An Adaptive Control Method With Low-Resolution Encoder

An adaptive control methodology with a low-resolution encoder feedback is presented for a biomedical application, the Ros-Drill (Rotationally Oscillating Drill). It is developed primarily for ICSI (Intra-Cytoplasmic Sperm Injection) operations, with the objective of tracking a desired oscillatory motion at the tip of a microscopic glass pipette. It is an inexpensive set-up, which creates high-frequency (higher than 500 Hz) and small-amplitude (around 0.2 deg) rotational oscillations at the tip of an injection pipette. These rotational oscillations enable the pipette to drill into cell membranes with minimum biological damage. Such a motion control procedure presents no particular difficulty when it uses sufficiently precise motion sensors. However, size, costs and accessibility of technology on the hardware components severely constrain the sensory capabilities. Consequently the control mission and the trajectory tracking are adversely affected. This paper presents a dedicated novel adaptive feedback control method to achieve a satisfactory trajectory tracking capability. We demonstrate via experiments that the tracking of the harmonic rotational motion is achieved with desirable fidelity.