Non-Holonomic Trajectory Planning for AGV's
Report 2005.TL.7005, Transport Engineering and Logistics.
Automated Guided Vehicles (AGVs) are generally not capable of moving
perpendicular to their direction in movement as a consequence of
non-holonomic constraints. AGVs are also known as mobile robots. Different
non-holonomic mobile robots are characterized: the two Wheeled and
Car-like Mobile Robot, the Fire truck and the Four Wheel Steering AGV.
An overview is made of the planning methods implemented till date for
Automated Guided Vehicles. Only few planning methods recognize the issue
of non-holonomy. Some methods implement the non-holonomic constraints
directly in the motion planner; others use a multiple step approach. In
this second approach a holonomic path from a geometric planner is adapted
for the non-holonomic constraints in a second step.
he basic problem with a single AGV can be extended to a configuration space
with multiple AGVs, either by treating all robots together as one
multi-bodied robot, or by planning the paths of every robot more or less
independent of the other robots.
The DEFT model is developed at the Delft University of Technology for
trajectory planning with multiple AGVs. It has proven to be successful in a
simulation with respect to obstacle and collision avoidance. Although the
non-holonomic constraints where not taken into account, the generated
trajectories satisfied the non-holonomic behavior of the AGVs. The
simulation of DEFT did not take into account any specific orientation for
the initial and final position. The specific orientation can be
implemented directly into the DEFT model, or a secondary planner can be
used to create so called endgame connection.
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