Realtime control with pressure_control_ros
Send Trajectories in Realtime
I wrote a handy python class within the pressure_controller_ros package to make executing trajectories on pressure controllers an easy process. In addition, I recommend using sorotraj to build trajectories from definitions similar to what is done in the raw python driver.
Here is a minimal example showing the relevant lines to add to your own ROS node:
Note: This requires sorotraj 1.3.1 or newer
import sorotraj
from pressure_controller_ros.msg import *
from pressure_controller_ros.live_traj_new import trajSender as pneu_traj_sender
# Make a sotortaj traj builder
builder = sorotraj.TrajBuilder()
# Load a trajectory from a file and make some modifications on the fly
file_to_use = 'my_trajectory.yaml'
builder.load_traj_def(file_to_use)
traj_def = builder.get_definition()
traj_def['setpoints']['main'][0] = [0.00, 10,10, 10,10, 10,10, 10,10] # Make some
# modifications to the definition (i.e. change a waypoints)
builder.set_definition(traj_def) # Reset the definition (this also rebuilds the trajectory)
# Alternatively, you can forgo the "load from file" step and set the trajectory
# definition directly if you have already loaded/created it.
# traf_def = {SOME DICTIONARY IN SOROTRAJ FORMAT}
# builder.set_definition(traj_def)
# Get a flattened trajectory in "sorotraj" format
traj = builder.get_flattened_trajectory(num_reps=1, speed_factor=1.0)
# Now execute the trajectory on the pressure controller
hand_sender = pneu_traj_sender(self.speed_factor) # Make a traj-sender object
traj_ros = hand_sender.build_traj(traj) # Convert the trajectory to a ROS trajectory
hand_sender.execute_traj(traj_ros, blocking=False) # Run the trajectory
hand_sender.traj_client.wait_for_result() # Wait until the trajectory is finished
Additional Documentation
The implementation for realtime control is based on the ur_modern_driver for Universal Robots, and is extensively used in my companion ROS package for coordinating with an arm: Hand+Arm Package. To check out how this works at a lower level, feel free to check out the source code and the live_traj_follower launch file.