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why given only the quaternion, a pose can be determined

asked 2019-12-20 21:35:28 -0500

lyh458 gravatar image

updated 2019-12-21 12:37:02 -0500

jayess gravatar image

line 121, 214, 337. eg,

geometry_msgs::Pose target_pose1;
target_pose1.orientation.w = 1.0;
target_pose1.position.x = 0.28;
target_pose1.position.y = -0.2;
target_pose1.position.z = 0.5;

question: why given only the quaternion, a pose can be determined??


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Can you please clarify your question ??

Abhishekpg gravatar image Abhishekpg  ( 2019-12-21 00:09:41 -0500 )edit

Sorry for my poor expression. I think a pose of a robot should be determined by both position and quaternion, because the quaternion only contain the orientation information of a joint. The "pose1", "pose2" and "pose3" presented in MoveIt tutorials, move_group_interface_tutorial.cpp only given the quaternion, I am so doubt that how can compute complete infromation of a joint only with this.

lyh458 gravatar image lyh458  ( 2019-12-21 00:34:39 -0500 )edit
gvdhoorn gravatar image gvdhoorn  ( 2019-12-22 05:06:31 -0500 )edit

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answered 2019-12-21 05:15:34 -0500

Abhishekpg gravatar image

updated 2019-12-21 12:37:30 -0500

jayess gravatar image

As you said the pose is determined by both orientation and the position. It is what exactly what they have done in the tutorial

target_pose1.position.x = 0.28;
target_pose1.position.y = -0.2;
target_pose1.position.z = 0.5;

This 3 lines defines the position.

target_pose1.orientation.w = 1.0

this line shows the orientation (quarternion). They haven't defined remaining 3 components of quarternion. So it will be set to default zero value. If you want you can define remaining components as per your requirements as

target_pose1.orientation.x = ...


target_pose1.orientation.z = ...

Hope this clarifies your question

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Yeah, thanks! I mistook the "position" for "orientation".

lyh458 gravatar image lyh458  ( 2019-12-22 21:25:45 -0500 )edit

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Asked: 2019-12-20 21:30:41 -0500

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Last updated: Dec 21 '19