CAR - TR - 854 N 00014 - 96 - 1 - 0521 CS - TR - 3780 March 1997

Many types of common objects, such as tools and vehicles, usually move in simple ways when they are wielded or driven: The natural axes of the object tend to remain aligned with the local trihedron defined by the object's trajectory. Based on this observation we use a model called Frenet-Serret motion which corresponds to the motion of a moving trihedron along a space curve. Knowing how the Frenet-Serret frame is changing relative to the observer gives us essential information for understanding the object's motion. This is illustrated here for four examples, involving tools (a wrench and a saw) and vehicles (an accelerating van, a turning taxi).