suzanne.soy/FreeCAD_assembly3
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity

Update readme

Browse Source
This commit is contained in:
Zheng, Lei 2018-01-07 19:07:29 +08:00
parent 76f3ed40d1
commit 3a252d48df
1 changed files with 37 additions and 10 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

47
Readme.md
View File

@ -10,6 +10,9 @@ assemblies.
## Installation
If you don't want to build everything yourself, please checkout the release
page for pre-built images.
At the moment of this writing, Assembly3 only works with a forked FreeCAD
[branch](https://github.com/realthunder/FreeCAD/tree/LinkStage3). You need to
first checkout this branch and build it yourself.
@ -156,20 +159,47 @@ SolveSpace's solver design, that is, symbolic algebraic + non-linear least
square minimization. It can be considered as a python implementation of the
SolveSpace's solver.
SciPy offers a dozen of different minimization algorithms, but most of which
cannot compete with SolveSpace performance wise. The reasons for writing this
backend are,
SciPy offers a dozen of different [minimization](https://docs.scipy.org/doc/scipy/reference/generated/scipy.optimize.minimize.html)
algorithms, but most of which cannot compete with SolveSpace performance wise.
The following list shows some non-formal testing result using default
parameters with the sample [assembly](#create-a-super-assembly-with-external-link-array)
described later
| Algorithm | Time |
| --------- | ---- |
| SolveSpace (as reference) | 0.006s |
| Nelder-Mead | Not converge |
| Powell | 7.8s |
| CG | 10+37s <sup>[1](#f1)</sup> |
| BFGS | 10+0.8 <sup>[1](#f1)</sup> |
| Newton-CG | 10+61+0.5s <sup>[2](#f2),</sup><sup>[3](#f3)</sup> |
| L-BFGS-B | 10+1.5s <sup>[1](#f1),</sup><sup>[3](#f3)</sup> |
| TNC | 10+0.8s <sup>[1](#f1)</sup> |
| COBYLA | 0.2s <sup>[3](#f3)</sup> |
| SLSQP | 10+0.3 <sup>[1](#f1),</sup><sup>[3](#f3)</sup> |
| dogleg | 10+61+?s <sup>[2](#f2)</sup> Failed to solve, linalg error |
| trust-ncg | 10+61+1.5s <sup>[2](#f2)</sup> |
<b name="f1">[1]</b> Including Jacobian matrix calculation (10s in this test
case), which is implemented using sympy lambdify with numpy.
<b name="f2">[2]</b> Including Hessian matrix calculation (61s in this test
case), in addition to Jacobian matrix.
<b name="f3">[3]</b> The obtained solution contains small gaps in some of
the coincedence constrained points. Incorrect use of the algorithm?
The reasons for writing this backend are,
* SolveSpace is under GPL, which is incompatible with FreeCAD's LGPL,
* To gain more insight of the solver system, and easy experimentation with new
ideas due to its python based nature,
* For future extension, physics based simulation, maybe?
You'll need to install SymPy and SciPy for your platform. For Ubuntu, simply
run
You'll need to install SymPy and SciPy for your platform.
```
apt-get install python-sympy python-scipy
pip install --upgrade sympy scipy
```
## Design
@ -184,10 +214,7 @@ which are summarized below,
The forked FreeCAD core supports external object linking (with a new type of
property, `PropertyXLink`, as a drop-in replacement of PropertyLink),
displaying, editing, importing and exporting. An important feature that's still
missing is cross document undo/redo. Currently, a single action involving
external objects may generate multiple transactions across multiple documents,
which is inconvenient and confusing if the user tries to undo/redo.
displaying, editing, importing/exporting, and cross-document undo/redo.
### Part-tree