STIM320 inertial sensing unit

The STIM320 is a tactical-grade MEMS inertial measurement unit from Safran, designed for stabilization, guidance and navigation in industrial, aerospace and defence systems. It outputs the angular rate and the acceleration along three axes, so a flight controller or navigation filter can estimate the attitude and the motion of a vehicle.

The sensor block contains three MEMS gyroscopes and three high-stability accelerometers. Every unit is calibrated at the factory and compensated for temperature across the full operating range, so the host receives corrected digital data and does not need its own calibration routine. Electronic axis alignment brings the axis misalignment down to as little as 1 mrad.

The performance figures describe how well the unit holds a stable reference. The gyro input range is plus or minus 400 deg/s, with the output limited to plus or minus 480 deg/s, and the accelerometer range is plus or minus 10 g. Gyro bias instability is 0.3 deg/h and gyro noise is 0.15 deg/sqrt(h), which sets how quickly a heading estimate drifts without outside aiding. Accelerometer bias instability is 0.003 mg and accelerometer noise is 0.015 m/s/sqrt(h). The time to valid data after power-up is 0.7 s.

For integration, the unit takes a single 5.0 V supply and uses 1.5 W in operation. Data leaves through a digital RS422 serial interface, and the output format, the sampling rate and the filter settings can be configured. Available outputs include angular rate, incremental angle, average angular rate, integrated angle, acceleration, integrated velocity, incremental velocity and average acceleration, and a user-programmable bias trim offset is provided. The unit is solid state, weighs less than 55 g, occupies less than 35 cubic centimetres and is insensitive to magnetic fields.

The operating temperature range is -40 C to +85 C and the mechanical shock rating is 1500 g, with continuous self-diagnostics. The product is ITAR-free, which simplifies export for international programmes.

Typical applications are inertial navigation and attitude systems of unmanned aircraft, antenna and gimbal stabilization, platform stabilization and guidance, and any aerospace or defence system that needs a small and light IMU with low drift.