蒙皮镜像加工机器人系统的主动顺应与协调控制研究

This project is inspired by the challenge to guarantee the thickness accuracy in milling of extremely low-rigidity large-size fuselage skins with more than 1000:1 length to thickness ratio. By combing the advantages of hybrid parallel robot and digital manufacturing, this project aims to develop the new techniques and equipment for efficient and accurate milling of fuselage skins through a novel dual-robot mirror milling system, i.e., one robot takes charge of machining and error compensation while the other one cooperatively takes charge of mirror-following supporting and thickness measurement. This project plans to achieve the active compliance and cooperative controls of the interactions among the machining robot, the fuselage skin and the supporting robot by profound research on four aspects: (1) Design and synchronization control of two hybrid parallel robots with large axial stiffness and compact structure for machining and supporting; (2) Design of the shape-adaptive mirror-following supporting end effector with controllable stiffness; (3) Closed-loop control of the skin thickness by cooperative control of the machining and supporting robots; (4) Construction of the robotic mirror milling system and its experimental validation. On this basis, the machining deformations and vibrations will be remarkably reduced by active control of the stiffness of the supporting robot end effector. Meanwhile, the thickness accuracy of the fuselage skins which suffer irregular deformation will be guaranteed by the cooperative actions of the supporting robot for real-time thickness error measurement and the machining robot for error compensation. This project reflects the frontiers of collaborative robot and intelligent manufacturing, and the outcomes will result in significant improvements on the capability and level of fuselage skin machining, which are urgently needed by the national aviation and aerospace industry.

本项目针对长厚比>1000的“极端”弱刚性大型蒙皮构件的壁厚加工精度保障难题，旨在将混联机器人装备技术和数字化加工技术相结合，创建双机器人“切削加工与误差补偿+随动支撑与壁厚测量”协同作业的镜像加工新原理与新装备。项目围绕机器人本体结构、末端执行器、双机器人协调控制三方面开展研究，具体内容包括：（1）高轴向刚度紧凑型混联机器人设计与双机器人同步控制；（2）工件形状自适应的随动支撑头设计与变刚度控制；（3）加工壁厚双机器人协同实时跟随测量与预测补偿；（4）机器人镜像加工系统构建与试验验证。预期将建立加工机器人-薄壁零件-支撑机器人交互过程的主动顺应与协调控制理论，通过支撑头的变刚度控制，实现对装备-零件交互过程的主动顺应，通过双机器人的协调控制，实现对不规则变形零件加工壁厚的闭环控制。研究结果对推动我国亟需的大型蒙皮构件制造能力和水平的突破，促进机器人化智能制造装备技术的发展具有重要意义。

项目针对长厚比>1000的“极端”弱刚性大型蒙皮构件的壁厚加工精度保障难题，旨在将混联机器人装备技术和数字化加工技术相结合，创建双机器人“切削加工与误差补偿+随动支撑与壁厚测量”协同作业的镜像加工新原理与新装备。经过四年研究，取得了一批规律性认识和创新性成果：（1）在五自由度混联加工机器人设计与控制方面，发明了新型位置型1T2R并联机构，提出了尺度综合和支链模块化、整机轻量化设计方法，研制出五轴混联加工机器人本体；设计了机器人全闭环位置控制系统与控制器；（2）在形状自适应支撑头设计与变刚度控制方面，发明了集成薄壁件法向测量与壁厚测量，“中心刚性支撑+四周柔性气动支撑”形式的刚柔混合支撑头；获得了柔性气动支撑中气缸气压对抑振效果的影响规律；（3）在双机器人协同加工壁厚实时闭环控制方面，制定了双机器人等壁厚镜像铣削协同运动控制方案，设计出“支撑端壁厚测量+加工端切深补偿”形式的加工壁厚实时控制系统，提出壁厚误差预测补偿控制和加工壁厚直接闭环控制两种控制方法；（4）在机器人镜像加工系统构建与试验验证方面，构建双机器人镜像铣削加工系统2套、镜像铣削加工实验平台2套，加工实验中大型弱刚性壁板零件的壁厚稳定控制在2±0.1mm以内。相关理论方法支撑了国产五轴镜像铣装备技术的自主创新。.项目研究成果在IEEE会刊（10篇）、ASME会刊（4篇）、Int J Mach Tool Manu（4篇）等国际学术期刊发表和录用SCI源刊论文44篇、国际会议论文4篇，其中IEEE/ASME Trans. On Mechatronics论文6篇、IEEE Trans. On Industrial Electronics论文2篇。申请发明专利17项，其中授权6项。获教育部自然科学一等奖1项、国际会议“ICIRA 2017”和“ICACAR 2020”最佳论文奖各1项。结合项目研究，出站博士后1人，毕业博士生3人，硕士生3人；在站博士后1人，在读博士生4人。项目负责人应邀担任IJIRA和CJME两份国际期刊编委。