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Describe icra_manipulation_demo/grasp_pipeline_pre_review here.

Informal page for pre-release discussion on the grasping pipeline

Key points

Package structure

ROS / C++ API's for object_manipulation

Only the object_manipulator will have a ROS API for now. The calls (see below) will offer all the functionality we have so far identified as needed. ROS API's for lower level modules might be added later hopefully without changing the high-level ROS API. 

                     |
                     |  ROS
                     |
                    \ /
                     V              C++
             object_manipulator  <------- Grasp planner
               |            |                   -cluster
               | C++        | C++               -database
               |            | 
              \ /          \ /
               V            V
     Place execution   Grasp execution
                                - without approach (we never used it)
                                - with interpolated approach
                                - with interpolated reactive approach

Proposed API

PickupGoal

The service must contain the following (in some exact syntax TBD): 

# which arm to be used for grasping
# Use string everywhere
# enforce naming conventions for getting service and action names from arm names
string arm_name

# The object to be grasped
GraspableObject target

# a list of grasps to be used
# if empty, the grasp executive will call one of its own planners
Grasp[] desired_grasps

# how the object should be approached
GripperTranslation approach

# how the object should be lifted
GripperTranslation lift

# the name that the target object has in the collision environment
# can be left empty if no name is available
string object_collision_name

# the name that the support surface (e.g. table) has in the collision map
# can be left empty if no name is available
string support_collision_name

### Potential future additions if lower-level modules get ROS API's ###

# which grasp planning service to use
# string grasp_planning_service_name

# which grasp execution service to use
# string grasp_execution_service_name

PickupResult

# the result of the grasp
ResultCode grasp_result

# the grasp that was successfully executed (if any)
Grasp executed_grasp

# the arm that was used
string arm_name

Gripper Translation

# the direction of the translation
geometry_msgs/Vector3Stamped direction

# the desired translation distance
float32 desired_distance

# the min distance that must be considered feasible before the
# grasp is even attempted
float32 min_distance

Result code

# task completed as expected
# generally means you can proceed as planned
int32 SUCCESS = 1

# task not possible (e.g. out of reach or obstacles in the way)
# generally means that the world was not disturbed, so you can try another task
int32 UNFEASIBLE = -1

# task was though possible, but failed due to unexpected events during execution
# it is likely that the world was disturbed, so you are encouraged to refresh
# your sensed world model before proceeding to another task
int32 FAILED = -2

# a lower level error prevented task completion (e.g. joint controller nor responding)
# generally requires human attention
int32 ERROR = -3

# a bit hackish, means that at some point during execution we ended up in a state that
# move_arm will not move out of. The world was likely not disturbed, but you probably
# need a new collision map to move_arm out of there
int32 MOVE_ARM_STUCK = -4

# the actual value of this error code
int32 value

Graspable Object

# what type of object this is
int32 DATABASE_MODEL = 1
int32 POINT_CLUSTER = 2
int32 type

# the database model and its pose, if type==DATABASE_MODEL
model_database/DatabaseModelPose model_pose

# the point cloud itself, if type==POINT_CLUSTER
sensor_msgs/PointCloud2 cluster

Placing

This is a perfect mirror image of grasping, but takes as input the grasp that has been executed and a desired place location. 

# the object currently held by this arm should be placed
ArmSelection which_arm

# information about the grasped object
Grasp executed_grasp

# where the object should be placed
geometry_msgs/PoseStamped place_location

# how much the object should be padded by when deciding if the grasp
# location is freasible or not
float64 place_padding

# the name that the target object has in the collision map
# can be left empty if no name is available
string target_collision_name

# the name that the support surface (e.g. table) has in the collision map
# can be left empty if no name is available
string support_collision_name

# how the place location should be approached
int32 APPROACH_VERTICALLY = 1
int32 APPROACH_ALONG_GRASP = 2
int32 approach_type

Hand Description

This goes into a yaml file which get associated with the arm name. 

# The frame of the end-effector
string end_effector_frame

# The preferred approach direction for the grasp
# relative to the end-effector frame
vector3 approach_direction

# The name of the entire end effector in the collision environment
string end_effector_group_collision_name;

# The names of the "fingertip" links
# better explanation to follow
string[] fingertip_link_names;

# The set of links that are allowed to be in contact 
# with the object during grasping
string[] touch_link_names

# The name of the link that a grasped object can be considered
# rigidly attached to
string attach_link_name

Grasp

# The internal posture of the hand for the pre-grasp
# only positions are used
JointState pre_grasp_posture

# The internal posture of the hand for the grasp
# positions and efforts are used
JointState grasp_posture

# The pose of the end-effector for the grasp relative to the object
Pose grasp_pose
2022-05-28 12:39