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BUG Algorithms

This section addresses a motion strategy problem that deals with uncertainty with sensing. The BUG algorithms make the following assumptions:

BUG1 This robot moves in the direction of the goal until an obstacle is encountered. A canonical direction is followed (clockwise) until the location of the initial encounter is reached. The robot then follows the boundary to reach the point along the boundary that is closest to the goal. At this location, the robot moves directly toward the goal. If another obstacle is encountered, the same procedure is applied.

\psfig {file=figs/bug1.idr,width=3.0truein}

The worst case performance, L, is

\begin{displaymath}
L \leq d + \frac{3}{2} \sum_{i=1}^{N} p_i\end{displaymath}

in which d is the Euclidean distance from the initial position to the goal position, pi is the perimeter of the ith obstacle, and N is the number of obstacles.

BUG2 In this algorithm, the robot always attempts to move along the line of sight toward the goal. If an obstacle is encountered, a canonical direction is followed until the line of sight is encountered.

\psfig {file=figs/bug2.idr,width=3.0truein}

The worst case performance, L, is

\begin{displaymath}
L \leq d + \frac{1}{2} \sum_{i=1}^{N} n_i p_i\end{displaymath}

in which ni is the number of times the ith obstacle crosses the line segment between the initial position and goal position.


next up previous
Next: Visibility-Based Pursuit-Evasion Up: Uncertainty Previous: General Uncertainty Concepts
Steven M. LaValle
8/29/2001