Pluck and Play: Chordophone Exploration

Publication

To refer to this work, please cite the following paper:

@inproceedings{goerner2024,
  title={{Pluck and Play: Self-supervised Exploration of Chordophones for Robotic Playing}},
  author={Görner, Michael and Hendrich, Norman and Zhang, Jianwei},
  booktitle={2024 IEEE International Conference on Robotics and Automation (ICRA)},
  year={2024}
}

Requires

• ROS Noetic (or 2024 ROS-O builds), see package.xml for most ROS dependencies
• The TAMS PR2 stack
• music_perception
• load_venv (and various packages from requirements.txt)

Demo flow (at TAMS' lab)

Startup the framework

• launch and calibrate regular PR2

• tape plectra to fingertips

• move Guzheng in front of PR2, connect microphone through USB soundcard to basestation

• mountpr2.sh on basestation to share workspace between c1 and basestation

• launch all.launch (which launches nodes on both basestation and c1)

• launch rviz.launch on basestation for a pre-setup visualization

• run rosrun tams_pr2_guzheng cli. It provides a command line with various commands to control the framework (see help for more information). Everything can be done outside the CLI as well with finer granularity, but it's a useful entry point.

Teach-in initial guesses for string position

• move MoveIt joint model group manipulation to named state guzheng_initial, cli: goto initial
• activate mannequin mode, cli: mannequin
  • very optional: set the head back to default position controller via hold_head_still.sh on basestation to keep it fixed
• teach-in string plucking until all strings appear roughly in the right location
• disable mannequin mode & go back to guzheng_initial, cli: mannequin off & cli: goto initial

Geometry exploration

throughout geometry exploration, optionally run rqt_reconfigure on fingertips, guzheng, and plectrum_poses namespaces to adjust detection thresholds, clock offsets, Cartesian plectrum poses, and string reconstruction options as dynamic calibration steps.

• explore geometry of demonstrated strings, e.g., cli: explore_geometry [a4 fis5 ...]
• notice that you have to confirm trajectory execution at first in the RvizVisualToolsGui as breakpoints are added before actual execution. Confirming with continue will drop further questions.
• Eventually fix strings cli: fix_strings once you are happy with the current result, this will automatically...
  • disable string fitter (dynamic reconfigure active flag), cli: fit_strings off
  • optionally store current geometry (guzheng/string_fitter/store_to_file service), cli: store_strings_to_file
  • clear the stored dynamics database

Dynamics exploration

• Explore Dynamics through Active Valid Pluck Exploration, cli: explore_dynamics or, e.g., cli: explore_dynamics 1.0 d6 d5 d4 to restrict to specific strings and inward (1.0) or outward (-1.0) direction

Reproduction

• After exploration, make the gathered plucks available for playing, cli: use_explored_plucks careful, this will overwrite the current plucks db if it exists

• start the module that receives pieces (music_perception/Piece) to play and builds/executes plucking paths, cli: start_play_piece

Demos

• run repeat after me demo node that listens for note onsets from the microphone and will try to imitate melodies, cli: repeat_after_me

• play note sequences, cli: play a4 fis5 d6 (each optionally followed with :loudness in range 1-127)

ROS Information Structure

Native PR2

• /joint_states - current joint readings for PR2 & Shadow Hand
• /hand/rh/tactile - BioTac readings
• /tf - Transforms
• /tf_static
• /diagnostics_agg - Diagnostics system (useful to detect runtime faults)
• /mannequin_mode_active - Is mannequin mode active? (if it is, the robot cannot move by itself)

(tf already includes plectrum/fingertip positions and detected string frames)

Guzheng

• /guzheng/audio - unused
• /guzheng/audio_stamped - time-stamped audio, depending on the publisher audio is ros::Time audio or audio pipeline time (drifts over time)
• /guzheng/audio_info - meta data (1 constant latched message)

