Beschreibung:
A wide range of control theory deals with the problem that, for a known system, a controller has to be designed in order that the feedback system achieves the prespecified control objective like stabilization or tracking. The fundamental difference between this approach and that of adaptive control in this paper is that the system is not known exactly, only structural information about the system, like the relative degree or the minimum phase condition, is available. In general, one cannot expect to have complete information about a sophisticated mechanical or biological system, but instead only structural properties (e.g. minimum phase condition, strict relative degree) are known. Therefore, the method of adaptive control is chosen in this paper. The aim is to design a universal adaptive controller, which learns from the behaviour of the system, so automatically adjusts its parameters and achieves a pre-specified control objective. - The paper deals with a mechanical system, which is inspired by biological ideas. We present some theoretical investigations and prototypes of a worm-like locomotion system that has the earthworm as a living example. This system is modelled in the form of a straight chain of k = 3 interconnected point masses. The ground contact can be described by non-symmetric dry friction. We consider the case where different point masses are under the action of external forces. Also the distance between the point masses can be given as a kinematical constraint (control input). Since we deal with nonlinearly perturbed multi-input, multi-output systems, which are not necessary autonomous, particular attention is paid to the lambda-tracking control objective. We stress that the introduced adaptive controllers consist of very simple feedback mechanisms and adaptation rules.