MANUAL GENERATION OF GRASP TABLE

1. Provide a collision mesh of the target object (as *.stl)

Most likely there already is a collada mesh (*.dae) available in cob_gazebo_objects. Thus you simply have to convert the mesh from *.dae to *.stl using MeshLab for example.
1. Open MeshLab -> File -> Import Mesh ... -> select respective mesh [object_name].dae from cob_simulation/cob_gazebo_objects/media/models 2. File -> Export Mesh As ... -> Save it as [object_name].stl within cob_manipulatiuon/cob_grasp_generation/files/meshes

2. Prepare a new grasp table

You need to provide a *.csv file of the name [gripper_type]_[object_name].csv at cob_manipulation/cob_grasp_generation/files/database/[object_name], where [object_name] is the same as for the collision mesh and [gripper_type] could e.g. be either sdh or sdhx (cob4-gripper). The *.csv file has the following layout (columns):

where id is the grasp_id, object is [object_name], followed by one column for each joint of the gripper specifying the joint configuration of the gripper when grasping the object (with gripper_joint_0 to gripper_joint_n being the gripper's joint_names), direction can be used to specify e.g. as [TOP|SIDE|BOTTOM|...] grasp, the grasp pose of the gripper reference coordinate system with respect to the object reference coordinate system (with [qw, qx, qy, qz] specifying the orientation as a quaternion and [pos-x, pos-y, pos-z] specifying the position in [mm]), eps_l1 and vol_l1 being grasp metrics e.g. force closure that can be used as grasp quality metric for sorting the grasps.

Notes: - each ros specifies another grasps (make sure to increase id accordingly) - the quaternion needs to be normalized, i.e. sqrt(qw² + qx² + qy² + qz²)!=1.0 (you might need to increase floating point precision to about 5 decimal digits. e.g. (0.0, 0.707, 0.0, 0.707) will throw an error; use (0.0, 0.707107, 0.0, 0.707107) instead! - you can initialize a grasptable by copying from an existing database entry

3. Use blender for generating initial grasp poses easily

1. Open the Blender
2. Clear the scene by removing all objects: press a (select all the objects), Entf (delete), Enter (confirm)
3. Load the object: File -> Import -> STL (.stl) -> select [object_name].stl from cob_manipulatiuon/cob_grasp_generation/files/meshes (see step (1))
4. Load the gripper: File -> Import -> STL (.stl) -> select [gripper].stl, e.g. palm.stl from cob_common/cob_descriptions/meshes/cob4_gripper for sdhx (cob4-gripper)
5. Move the gripper to various grasp poses (do not move the object) by either using
   • g+x,g+y,g+z: for translation along x,y,z - r+x,r+y,r+z: for rotation around x,y,z
   • enter values directly 6. Transfer the values from the Blender (position in [m], use the Quaternion RotationMode from the Dropdown menue!) to the grasp table (pos in [mm]!)

4. Visualization of the grasps in rviz

1. roslaunch cob_grasp_generation show_grasp_rviz.launch gripper:=[gripper_type]
2. rosrun cob_grasp_generation show_grasps_rviz_client.py (then enter [object_name] and [gripper_type] when prompted)

5. Tune grasps

Optimize the grasp entries in the table by modifying the grasp pose and/or grasp joint config based on the rviz visualization. Add more grasps

Could not convert RST to MD: No such file or directory - pandoc