(Georgia Institute of Technology, 2004-12)
Sattigeri, Ramachandra J.; Calise, Anthony J.; Evers, Johnny H.
In considering the problem of formation control in the deployment of intelligent
munitions, it would be highly desirable, both from a mission and a cost perspective, to limit
the information that is transmitted between vehicles in formation. We have proposed an
adaptive output feedback approach to address this problem. Adaptive formation controllers
are designed that allow each vehicle in formation to maintain separation and relative
orientation with respect to neighboring vehicles, while avoiding obstacles. We have
implemented two approaches for formation control, namely, leader-follower formations and
leaderless formations. In leader-follower formations, there is a unique leader and all the
other vehicles are followers. In leaderless formations, there is no unique leader. Each vehicle
tracks line-of-sight range to up to two nearest vehicles while simultaneously navigating
towards a common set of waypoints. As our results show, such leaderless formations can
perform maneuvers like splitting to go around obstacles, rejoining after negotiating the
obstacles, and changing into line-shaped formation in order to move through narrow
corridors.
(Georgia Institute of Technology, 2004-08)
Sattigeri, Ramachandra J.; Calise, Anthony J.; Evers, Johnny H.
In considering the problem of formation control in the deployment of intelligent
munitions, it would be highly desirable, both from a mission and a cost perspective, to limit
the information that is transmitted between vehicles in formation. In a previous paper, we
proposed an adaptive output feedback approach to address this problem. Adaptive
formation controllers were designed that allow each vehicle in formation to maintain
separation and relative orientation with respect to neighboring vehicles, while avoiding
obstacles. In this paper, we consider a modification to the adaptive control law that enables
each vehicle in a leader-follower formation to track line-of-sight (LOS) range with respect to two or more neighboring vehicles with zero steady-state error. We also propose a
coordination scheme in which each vehicle tracks LOS range to up to two nearest vehicles
while simultaneously navigating towards a common set of waypoints. This coordination
scheme does not require a unique leader for the formation, increasing robustness of the
formation. As our results show, such leaderless formations can perform maneuvers like
splitting to go around obstacles, rejoining after negotiating the obstacles, and changing into
line-shaped formation in order to move through narrow corridors.
(Georgia Institute of Technology, 2003-08)
Sattigeri, Ramachandra J.; Calise, Anthony J.; Evers, Johnny H.
In considering the problem of formation control in the
deployment of intelligent munitions, it would be
highly desirable, both from a mission and a cost
perspective, to limit the information that is transmitted between vehicles in formation. However,
the lack of information regarding the state of motion
of neighboring vehicles can lead to degraded
performance and even instability. This paper presents
an adaptive output feedback approach for addressing
this problem. We design adaptive formation
controllers that allow each vehicle in formation to
maintain separation and relative orientation with
respect to neighboring vehicles, while avoiding
obstacles. The method works by enabling each
vehicle in the formation to adaptively correct for the
effect that the motions of neighboring vehicles have
when regulating relative variables like range and line
of sight. It is assumed that estimates of these
variables can be derived using passive, vision-based
sensors. The need for explicit communication to
maintain formation is minimized and the resulting
controller solution is decentralized. We implement a
reactive obstacle avoidance controller to navigate in
an environment with obstacles. The formation
controller and obstacle avoidance controller are
outer-loop controllers whose outputs are speed and heading commands. These commands are blended
together to generate composite speed and heading
commands that are inputs to the inner-loop controller.
The weights used for blending the commands depend
upon the priority of the task at hand. We illustrate the
method with an example involving a team of three
aircraft keeping formation in the presence of
obstacles.