7 Final Remarks
We have presented a nonlinear control law, a state
transformation and a choice of outputs that produces
minimum phase underwater glider dynamics. The control law can be interpreted as the realization of constraint forces associated with a suspension system for a
controlled internal shifting mass. We proved exponential stability of glide paths using an additional linear
control law for the acceleration of the shifting mass and
the rate of change of the variable buoyancy mass. We
discussed how this produces large regions of attraction
and illustrated it in the case of switching between two
glide paths. Extensions to tracking were also discussed.
Finally, we showed how to use the I/O linearized multivehicle system to design inter-vehicle coupling to coordinate the glide paths of n identical underwater gliders.