Niryo robot - Calculation of inverse kinematis

[MADONOKOUKI]

Hi, I try to conduct to draw a straight line by calculating inverse kinematics with niryo one robot.

input position (x : 0.073, y : 0.001, z : 0.168)
input orientation (roll : 0.029, yaw: 1.407, pitch: 0.204)
Answer of joints 1 ~ 6 axis : [ -0.007, 0.129, -1.360, 0.189, -0.183, -0.360]

I use blow's model.urdf code.
Then, calculate inverse kinematics using these code lines.

Do you know any solution to solve this problem?

from ikpy.chain import Chain
my_chain = Chain.from_urdf_file("model.urdf")
print(my_chain)
ik = my_chain.inverse_kinematics(target_position=[0.083, 0.001, 0.168], target_orientation=[0.029, 1.407, 0.203],orientation_mode="all")
print(ik)
print(my_chain.forward_kinematics(ik)[:3, 3])
print(my_chain.forward_kinematics(ik))

I think the calculation of inverse kinematics is bad.
The first line is correct, although the second line is wrong.

print(my_chain.forward_kinematics([0, 0.030, 0.152, -1.334, -0.184, -0.029, -0.030, 0])[:3, 3])
print(my_chain.inverse_kinematics(target_position=my_chain.forward_kinematics([0, 0.030, 0.152, -1.334, -0.184, -0.029, -0.030, 0])[:3, 3]))

<?xml version="1.0" ?>
<!-- =================================================================================== -->
<!-- |    This document was autogenerated by xacro from niryo_one.urdf.xacro           | -->
<!-- |    EDITING THIS FILE BY HAND IS NOT RECOMMENDED                                 | -->
<!-- =================================================================================== -->
<!--
    niryo_one.urdf.xacro
    Copyright (C) 2017 Niryo
    All rights reserved.

    This program is free software: you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
    the Free Software Foundation, either version 3 of the License, or
    (at your option) any later version.

    This program is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU General Public License for more details.

