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Accelerometer

The Antares 4G accelerometer measures how the vehicle changes speed and direction. It is one of the core inputs used for:

  • Motion detection (F12, F16)
  • Driving behavior events (F40 to F43)
  • Collision detection (F44 to F47)

A well-tuned accelerometer profile helps reduce false alerts and improves event quality in your reports.

Why This Matters​

  • Better safety analytics: detect harsh acceleration, hard braking, and aggressive turns.
  • Better fleet scoring: compare driving style between vehicles.
  • Better maintenance decisions: identify risky operation patterns early.

If thresholds are too low, you may get too many false events. If they are too high, real risky maneuvers may be missed.

How It Works​

Antares reads acceleration from the internal IMU and compares the measurements against configured thresholds.

Accelerometer axes and event direction

Practical mapping:

  • Longitudinal axis (X): harsh acceleration and hard braking
  • Lateral axis (Y): cornering right/left
  • Higher absolute acceleration values indicate stronger maneuvers

Important Prerequisite: Alignment​

Before relying on hard-motion signals, verify IMU alignment status with XAICAR — Axis Alignment Status.

Until alignment is complete, driving-behavior and collision signals can be gated and may not trigger as expected.

The following recommendations are tuned for basic deployment by vehicle type.

Recommended hard-motion thresholds

Vehicle TypeHarsh Acceleration (signed mg)Hard Braking (signed mg)Cornering Right (signed mg)Cornering Left (signed mg)Command Values to Configure (mg magnitude)
Cars300-300-300300XAICHA=300, XAICHB=300, XAICCR=300, XAICCL=300
Pickups / Vans / SUV240-240-300300XAICHA=240, XAICHB=240, XAICCR=300, XAICCL=300
Small trucks120-120-300300XAICHA=120, XAICHB=120, XAICCR=300, XAICCL=300
Bus102-102-300300XAICHA=102, XAICHB=102, XAICCR=300, XAICCL=300
Trucks70-70-300300XAICHA=70, XAICHB=70, XAICCR=300, XAICCL=300

Note: Commands use threshold magnitude values. Direction is implicit in the signal logic (forward/backward, right/left).

Configuration Steps​

  1. Install the Antares device and make sure it is securely mounted to the vehicle chassis.
  2. Once the vehicle has come to a complete stop on a flat, level surface, send the following command:
>SXAICAR<
  1. Once you receive the response, statrt to drive normally.
>RXAICAR0< : The alignment is in progress.

  1. To ensure that the alignment is completed, perform the following maneuver:

    1. Accelerate above 15 mph (25 km/h).
    2. Perform a firm braking action.
    3. Decelerate until the vehicle speed drops below 3 mph (5 km/h).

  2. Confirm alignment state with the following command:

>QXAICAR<

Possible responses:

>RXAICAR0< : The alignment is still in progress or cannot be completed.
>RXAICAR1< : The alignment was successfully completed.
Syrus Cloud Diagnostics

If you have access to Syrus Cloud, the alignment process reports real-time progress as a diagnostic percentage:

ProgressStage
0%Calibration has started
10%Waiting for GPS signal
30%Device tilt detected — leveling complete
50%Detecting vehicle orientation
70%Waiting for the vehicle to reach cruising speed
80%Waiting for a braking maneuver
90%Confirming the braking was valid
100%Calibration complete — ready to use

You can monitor these values in the device diagnostics panel to track calibration without needing to query the device manually.

  1. Apply the thresholds for your vehicle class:
>SXAICHA240<
>SXAICHB240<
>SXAICCR300<
>SXAICCL300<

  1. Drive normally for validation and review triggered events (F40, F41, F42, F43).

  2. Fine-tune if needed:

  • Too many events: increase values by 10% to 20%
  • Missed harsh events: decrease values by 10% to 20%
  • F12: motion detected
  • F16: hard motion detected
  • F40: harsh forward acceleration
  • F41: hard braking
  • F42: cornering right
  • F43: cornering left
  • F44 to F47: collision signals