基于局部模型的多更新率切削仿真力觉渲染算法

提出了一种牙科手术虚拟现实模拟训练系统的力觉计算方法。为了保证切削仿真的逼真度、力觉计算的快速性和交互稳定性,提出了基于局部模型的多更新率体系架构的计算方案。仿真系统分解为三个不同计算频率的线程,即切削仿真、力觉伺服和图形显示线程。提出虚拟工具和切削工具的概念,实现交互力计算和牙齿三角片网格模型切削变形的协调;基于虚拟工具和牙齿三角片碰撞检测信息构造局部模型,实现力觉设备控制与切削仿真线程的解耦,降低了对切削仿真线程计算频率的要求;利用多线程技术保证图形显示和力觉显示的数据传输和时间同步。针对局部模型更新时的振荡问题,采用改进的恢复时间方法对局部模型进行插值,增强了仿真系统稳定性。基于力觉交互设备Phantom建立试验平台,开发了牙科手术力觉交互仿真软件,通过试验验证了本文算法的有效性。

Local Model Based Multi-rate Force Rendering Architecture for Cutting Simulation

Proposes a method to enable force rendering in virtual reality dental surgery simulation system. Local model based multi-rate rendering architecture is proposed to ensure fidelity, computation speed and stability of cutting simulation. The simulation system is divided into three loops with different update rate: cutting simulation loop, force servo loop and graphical display loop. Virtual tool and cutting tool are devised to match force computation with material removal of the tooth triangle mesh. Local model is constructed via collision detection information between virtual tool and tooth mesh, and cutting simulation loop is decoupled from high update rated haptic loop. Multi-thread method is utilized to synchronize force and graphical display. Modified recovery time algorithm is proposed to solve the stability problem resulted from local models update. Experiment platform is constructed using Phantom, and dental simulation software is developed. Experiment indicates the validity of the proposed force rendering architecture.