Error was "IPython is not defined".

Moreover, during running qt.q , this error is occurred : "'Trajectory' object has no attribute 'q'" . Thanks.

I have attached the screenshot here. I am trying to run kinematics.ipynb file of your code. line 5 and 6 is my problem. Line 6 don't show output.

I guess I put this out a little too soon and found out shortly after. For anyone wondering the same thing, the individual joint angles from the inverse kinematics can be called by using sol.q[n] where n is the joint number.

Hi MCollins,
Once you want to create a rigid body tree, "alpha, d and, a" are required, but "theta" is the input parameters.

Can you send a complete code snippet.

(rtb) >>> tg=jtraj(puma.qr, puma.qz, 20)

(rtb) >>> tg.q
Out[3]:
array([[ 0, 1.571, -1.571, 0, 0, 0],
[ 0, 1.569, -1.569, 0, 0, 0],
[ 0, 1.555, -1.555, 0, 0, 0],
[ 0, 1.523, -1.523, 0, 0, 0],
[ 0, 1.467, -1.467, 0, 0, 0],
[ 0, 1.386, -1.386, 0, 0, 0],
[ 0, 1.281, -1.281, 0, 0, 0],
[ 0, 1.155, -1.155, 0, 0, 0],
[ 0, 1.014, -1.014, 0, 0, 0],
[ 0, 0.8628, -0.8628, 0, 0, 0],
[ 0, 0.708, -0.708, 0, 0, 0],
[ 0, 0.5567, -0.5567, 0, 0, 0],
[ 0, 0.4154, -0.4154, 0, 0, 0],
[ 0, 0.2899, -0.2899, 0, 0, 0],
[ 0, 0.1852, -0.1852, 0, 0, 0],
[ 0, 0.1042, -0.1042, 0, 0, 0],
[ 0, 0.04811, -0.04811, 0, 0, 0],
[ 0, 0.01555, -0.01555, 0, 0, 0],
[ 0, 0.002113, -0.002113, 0, 0, 0],
[ 0, 0, 0, 0, 0, 0]])

Here is what I have from the readme

import roboticstoolbox as rtb
from spatialmath import SE3

robot = rtb.models.DH.Panda()

T = robot.fkine(robot.qz) # forward kinematics

T = SE3(0.7, 0.2, 0.1) * SE3.OA([0, 1, 0], [0, 0, -1])
sol = robot.ikine_LM(T) # solve IK

q_pickup = sol.q
print(robot.fkine(q_pickup)) # FK shows that desired end-effector pose was achieved

qt = rtb.jtraj(robot.qz, q_pickup, 50)
robot.plot(qt.q, movie='panda1.gif')

Here's what would have saved a lot of time. You send me the error traceback like below for the simplest case that will cause the problem.

>>> robot.plot(robot.qz)
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "code/robotics-toolbox-python/roboticstoolbox/robot/Robot.py", line 1375, in plot
    env.add(
  File "code/robotics-toolbox-python/roboticstoolbox/backends/PyPlot/PyPlot.py", line 281, in add
    self.robots[len(self.robots) - 1].draw()
  File "code/robotics-toolbox-python/roboticstoolbox/backends/PyPlot/RobotPlot.py", line 79, in draw
    self.init()
  File "code/robotics-toolbox-python/roboticstoolbox/backends/PyPlot/RobotPlot.py", line 204, in init
    shadow, = self.ax.plot(
  File "opt/anaconda3/lib/python3.8/site-packages/mpl_toolkits/mplot3d/axes3d.py", line 1421, in plot
    zs = np.broadcast_to(zs, len(xs))
TypeError: object of type 'int' has no len()

The problem I'm seeing is in matplotlib from plot, nothing to do with trajectories. I'll check this out over the weekend.

The error traceback I get from my code above is only one line, which is also above. It says the trajectory object has no attribute q. Everything is in the first comment I made.

I also changed qt.q to qt.y and get no errors, but there is still a blank plot showing up. I can also now print the trajectory so the problem is with plotting.

Hi Peter, Many Thanks!

Error:
I have tested, but I have received the following error:
AttributeError: type object 'ERobot' has no attribute 'URDF'

My Code:
from roboticstoolbox import ERobot
import os

pwd = os.getcwd()
pth = os.path.dirname(pwd)
urdf_loc = pth + "\two_links_robot\two_links_robot.urdf"

robot = ERobot.URDF(urdf_loc)

Extra Explanation:
As a simple example, I've created a two links robot by Solidwork and export it as URDF. That creates a URDF as a package (For example "mesh filename="package://two_links_robot/meshes/Base.STL" />" for Base) which directly can be loaded to MATLAB. However, I have found this should be modified for some URDF readers such as urdfpy. Both files have been attached.
+++++++++++++++++++++++++++++++ Code ++++++++++++
from urdfpy import URDF
import os
import numpy as np

pwd = os.getcwd()
pth = os.path.dirname(pwd)
urdf_loc = pth + "\two_links_robot\two_links_robot.urdf"
robot = URDF.load(urdf_loc)
robot.animate(cfg_trajectory={
'q0': [-np.pi / 4, np.pi / 4],
'q1': [0.0, -np.pi / 2.0],
})

two_links_robot - Modified.zip
two_links_robot.zip

I'm not sure. Is there any way to check this?

