面向大型自由曲面加工的全气动移动研抛机器人柔顺研抛复合控制策略研究

本项目以面向大型自由曲面加工的全气动移动研抛机器人为研究对象，开展其运动控制、加载过程控制和转速控制研究。为实现轻量化设计，研究全局稳定负载独立压力观测器和长管路时延逆模型的前馈补偿。为提高运动轨迹跟踪精度、抗干扰性能和研抛柔顺性，提出基于改进LuGre模型的摩擦力补偿方法及运动和刚度最值化同时控制的优化的直接自适应鲁棒控制算法；对于工具接触工件表面瞬间突发接触力对系统稳定性影响问题，研究接触力观测器和基于位置控制的阻抗控制算法；对不同粗糙度工件表面，提出柔/刚性双模研抛控制策略，研究基于力和刚度最值化同时控制的优化的直接自适应鲁棒控制；为实现鲁棒转速控制，建立叶片气马达系统连续化数学模型，提出基于模型的自适应鲁棒转速控制。根据研抛加工流程提出柔顺研抛复合控制策略，解决工具接触工件前、接触工件初期和接触工件后控制的稳定光滑切换问题，实现高质高效研抛，为控制系统研究提供重要的理论基础支撑。

A hybrid control strategy including motion control, loading process control and rotational speed control is developed and verified based on typical polishing procedure for the pneumatically actuated mobile polishing robot facing large free-form surface. A globally stable and load-independent pressure observer and an inverse model-based long line time delay feed-forward compensation are constructed for light-weight design. In order to improve trajectory tracking accuracy, anti-jamming performance and compliance of the polishing robot’s motion control system, stiffness-maximizing/minimizing control is introduced into a modified adaptive robust motion controller with improved LuGre model-based friction compensation. To solve the contact stability problem when tool comes in contact with unknown environmental surface, a contact force observer is designed and a motion-type impedance control method is adopted. Furthermore, to be adaptive to different surface roughness, a modified adaptive robust force controller with stiffness-maximizing/minimizing control is proposed to implement dual-mode (flexible or rigid) force control. In polishing process, tool rotational speed is a critical factor affecting polishing quality. Therefore, to guarantee robust constant rotational speed control, an equivalent continuous model of vane-type air motor is established, and a model-based modified adaptive robust rotational speed controller is presented. According to the typical polishing procedure, a hybrid control strategy is proposed to ensure smooth and stable switch between each control stages, especially during the loading process control of pneumatic polishing actuated device. Hence, the proposed hybrid control strategy can further improve polishing quality and polishing efficiency. The achievements of the project can provide theoretical support for developing the pneumatic polishing robot facing free--form surface.