How to get simIK and simOMPL in python?

[zhengkz]

Hi,

I copy the same command for sim, where

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sim = coppeliasim.bridge.require('sim')

, but it fails on simIK and simOMPL about

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simIK = coppeliasim.bridge.require('simIK')
simOMPL = coppeliasim.bridge.require('simOMPL')

The error is:

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AttributeError: 'NoneType' object has no attribute 'items'

at line 39 of CoppeliaSim_Edu_V4_6_0_rev8_Ubuntu20_04/coppeliasim/bridge.py, where '_info' is None.

I wonder what is the correct way to load these plugs. Thanks!

[coppelia]

Hello,

try with following as a workaround:

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    global simIK
    simIK = coppeliasim.bridge.call('scriptClientBridge.require', ['simIK'])
    simIK = coppeliasim.bridge.require('simIK')

The middle command should normally not be needed, and this should be corrected in next revision (rev 10)

Cheers

[zhengkz]

I have tried to use

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    simIK = coppeliasim.bridge.call('scriptClientBridge.require', ['simIK'])
    simIK = coppeliasim.bridge.require('simIK')

But it cannot pass a Python function as an argument for validation callback in simIK.generatePath function.
The error is about

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ValueError: cannot serialize unknown object: <function Arm.get_linear_path.<locals>._check_collisions_callback at 0x7f68a0530ca0>

If I use zmq RemoteAPIClient, it can pass the python function as a validation callback function. What should I pass here, and how can I fix it?

Thanks,
Kz

[coppelia]

In that situation, callbacks are currently not supported. What is your use case exactly, or why do you need to use Ik or path planning from that location?

There are workarounds for this, but not that straightforward...

Cheers

[zhengkz]

I'm using IK to generate linear paths for the robot arm during some manipulation tasks. The callback function is used to check for collisions during planning. I checked the IK and OMPL documents and I didn't find an easier way for collision checking. Is there any demo or example to show how to add collision checking without using validation callback?

Best,
Kz

[coppelia]

Right now, if you want to use a state validation callback or simIK.findConfig (also with a validation callback), you'll have to set-up a Python ZeroMQ remote API client in a separate thread.

Otherwise you can use simOMPL.setCollisionPairs, which will internally simply check the two+ entities for collision.

But we can implement the callback functionality for situations like yours... need to evaluate a few options...

Cheers