduction of the end actuator, the cable and the mechanical arm are prone to squeeze, winding or excessive torsion, resulting in cable damage, which has a serious impact on the operation process. Therefore, considering the influence of the interference of the terminal cable on the trajectory of the robot, it is of great practical significance to realize the trajectory planning and optimization of the robot, aiming at the off-line programming of the robot which can be replaced by the end actuator. In this paper, a six-degree-of-freedom milling robot with cable ends is taken as the research object. The aim of this paper is to avoid cable interference and excessive torsion of the robot in the cutter feed process, based on Descartes spatial planning method. A robot Euler angle interpolation model is constructed, and the feeding path is optimized by firefly algorithm. The main contents of this paper are as follows: (1) A circular interpolation strategy based on Cartesian space is proposed to interpolate the moving-end trajectory of the cable. Based on one end of the flexible cable fixed and the other end fixed on the robot end actuator, the real-time state of the flexible cable is indirectly analyzed by analyzing the position and orientation of the two ends of the cable during the cutting process of the robot. While reducing the impact and vibration, the robot can run smoothly and stably, and the Euler angle of the end of the cable is interpolated linearly in the feed path. The attitude difference between the two ends of cable is controlled within a certain range to avoid cable interference and excessive torsion of the robot in operation. (2) under the constraint of avoiding cable interference and excessive torsion by itself, In order to reduce the jitter and improve the working efficiency of the robot, the length and smoothness of the feed path are taken as the optimization targets, and then the multi-objective optimization mathematical model is established. The firefly algorithm is used to search the jump point space and finally get the optimal trajectory of multi-target. (3) for the Staubli TX90 milling robot system, simulation and physical experiments are carried out, respectively. The multi-target optimal trajectory method proposed in this paper is verified. The validity of the proposed method is verified by the analysis of the motion state and the comparison of the data.
【学位授予单位】：湘潭大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TP242

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