Underwater Robotics: control of marine manipulator-vehicle systems
For using underwater vehicle-manipulator systems (UVMS) in a challenging envi-
ronment, it is important to have a good mathematical description of the system
which accounts for disturbances such as ocean currents. The dynamics equation on
matrix form is therefore derived and different properties such as positive definiteness
and skew symmetry is obtained. Based on the derived equations, a sliding mode
controller has been designed in order to track trajectories in the configuration space
of the UVMS. The controller is robust when it comes to uncertainties in dynamics
parameters and uncertainties in ocean current, yielding global asymptotic stability
as long as the uncertainties are bounded.
Furthermore, a kinematic control system has been designed for facilitating human
operation of a UVMS, by allowing an operator to only control the end effector
motion. The rest of the motion is then resolved through a weighted least-norm
pseudo inverse solution of the Jacobian matrix, in order to avoid mechanical joint
limits. Moreover, the vehicles motion is controlled by an event based algorithm to
limit the motion of the vehicle. This is done by attaching a 3D meshed polygon to
the vehicle frame and check if the end effector is inside or outside this mesh. The
mesh then represents the space, relative to the manipulator, were the end effector
is fully dexterous. The vehicle will then be commanded to move only when the end
effector reaches the outside of the meshed polygon.
A simulator has been implemented, based on the derived equations. The simula-
tions of the UVMS, with the two controllers, yields good tracking results for tracking
trajectories both in the workspace of the end effector and in the configuration space
of the UVMS.
Place, publisher, year, edition, pages
Institutt for teknisk kybernetikk , 2014. , 106 p.
IdentifiersURN: urn:nbn:no:ntnu:diva-25875Local ID: ntnudaim:10675OAI: oai:DiVA.org:ntnu-25875DiVA: diva2:742046
Pettersen, Kristin Ytterstad, Professor