Contributions à l'analyse et à l'optimisation de mécanismes poly-articulés
Bibliographic record
Abstract
In that thesis, I present the research that I conducted at IRCCyN and McGill University on the analysis and design of mechanisms. <br />Concerning the analysis of the mechanism, I followed the same research plan for serial and parallel mechanisms. The classification of mechanisms 3R orthogonal according to the typology of their workspace and the definition of a necessary and sufficient condition for having binary or quaternary mechanisms are significant achievements for mechanisms serial. The concept of isotropy and characteristic length are two concepts that I discussed for serial and parallel mechanisms. In both cases, I have made a contribution by working on the characteristic length optimised for serial mechanisms and defining characteristic length for a number of parallel mechanisms. I transposed the notion of aspect and of uniqueness domains during my thesis for parallel mechanisms. These definitions are based on the concept of working modes that I outlined in 1997. We then worked on defining cusp points using the work of McAree and introducing an algorithm to characterize. By studying the non-singular changing assembly mode trajectory, we have highlighted, in the joint space, the encircle of one or more points cusp. <br />Regarding the mechanism design, we used the results of the analysis of serial and parallel mechanisms for calculating performance indices (characteristic length) or to find new classes of mechanisms (classification of serial mechanisms, concept of isotropy ). The classification of serial mechanisms enabled us to achieve several classes of mechanisms whose properties remain stable on the basis of their design parameters. Among the 3R orthogonal mechanisms, we classified two types that seem attractive to the engineer. For planar mechanisms with three degrees of freedom, we looked mainly 3-PRR using the surface of the workspace and average of the inverse conditioning. This multi-objective optimisation was new to me when I made. We conducted several studies on optimising and comparison of parallel mechanisms for planar and spatial movements of pure translation. These results were used to justify, according to several indices of performance, the relevance of the use of isotropy. <br />We realized the design of the vertebrae of an eel like robot in the project "ROBEA anguille" using our knowledge of the parallel mechanisms. The mechanism of parallel architecture allows for lower power of motor. For swimming, two engines work together in the same direction and to plunge these two engines work well together but also in opposition. The placement of these motors has been optimised to fit into the elliptical cross-section of the eel. A prototype has been built and assembled at IRCCyN. <br />Within the European project NEXT, we studied the kinematics of the machine Verne. We studied the assembly modes and the working modes then modelled the workspace within the limitations of the actuated and passive joints. We have also shown that the workspace is free of singularity and collision was larger than that currently used. To solve the problem of coupling between the size of the workspace and the length of the tool, we can generate a workspace tailored to each situation that can be exported in the form of CAD file in CATIA for example. <br />We realized optimisation of the Slide-o-Cam as a mechanism for transforming rotary motion in translation using multiple objective functions (the angle of pressure, the hertz pressure, the size and the inertia of moving parts). The resolution of this problem has allowed me to address the problem of multi-objective optimisation, which is one of the themes of our team. <br />I presented the two versions of Orthoglide, 3-axis and 5-axis. Many results have been obtained and presented in this thesis. The design approach has allowed us to define the size of the prototype in terms of specifications oriented machines at high speeds. We have defined the concept of regular dexterous workspace for the Orthoglide and used this notion to compare several parallel mechanisms. We conducted an analysis of the rigidity using a model using localized flexibilities.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.003 | 0.001 |
| Meta-epidemiology (narrow) | 0.001 | 0.001 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.001 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.000 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one teacher head, not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".