Abstract
The research work of this thesis manuscript focus on the analysis of the frequency of robots’ vibrations. Our applications mainly revolve around architectures with parallel kinematics. First we examined parallel robots which are redundant in actuation and for which we are considering an increase of their oscillations’ frequency using the internal forces inherent to this type of structure. The aim is to use their actuation is the tensioning of their structure, and consequently, by analogy with a vibrating-wire, to enhance theiroscillation frequency. We have studied several redundancy planar robots and we demonstrate that in the case of robots which are typically designed to be stiff, the impact of added internal forces is of low relevance. The continuation of our research supports the following proposal: “High dynamics trajectories have an impact on the oscillation frequency of the mobile platform.” Indeed parallel robots, when designed to be light, can reach greater accelerations. We chose to concentrate on the study of the impact that dynamic effects canhave on the oscillation frequency of those robots’ mobile platform. The robots examined for our developments are planar parallel robots whether they have redundant actuation or not. We offer to study this impact based on a prime order development of the dynamic model. This linearisation of the dynamic model is intended to be more complete than those suggested by literature. We explain and verify the validity of our approach with a study on the link between speed and oscillation frequency on PR robots (pendulum on a vertical sliding guide) and RR robots ( double pendulum rotating horizontally). Then we will generalize our first order model and apply it to the four robots ( PRR-2 PRR-3, PRR-4, and Dual-V) to see if we are able to identify a pattern regarding the evolution ofoscillation frequencies. We observe that, depending on the trajectories, the dynamics have a low but noticeable, and often positive, impact on the increase of oscillation frequency of the mobile platform. However, since the trajectories and speed input laws are imposed, we have no choice but to be subjected to this impact.