Add gripper to MuJoCo simulation (#35)

* Add gripper to MuJoCo simulation

Signed-off-by: Steven Desvars <steven.desvars@ekumenlabs.com>

* Add equality constraint to make the grippers close

Signed-off-by: Steven Desvars <steven.desvars@ekumenlabs.com>

* Remove unnecessary meshes

Signed-off-by: Steven Desvars <steven.desvars@ekumenlabs.com>

* Add the meshes for MuJoCo

Signed-off-by: Steven Desvars <steven.desvars@ekumenlabs.com>

* Add instructions for update the model

Signed-off-by: Steven Desvars <steven.desvars@ekumenlabs.com>

* Address comments - part 1

Signed-off-by: Steven Desvars <steven.desvars@ekumenlabs.com>

---------

Signed-off-by: Steven Desvars <steven.desvars@ekumenlabs.com>

Author: stevendes

ar4_description/meshes/gripper_finger_2.stl

@@ -18,6 +18,14 @@ ros2 launch ar4_mujoco_bringup main.launch.py
 The MuJoCo model of the AR4 robot can be imported from the URDF description in the `ar4_description` package. The process requires running the two scripts in the `scripts/` folder in sequence.
 
 1. First run `stage1_create_urdf_from_xacro.sh` from **within** the development container. This script will generate the URDF file from the xacro description.
-1. Then run `stage2_create_mjcf_from_urdf.sh` from **outside** the development container (this script needs to create a new containerized environment running Ubuntu 24.04). This script will generate the MuJoCo model from the URDF file.
+2. Then run `stage2_create_mjcf_from_urdf.sh` from **outside** the development container (this script needs to create a new containerized environment running Ubuntu 24.04). This script will generate the MuJoCo model from the URDF file.
+3. For the gripper mimic function to work correctly, this code needs to be added into the [mj_ar4.mjcf](../ar4_mujoco_sim/mjcf/robot/mj_ar4.mjcf) file
+
+```
+  <equality>
+    <joint joint1="finger_joint_1" joint2="finger_joint_2" solimp="0.95 0.99 0.001" solref="0.005 1"/>
+  </equality>
+
+```
 
 At this point you'll see the `urdf/` and `mjcf/` folders in the `ar4_mujoco_sim` package as updated. Commit those changes.

ar4_mujoco_bringup/README.md

@@ -117,7 +117,7 @@ def generate_launch_description():
     spawn_joint_trajectory_controller = Node(
         package="controller_manager",
         executable="spawner",
-        arguments=["arm_controller"],
+        arguments=["arm_controller", "gripper_controller"],
         output="screen",
     )