    You should have received a copy of the GNU General Public License
    along with this program.  If not, see <http://www.gnu.org/licenses/>.
-->
<robot name="niryo_one" xmlns:xacro="http://www.ros.org/wiki/xacro">
  <!-- Properties -->
  <!-- Links -->
  <link name="world"/>
  <link name="base_link">
    <visual>
      <origin rpy="0 0 0" xyz="0 0 0"/>
      <geometry>
        <mesh filename="package://niryo_one_description/meshes/v2/collada/base_link.dae"/>
      </geometry>
    </visual>
    <collision>
      <origin rpy="0 0 0" xyz="0 0 0"/>
      <geometry>
        <mesh filename="package://niryo_one_description/meshes/v2/stl/base_link.stl"/>
      </geometry>
    </collision>
  </link>
  <link name="shoulder_link">
    <visual>
      <origin rpy="0 0 0" xyz="0 0 0"/>
      <geometry>
        <mesh filename="package://niryo_one_description/meshes/v2/collada/shoulder_link.dae"/>
      </geometry>
    </visual>
    <collision>
      <origin rpy="0 0 0" xyz="0 0 0"/>
      <geometry>
        <mesh filename="package://niryo_one_description/meshes/v2/stl/shoulder_link.stl"/>
      </geometry>
    </collision>
  </link>
  <link name="arm_link">
    <visual>
      <origin rpy="0 0 0" xyz="0 0 0"/>
      <geometry>
        <mesh filename="package://niryo_one_description/meshes/v2/collada/arm_link.dae"/>
      </geometry>
    </visual>
    <collision>
      <origin rpy="0 0 0" xyz="0 0 0"/>
      <geometry>
        <mesh filename="package://niryo_one_description/meshes/v2/stl/arm_link.stl"/>
      </geometry>
    </collision>
  </link>
  <link name="elbow_link">
    <visual>
      <origin rpy="0 0 0" xyz="0 0 0"/>
      <geometry>
        <mesh filename="package://niryo_one_description/meshes/v2/collada/elbow_link.dae"/>
      </geometry>
    </visual>
    <collision>
      <origin rpy="0 0 0" xyz="0 0 0"/>
      <geometry>
        <mesh filename="package://niryo_one_description/meshes/v2/stl/elbow_link.stl"/>
      </geometry>
    </collision>
  </link>
  <link name="forearm_link">
    <visual>
      <origin rpy="0 0 0" xyz="0 0 0"/>
      <geometry>
        <mesh filename="package://niryo_one_description/meshes/v2/collada/forearm_link.dae"/>
      </geometry>
    </visual>
    <collision>
      <origin rpy="0 0 0" xyz="0 0 0"/>
      <geometry>
        <mesh filename="package://niryo_one_description/meshes/v2/stl/forearm_link.stl"/>
      </geometry>
    </collision>
  </link>
  <link name="wrist_link">
    <visual>
      <origin rpy="0 0 0" xyz="0 0 0"/>
      <geometry>
        <mesh filename="package://niryo_one_description/meshes/v2/collada/wrist_link.dae"/>
      </geometry>
    </visual>
    <collision>
      <origin rpy="0 0 0" xyz="0 0 0"/>
      <geometry>
        <mesh filename="package://niryo_one_description/meshes/v2/stl/wrist_link.stl"/>
      </geometry>
    </collision>
  </link>
  <link name="hand_link">
    <visual>
      <origin rpy="0 0 0" xyz="0 0 0"/>
      <geometry>
        <mesh filename="package://niryo_one_description/meshes/v2/collada/hand_link.dae"/>
      </geometry>
    </visual>
    <collision>
      <origin rpy="0 0 0" xyz="0 0 0"/>
      <geometry>
        <mesh filename="package://niryo_one_description/meshes/v2/stl/hand_link.stl"/>
      </geometry>
    </collision>
  </link>
  <link name="tool_link">
	</link>
  <!--Joints -->
  <joint name="joint_world" type="fixed">
    <parent link="world"/>
    <child link="base_link"/>
    <origin rpy="0 0 0" xyz="0 0 0"/>
  </joint>
  <joint name="joint_1" type="revolute">
    <parent link="base_link"/>
    <child link="shoulder_link"/>
    <origin rpy="0 0 0" xyz="0 0 0.103"/>
    <axis xyz="0 0 1"/>
    <limit effort="1" lower="-3.05433" upper="3.05433" velocity="1.0"/>
  </joint>
  <joint name="joint_2" type="revolute">
    <parent link="shoulder_link"/>
    <child link="arm_link"/>
    <origin rpy="1.5707963268 -1.5707963268 0" xyz="0 0 0.08"/>
    <limit effort="1" lower="-1.5708" upper="0.640187" velocity="1.0"/>
    <axis xyz="0 0 1"/>
  </joint>
  <joint name="joint_3" type="revolute">
    <parent link="arm_link"/>
    <child link="elbow_link"/>
    <origin rpy="0 0 -1.5707963268" xyz="0.21 0.0 0"/>
    <limit effort="1" lower="-1.397485" upper="1.5707963268" velocity="1.0"/>
    <axis xyz="0 0 1"/>
  </joint>
  <joint name="joint_4" type="revolute">
    <parent link="elbow_link"/>
    <child link="forearm_link"/>
    <origin rpy="0 1.5707963268 0" xyz="0.0415 0.03 0"/>
    <limit effort="1" lower="-3.05433" upper="3.05433" velocity="1.0"/>
    <axis xyz="0 0 1"/>
  </joint>
  <joint name="joint_5" type="revolute">
    <parent link="forearm_link"/>
    <child link="wrist_link"/>
    <origin rpy="0 -1.5707963268 0" xyz="0 0 0.18"/>
    <limit effort="1" lower="-1.74533" upper="1.91986" velocity="1.0"/>
    <axis xyz="0 0 1"/>
  </joint>
  <joint name="joint_6" type="revolute">
    <parent link="wrist_link"/>
    <child link="hand_link"/>
    <origin rpy="0 1.5707963268 0" xyz="0.0164 -0.0055 0"/>
    <limit effort="1" lower="-2.57436" upper="2.57436" velocity="1.0"/>
    <axis xyz="0 0 1"/>
  </joint>
  <joint name="hand_tool_joint" type="fixed">
    <parent link="hand_link"/>
    <child link="tool_link"/>
    <origin rpy="-1.5707963268 -1.5707963268 0" xyz="0 0 0.0073"/>
  </joint>
</robot>

[stale]

This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. Thank you for your contributions.

[Phylliade]

Hello @MADONOKOUKI, the issue is unfortunately on the IKPy side, but on the overall difficulty of the task regarding the configuration of your robot.

The overall solution is on the user side: to try IK on simpler target positions, or providing a starting position to your chain, that will help your IK computation.

I'm marking this issue as "robot-related": don't hesitate to give me some updates of you solve your problem!