A Study on Control Method of Artificial Muscle to Scale Up the Fish Type Robot

Abstract

The authors involved in developing fish type robots using artificial muscle for several years. The authors have developed small sized fish type robot in the length of 20cm. These robots mimic the motion of actual fish such as transient swimming motions and phototaxis. But the limitation of payload becomes problem to develop a practical robot. To address this problem, the authors attempted to scale-up the fish type robot. The actuators for the up-scaled robots need to overcome the rigidity of their body and fluid force produced by moving their caudal fins. The present paper proposes a control method of artificial muscle for the fish type robots using "Segmented Binary Control (SBC)". This method uses several artificial muscles connected in series, instead of using one artificial muscle of the same overall length. Each artificial muscle is individually activated to produce displacement. The authors developed an artificial muscle unit and examined its performance. Newly developed artificial muscle unit shows same displacement regardless to load, produces tip displacement in step, and the tip displacement of the unit is not affected by ambient water temperature. With these results, proposing control method of artificial muscle is effective for the up-scaled fish type robots.