| Volume 24 Issue 10 - Publication Date: 1 October 2005 |
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| A Foothold Selection Algorithm
for Spider Robot Locomotion in Planar Tunnel Environments |
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| A. Shapiro Department
of Mechanical Engineering Ben Gurion University of the Negeu, Israel
, E. Rimon Department of Mechanical Engineering Technion, Israel,
and S. Shoval Department of Industrial Engineering and Management
College of Judea and Samaria, Israel |
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| In this paper we present an
algorithm, called the partitioned cubes gaiting (PCG) algorithm, for planning
the foothold positions of spider-like robots in planar tunnels bounded by
piecewise linear walls. The paper focuses on three-limb robots, but the
algorithm generalizes to robots with a larger number of limbs. The input
to the PCG algorithm is a geometric description of the tunnel, a lower bound
on the amount of friction at the contacts, as well as start and target foothold
positions. Using efficient convex programming techniques, the algorithm
approximates the possible foothold positions as a collection of cubes in
contact configuration space (c-space). Each cube represents a contact independent
set of feasible three-limb postures. A graph structure induced by the cubes
has the property that its edges represent feasible motion between neighboring
sets of three-limb postures. This motion is realized by lifting one limb
while the other two limbs brace the robot against the tunnel walls. A shortest-path
search along the graph yields a three-two-three gait pattern that moves
the robot from start to target using a minimum number of foothold exchanges.
In practical environments the algorithm runs in time, which is linear in
the number of tunnel walls and polynomial in the degree of cube approximation
of contact c-space. Simulations as well as experiments demonstrate the PCG
algorithm in tunnel environments. |
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| Multimedia Key |
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 = Data |
= Code |
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Extension |
Type |
Description |
1 |
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Example
1: Spider robot motion in a tunnel. (6.8 MB) |
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