Successful Swapping

Wednesday, March 11, 2020

We are pleased to announce that SwapStop is functionally complete! The system now performs autonomous end-to-end battery swaps. This procedure includes communication with the drone, which can request a swap when it detects low batteries, detects its own landing using computer vision and static April Tags, and responds to directives to take off again.

Full battery swap with a live drone.

As well as swapping depleted batteries on drones, the system can optimize the charging and storage of all the battery cells it has on hand. This includes shuffling cells out of charging slots when they hit 100% (using colour sensors to detect the status LEDs on the chargers) and shifting more fully-charged batteries closer to the top, where they can reach the landing pad a few seconds faster.

A number of safety measures are in place as well - limit switches, heartbeats, current sensors, and a physical switch, all of which can trigger the emergency stop mode, shutting down all the actuators instantly. Flicking the switch again causes a re-initialization cycle to a safe starting position.

There is some remaining work, but it's mostly cosmetic. We have some machined plexiglass panels to enclose the system, and the remaining 6 charging bays are still being 3D printed. There will also be larger cones for the drone legs to sit in, mostly to aid autonomous drone landing (we got awfully close with that, but unfortunately not with enough consistency, especially in indoor environments).

Our public demonstration day is this Friday, March 13th. If you want to view the system live, we will be set up on the ground floor of the University of Waterloo's E7 building between about 11 AM and 4 PM. Group 42. Be there.

There will be a final progress post afterwards to share any additional changes and reflect back on this marathon of a project. Until then, take care and happy building!