G-Meter

1.Overview

The G-meter extracts vehicle G from the device's built-in 3-axis accelerometer and renders a ball with a trail on a circular grid. The center is zero G; the further out the ball moves, the higher the force.

Accurate readings require a calibration step that compensates for the device's mounting angle. Calibration runs on a long-press while stopped, or automatically when a recording starts.

2.On-screen elements

The display contains the following elements:

Axis mapping

3.Calibration

Because the G-meter depends on the device's mounting angle (dashboard tilt, mount orientation), calibration before use is mandatory. Two methods are available: manual and automatic.

Manual calibration (long-press)

1. Long-press the G-meter widget while stopped
2. The app averages the last 2 seconds (20 samples) to estimate the gravity vector
3. A rotation matrix is computed so that gravity points straight down
4. The matrix is saved on-device (persists across app launches)

The long-press only triggers when vehicle speed is 0 km/h (from ECU or GPS). It will not run while moving.

Auto-calibration on recording start

The same calibration runs automatically the moment a recording starts. You don't need to remember to long-press — starting a recording resets calibration. A snackbar at the bottom of the screen confirms completion.

Calibration logic

Raw data (m/s², gravity included)
  ↓
[1] Apply rotation matrix (pitch / roll correction)
  ↓
[2] Subtract gravity (-9.80665 m/s²)
  ↓
[3] Convert to G units (÷ 9.80665)
  ↓
Calibrated G values (gX, gY, gZ)

Only pitch and roll are corrected — yaw (heading) is not. Mount the phone in portrait orientation with the device's Y-axis (top edge) aligned with the vehicle's forward direction.

4.Why it does not work on motorcycles

As noted in the slot setting screen, the G-meter does not function correctly on motorcycles. This is because the calibration logic assumes the device and vehicle stay in fixed alignment.

Motorcycles lean into corners, so lateral G is measured along an axis tilted relative to the road, not relative to the bike. As a result, gravity bleeds into the lateral G channel during cornering, and the pure centripetal force can't be isolated.

On four-wheel vehicles roll angles are small enough to ignore in practice, but on two wheels the error dominates.

5.Detail settings

The only configurable item under the Detail Settings tab is the meter range (maxValue), which defaults to 1.5 G. This is the maximum G represented by the outer ring — raise it if values clip during sport driving, or lower it for daily driving where the ball would otherwise sit close to the center.

The warning threshold (ball color shifts above 0.3 G) and the smoothing factor are fixed as internal constants and are not currently user-configurable.

6.Update rate and smoothing

7.Tips

• Always calibrate on first use (mount the phone first, then long-press)
• Re-calibrate after changing the mount angle or moving the holder
• Stopped-only: long-press only works at 0 km/h
• Auto-calibration on recording start means forgetting the manual step is not fatal
• The combined G value (bottom-right) is the live reading, not a session maximum
• Not recommended for motorcycles

8.FAQ