IMU Drift
How fast your inertial sensor's heading wanders while the robot sits still, how wrong it is by the end of an autonomous, and when it stops being trustworthy.
Inputs
Zero the sensor, leave the robot completely still, and read the heading back after a set time. Repeat at several durations. Do not nudge the robot: this measures the sensor on its own, and a bump makes the number meaningless.
A V5RC autonomous is 15 seconds. Use the whole match if you rely on heading through driver control too, and remember the sensor has usually been on far longer than either.
How far off you can be before a routine misses. A gap it has to drive through is the usual limit: work back from the width of the gap and the distance to it.
Used to turn degrees of heading error into inches of sideways miss at the far end, which is the number that actually decides whether a routine works.
Results
Drift rate
—°/min
Error by the end of that window
—°
Which is a sideways miss of
—in
Time until it exceeds tolerance
—sec
How linear the drift is
—
Steady drift can be corrected for. Scatter cannot.
Typical miss from the trend
—°
Past the end of the bar the heading is already outside your tolerance before the routine finishes.
Aim across the field as it drifts
The robot at the left, aiming at a target your chosen distance away. The dashed line is where the sensor says it is pointing, straight at the target. The solid line is where it really points once the drift your readings show has built up. A fraction of a degree sounds like nothing; across the field it is inches.
How this is calculated
An inertial sensor works out heading by adding up rotation rate over time. Any small bias in that rate gets added up too, so the heading walks away steadily even with the robot bolted to the floor. That is drift, and it is a rate rather than a fixed error.
drift rate = Σ(t × error) ÷ Σ(t²) through the origin error at t = drift rate × t sideways miss = distance × tan(error)With your numbers
The fit is forced through the origin because at the moment you zero the sensor the error is zero by definition. That makes the slope the only thing being fitted, which is what you want from a handful of readings.
Steady drift is the good case
If the readings sit close to a straight line, the drift is systematic and you can subtract it in code: track how long since you zeroed and correct the heading by the rate. What is left is the scatter, and that is the part no amount of cleverness removes.
If the readings are all over the place, the sensor is noisy rather than biased, and the fix is to re-zero more often rather than to correct. The scatter figure is the honest floor on how well you can know your heading.
Degrees are not the unit that matters
Two degrees sounds small. Over six feet it puts you two and a half inches to the side, which is the difference between driving through a gap and hitting the edge of it. Always convert to the miss at the distance you actually drive before deciding whether an error is acceptable.
What this does not cover
Drift while moving is worse than drift sitting still, because vibration and impacts add error the still test never sees. Treat this as the floor. Temperature matters too: a sensor zeroed cold in the pits and used warm on the field drifts differently from one zeroed on the field.
Sources & assumptions
Autonomous is 15 seconds, which is published.
Every drift figure is yours. No inertial sensor specification is quoted here, because the drift of the sensor on your robot is what matters and it varies between units, mountings and temperatures. The fit and the scatter are derived from your readings with the formulas above.
- V5RC Override Game Manual v1.1 (2026-27) — checked August 2026
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Where this goes next
Explore further on the full mapWhere the answers on this page can be used, and which tools could have given you the numbers it asks for.
Comes after
Autonomous Time Estimatorfills in your routine length hereAutonomous Route Optimizerfills in your routine length hereCoordinate Waypoint Plannergives you your distanceTracking Wheel SetupAutonomous ConsistencyYou are here
IMU Drift
Where your answer goes
Sensor Fusion Calculatoruse the gyro's measured error to weigh it against your other sensorsuses your position error againAutonomous Time Estimatorcheck your routine finishes before the heading error grows too biguses your distance againTracking Wheel Setupsee how finely a pair of tracking wheels could hold headingOdometry Error Simulatorsee what this drift does to your tracking along a whole routebrings your heading drift with ita number carries across the next question it raises