Control of a slide flute: a mechatronic project

In this paper, we consider the problem of controlling a slide flute: a kind of recorder without finger holes but ended by a piston mechanism to modify the length of the resonator. From a physical point of view, stopped pipes have not been studied so widely as open pipes, and moving boundary conditions introduce interesting mathematical problems. To control dynamical systems, it is important to elaborate a realistic model, so that control laws can be tested efficiently before they are implemented on real size prototypes. This dynamical model has been elaborated in a previous work and the control law has been validated on a first prototype. The feedback term of this control law used on-line measurements on the system: the length of the piston through an encoder and the blowing pressure through a pressure sensor. But the flute moved too slowly. To improve the precision of the control and the velocity of the piston we have developed a new "mechatronic" prototype in our laboratory which is the object of the present paper.