系统仿真-第10讲-系统建模-131209课件.pptVIP

Zhejiang University of Technology 3. 刚体模块（Body） Body CS A local coordinate system (CS) attached to a body, carried along with that bodys motion. In general, bodies accelerate as they move, and therefore Body CSs define noninertial reference frames. You can attach any number of Body CSs to a Body block, and you can choose where to place the Body CS origins and how to orient the Body CS axes. The Body block has distinctive axis triad Body CS ports instead of the open, round connector ports, to give you access to these Body CSs for connecting Joint, Sensor, and Actuator blocks. Every Body block has an automatic, minimum Body CS at its center of gravity (CG). By default, it also has two other Body CSs for connection to adjacent Joints. The origin and axis orientation of each Body CSs once set by the user during Body configuration, are interpreted as fixed rigidly in that body during the simulation. Zhejiang University of Technology 3. 刚体模块（Body） inertia tensor The inertia or moment of inertia tensor of an extended rigid body describes its internal mass distribution and the bodys angular acceleration in response to an applied torque. Let V be the bodys volume and ρ(r) its mass density, a function of vector position r within the body. Then the components of the inertia tensor I are: The indices i, j range over 1, 2, 3, or x, y, z. This tensor is a real, symmetric 3-by-3 matrix or equivalent MATLAB expression. The inertia tensor of a SimMechanics body is always evaluated in that bodys center of gravity coordinate system (CG CS). That is, the origin is set to the bodys CG and the coordinate axes are the CG CS axes. Because the CG CS of a Body block is fixed rigidly in the body during simulation, the values of the inertia tensor components do not change as the body rotates. Zhejiang University of Technology 4. 关节模块 1）装配型关节(Assembled Joints) 2）非装配型关节（Disassembled Joints） 3）无质量连接器（Massless Connectors） 关节模块用于连接两个刚体模块，并表述刚体运动的自由度（即刚体可能运动的方向）。对关节作一个理想约定，即关节本身没有质量或惯量，被关节