STIM

Mechanical models of housing exterior.

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Mechanical models of housing exterior.

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Mechanical model of housing exterior.

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This example only decodes STIM300 datagrams which fulfills the following requirements:Datagram contents: gyro output, accelerometer output and inclinometer output (Datagram identifier 0x93)Output unit, gyros: angular rate (output scaled for 400°/s gyros)Output unit, accelerometers: acceleration (output scaled for 10g accelerometers)Output unit, inclinometers: accelerationData starts at first byte of a datagram (i.e., datagram identifier) and contains only…

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We manufacture MEMS vibratory gyros based on the Coriolis effect. Below is a model of the Butterfly Gyro with two masses which are driven (excited) to oscillate at a resonance frequency close to 10 kHz. When a rotation of the gyro around the sensitive axis is applied, the two masses will deflect in a direction different to the oscillation. This is called the detection motion, which ultimately gives the angular rate sensed by the gyro.

No, the STIM gyros are mounted to the housings before calibration which is necessary for achieving the high performance they have. Housings cannot be modified.

We can in some cases perform FW updates. The STIM products are not designed for mechanical repair.

Our standard CoC is available with each shipment for customers that require this.

The STIM firmware can only be updated by our staff at our facilities.

Yes, the gyros (as well as accelerometers and inclinometers where available) use internal temperature measurements to continuously compensate the output signal.

This is the time needed from power-on or reset to clearing of the start-up bit (bit 6 in the status byte). During this period the output data should be regarded as non-valid. Details for each product is given by the product specifications.

STIM202 is designed with internal mechanical dampers for operation in environments with shocks, e.g. direct mounting on remote weapon stations. STIM210 does not have mechanical dampers and also has twice as high data output rate compared to STIM202.

Bias instability is measured by Allan Variance method, according to IEEE std. 952.

Test is performed at room temperature (~25°C)

Power is applied 2 hours prior to data collection

Data are collected for 18 hours

The root Allan variance is plotted and the bias instability is defined as the lowest point of the curve.

ARW is the white (random) noise of the sensor and is read from the root Allan variance curve at 1 second averaging time.

STIM uses cascaded integrator-comb (CIC) low pass filters with linear phase response. Filter bandwidth (-3dB) is user configurable and can be set to 16Hz, 33Hz, 66Hz, 131Hz or 262Hz.

Group delay is the processing time of the signal through the low pass filter. The delay depends on filter bandwidth.

Time Of Validity (TOV) is for synchronization of datagram transmission with external events. TOV falling edge occurs synchronous to the sample rate. Raising edge occurs after last bit of datagram.

No, STIM does not operate as a standalone AHRS.

The gyros can output angular rate, or integrated and incremental angle.

The accelerometers can output acceleration, or integrated and incremental velocity.

The integrated angle output is the angle since start-up or reset. The integrated angle is limited to ±4°, at which points a wrap-around occur.

Incremental angle is the change in angle since the previous sample.

E.g.: (100 °/s) / (125 sample/s) = 0.8°.

STIM IMUs does not output position, but is used in several positioning systems.

One of the leading GNSS/INS system builders obtain about 6 m horizontal position error after 60 seconds during a GNSS outage.

2g: 0.5μg
5g: 1.0μg
10g: 1.9μg
30g: 3.8μg
80g: 15.3μg

Verify that the bit rate settings of the computer serial port are in accordance with the STIM communication settings.

This error message occur when the EVK software don’t detect the startup datagrams. This happens when the STIM device is powered before the “Apply voltage” switch is flipped when connecting the STIM to the EVK SW.

Disconnect the STIM and make sure the correct procedure is followed when connecting as described by the EVK user manual.

We can help with examples e.g. for converting data bytes to angular rate measurements or how to calculate the cyclic redundancy check (CRC).

The cyclic redundancy check (CRC) is a common way of making sure the data has been correctly transmitted – i.e. that the received data is identical to what was transmitted. The STIM calculates and output a check-number based on the contents of the transmitted data itself. The receiver will perform the same CRC calculation and compare to the received CRC to verify that the transmission was successful.