A drive unit includes an ultrasonic actuator having an actuator body generating vibration, and diver elements attached to the actuator body to output drive force by generating orbit motion in response to the vibration of the actuator body; and a movable body contacting the driver elements, and relatively moving with respect to the ultrasonic actuator. More particularly, the assembly includes a capacitor element that is positioned within an interior cavity of a housing. Moreover, a sensor is provided that emits a signal in response to a flow of current out of or into the accumulator battery. The interval sequence is converted into an absence length sequence whose entries indicate null value periods in performance data. 9 dtex, an elongation at break in a range from 36 to 60% and the fluctuation value of yarn size is 1.