Hello,

I am trying to write a script using move_group in order to move a custom robot in Moveit!. Using the joints as targets works perfectly, bu I have an issue when I try to target a pose, I get this error and the robot doesn't move :

Traceback (most recent call last):
File "/home/edith/catkinws/src/testmoveit/scripts/test.py", line 84, in movegroup.setjointvaluetarget(posegoal, "linkeff",True) File "/opt/ros/melodic/lib/python2.7/dist-packages/moveitcommander/movegroup.py", line 219, in setjointvaluetarget raise MoveItCommanderException("Error setting joint target. Does your IK solver support approximate IK?") moveitcommander.exception.MoveItCommanderException: Error setting joint target. Does your IK solver support approximate IK?

I use ROS melodic on a virtual machine with Ubuntu 18.04. My robot is a RRR robot (3DOF) and I use an IKFast solver, with parameter "TranslationXY2D".

I follow this tutorial : https://ros-planning.github.io/moveit_tutorials/doc/move_group_python_interface/move_group_python_interface_tutorial.html

Instead of

movegroup.setposetarget(posegoal)

I used

movegroup.setjointvaluetarget(posegoal, "linkeff",True)

Because this instruction allows IK approximate solutions with the boolean "True", unlike the other one : http://docs.ros.org/jade/api/moveit_commander/html/classmoveit__commander_1_1move__group_1_1MoveGroupCommander.html#a55db2d061bbf73d05b9a06df7f31ea39

I know that the pose asked is reachable by the robot arm. At this point I don't know what else I can do, so thank to those who will take some time to answer ! Please find the URDF file and the concerned code. The URDF was generated from Solidworks with the exporter SW2URDF.

Code :

import sys import copy import rospy import moveitcommander import moveitmsgs.msg import math import time import stdmsgs.msg import geometrymsgs.msg import moveit_commander.conversions

moveitcommander.roscppinitialize(sys.argv)

rospy.initnode('movegrouppythoninterface_tutorial', anonymous=True)

robot = moveit_commander.RobotCommander()

groupname = "Arm" movegroup = moveitcommander.MoveGroupCommander(groupname)

jointgoal = movegroup.getcurrentjoint_values()

jointgoal[0] = 0.1744 jointgoal[1] = 0 jointgoal[2] = 0.3489 movegroup.go(jointgoal, wait=True) movegroup.stop()

posegoal = movegroup.getcurrentpose()

time.sleep(0.5) posegoal.pose.orientation.w = 1.0 time.sleep(0.5) posegoal.pose.position.x = 0.671 time.sleep(0.5) pose_goal.pose.position.y = -0.667

movegroup.setjointvaluetarget(posegoal, "linkeff",True)*

URDF :

<?xml version="1.0" encoding="utf-8"?>

<robot

name="swurdf">

<link

name="base_link">

<visual>

  <origin

    xyz="0 0 0"

    rpy="0 0 0" />

  <geometry>

    <mesh

      filename="package://swurdf/meshes/base_link.STL" />

  </geometry>

  <material

    name="">

    <color

      rgba="1 0 0 1" />

  </material>

</visual>

<collision>

  <origin

    xyz="0 0 0"

    rpy="0 0 0" />

  <geometry>

    <mesh

      filename="package://swurdf/meshes/base_link.STL" />

  </geometry>

</collision>

<link

name="link_1">

<inertial>

  <origin

    xyz="0.19475 -1.4951E-18 6.6018E-18"

    rpy="0 0 0" />

  <mass

    value="60" />

  <inertia

    ixx="0.0084601"

    ixy="3.2514E-18"

    ixz="5.5791E-19"

    iyy="0.062842"

    iyz="3.9785E-19"

    izz="0.069912" />

</inertial>

<visual>

  <origin

    xyz="0 0 0"

    rpy="0 0 0" />

  <geometry>

    <mesh

      filename="package://swurdf/meshes/link_1.STL" />

  </geometry>

  <material

    name="">

    <color

      rgba="0 1 0 1" />

  </material>

</visual>

<collision>

  <origin

    xyz="0 0 0"

