How to create chain of links from DH table, I got an error while trying to do that.

[Abhi001vj]

l0 = ikpy.link.OriginLink() l1 = ikpy.link.DHLink('l1', d=3, a=0, bounds=None, use_symbolic_matrix=True) l2 = ikpy.link.DHLink('l2', d=0, a=5.75, bounds=None, use_symbolic_matrix=True) l3 = ikpy.link.DHLink('l3', d=0, a=7.375, bounds=None, use_symbolic_matrix=True) l4 = ikpy.link.DHLink('l4', d=0, a=0, bounds=None, use_symbolic_matrix=True) l5 = ikpy.link.DHLink('l5', d=4.125, a=0, bounds=None, use_symbolic_matrix=True) my_chain = ikpy.chain.Chain([l0,l1,l2,l3,l4,l5])
I got this error
`---------------------------------------------------------------------------
AttributeError Traceback (most recent call last)
in ()
----> 1 my_chain = ikpy.chain.Chain([l0,l1,l2,l3,l4,l5])

~/.local/lib/python3.5/site-packages/ikpy/chain.py in init(self, links, active_links_mask, name, profile, **kwargs)
21 self.name = name
22 self.links = links
---> 23 self._length = sum([link._length for link in links])
24 # Avoid length of zero in a link
25 for (index, link) in enumerate(self.links):

~/.local/lib/python3.5/site-packages/ikpy/chain.py in (.0)
21 self.name = name
22 self.links = links
---> 23 self._length = sum([link._length for link in links])
24 # Avoid length of zero in a link
25 for (index, link) in enumerate(self.links):

AttributeError: 'DHLink' object has no attribute '_length'`

Also I got this error when trying to import from ikpy import plot_utils

from ikpy import plot_utils

error

`---------------------------------------------------------------------------
ImportError Traceback (most recent call last)
in ()
1 import ikpy
2 import numpy as np
----> 3 from ikpy import plot_utils

~/.local/lib/python3.5/site-packages/ikpy/plot_utils.py in ()
4 from . import geometry_utils
5 import matplotlib.animation
----> 6 from mpl_toolkits.mplot3d import Axes3D
7
8

/usr/lib/python3/dist-packages/mpl_toolkits/mplot3d/init.py in ()
2 unicode_literals)
3
----> 4 from matplotlib.externals import six
5
6 from .axes3d import Axes3D

ImportError: No module named 'matplotlib.externals'`

Thank you.

[ChunJyeBehBeh]

Hello, may I know have you solved the problem?

[Phylliade]

Hey,

This seems to be a bug in the DH links.

Actually the DH implementation is preliminary and lacks uses-cases: is the code you presented coming from a real robot? In this case, could you provide the complete set of DH parameters and the robot metadata so I can use it as a base for the test cases to develop further the DH parameters?

[Phylliade]

Additionally, the second issue you got (with matplotlib) is an ubuntu issue.

Take a look at this, this may help you:
https://stackoverflow.com/questions/45103248/importerror-no-module-named-matplotlib-externals

[stale]

This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. Thank you for your contributions.

[Tanneguydv]

I've written some code to resolve the problem of creating a chain link from DH parameters table, see #143