Abstract: A communication method includes: switching an operation mode of a first station from a first operation mode to a second operation mode; transmitting a first signal from the first station to a second station; transmitting data from the second station to the first station in response to the first signal; storing the data received by the first station from the second station into a storage of the first station; switching the operation mode of the first station from the second operation mode to the first operation mode; transmitting a second signal from an access point to the first station; and transmitting the data stored into the storage from the first station operating in the first operation mode to the access point in response to the second signal.

Abstract: A communication method includes: switching an operation mode of a first station from a first operation mode to a second operation mode; transmitting a first signal from the first station to a second station; transmitting data from the second station to the first station in response to the first signal; storing the data received by the first station from the second station into a storage of the first station; switching the operation mode of the first station from the second operation mode to the first operation mode; transmitting a second signal from an access point to the first station; and transmitting the data stored into the storage from the first station operating in the first operation mode to the access point in response to the second signal.

Abstract: An automatic battery charging apparatus for driverless transport vehicle is presented so as to enable disconnecting the charging source from the batteries when a certain pressure is reached in the interior of at least one battery. A pressure sensor provided inside the battery is set so that the contact of a relay opens when a certain interior pressure which is lower than the activating pressure for a safety valve provided on the battery. This prevents an excessive pressure build up in the battery interior caused, for example, by accidental over-charging, which would release damaging gases and corrosive vapors from the over-charged battery to the outside environment.