To define the essential qualities that the energy powering of communicating objects should possess, it seemed that it would be useful to describe the use constraints that depend on the degree of mobility. They are inspired by wider studies on known objects:
Very mobile objects , permanently or often carried about (eg clock, e-pen, PDA, phone, MP3, DVD, CD walkman, e-book etc.). The power source must be light and compact. It may possess perfect autonomy, for example, several weeks for the Palm PDA, that avoids the need to bring the charger; another example is the clock battery that may last several years . Except in these rare cases, energy recovery must be easy, either with a powerful, light and compact charger, by primary battery replacement, or by accepting several energy sources [3 MARQUET, 2001]. A level meter is also necessary.
Mobile objects that we occasionally or regularly bring (digital camera, movie recorder, handbook etc). Extension or restoration of energy must be easy (battery replacement, primary/secondary cell compatibility, light and compact charger). These objects could be stored for a long time, and we need always-available energy when needed (with low self discharge taken into account by the energy meter). A small object may be charged by a larger one (a PC may power an external device via the USB plug).
Limited mobility objects in space that we use and move about in the house or in the garden (remote control, wireless phone, radio etc). The energy restoration must be transparent (docking for charge of the object, infrequent primary battery replacement). A discharge signal at least is needed.
Slightly movable objects (keyboard, mouse, wireless joystick, temperature or light sensors, heating or cooling control, RF ID label, webcam). Solutions are autonomous powering, or a single cable that transports signal and energy or inductive charge. The aim is to reduce wiring. RF ID, i-cards, e- buttons must be in contact or centimetres away to receive energy.
Heavy and rather static objects , (play station, computer, HIFI, TV-movie recorder, home movie, house devices etc). These devices are plugged in on main. Here also the target is to reduce the wiring, employing for that purpose appropriate energy distribution (low voltage bus, remote powering). Moreover, the standardisation of "green electronic" includes a standby mode or an on-off switch and consequently management of the consumption and the parameter back-up in memory.
Particular objects with move autonomy like robots . Such robots have their own energy source. The move autonomy is associated with the self-powering [3 SEMPE 2001]. An ultra -fast charge is useful for these objects when strongly solicited or when several objects share the same charging dock.
This classification of objects is not absolute nor complete, but allows one to identify the problems of energy powering.