The stereo-vision-aided Inertial Navigation System (INS) module is a base module which is available on every rc_visard and is part of the sensor dynamics module. It combines visual-odometry measurements with inertial measurement unit (IMU) data and provides robust, low latency, real-time state estimates at a high rate. The IMU consists of three accelerometers and three gyroscopes, which measure accelerations and turn rates in all three dimensions. By fusing IMU and visual-odometry measurements, the state estimate has the same frequency as the IMU (200 Hz) and is very robust even under challenging lighting conditions and for fast motions.
To achieve high-quality pose estimates, it must be ensured that sufficient texture is visible during runtime of the stereo INS module. In case no texture is visible for a longer period of time, the stereo INS module will stop instead of providing highly erroneous data.
During startup of the stereo INS module, it will self-calibrate the IMU using the visual-odometry measurements. For the self-calibration to succeed, it is required that
- the rc_visard is not moving and
- sufficient texture is visible
during startup of the stereo INS module. Failure to meet these requirements will most likely result in a constant drift of the pose estimates.
The stereo INS module’s node name is
This module has no run-time parameters.