    rpy="0 0 0" />

  <geometry>

    <mesh

      filename="package://swurdf/meshes/link_1.STL" />

  </geometry>

</collision>

<joint

name="J1"

type="revolute">

<origin

  xyz="0 0 0"

  rpy="0 0 0" />

<parent

  link="base_link" />

<child

  link="link_1" />

<axis

  xyz="0 0 -1" />

<limit

  lower="-0.349"

  upper="0.1745"

  effort="1000"

  velocity="0.1745" />

<link

name="link_2">

<inertial>

  <origin

    xyz="0.2353 -5.5511E-17 3.6564E-18"

    rpy="0 0 0" />

  <mass

    value="50" />

  <inertia

    ixx="0.012036"

    ixy="1.4745E-17"

    ixz="-2.5398E-18"

    iyy="0.11576"

    iyz="-4.117E-19"

    izz="0.12386" />

</inertial>

<visual>

  <origin

    xyz="0 0 0"

    rpy="0 0 0" />

  <geometry>

    <mesh

      filename="package://swurdf/meshes/link_2.STL" />

  </geometry>

  <material

    name="">

    <color

      rgba="0 0 1 1" />

  </material>

</visual>

<collision>

  <origin

    xyz="0 0 0"

    rpy="0 0 0" />

  <geometry>

    <mesh

      filename="package://swurdf/meshes/link_2.STL" />

  </geometry>

</collision>

<joint

name="J2"

type="revolute">

<origin

  xyz="0.3895 0 0"

  rpy="0 0 -0.37437" />

<parent

  link="link_1" />

<child

  link="link_2" />

<axis

  xyz="0 0 -1" />

<limit

  lower="-0.349"

  upper="0"

  effort="1000"

  velocity="0.1745" />

<link

name="link_3">

<inertial>

  <origin

    xyz="-0.17974 2.2204E-16 9.2478E-18"

    rpy="0 0 0" />

  <mass

    value="55" />

  <inertia

    ixx="0.0089046"

    ixy="9.541E-18"

    ixz="4.0602E-20"

    iyy="0.060983"

    iyz="-3.5161E-19"

    izz="0.066959" />

</inertial>

<visual>

  <origin

    xyz="0 0 0"

    rpy="0 0 0" />

  <geometry>

    <mesh

      filename="package://swurdf/meshes/link_3.STL" />

  </geometry>

  <material

    name="">

    <color

      rgba="0 1 1 1" />

  </material>

</visual>

<collision>

  <origin

    xyz="0 0 0"

    rpy="0 0 0" />

  <geometry>

    <mesh

      filename="package://swurdf/meshes/link_3.STL" />

  </geometry>

</collision>

<joint

name="J3"

type="revolute">

<origin

  xyz="0.48 0 0"

  rpy="3.1416 0 2.1331" />

<parent

  link="link_2" />

<child

  link="link_3" />

<axis

  xyz="0 0 1" />

<limit

  lower="-0.349"

  upper="0.349"

  effort="1000"

  velocity="0.1745" />

<link

name="link_eff">

<inertial>

  <origin

    xyz="-0.18691 -0.035548 -1.5796E-17"

    rpy="0 0 0" />

  <mass

    value="0" />

  <inertia

    ixx="0.010723"

    ixy="-0.0095589"

    ixz="-3.6746E-20"

    iyy="0.059165"

    iyz="4.3033E-19"

    izz="0.066959" />

</inertial>

<visual>

  <origin

    xyz="0 0 0"

    rpy="0 0 0" />

  <geometry>

    <mesh

      filename="package://swurdf/meshes/link_eff.STL" />

  </geometry>

  <material

    name="">

    <color

      rgba="0 1 1 0" />

  </material>

</visual>

<collision>

  <origin

    xyz="0 0 0"

    rpy="0 0 0" />

  <geometry>

    <mesh

      filename="package://swurdf/meshes/link_eff.STL" />

  </geometry>

</collision>

<joint

name="JE"

type="fixed">

<origin

  xyz="-0.37 0 0"

  rpy="3.1416 0 -2.9536" />

<parent

  link="link_3" />

<child

  link="link_eff" />

<axis

  xyz="0 0 0" />