Abstract
We have been investigated how to use protists as living micromachines by controlling their behavior using their taxis. However, there are various multicellular microorganisms that have not been investigated well. In our previous paper, we found that Daphnia showed strong positive phototaxis to the blue light. A motion control system was produced by using a dish-shaped motion control pool with blue LEDs installed in the vertical wall of the pool. The control results showed that Daphnia has much better controllability and maneuverability than protists such as Paramecium or Euglena. We also made an automatic motion control program was made based on a proportional control method. By using the program that can predict the reaction delay of Daphnia, the positioning accuracy of the motion control was remarkably improved. In this paper, we proposed a new scheme to switch the target point (each summit of the star shape) when Daphnia was controlled along the star-shaped target route. In our previous program, we switch the target point when Daphnia pass an arc that the center of the arc is the start point and the arc cross the goal point. In the new scheme we switch the target point when Daphnia cross the line that cross the target point. We were aiming to reduce the positioning error to the guiding line by setting the angle of the switching line to the same angle of the guiding line. The experimental results, however, showed that the positioning accuracy in the automatic motion control experiment did not improve. Daphnia's positioning accuracy may be decided not from the positioning error of the starting point but from the accuracy of swimming along the target line.
