![](bg6.png)
ment, both linear and angular velocities calculated by
the controller are equal to zero. This happened be-
cause in this instant, the robot lost the information
about the person for, at least, one of the cameras of
the stereo vision system. This behavior was adopted
in order to avoid having the robot be out of control ev-
ery time the vision system loses the information about
the human. Thus, whenever the robot loses the infor-
mation about its leader, it stops and waits for a new
face detection.
Although an obstacle in the middle of the desired
trajectory, the human managed to guide the robot to
avoid this object and reach the desired point.
5 CONCLUSIONS AND FUTURE
WORK
This paper presented an approach to a formation con-
trol between a human and a mobile robot using stereo
vision. The strategy uses the recognition method pre-
sented by (Viola and Jones, 2001) in order to find the
facial features needed to estimate the human position.
A stable nonlinear controller is proposed to allow the
robot to perform the task in cooperation with a hu-
man. The effectiveness of the proposed method is
verified through experiments where a human guides
the robot from an initial position to a desired point,
when the human moves either forward or backwards.
Our future work is concerned in improving the
features detection in order to better estimate the hu-
man position and orientation. Besides, we also intend
to introduce a second robot to the formation. Thus,
the robots will be able to carry a bigger and heavier
load.
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