Operational summary
For isolated work, a Dead Man Switch (DMS) requires periodic proof the operator is OK. If check-in is late, the system can escalate to supervisors or spawn a welfare mission.
Configure intervals and contacts to match site risk; align with legal and HSE before enabling aggressive policies.
Deep dive
Isolated work—night security at a remote site, technical maintenance on a comm tower, inspection over extensive terrain—shares one risk: if something happens, no one is around to call for help on the operator's behalf. The dead man switch (DMS) is the classic operational safety answer.
The setup is: the system expects periodic evidence the operator is OK (a check-in, valid GPS, movement). If that evidence doesn't arrive within the configured interval, it assumes something bad happened and escalates per the SOP. In Sentinel, that evidence is the node's last valid GPS fix, monitored by backend with a configurable threshold (default 30 minutes).
SOP design is the most important: who to call first, in what time, by what medium. A common practice: minute 30 (DMS threshold) → notify center operator, attempt radio contact. Minute 35 → call shift supervisor. Minute 45 → dispatch backup unit to last known position. That sequence must be written, trained, and reviewed periodically with HSE and legal.
Threshold must be realistic: too low (5-10 min) generates false positives from GPS blocks or legit pauses; too high (60+ min) defeats the DMS. For continuous-movement security, 20-30 min is reasonable. For long stationary tasks (point maintenance), complement with explicit manual check-ins via the app. Rule of thumb: threshold should be short compared to the time an unconscious operator can deteriorate critically, but long compared to normal operational interruptions.
Flow diagram
Operator in field
+---------------------+
| Periodic check-in +---- DMS timer
+----------+----------+
|
on time? ---- no
| |
v v
Normal Escalation (alert / mission)Open in product