Ahmet Fatih Tabak

Ahmet Fatih Tabak

The demonstrations of micro-robotic systems in minimally invasive medicine include an individual or a swarm of microswimmer of various origin, artificial or biohybrid, often with an external computer-controlled electromagnetic field. There are several in vivo and in vitro control performances with artificial microswimmers but control of a bio-hybrid microswimmer using an open kinematic chain remains untouched. In this work, non-contact maneuvering control of a single magnetotactic bacterium cell is simulated. The results show that the proposed system is capable of adjusting the heading of the microswimmer moving at proximity to a 2D boundary under the guidance of the set-point tracking scheme. The performance of the coupled model and the sensitivity to control parameters are demonstrated with the help of a time-dependent error to the yaw-angle reference under the influence of PID with adaptive integral gain.

Ahmet Fatih Tabak, Serhat Yesilyurt

Research on untethered micro-swimming robots is growing fast owing to their potential impact on minimally invasive medical procedures. Candidate propulsion mechanisms of robots are based on flagellar mechanisms of microorganisms such as rotating rigid helices and traveling plane-waves on flexible rods and parameterized by wavelength, amplitude, and frequency. For design and control of swimming robots, accurate real-time models are necessary to compute trajectories, velocities and hydrodynamic forces acting on robots. Resistive force theory (RFT) provides an excellent framework for the development of real-time six degrees-of-freedom surrogate models for design optimization and control. However, the accuracy of RFT-based models depends strongly on hydrodynamic interactions. Here, we introduce interaction coefficients that only multiply body resistance coefficients with no modification to local resistance coefficients on the tail. Interaction coefficients are obtained for a single specimen of Vibrio Algino reported in the literature, and used in the RFT model for comparisons of the forward-swimming component of the resultant velocities and body rotation rates against other specimens. Furthermore, CFD simulations are used to obtain forward and lateral velocities and body rotation rates of bio-inspired swimmers with helical tails and traveling-plane waves for a range of amplitudes and wavelengths. Interaction coefficients are obtained from the CFD simulation for the helical tail with the specified amplitude and wavelength and used in the RFT model for comparisons of velocities and body rotation rates for other designs. Comparisons indicate that hydrodynamic models that employ interaction coefficients prove to be viable surrogates for computationally intensive three-dimensional time-dependent CFD models.