Accelerometer Axis Calibration

Calibration process to obtain precise vehicle inclination and movement measurements.

What is it for?

Use case	Description
🎯 Measurement precision	Correct mounting or installation errors
🚗 Maneuver detection	Improve precision in braking, acceleration and turns
📐 Real inclination	Obtain correct roll, pitch and yaw angles
🔧 Post-installation	Calibrate after mounting equipment in vehicle

Calibration Methods

⭐ Smart Calibration (Recommended)


SCALINT

Feature	Description
🤖 Automatic	No manual intervention required
📡 With GPS	Uses GPS signal for greater yaw precision
🔍 Automatic detection	Identifies rest and movement conditions

Recommendation: Use SCALINT for most installations. It’s the simplest and most accurate method.

Manual Calibration

For cases where specific angles need to be established:


SCALroll,pitch,yaw

Parameter	Description	Range
roll	Lateral inclination	-180° to +180°
pitch	Frontal inclination	-180° to +180°
yaw	Orientation	0° to 360°

Example:


>SCAL0.5,-2.1,45.0<    // Roll: 0.5°, Pitch: -2.1°, Yaw: 45.0°

Process Control

Command	Description
`SCALSTOP`	Stops calibration in progress
`SCALNEXT`	Advances to next step (manual)
`QCALSTAT`	Query process status
`QCAL`	Query current values (roll, pitch, yaw)

Calibration States

State	Meaning
Inactive	No calibration in process
Initializing	Preparing the process
Collecting data	Taking measurements
Waiting for movement	Requires moving the vehicle
Calculating	Processing collected data
✅ Completed	Successful calibration
❌ Error	Problem during process

Axis Orientation

🔴 X Axis — Longitudinal (Forward/Backward)

Direction	Value	Example
Accelerating	+X	`X+008`
Braking	-X	`X-015`

🟢 Y Axis — Lateral (Left/Right)

Direction	Value	Example
Left turn	+Y	`Y+010`
Right turn	-Y	`Y-012`

Mnemonic rule: “The driver feels the OPPOSITE of the Y sign”

Negative Y → Driver leans to the left
Positive Y → Driver leans to the right

🔵 Z Axis — Vertical (Up/Down)

Direction	Value	Example
Downward (gravity)	+Z	`Z+105`
Normal on flat surface	~100 dg	`Z+090` to `Z+120`

Reference Values

Condition	X Axis	Y Axis	Z Axis
🅿️ Rest	≈ 0	≈ 0	≈ 100 dg
🚗 Normal driving	± 20 dg	± 20 dg	≈ 100 dg
⚠️ Sudden maneuver	> ± 50 dg	> ± 50 dg	Variable

Unit: 100 dg = 1G (gravitational force)

When to Calibrate

Situation	Action
🆕 First installation	Always calibrate after mounting
🔄 Orientation change	Recalibrate if position is modified
❓ Erroneous readings	Verify and recalibrate
🔧 Maintenance	Periodic calibration recommended

Optimal Conditions

✅ Level surface
✅ Stable vehicle (no vibrations)
✅ GPS available (for SCALINT)
✅ Sufficient battery (process may take several minutes)

Troubleshooting

Problem	Solution
Calibration won’t start	Verify with `>SCALSTOP<` that no other is in progress
Process stops	Use `>QCALSTAT<` and then `>SCALNEXT<` to continue
Incorrect results	Restart with `>SCALSTOP<` and begin again
Error during process	Verify conditions (level surface, GPS available)