An idealized hovercraft floating without friction over the ground or water is considered. Putting the sustentation system aside, the modelling equations of the hovercraft’s dynamics are similar to these of a motor boat, except for the absence of damping hydraulic forces that facilitate the control of the vehicle,regardless of energy consumption issues. When these forces do not exist, and no thrust is applied, the vehicle is either motionless or it drifts with constant velocity along a straight line, independently of the vehicle’s orientation. Controlling such a system is theoretically more challenging than controlling a motor boat. For instance, by contrast with a boat, linearization of the system’s equations about a straight-line trajectory with constant velocity yields a system which is not controllable.

The first simulation video illustrates the problem of tracking a reference point (the origin of the yellow frame) moving on the plane with no constraint concerning the vehicle’s orientation, except that the vehicle’s angular velocity should converge to zero when the reference point comes to a stop.

Click here to watch the video.

The second video illustrates the same problem, with the complementary objective (or constraint) of keeping the hovercraft “almost” horizontal all the time. Except for the specification of a constant reference orientation, the same controller is used.

Click here to watch the video.