Why can't they cycle through coils one by one and see where the biggest drain is?
I mean:
1. Cycle through coils until you discover a drain. (From two (or more) overlapping coils which both show drain, pick just the one with the biggest drain.)
2. Assume that's where a device to be charged is (or aligns best to a coil).
3. Give power only to the this best-fitting coil (one per device)
4. Pause charging for a few ms every 500ms to repeat at (1.)
As they have full control over the receiving hardware they could also easily hide the small pauses in charging when a "search cycle" happens.
I mean:
1. Cycle through coils until you discover a drain. (From two (or more) overlapping coils which both show drain, pick just the one with the biggest drain.)
2. Assume that's where a device to be charged is (or aligns best to a coil).
3. Give power only to the this best-fitting coil (one per device)
4. Pause charging for a few ms every 500ms to repeat at (1.)
As they have full control over the receiving hardware they could also easily hide the small pauses in charging when a "search cycle" happens.