IMU tilt compensation

This topic applies to the Trimble R12i receiver which has a built-in IMU sensor.

Using a Trimble receiver with IMU tilt compensation allows points to be measured or staked out while the survey rod is tilted or tipped. This enables accurate measurements to be taken without having to level the antenna, and a focus on the pole tip during stakeout, allowing for faster, more efficient work in the field.

The IMU in the receiver uses information from acceleration sensors (accelerometers) and rotational sensors (gyroscopes) as well as GNSS to continuously determine its position, rotation, and degree of tilt, and correct for any amount of tilt. With IMU tilt compensation, the pole can be tilted at any angle and the software is able to calculate the tilt angle and the tilt distance to determine the position of the pole tip on the ground.

When enabled, IMU tilt compensation is "always on" and can be used for any measurement method except observed control point. When measuring an observed control point, the receiver automatically switches to GNSS-only mode, and the GNSS eBubble appears automatically if it is enabled.

IMU tilt compensation offers a completely different way of working because you can:

  • Measure accurate points quickly while standing or walking without having to level the pole.
  • Concentrate on where the pole tip needs to go, which is especially useful during stakeout.
  • Easily survey hard-to-reach locations such as building corners and pipe inverts.
  • No longer worry about movement of the pole when measuring, because the receiver automatically corrects for “pole wobble” when the pole tip is stationary.

Because performance is unaffected by magnetic interference, IMU tilt compensation can be used in environments susceptible to magnetic disturbance such as around vehicles, heavy machinery, or steel reinforced buildings.

In situations where IMU tilt compensation may not be able to be used, such as in very difficult RTK environments, you can manually switch to GNSS-only mode. To do this, tap the receiver icon in the status bar to view the GNSS functions screen and then tap IMU tilt compensation to toggle on/toggle off GNSS‑only mode.