June 27, 2019, 08:34:38 AM

# Relative pose of tool0

### Author Topic:  Relative pose of tool0  (Read 345 times)

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April 05, 2019, 10:26:20 AM

#### JonasHS

##### Relative pose of tool0
Does anyone know how I can find and calculate the relative pose of tool0 (end effector) coordinate frame with respect to base coordinate frame on an ABB IRB120? All other relative poses are known.

I have attached a picture of the robot. User frame and object frame should be swapped around.

Hope it makes sense.
« Last Edit: April 05, 2019, 10:30:22 AM by JonasHS »

Today at 08:34:38 AM

Guest
##### Re:  Relative pose of tool0

April 05, 2019, 05:10:02 PM

#### SkyeFire

Global Moderator
##### Re: Relative pose of tool0
Well, it's been a looong time since I had to do anything like this in RAPID, but if I understand you correctly, you could probably do something like PoseMult(CRobT, PoseInv(tool data))

The idea is, you take the current position of the TCP, and multiply it by the inverse of the active tool.  That should get you the position of "Tool 0", the center of the A6 flange, in the active Work Object.

April 05, 2019, 05:38:28 PM

#### SAABoholic

##### Re: Relative pose of tool0
If your World/Base is not the same, the relationship between them should be known (check your system parameters if nothing else).

Easiest way to accomplish what you're looking to do is to convert your current position into joint target (using your active tool/wobj)
and then convert the joint target back to a robtarget using Tool0 and a wobj with the known "negative" relationship between your Base/world. This should (in theory anyway, I haven't tested it yet) give you the robtarget in BASE using tool 0 and from there you can extract the pose (if that's all you want).

April 05, 2019, 05:43:34 PM

#### Lemster68

Global Moderator
##### Re: Relative pose of tool0
Why not just CRobT(Tool0,Wobj0) ?

April 05, 2019, 05:53:24 PM

#### SAABoholic

##### Re: Relative pose of tool0
Last I checked that would give you the coordinates relative to World.

April 05, 2019, 05:59:46 PM

#### Lemster68

Global Moderator
##### Re: Relative pose of tool0
So if the world and base are coincident, that would be sufficient.  But like you said, if they are not, then perhaps more work needs to be done.

April 15, 2019, 03:28:13 PM

#### robotero

##### Re: Relative pose of tool0
The position of the tool relative to world object is known
And is the product of three transformations:
Worldtobase*basetotool0*TCP

You want to know the position tool0 relative to base

You then need to premultiply by the inverse of Worldtobase and post multiply by the inverse of TCP

I am sure there are commands inside RAPID to do the math

What robot were version is installed in your robot?

IN version 6.5 new useful mathematical functions were added

Today at 08:34:38 AM

Guest

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