Value Error inverse_kinematics

[HaffmannGG]

Following the getting started i got an issue with Setting the position of your chain (aka Inverse Kinematics, aka IK).

File "C:\Users\Jonas\untitled1.py", line 46, in frame_target[:3,:3] = target_position

ValueError: cannot copy sequence with size 4 to array axis with dimension 3

After changing the line to "frame_target = target_position" the error is gone and the presented results appear in the console. Am i just a noob or is this broken?

[Phylliade]

Hello @HaffmannGG, can you provide the full code snippet that appears?

(i.e. what is target_position?)

[HaffmannGG]

`from ikpy.chain import Chain from ikpy.link import OriginLink, URDFLink

my_chain = Chain.from_urdf_file("C:\X\X\X\ikpy-master\ikpy-master\resources\poppy_ergo.URDF")

my_chain.inverse_kinematics([[1, 0, 0, 2], [0, 1, 0, 2], [0, 0, 1, 2], [0, 0, 0, 1]])`

I use Anaconda and Spyder as my env.

runfile('C:/X/X/untitled1.py', wdir='C:/X/X') Traceback (most recent call last):

File "C:\X\X\untitled1.py", line 16, in [0, 0, 0, 1]])

File "C:\X\X\anaconda3\lib\site-packages\ikpy\chain.py", line 138, in inverse_kinematics frame_target[:3, 3] = target_position

ValueError: cannot copy sequence with size 4 to array axis with dimension 3

[Phylliade]

It seems your target_position is not a three dimensional vector, as it should be

[HaffmannGG]

The inserted matrix is 4 by 4 and if i call "inverse_kinematics" it takes the only argument as target_position. Am i missing something?

[HaffmannGG]

My bad. I did follow the Getting Started from your wiki page (https://github.com/Phylliade/ikpy/wiki). In these steps you call the inverse kinematics function with a 4x4 matrix. I checked your Quickstart file and in this case you use a 1x3 vector. Everythin is working fine.

[alxy]

I have a actually the same same issue and a script at hand which passes a 4x4 matrix to the inverse_kinematics function as described here: https://github.com/Phylliade/ikpy/wiki#setting-the-position-of-your-chain-aka-inverse-kinematics-aka-ik

Has this been possible in a former version of the library and now it only accepts a three valued vector? In this case, you should update the wiki ;) @Phylliade If I see that correctly the orientation is now handled via the second argument of that function, right?

[HaffmannGG]

@alxy you are right. This link is outdated.

[Phylliade]

Hello @HaffmannGG @alxy, thanks for pointing this out, it's now fixed!