Multi-segmented artificial locomotion systems with adaptively controlled gait transitions
This paper is devoted to the analysis and simulation of multi-segmented artificial locomotion systems. The biological paradigm is the earthworm. Here, we restrict our investigation to a crawling system which is moving along a straight line, more precisely, the system is firstly moving unidirectionally. Recent results from the examined literature present investigations of short worms (n < 4). In contrast to this, the developed mechanical model in this paper consists of a chain of 10 discrete mass points. Let us point out, that the presented investigations are not restricted to a fixed number of mass points. To achieve a movement of the system, the distances between neighboring mass points are controlled by viscoelastic force actuators. Due to a prescribed reference gait, an adaptive controller determines the necessary forces to adjust the prescribed values. Then, due shortening and lengthening of these distances together with a spiky ground contact at the mass point (preventing velocities from being negative), we achieve a global movement of the whole system – called undulatory locomotion. Specific prescribed gaits are required to guarantee a controlled movement that differ especially in the number of resting mass points and the load of actuators and spikes. To determine the most advantageous gaits, numerical investigations are performed and a weighting function offers a decision of best possible gaits. Finally, a gait transition algorithm for an autonomously change of the locomotion velocity and number of resting mass points in dependence on the spike and actuator force load is presented and tested in numerical simulations.
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