**
**
- - G is the body of the spider
- - Each foot of the robot can reach the points of the plane inside the disk of radius R
- - This disk is called the
*range of action* of the robot.

- -
*Configuration*: A position of the robot body G
- - For some configuration, the
*placement* of the robot is a set of pairings between some of the robot feet and some point of M,

M = {points p within the range of action}
- - A placement is defined by I, the set of resting legs and by

p_{i} M, i I, the set of resting feet.
- - We say that a placement is an
*l-leg placement* if |I| = l

For a given configuration, a placement is said to be *l-feasible* if there is a set of indices I such that:
### For all i I, d(G, p_{i}) ≤ R and |I| ≥ l

where d(A, B) is the Euclidean distance between two points A and B of the plane, i.e. there must be at least l-feasible sites in the range of action of the robot.

Spider Home

Created with Cinderella