A charging apparatus for wireless charging of one or more robotic devices includes a power transmitting unit having a plurality of conducting wires each configured to carry a respective alternating current signal and to generate a time-varying magnetic flux when the conducting wire carries the alternating current signal, a processor configured to detect a presence or an absence of an induction coil of a robotic device within a predetermined distance of a conducting wire and to generate control data based on the result of the detection, and a control unit configured to control at least one of an amplitude and a frequency of each respective alternating current signal supplied to each of the conducting wires based on the control data, where the control unit is configured to increase at least one of an amplitude and a frequency of an alternating current signal supplied to a conducting wire in response to control data indicating the presence of the induction coil within the predetermined distance of the conducting wire.