I believe git clone, but I tried both ways and had some trouble and eventually got it.

Hi Peter, Thanks again!
I have found GH version can not recognize "quadprog" and "qpsolver" on Windows 10 and I've received the attached errors. However, I was able to completely install it on ubuntu.
Now I am able to create my robot object from the URDF file. However, I have to copy the URDF package on rtb-data!
New Error:
Once I want to calculate "acc", "tau" and M, C, G matrix, I have received this error:

s[j] = link.v.s
AttributeError: 'NoneType' object has no attribute 's'

Which seems related to line 2105 of the ERobot module.
#################error: installing on windows ####################
ERROR: Command errored out with exit status 1:
command: 'C:\Users\moham\miniconda3\envs\rtb\python.exe' -u -c 'import sys, setuptools, tokenize; sys.argv[0] = '"'"'C:\Users\moham\AppData\Local\Temp
\pip-install-3f548fr0\quadprog_e756ac553e55447faa445d89b72774ea\setup.py'"'"'; file='"'"'C:\Users\moham\AppData\Local\Temp\pip-install-3f548fr0\
quadprog_e756ac553e55447faa445d89b72774ea\setup.py'"'"';f=getattr(tokenize, '"'"'open'"'"', open)(file);code=f.read().replace('"'"'\r\n'"'"', '"'"'\n'"'"
');f.close();exec(compile(code, file, '"'"'exec'"'"'))' bdist_wheel -d 'C:\Users\moham\AppData\Local\Temp\pip-wheel-i7s52nqp'
cwd: C:\Users\moham\AppData\Local\Temp\pip-install-3f548fr0\quadprog_e756ac553e55447faa445d89b72774ea
Complete output (6 lines):
running bdist_wheel
running build
running build_ext
skipping 'quadprog\quadprog.cpp' Cython extension (up-to-date)
building 'quadprog' extension
error: Microsoft Visual C++ 14.0 or greater is required. Get it with "Microsoft C++ Build Tools": https://visualstudio.microsoft.com/visual-cpp-build-tools/

ERROR: Failed building wheel for quadprog

ERROR: Command errored out with exit status 1:
command: 'C:\Users\moham\miniconda3\envs\rtb\python.exe' -u -c 'import sys, setuptools, tokenize; sys.argv[0] = '"'"'C:\Users\moham\AppData\Local\Te
mp\pip-install-3f548fr0\quadprog_e756ac553e55447faa445d89b72774ea\setup.py'"'"'; file='"'"'C:\Users\moham\AppData\Local\Temp\pip-install-3f548fr0
\quadprog_e756ac553e55447faa445d89b72774ea\setup.py'"'"';f=getattr(tokenize, '"'"'open'"'"', open)(file);code=f.read().replace('"'"'\r\n'"'"', '"'"'\n'"
'"');f.close();exec(compile(code, file, '"'"'exec'"'"'))' install --record 'C:\Users\moham\AppData\Local\Temp\pip-record-t84keeva\install-record.txt' --si
ngle-version-externally-managed --compile --install-headers 'C:\Users\moham\miniconda3\envs\rtb\Include\quadprog'
cwd: C:\Users\moham\AppData\Local\Temp\pip-install-3f548fr0\quadprog_e756ac553e55447faa445d89b72774ea
Complete output (6 lines):
running install
running build
running build_ext
skipping 'quadprog\quadprog.cpp' Cython extension (up-to-date)
building 'quadprog' extension
error: Microsoft Visual C++ 14.0 or greater is required. Get it with "Microsoft C++ Build Tools": https://visualstudio.microsoft.com/visual-cpp-build-tool
s/
----------------------------------------
ERROR: Command errored out with exit status 1: 'C:\Users\moham\miniconda3\envs\rtb\python.exe' -u -c 'import sys, setuptools, tokenize; sys.argv[0] = '"'"'C:
\Users\moham\AppData\Local\Temp\pip-install-3f548fr0\quadprog_e756ac553e55447faa445d89b72774ea\setup.py'"'"'; file='"'"'C:\Users\moham\AppData\
Local\Temp\pip-install-3f548fr0\quadprog_e756ac553e55447faa445d89b72774ea\setup.py'"'"';f=getattr(tokenize, '"'"'open'"'"', open)(file);code=f.read().
replace('"'"'\r\n'"'"', '"'"'\n'"'"');f.close();exec(compile(code, file, '"'"'exec'"'"'))' install --record 'C:\Users\moham\AppData\Local\Temp\pip-record-
t84keeva\install-record.txt' --single-version-externally-managed --compile --install-headers 'C:\Users\moham\miniconda3\envs\rtb\Include\quadprog' Check the l
ogs for full command output.

Hi @kraudust. self-collision check has been imlemented for Panda in DH models. Make sure to have install prtb with collision and try the following code snippet.

import roboticstoolbox as rtb 

panda = rtb.models.DH.Panda() 

panda.collided(panda.q, panda)