MoveIt

• /move_group/monitored_planning_scene - MoveIt's world model
• /execute_trajectory/goal - MoveIt's Trajectory Execution action (which splits trajectories for hand/arm controller and sends them on)
• /execute_trajectory/result

Experiment control flow

• /run_episode/goal - generate, execute, and analyze a single pluck (including approach motion)

• /run_episode/result

• /episode/state - "start"/"end" before/after path is sent to /pluck/pluck action

• /episode/action_parameters - selected and executed parameters for single episode pluck

• /pluck/execute_path/goal - generate and execute a generic Cartesian trajectory with a target frame

• /pluck/execute_path/result

• /pluck/pluck/goal - same as execute_path but provides the following additional debugging output/data collection

• /pluck/pluck/result

• /pluck/commanded_path - Cartesian path to execute in pluck action

• /pluck/planned_path - path from generated joint trajectory

• /pluck/executed_path - eventually executed path

• /pluck/projected_img - image summarizing the three paths in 2d string space

• /pluck/trajectory - generated Trajectory

• /pluck/executed_trajectory - recorded trajectory execution

• /pluck/active_finger - current finger used in /pluck action (used for projection)

• /pluck/keypoint - keypoint of the ruckig parameterization selected in run_episode

• /fingertips/plucks - detected plucking events

• /fingertips/plucks_projected - all projected plucks

• /fingertips/plucks_latest - latest projected pluck only for visualization

• /fingertips/pluck_detector/signal - thresholding signal

• /fingertips/pluck_detector/detection - high/low signal to debug signal processing

• /fingertips/pluck_detector/parameter_descriptions - dynamic reconfigure for threshold

• /fingertips/pluck_detector/parameter_updates

• /fingertips/pluck_projector/parameter_descriptions - dynamic reconfigure for pluck projection

• /fingertips/pluck_projector/parameter_updates

• /guzheng/onsets - currently detected NoteOnsets

• /guzheng/onsets_markers - Markers generated from onsets

• /guzheng/onsets_projected - all onsets projected according to current parameters

• /guzheng/onsets_latest - latest onsets projected for visualization

• /guzheng/cqt - cqt generated as a side-product by detect_onset

• /guzheng/onset_detector/envelope - envelope used to extract peaks as maxima

• /guzheng/onset_detector/compute_time - debugging topic to measure computation time

• /guzheng/onset_detector/drift - drift compensation for audio input (onsets are shifted by the value)

• /guzheng/spectrogram - image visualization of cqt

• /guzheng/onset_projector/parameter_descriptions - dynamic reconfigure for onset projection

• /guzheng/onset_projector/parameter_updates

• /guzheng/events - unused (alternative projector input)

• /fingertips/events - unused (alternative projector input)

• /guzheng/estimate - current estimate of strings

• /guzheng/estimate_markers - visual_markers visualization with additional (possibly rejected) candidates

• /explore/p - shaped exploration distribution used to sample which strings to explore next

• /explore/sample_H - MC sample visualization to determine NBP for string

• /explore/loudness_strips - overview of all observed valid loudness samples across strings

• /explore/episodes_loudness - observed loudness for all valid samples for string

• /explore/gp_loudness - visualization of Gaussian Process from samples for string

• /explore/gp_std_loudness - stddev of the same GP

• /explore/episodes_validity_score - validity label for all samples for string

• /explore/p_validity - visualization of GP probit-regression for validity for string

• /play_piece/action - takes music_perception/Piece, infers pluck parameters, generate paths, and execute through execute_path

• /play_piece/piece - message interface for action goals

• /play_piece/piece_midi_loudness - same, but loudness scaled between 1-127 for each onset interpreted relative to explored plucks

• /play_piece/expressive_range - summary information of known notes/loudness ranges

TF frames

• target_pluck_string - a dynamic frame published when run_episode attempts to target a string
• rh_{finger}_plectrum - tip of the plectrum as calibrated