A method for compensation of nonlinearities, mainly hysteresis, using augmented linear control for a piezoelectric stack actuator is presented in this paper, with its application in intra-cytoplasmic
sperm injection (ICSI). The linear control, realized via a PID control, is enhanced by a regulated chatter signal with variation of duty cycle as well as direction (sign), with constant magnitude and period. The main idea is to augment the PID control signal, which does most of the feedback control, in a low hassle manner by increasing or decreasing the signal via the regulated chatter signal, which does most of the nonlinearities compensation. The variation of duty cycle and direction
is updated via an iterative learning technique, taking into consideration the repetitive motion required in
the ICSI application. This device is used for assisting oocyte (egg cell) penetration during ICSI process,
where the actuator is required to drive a needle, containing a sperm cell, to penetrate an oocyte and
then inject the sperm into the oocyte. This technique is able to satisfy the requirements of the process, where
a highly-precise motion is mandatory.
In this paper, the development of an integrated and open-architecture precision motion control system is presented. The control system is generally applicable, but it is developed with a particular focus on direct drive servo systems based on linear motors. The overall control system is comprehensive, comprising of various selected control and instrumentation components, integrated within a configuration of hardware architecture centred around a dSPACE DS1004 DSP processor board. These components include a precision composite controller (comprising of feedforward and feedback control), a disturbance observer, an adaptive notch filter, and a geometrical error compensator. The hardware architecture, software development platform, user interface, and all constituent control components will be elaborated on in the paper.