Publications

Recent research topics in bionics focus on the analysis and synthesis of animal spatial perception of their environment by means of their tactile sensory organs: vibrissae and their follicles. Using the vibrissae, these mammals (e.g., rats) are able to determine an obstacle shape using only a few contacts of the vibrissa with the object. The investigations lead to the task of creating models and a stringent exploitation of these models in form of analytical and numerical calculations to achieve a better understanding of this sense. The sensing lever element vibrissa for the stimulus transmission is frequently modeled as an EulerBernoulli bending rod. We assume that the rod is one-sided clamped and interacts with a rigid obstacle in the plane. But, most of the literature is limited to the research on cylindrical and straight, or tapered and straight rods. The (natural) combination of a cylindrical and pre-curved shape is rarely analyzed. The aim is to determine the obstacles contour by one quasi-static sweep along the obstacle and to figure out the dependence on the precurvature of the rod. To do this, we proceed in several steps: At first, we have to determine the support reactions during a sweep. These support reactions are equate with the observables an animal solely relies on and have to be measured by a technical device. Then, the object shape has to be reconstructed in using only these generated observables. The consideration of the precurvature makes the analytical treatment a bit harder and results in numerical solutions of the process. But, the analysis of the problem results in an extension of a former decision criterion for the reconstruction by the radius of pre-curvature. Is is possible to determine a formula for the contact point of the rod with the profile, which is new in literature in context of pre-curvature.

This is the second part of the contribution to the adaptive control of worm-systems, which are inspired by biological ideas. Part 1 is the basis for this part. We focus now on the adaptive control since one cannot expect to have complete information about a sophisticated mechanical or biological system in general. Only structural properties (known type of actuator with unknown parameters) are known. Additionally, in a rough terrain, unknown or changing friction coefficients lead to uncertain systems, too. The consideration of uncertain systems leads us now to the use of adaptive control. We still assume that the worm-system contacts the ground via spikes and track gaits from the kinematical theory (preferred motion patterns to achieve movement) by means of adaptive controllers (lambda-trackers). Then we replace the worm-ground interaction by stiction combined with Coulomb sliding friction (modification of a Karnopp friction model) and point out the main differences for the worm-like locomotion.