PDS node

The ifm3d-ros2 package provides a Pick and Drop System (PDS) node, which has the capability to detect pallets, open rack space, and check volumes for occupation. Results are visualized using visualization_markers.

• PDS configuration
  • Camera head calibration
  • Using the Vision Assistant
  • Using the Config service
  • Using the config_file parameter
• Launch
• Topics
  • Published topics
  • Subscribed topics
• Parameters

Operating Modes

The PDS node has different operating modes, which can be set via the ~/set_pds_mode service. The default mode is 0 which is the ACTION_ONLY mode.

In ACTION_ONLY mode, the node does provide three action servers ~/get_pallet, ~/get_rack, and ~/volume_check. Using these actions, the PDS functions getPallet, getRack, and volCheck can be used to get a singular detection result.

The following modes allow for continuous detections, which are published to their respective topic: GET_PALLET_CONTINUOUS (1), GET_RACK_CONTINUOUS (2), and VOLUME_CHECK_CONTINUOUS (3). To activate these modes, select the correct mode and provide the corresponding request via the ~/set_pds_mode service.

Calling one of the actions mentioned above while in continuous mode switches the mode to ACTION_ONLY (0). If the goal field switch_to_continuous_mode is set to true, the action switches the node to continuous mode and keeps publishing new detections to the corresponding topic.

Usage Examples

Using Actions

Actions use a nested request field for their parameters. Here are examples for each action type:

Get Pallet (single detection)

ros2 action send_goal /ifm3d/pds/get_pallet ifm3d_ros2/action/GetPallet "{request: {depth_hint: 1.5, pallet_index: 0, pallet_order: \"zDescending\"}}" --feedback

Get Rack (single detection)

ros2 action send_goal /ifm3d/pds/get_rack ifm3d_ros2/action/GetRack "{request: {horizontal_drop_position: \"left\", vertical_drop_position: \"interior\", depth_hint: 1.8, z_hint: -0.4}}" --feedback

With a custom clearing volume:

ros2 action send_goal /ifm3d/pds/get_rack ifm3d_ros2/action/GetRack "{request: {horizontal_drop_position: \"left\", vertical_drop_position: \"interior\", depth_hint: 1.8, z_hint: 0.4, clearing_volume: {x_min: -0.1, x_max: 1.2, y_min: 0.1, y_max: 1.3, z_min: 0.1, z_max: 0.4}}}" --feedback

Volume Check (single detection)

ros2 action send_goal /ifm3d/pds/volume_check ifm3d_ros2/action/VolumeCheck "{request: {x_min: 1.0, x_max: 3.0, y_min: -0.5, y_max: 0.5, z_min: -0.2, z_max: 0.5}}" --feedback

Switching to Continuous Mode

There are two ways to enable continuous mode:

Option 1: Using the set_pds_mode service

Switch to continuous pallet detection:

ros2 service call /ifm3d/pds/set_pds_mode ifm3d_ros2/srv/SetPdsMode "{mode: 1, get_pallet_request: {depth_hint: 1.5, pallet_index: 0}}"

Switch to continuous rack detection:

ros2 service call /ifm3d/pds/set_pds_mode ifm3d_ros2/srv/SetPdsMode "{mode: 2, get_rack_request: {horizontal_drop_position: \"right\", vertical_drop_position: \"interior\", depth_hint: 1.6, z_hint: 0.4}}"

Switch to continuous volume check:

ros2 service call /ifm3d/pds/set_pds_mode ifm3d_ros2/srv/SetPdsMode "{mode: 3, volume_check_request: {x_min: 1.0, x_max: 3.0, y_min: -0.5, y_max: 0.5, z_min: -0.2, z_max: 0.5}}"

Option 2: Using action goals with switch_to_continuous_mode: true

ros2 action send_goal /ifm3d/pds/get_rack ifm3d_ros2/action/GetRack "{request: {depth_hint: 1.4, z_hint: 0.4}, switch_to_continuous_mode: true}" --feedback

This sends the action goal, returns the result, and then switches to continuous mode, continuously publishing detections to the ~/rack_detection topic.

Switching Back to ACTION_ONLY Mode

To stop continuous detections and return to action-only mode, use the set_pds_mode service:

ros2 service call /ifm3d/pds/set_pds_mode ifm3d_ros2/srv/SetPdsMode "{mode: 0}"

Note

While in continuous mode, action goals will be rejected. You must first switch back to ACTION_ONLY mode using the service above before actions can be accepted again.

Actions

The actions return their detection as result to the action client. Additionally, they publish a message to the corresponding topic.

Topics

Whenever a PDS function is used, the full detection result is published on the ~/pds_full_result topic. With the default launch namespace (/ifm3d) and node name (pds), this resolves to /ifm3d/pds/pds_full_result. Additionally, messages are sent to specialized topics dependent on the used function:

Mode	Default Topic
ACTION_ONLY (0)	Action-dependent
GET_PALLET_CONTINUOUS (1)	~/pallet_detection
GET_RACK_CONTINUOUS (2)	~/rack_detection
VOLUME_CHECK_CONTINUOUS (3)	~/volume_check