A familiar theme from Chapter 2 is that planning algorithms must deal with implicit representations of the state space. In motion planning, this will become even more important because the state space is uncountably infinite. Furthermore, a complicated transformation exists between the world in which the models are defined and the space in which the planning occurs. Chapter 3 covers ways to model motion planning problems, which includes defining 2D and 3D geometric models and transforming them. Chapter 4 introduces the state space that arises for these problems. Following motion planning literature [657,588], we will refer to this state space as the configuration space. The dimension of the configuration space corresponds to the number of degrees of freedom of the robot. Using the configuration space, motion planning will be viewed as a kind of search in a high-dimensional configuration space that contains implicitly represented obstacles. One additional complication is that configuration spaces have unusual topological structure that must be correctly characterized to ensure correct operation of planning algorithms. A motion plan will then be defined as a continuous path in the configuration space.
Steven M LaValle 2012-04-20