Open-loop control of a robotized artificial mouth for brass instruments
Résumé
In order to have reproducible and controllable experiments, a robotized artificial mouth dedicated to brass instruments has been developed (CONSONNES project of the French National Research Agency). The actuators control: (A1) the airflow, (A2) the mouth position (monitoring the lips force applied to the mouthpiece), (A3-4) the water volume in each lip (water-filled latex chamber). The sensors measure: (S1-2) the pressure in the mouth and the mouthpiece, (S3: optical sensor) the area between the lips, (S4) the force lips/mouthpiece, (S5-6) the water pressure in each lip, and (S2bis-S4bis) the position of the moving coils (A2-4). We present an open-loop control obtained from measures, according to the following steps. First, a calibration for the lips control is performed, by analyzing signals (S4-6) w.r.t. positions (S2bis-S4bis), with no airflow. Second, slowly time-varying calibrated commands (A2-A4) are used to obtain quasi-stationary regimes (non oscillating, quasi-periodic, etc), for constant airflows. Third, a sound analysis is processed to generate cartographies of features (energy, fundamental frequency, etc) w.r.t. to the calibrated control parameters. This exploratory tool allows to build a dictionary of relevant control parameters from which basic sequences of notes can be played, and during which all the signals (S1-6) can be recorded.