仿下颌机器人冗余驱动机理与力和位置柔顺控制方法研究

Defects of tooth and dentition, Morphologic changes and functional disabilities of temporomandibular joint (TMJ) are common diseases in oral clinical treatment. Implanting denture and TMJ prosthesis are the general solution at present. A robotic human jaw is able to provide an important technical means for performance testing of denture and TMJ prosthesis. So far, the robotic human jaw has a low level of reproducing occlusal force and TMJ force at the same time and cannot simulate the redundant actuation of masticatory system itself. This proposal studies internal force equilibrium optimization and position and force compliance control of the robotic human jaw based on the actuation redundant mechanism. At first, it analyzes the physiological structure of human masticatory system, establishes mathematic model of the force system of the masticatory system, and studies the mechanism of complex forces and actuation redundancy. Second, based on the dynamic model of the 6PUS-2HKP actuation redundant parallel mechanism, an internal force equilibrium optimization method of the robotic human jaw with point contact higher kinematic pair (HKP) is proposed. Third, considering the functions of human masticatory muscles, a force/position hybrid control based on internal force optimization is presented. In consideration of the impedance characteristics of the external occlusion environment, an adaptive impedance control with internal force optimization as feed forward is proposed. Finally, Dynamic performances of different control strategies are compared through experimentation in order to develop the most suitable control strategy for an actuation redundant parallel robot with point contact HKPs. This research will provide theoretical and technical support for development of robotic human jaw with better bio-imitability.

牙体、牙列缺损与颞下颌关节形态缺陷和功能丧失是口腔临床常见疾病，植入义齿和颞下颌关节假体是目前通用解决方案，仿下颌机器人为义齿与颞下颌关节假体性能测试提供重要技术手段。本项目针对目前仿下颌机器人咬合力与颞下颌关节受力仿生度不足，不能再现咀嚼系统冗余驱动特性问题，提出研究基于冗余驱动机理的仿下颌机器人内力均衡优化及力和位置柔顺控制方法。分析人体咀嚼系统生理结构，建立咀嚼系统力系的数学模型，研究咀嚼系统受力与冗余驱动的工作机理；基于6PUS-2HKP冗余驱动机构动力学模型，提出含点接触高副的仿下颌机器人内力均衡优化方法；基于人类咀嚼系统肌肉的功能与咬合外界环境的阻抗特性，提出适用于仿下颌机器人的基于内力优化的力/位混合控制方法和内力优化作前馈的自适应阻抗控制方法；实验对比控制方法的动力学性能，形成适用于含点接触高副冗余驱动并联机构的最优控制策略，为高仿生度的仿下颌机器人研制提供理论和技术支撑。

仿下颌并联机器人在模拟人体咀嚼运动和咬合力方面具有机构学优势，但其对牙列咬合接触与颞下颌关节受力的仿生度不足，使其不能复现咀嚼系统的冗余驱动特性。针对颞下颌关节生理结构及运动特点，本项目使用点接触高副机构模拟左右两侧的颞下颌关节，形成冗余驱动仿下颌机器人。对咀嚼系统冗余驱动机理进行研究，揭示咀嚼系统受力与冗余驱动的工作机理。在基于第一类拉格朗日方程的动力学建模方法的基础上，分别以颞下颌关节内力2范数最小和驱动力2范数最小为优化目标，建立了冗余驱动咀嚼机器人驱动力优化分配数学模型。考虑内力优化环节，设计了力/位混合控制方法（咬肌与颞肌采用位置控制模式，翼外肌采用转矩控制模式）与基于模型参考的自适应阻抗控制方法。仿真与试验结果表明，优化分配数学模型提高了咀嚼机器人机构的综合力学性能，力/位混合控制相比纯粹的位置控制对机构内力具有改善作用，柔顺控制实现了咬合接触过程中咬合力引导下的运动控制。项目形成了新型冗余驱动并联机构动力学与控制的新理论和新方法，将有利于仿下颌机器人在食品物性测试和义齿力学性能测试等领域开展工程应用。