Modeling and Calibration of Contact, Friction and Deformation between a Rigid Object and another Rigid or Rheology Object

本研究的目的是建立刚体之间的接触(包括摩擦)模型，并设计受推流变(复杂粘弹性)物体的变形模型。针对上述问题，我们提出了一种基于冲量动量的方法来人工产生任意冲量(力序列)。这是Mirtich著名方法的修改版本。我们的新方法有足够的参数来表达几个物理现象。例如，两个相遇的物体之间存在静摩擦系数和运动摩擦系数，泊松接触模型中的恢复系数等。在大量的实验数据…下，利用随机化算法和遗传算法等两种近似最优的概率搜索算法对未知参数进行了有效的校正更重要的是，定标基于动量守恒定律。为此，需要用高速摄像机准确测量碰撞前后的速度。最后，在气球和台球比赛中验证了新方法的可行性。针对后者的问题，我们提出了智能MSD(质量-弹簧-阻尼器)模型来描述变形物体的粘性、弹性和残余位移。一般说来，我们生活中的流变学对象种类繁多。因此，对于每一种材料，我们用遗传算法对MSD模型中的许多不确定参数进行了标定。每个MSD元件由Voigt和阻尼器部件串联组成。因此，需要标定的参数有两个阻尼器系数、一个弹簧系数、Voigh与阻尼器的长度比等。为了校准所有的参数，我们最小化了真实的和虚拟的流变学对象之间的形状差异。真实流变学对象的形状变形由两个或多个立体视觉摄像系统Digiclops及其软件开发工具包(SDK)Triclops(由加拿大Point Grey Research Inc.提供)精确捕获。每个实时捕捉大约3000个或更多的点作为真实流变学对象的形状。较少

The purpose of this research is to construct contact (including friction) model between rigid bodies and also design deformation model of pushed rhelogy (complex viscous - elastic) object. These models are quite useful for manipulating many kinds of materials by robotic manipulator in a real world and also for manipulating them by haptics in a virtual world.Concerning to the former problem, we propose an impulse-momentum-based approach to generate an arbitrary impulse (sequence of forces) artificially. This is a modified version of Mirtich's famous approach. Our new approach has enough parameters to express several physical phenomena. For example, there are static and kinetic friction coefficients between two encountered objects, restitution coefficient in the Poisson's contact model, and so on. The unknown parameters are efficiently calibrated by two kinds of near-optimal probabilistic search algorithms such as the randomized algorithm and genetic algorithm under many experimental dat … More a. The calibration is based on the conservative law of momentum variation. For this purpose, we should exactly measure velocities before and after collision by high-speed camera. Finally, we check the feasibility of our new approach in the air hokey and billiard games.Concerning to the latter problem, we propose smart MSD (Mass-Spring-Damper) model to represent the viscosity, elasticity, and residual displacement of deformed object. In general, there are many kinds of rheology objects in our living life. Therefore for each material, we calibrate many uncertain parameters of MSD model by the genetic algorithm. Each MSD element consists of Voigt and damper parts serially. Therefore, parameters to calibrate are two coefficients of dampers, one coefficient of spring, length ratio of Voigh and damper and so on. In order to calibrate all the parameters, we minimize the shape difference between real and virtual rheology objects. The shape deformation of real rheology object is precisely captured by two or more stereo vision camera systems Digiclops and its software development kit (SDK) Triclops (provided by Point Grey Research Inc, Canada). Each captures about three or more thousand points as shape of real rheology object in the real-time manner. Less