A rigid body is a theoretical model where any two distinct points on the body (or object) have a fixed time-invariant distance. Otherwise, the object is called a deformable body. In the areas of robotics and digital human modeling research, we often assume that each link of a robotic manipulator or a human body segment (link) is a rigid body, unless it indicates otherwise. A rigid body is
... [Show full abstract] relatively easy to be studied in both kinematics and dynamics.