A Servo-Motor-Actuated Artificial Lung for Robotic Speech Production

Breathing is fundamental to speech production, supplying airflow for both voicing and fricative noise generation. We developed an autonomous robotic lung system that prioritizes functionally relevant, speech-oriented airflow over biological realism, using an accordion-style polyurethane duct actuated by a motor-driven crankslider mechanism. A kinematic and volumetric analysis is presented that provides a direct, predictive mapping from motor commands to lung displacement and speechrelevant airflow, enabling controlled generation of voiced and unvoiced excitation without requiring a full physiological respiratory model. The system has a tidal volume of approximately 2,000 cm³, placing it well within the range required for normal adult speech breathing. Experimental results show that the mechanical lung produces inhalation–exhalation cycles and sufficient airflow modulation to support robotic speech production and can drive a simple artificial larynx to generate voicing-like excitation.