4,099 research outputs found
Controlling rigid formations of mobile agents under inconsistent measurements
Despite the great success of using gradient-based controllers to stabilize
rigid formations of autonomous agents in the past years, surprising yet
intriguing undesirable collective motions have been reported recently when
inconsistent measurements are used in the agents' local controllers. To make
the existing gradient control robust against such measurement inconsistency, we
exploit local estimators following the well known internal model principle for
robust output regulation control. The new estimator-based gradient control is
still distributed in nature and can be constructed systematically even when the
number of agents in a rigid formation grows. We prove rigorously that the
proposed control is able to guarantee exponential convergence and then
demonstrate through robotic experiments and computer simulations that the
reported inconsistency-induced orbits of collective movements are effectively
eliminated.Comment: 10 page
Distributed scaling control of rigid formations
Recently it has been reported that biased range-measurements among
neighboring agents in the gradient distance-based formation control can lead to
predictable collective motion. In this paper we take advantage of this effect
and by introducing distributed parameters to the prescribed inter-distances we
are able to manipulate the steady-state motion of the formation. This
manipulation is in the form of inducing simultaneously the combination of
constant translational and angular velocities and a controlled scaling of the
rigid formation. While the computation of the distributed parameters for the
translational and angular velocities is based on the well-known graph rigidity
theory, the parameters responsible for the scaling are based on some recent
findings in bearing rigidity theory. We carry out the stability analysis of the
modified gradient system and simulations in order to validate the main result.Comment: 6 pages In proceedings 55th Conference on Decision and Control, year
201
Mobile Formation Coordination and Tracking Control for Multiple Non-holonomic Vehicles
This paper addresses forward motion control for trajectory tracking and
mobile formation coordination for a group of non-holonomic vehicles on SE(2).
Firstly, by constructing an intermediate attitude variable which involves
vehicles' position information and desired attitude, the translational and
rotational control inputs are designed in two stages to solve the trajectory
tracking problem. Secondly, the coordination relationships of relative
positions and headings are explored thoroughly for a group of non-holonomic
vehicles to maintain a mobile formation with rigid body motion constraints. We
prove that, except for the cases of parallel formation and translational
straight line formation, a mobile formation with strict rigid-body motion can
be achieved if and only if the ratios of linear speed to angular speed for each
individual vehicle are constants. Motion properties for mobile formation with
weak rigid-body motion are also demonstrated. Thereafter, based on the proposed
trajectory tracking approach, a distributed mobile formation control law is
designed under a directed tree graph. The performance of the proposed
controllers is validated by both numerical simulations and experiments
Circular formation control of fixed-wing UAVs with constant speeds
In this paper we propose an algorithm for stabilizing circular formations of
fixed-wing UAVs with constant speeds. The algorithm is based on the idea of
tracking circles with different radii in order to control the inter-vehicle
phases with respect to a target circumference. We prove that the desired
equilibrium is exponentially stable and thanks to the guidance vector field
that guides the vehicles, the algorithm can be extended to other closed
trajectories. One of the main advantages of this approach is that the algorithm
guarantees the confinement of the team in a specific area, even when
communications or sensing among vehicles are lost. We show the effectiveness of
the algorithm with an actual formation flight of three aircraft. The algorithm
is ready to use for the general public in the open-source Paparazzi autopilot.Comment: 6 pages, submitted to IROS 201
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