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Wire hand mesh into parallel gripper URDF and fix calibration #64

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Merged
tokirobot merged 4 commits into from
Jun 8, 2026
Merged

Wire hand mesh into parallel gripper URDF and fix calibration #64

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b0c3203
feat - integrate hand mesh and fix calibration
oguzhanbzglu Jun 3, 2026
f2fe1a6
Add kinematics parameters and inertial for the hand
oguzhanbzglu Jun 5, 2026
d83b455
Calibrated to place hand_tcp at the fingertip centre
oguzhanbzglu Jun 5, 2026
be551ac
keep the end effector chain proper
oguzhanbzglu Jun 5, 2026
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2 changes: 1 addition & 1 deletion assets/end_effector/parallel_link/config/kinematics.yaml
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Original file line number Diff line number Diff line change
Expand Up @@ -15,7 +15,7 @@
finger_joint:
kinematic:
x: 0.0
y: 0.0
y: -0.005
z: 0.1025
roll: 0
pitch: 0
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13 changes: 11 additions & 2 deletions assets/end_effector/parallel_link/config/kinematics_link.yaml
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Expand Up @@ -12,11 +12,20 @@
# See the License for the specific language governing permissions and
# limitations under the License.

hand:
kinematic:
x: 0.0
y: 0.0
z: -0.661001
roll: 0.0
pitch: 0.0
yaw: 0.0

left_finger:
kinematic:
x: 0.0
y: -0.05
z: -0.673001
z: -0.661001
roll: 0.0
pitch: 0.0
yaw: 0.0
Expand All @@ -25,7 +34,7 @@ right_finger:
kinematic:
x: 0.0
y: 0.05
z: -0.673001
z: -0.661001
roll: 0.0
pitch: 0.0
yaw: 0.0
24 changes: 23 additions & 1 deletion assets/robot/openarm_v1.0/urdf/ee/parallel_link/openarm_parallel_gripper.xacro
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Expand Up @@ -14,14 +14,36 @@ limitations under the License.

<robot xmlns:xacro="http://www.ros.org/wiki/xacro" name="parallel_gripper">

<xacro:macro name="openarm_parallel_gripper" params="connected_to:='' arm_type arm_prefix:='' ee_type ee_inertials ee_kinematics ee_kinematics_link ee_joints_limits rpy_ee:='0 0 0' xyz_ee:='0 0 0' tcp_xyz:='0 0 0' tcp_rpy:='0 0 0' description_pkg:=openarm_description">
<xacro:macro name="openarm_parallel_gripper" params="connected_to:='' arm_type arm_prefix:='' ee_type ee_inertials ee_kinematics ee_kinematics_link ee_joints_limits rpy_ee:='0 0 0' xyz_ee:='0 0 0' tcp_xyz:='0 0 0.1801' tcp_rpy:='0 0 0' description_pkg:=openarm_description">
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<xacro:property name="ee_prefix" default=""/>

<xacro:unless value="${arm_type == ''}">
<xacro:property name="ee_prefix" value="openarm_${arm_prefix}" />
</xacro:unless>

<link name="${ee_prefix}hand">
<visual name="${ee_prefix}hand_visual">
<xacro:openarm-ee-kinematics-link config="${ee_kinematics_link}" name="hand" />
<geometry>
<mesh filename="package://${description_pkg}/assets/end_effector/parallel_link/meshes/visual/hand.dae" scale="0.001 0.001 0.001"/>
</geometry>
</visual>
<collision name="${ee_prefix}hand_collision">
<xacro:openarm-ee-kinematics-link config="${ee_kinematics_link}" name="hand" />
<geometry>
<mesh filename="package://${description_pkg}/assets/end_effector/parallel_link/meshes/collision/hand.stl" scale="0.001 0.001 0.001" />
</geometry>
</collision>
</link>
Comment on lines +30 to +44

@abetomo abetomo Jun 3, 2026

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@oguzhanbzglu Thanks for the contribution!
I think Copilot is right here.
The hand link has no inertial, so its mass isn't included in the dynamics. Could you add one?

@oguzhanbzglu oguzhanbzglu Jun 5, 2026

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Hi Abe, thank you for the comment, it is true that inertial was missing. I have added this to the ee inertial configuration yaml. The inertial was observed from OnShape with CAD model of it. That can be seen in the image below.

image

@abetomo abetomo Jun 5, 2026

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Awesome, thanks for adding it!


<joint name="${ee_prefix}hand_joint" type="fixed">
<xacro:property name="fj" value="${ee_kinematics['finger_joint']['kinematic']}" />
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<origin xyz="0 0 ${fj.z}" rpy="0 0 0" />
<parent link="${connected_to}" />
<child link="${ee_prefix}hand" />
</joint>
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<link name="${ee_prefix}hand_tcp" />

<joint name="${ee_prefix}hand_tcp_joint" type="fixed">
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