Triple-axis spectrometers (TAS) for neutron inelastic scattering have a complex measuring strategy and only skilled and well trained users can drive them safely. The software TAS-Paths is part of the efforts of the Institut Laue-Langevin in the field of autonomous instrument control, It implements a safe pathfinding algorithm for TAS spectrometers which computes safe paths to move the spectrometer from one position to another.
Due to angular constraints in the instrument space, as well as from obstacles such as walls, not every (Q, E) coordinate point is accessible for the instrument. A careful mapping of the available positions is usually required before each experiment to avoid any collisions. The present algorithm is able to automatically find the optimal safe path for the instrument, keeping it at the furthest possible distance from obstacles. It does so by calculating the Voronoi bisectors of the instrument's angular configuration space. Of these it creates a mesh of possible paths and finds the shortest path along the bisectors.
If you have never used TAS-Paths before, here are a few steps to try out the pathfinding functionality:
- Main window: move existing walls or obstacles with the cursor and/or use menu "Geometry" to add new obstacles to the scene.
- Menu Calculation/Angular Configuration Space...: this opens the Angular Configuration Space dialogue.
- Click the "Calculate Mesh" button to compute the roadmap corresponding to the current instrument and wall configuration.
- Set the start and target instrument positions by selecting "Move Instrument Position" or "Move Target Position" radio buttons respectively and then by clicking in the configuration space plot. Note that the instrument is moved accordingly in the main window.
- A safe path from the start to the target position is calculated.
- Main window: The above safe path can be directly traced by clicking the "Go" button in the "Path Properties" dock window. (Use menu "View" to make it visible if it was closed)
- https://code.ill.fr/scientific-software/takin/paths (for the repository)
©2021 by Tobias Weber (ILL, Grenoble, France). Copyleft: GPLv3.
01/2022 v1.4.0 - auxiliary binaries taspaths-hull, taspaths-lines, taspaths-poly were incorporated to the main binary
12/2021 v1.3.7 - fixed some path calculation bugs which could have occurred in (hopefully) rare cases.
12/2021 v1.3.5 - small bugfixes and more tooltips for each element of the GUI. Known bug: Save and Save as... dialogues not yet compatible with sandboxing.
12/2021 v1.3.5 - Dec 2021 - first macOS version made available to users.
12/2021 v1.3.4 - improved Save/Save as.. dialogues. Menu item Apple/About TAS-Paths
12/2021 v1.3.3 - improved GUI and new App Preview movie. New icon for .taspath files.
11/2021 v1.3.2 - TASPaths was renamed to TAS-Paths
10/2021 v1.3.0 - TASPaths needs macOS 11 or higher due to the use of extra homebrew libraries. The dedicated page <https://www.ill.eu/TAS-Paths> was created
29/2021 v1.2 - improved the pathfinding algorithm
15/2021 v1.1 - improved the pathfinding algorithm
01/2021 v1.0 - first fully working release version