Pushpace
A workout tracker for pushing a lawn mower, a stroller, or a shopping cart — activities where standard fitness tracking falls apart because the wrist stays nearly still and neither device alone gets a clean GPS fix.
Live cross-device sensor fusion
iPhone and Apple Watch each run their own fusion engine and stream samples to one another, blending GPS position by measurement confidence rather than simply picking one device's reading — so the estimate keeps improving as long as either device is reporting cleanly.
Anomaly rejection
Every incoming GPS fix is screened against an accuracy threshold and a physically-plausible speed bound before it's allowed to contribute, so a multipath "jump" near a building doesn't corrupt the session's distance total.
Step-count fallback during GPS gaps
When GPS goes quiet, distance is filled in from step count instead — sourced from whichever device is actually on-body with the person doing the pushing, since a phone sitting in a stroller pouch isn't a reliable source on its own.
A deliberately silent UI
None of the fusion, correction, or anomaly-rejection logic surfaces in the app itself. The interface is just start, stop, and an elapsed-time counter — the corrections happen, they're just never narrated to the user.