H∞-based position control of a 2DOF piezocantilever using magnetic sensors

The article addresses the position control problem of a 2 degrees of freedom (DOF) piezoelectric cantilever by means of an embedded magnetic-based position sensor. The active part of the piezocantilever used in the experimental setup is similar to cantilevers previously developed and already used for low-frequency micro-actuators in microrobotics devices. The contribution relies on the estimation of the biaxial displacement of the piezo-cantilever via conventional Hall-effect (HE) sensors, reducing the mechanical complexity and cost aspects. The actual sensing approach is validated via the implementation of a real-time position control based on the H_∞ scheme. In comparison with high resolution sensors, as laser or confocal chromatic (high-cost) or capacitive displacement (bulky), the actual sensor-control system is provides a satisfactory performance to cope with traditional micro-positioning tasks requiring a micrometer resolution. The performance of the embedded magnetic-based position sensor is evaluated, in open- and closed-loop, with respect the measurements provided by a Keyence laser sensors.