Self-supporting is a term used for a type of pattern, specifically a macro-spaceship, that constructs signals or tracks or other scaffolding to assist its movement, but does not contain complete information about its own structure. Examples include the Caterpillar, Centipede, half-baked knightship, waterbear, and the Caterloopillars. Caterpillar has been used as a general term for self-supporting spaceships, but it is not very appropriate for the HBKs.
In general a self-supporting pattern cannot be trivially adjusted to alter its speed or direction. The variable speeds of the HBKs and the Caterloopillars are exceptions, but their direction of travel is fixed, and a specific Caterloopillar can't be made to change its speed without completely rebuilding it. Compare self-constructing, elementary.