Implementation of an overblowing correction controller and the proposal of a quantitative assessment of the sound's pitch for the anthropomorphic saxophonist robot WAS-2

Since 2007, our research is related to the development of an anthropomorphic saxophonist robot, which it has been designed to imitate the saxophonist playing by mechanically reproducing the organs involved for playing a saxophone. Our research aims in understanding the motor control from an engineering point of view and enabling the communication. In a previous paper, the Waseda Saxophone Robot No. 2 (WAS-2) which is composed by 22-DOFs has been presented. Moreover, a feedback error learning with dead time compensation has been implemented to control the air pressure of the robot. However, such a controller couldn't deal with the overblowing effects (unsteady tones) that are found during a musical performance. Therefore; in this paper, the implementation of an Overblowing Correction Controller (OCC) has been proposed and implemented in order to assure the steady tone during the performance by using the pitch feedback signal to detect the overblowing condition and by defining a recovery position (off-line) to correct it. Moreover, a saxophone sound evaluation function (sustain phase) has been proposed to compare the sound produced by human players and the robot. A set of experiments were carried out to verify the improvements on the musical performance of the robot and its sound has been quantitatively compared with human saxophonists. From the experimental results, we could observe improvements on the pitch (correctness) and tone stability.