| ArduPilot |
Open-source autopilot firmware for drones, planes, rovers and boats. |
| Armed |
Motors are allowed to spin. An episode is one armed period. |
| Attitude |
Orientation of the drone: roll, pitch and yaw. |
| Baseline altitude |
Median altitude over the first 2 s after arming, treated as "ground". |
| Ceiling / floor |
The highest / lowest motor command allowed (MOT_SPIN_MAX / MOT_SPIN_MIN). |
| Clipping |
An accelerometer reading hit the sensor's maximum, so the true value is unknown. |
| DataFlash log |
On-board log (.bin/.log) written to the flight controller's SD card. |
| EKF |
Extended Kalman Filter, ArduPilot's sensor-fusion estimator. |
| Epoch |
A stretch of a log in which the clock only moves forward (split at reboots). |
| Event guard |
The pre-event window ends 3 s before an autopilot crash report. |
| Family (evidence) |
A group of related rules; its contribution to a hypothesis is capped at 1.5. |
| Haversine |
Formula for distance between two latitude/longitude points on a sphere. |
| Hypothesis |
A possible explanation, scored by evidence for and against. Not a probability. |
| Innovation / test ratio |
How far a sensor reading is from the EKF's prediction, scaled so 1.0 is the limit. |
| MAVLink |
The message protocol between drones and ground stations. |
| Mixer |
Turns throttle/roll/pitch/yaw demands into individual motor commands. |
| Persistence |
A condition must hold continuously for a minimum time to count. |
| Pre-event window |
From takeoff to just before the upset or crash report; where rules look for causes. |
| PWM |
Pulse width (µs) sent to a motor controller; here 1000 = off, 2000 = full. |
| Rule pack |
The versioned YAML file of all rules and hypotheses. |
| Rule state |
triggered / not triggered / unassessable / not applicable. |
| Saturation |
A motor stuck at its ceiling or floor, so the controller has no headroom left. |
| Source |
One MAVLink sender (system id : component id), e.g. 1:1. |
| STATUSTEXT |
Human-readable text messages from the autopilot (e.g. "Crash: Disarming"). |
| Tilt error |
Angle between desired and actual thrust direction. |
| .tlog |
Telemetry log saved by the ground station from the radio link. |
| .ant |
AnaTele's shareable, hash-verified analysis file. |
| Unassessable |
The data needed to check something is missing or too sparse. Never "healthy". |
| WP_RADIUS_M |
How close the drone must get for a waypoint to count as reached. |