mikeroberts3000 / flashlight Goto Github PK

Hey! Thank you for uploading this, I am glad to see a good control library for quadrotors with really good looking viz. I wanted to play around with this, but I realized that the library files are Mach-O formats but I use Linux. I was wondering if you will be providing Linux complied versions of the libraries?

Otherwise I get this ..

ImportError: quadrotor_2d_H.so: invalid ELF header

When running any file that imports transformations.py. I get a user warning which says that it failed to run line 1902:

/home/arun/git_projs/flashlight/code/lib/flashlight/transformations.py:1888: UserWarning: failed to import module _transformations
  warnings.warn("failed to import module %s" % name)

@mikeroberts3000 : Pondering about the use case of trigonometric spline and its coefficients. Since I could not find documentation, I am asking here. Can you provide an an insight or at the least any reference.

Thanks for this really great library! I'm excited to start using it! I was able to run the first example but I had to work around a couple of spots in sympy_utils.py which didn't work on my platform, anaconda python 2.7.15 with sympy 1.2 on OSX (with Apple's gcc).

Any advice on what I should change or what dependencies I should add on my platform? Thanks!

The workarounds I needed to run the first example are as follows:

First, after changing build_sympy_modules_on_import = True, line 476 raised an error:

'module' object has no attribute '_get_code_wrapper_class'

My hasty workaround for 476(without support for other backends):

-    CodeWrapperClass = sympy.utilities.autowrap._get_code_wrapper_class(backend)
+    if backend == "f2py":
+        CodeWrapperClass = sympy.utilities.autowrap.F2PyCodeWrapper
+    elif backend == "cython":    
+        CodeWrapperClass = sympy.utilities.autowrap.CythonCodeWrapper

Nominally, should build_module_autowrap not be running down that codepath? (I haven't taken any time to understand what's going on inside of it yet.)

I also am using osx's clang-/llvm gcc, without openmp installed, and had to edit a few other items:

1. I had to remove the compile and link arguments to openmp, and also -fno-var-tracking-assignments in this template, since clang raises an error:

clang: error: unknown argument: '-fno-var-tracking-assignments'

2. similarly I had to remove -fno-var-tracking-assignments and also remove the second instance of include_dirs here due to the following error:

extra_compile_args=['-std=c99','-fno-var-tracking','-fno-var-tracking-assignments'], include_dirs=[numpy.get_include()],
SyntaxError: keyword argument repeated

After these changes, the first example on the homepage worked.

Again, thanks so much for providing this library!

Update, 9/4/18

I did also try linking to openmp on my platform with brew install libomp. The brew formula comes with "caveat" instructions, quoting:

"On Apple Clang, you need to add several options to use OpenMP... This usually looks like
-Xpreprocessor -fopenmp -lomp"

So now my sympy_utils.py looks like this (in a blind attempt to follow the instructions without knowing proper OpenMP linking procedures):

-extra_compile_args = [ "-fopenmp", "-fno-var-tracking", "-fno-var-tracking-assignments" ]
-extra_link_args    = [ "-fopenmp" ]
+extra_compile_args = [ "-fno-var-tracking", "-Xpreprocessor", "-fopenmp", "-lomp" ]
+extra_link_args    = [ "-Xpreprocessor", "-fopenmp", "-lomp" ]

This does generate some clang warnings after setting build_sympy_modules_on_import = True (this time in quadrotor_3d.py which I did not build as part of my initial issue posting, since the first example on the homepage uses quadrotor_2d.py):

clang: warning: -lomp: 'linker' input unused [-Wunused-command-line-argument]
clang: warning: argument unused during compilation: '-Xpreprocessor -fopenmp' [-Wunused-command-line-argument]

In any case, I'm able to run the examples in this notebook so in the short-term I will wait to dig in further.

Hello!
Kindly, I want to as if I can, with Flashlight, impose inequality constraints on the first and second derivatives of the piecewise polynomial trajectory.
What I am aiming to do is to generate a snap optimized piecewise polynomial trajectory (based on a number of 3D waypoints), in which the zeroth (the minimum snap piecewise polynomial), the first (speed), and the second (acceleration) derivatives won't exceed a certain value.
Any example/guidance would be highly appreciated.

You don't seem to use any of the files from code/lib/flashlight/trajectory_optimization, just curious as to why it is there?

Thanks!

I was getting the following error from scipy.interpolate.interp1d() in interpolate_utils.resample_scalar_wrt_scalar():

 in reparameterize_curve
    t_user_progress_cubic = interpolate_utils.resample_scalar_wrt_scalar(l_cum_norm,t_p_linspace_norm,user_progress,kind="cubic")
  File "code/lib/flashlight/interpolate_utils.py", line 27, in resample_scalar_wrt_scalar
    x_new         = x_interp_func(t_new)
  File "scipy/interpolate/polyint.py", line 79, in __call__
    y = self._evaluate(x)
  File "scipy/interpolate/interpolate.py", line 664, in _evaluate
    below_bounds, above_bounds = self._check_bounds(x_new)
  File "site-packages/scipy/interpolate/interpolate.py", line 696, in _check_bounds
    raise ValueError("A value in x_new is above the interpolation "

ValueError: A value in x_new is above the interpolation range.

From this StackOverflow post I'm guessing this is from an update to scipy, so I have added in fill_value='extrapolate' in interpolate_utils.py:

-    x_interp_func = scipy.interpolate.interp1d(t,x,kind=kind)
+    x_interp_func = scipy.interpolate.interp1d(t,x,kind=kind, fill_value='extrapolate')

I am guessing this was the default behavior of the version of scipy that flashlight was written with, (but I haven't looked in scipy changelogs to check). The generated trajectory in the notebook example looks good though.

Thanks again for this great library! Excited to start using it more!

Platform info

I'm using scipy 1.1.0: on OSX:

$ conda list | grep scipy
scipy                     1.1.0           py27_blas_openblash7943236_201  [blas_openblas]  conda-forge