  We investigated the bifurcation structure on the self-propelled motion of a
camphor rotor at a water surface. The center of the camphor rotor was fixed by
the axis, and it showed rotational motion around it. Due to the chiral
asymmetry of its shape, the absolute values of the angular velocities in
clockwise and counterclockwise directions were different. This asymmetry in the
angular velocities implies an imperfect bifurcation. From the numerical
simulation results, we discuss the condition for the occurrence of the
imperfect bifurcation.
