Description

depthscan takes in protobuf packets from the fathom depth sensor, and generates laser scans, point clouds, and cliff messages, to be used in may_nav (navigation), lifelong_mapping (SLAM), and fathom_obstacle_finder (low/high obstacle cloud generation).

If you activate the depth and/or amplitude images via the fathom curl-command interface, it will broadcast those as ROS images.

The node also safety-stops the robot and hard-resets the depth sensor if no data is seen for 0.5 and 10 seconds, respectively.

Also, if the depth sensor has not time synced to the high-speed board yet (incoming data time stamp is more than 1 second away from current time), the outgoing ROS messages will be stamped with current time - 0.2 secs.

Dependencies

• mayfield_msgs
• depth_sensor_msgs
• sensor_msgs

Published Topics

/scan

sensor_msgs::LaserScan
The laser scan from the depth sensor (created from the main beam portion
of the point cloud, with “ghost points” from external reflections removed)
contains 360 readings over 180 degrees (one reading every 0.5 deg)

/scan_reduced_mapping

sensor_msgs::LaserScan
Same as /scan, but with every other reading removed (one beam every 1 deg)
used for mapping

/scan_reduced_nav

sensor_msgs::LaserScan
Same as /scan (published for legacy reasons, used for nav)

/cloud

sensor_msgs::PointCloud2
The full point cloud from the depth sensor, in the frame of the sensor
Points are (x,y,z)

/depthscan/depth_image

sensor_msgs::Image
If activated via curl commands on the robot, the sensor’s depth image

/depthscan/amplitude_image

sensor_msgs::Image
If activated via curl commands on the robot, the sensor’s amplitude image

/depthscan/front_cliff

depth_sensor_msgs::CliffArray
Readings from the front “cliff sensors,” generated on the sensor from the low/cliff beam’s point cloud (for feeding to may_nav)

/depthscan/cliff_cloud

sensor_msgs::PointCloud2
For debugging, the portion of the cloud used in cliff detection

/depthscan/active

std_msgs::Bool
If the depth sensor stops responding for 0.5 seconds, goes false to stop the robot from driving (safety check)

/node_online

mayfield_msgs::NodeStatus
Latched node status publisher that goes true when it gets the first message, just for making startup order predictable

Service Calls

/mobile_base/depth_sensor_reset
std_srvs::Empty
Used to hard-reset the depth sensor, if no data is seen for 10 seconds

Parameters

/depthscan/replay_file

Used to broadcast ROS topics based on a saved protobuf file

/depthscan/time_between_cliff_msgs

double, default 0.4 Only broadcast cliff messages if something changes, or every time_between_cliff_msgs secs

/depthscan/ignore_cliff_count

int, default 0 (but default-set to 1 in depthsensor.launch’s args) Number of (potentially false-positive) cliffs to ignore before broadcasting on /depthscan/front_cliff

Launch File

depthsensor.launch