An ion storage compound of cathode material and method for preparing the same are disclosed. The relief recesses counter variation in leakback flow with angular position intrinsic to helical cycloidal rotors, attenuating a noise source. The driver interaction is then used to determine an estimated driver workload based on the driver interaction. The control device performs the first connection process at a time that is outside a period during which a second connection process of connecting a second predetermined communication protocol between the communication-destination-side connection device and a different connection device is performed.