Welcome to the training module on Medium Performance Gyro Sensors.
This training module will introduce medium performance gyroscopes from Sensonor Technologies.
The medium performance gyroscopes contain a ButterflyGyro ™ MEMS die. The sensing element, manufactured entirely in a single crystal silicon substrate, consists of two identical seismic masses suspended by means of asymmetric driving beams to pedestals designed to minimize the mechanical and thermal stress. The two masses are connected to each other by means of a centrally located synchronizing beam. The seismic masses and the beams are arranged to provide a first degree of rotational freedom about the excitation axes, which are perpendicular to the plane of the substrate, and a second degree of rotational freedom about the detection axis, which is coincident with the longitudinal axis of the beams, as illustrated in the figure.
The SAR10 gyro contains a ButterflyGyro™ MEMS die and a BiCMOS mixed mode ASIC housed in a custom SOIC package. The gyro sensor is factory-calibrated and compensated for temperature effects to provide high-accuracy digital output data over a broad temperature range. By utilizing a unique sealed cavity technology, the sensors have high reliability and robustness over long lifetime. A closed-loop force feedback operation with electrostatic tuning of excitation and detection frequencies, as well as perfect mechanical and electrical balancing of the vibrating masses, results in exceptionally low shock and vibration sensitivity. An SPI interface implemented in the device enables easy and effective communication with the device. A number of functions are available through the digital SPI interface of the device, including advanced self diagnostics. Digital high-pass (0.01Hz) and low-pass filters (50Hz) are included for SAR10.
The robustness and low vibration sensitivity of this gyro makes it ideal for use in many hostile and tough applications. Typical applications are found within robotics, industry, platform stabilization, directional drilling, short time GPS aided inertial navigation systems (INS), high-end gaming systems and in any other rate detection system where the response below the high pass filter frequency is not applicable.
4 products in this medium performance category are available depending on demands in the target application. The lower range model has a lower scale factor (higher resolution) and better performance in regards to noise. The SAR10Z includes the bias signal and offers better noise and a higher resolution compared with SAR10. All parts have DC response, with low bias drift, and incorporate a temperature sensor. A SPI interface enables easy and effective communication between customer application and sensor. A number of functions are available through the digital SPI interface including advanced self diagnostics.
SAR10 is a fully calibrated and compensated digital angular rate sensor with SPI interface in a robust miniaturized surface mountable SOIC-package. Functions like temperature sensor and diagnostics are included. Digital high-pass and low-pass filters are included. The high-pass filter blocks the bias (zero-point) signal and makes the device non-sensitive for bias drift effects.
An SPI interface implemented in the sensor enables easy and effective communication with the device. Serial data bus frequencies up to 8.5MHz are supported, and the angular rate data output format is 10-bit or 12-bit 2’s complement at a maximum sampling rate of 2000SPS. After a negative edge on LOAD, 8-bit command is shifted in on MOSI, clocked by SCLK (MSB first). Output from previous command is stored in a Data Register. At a negative edge on LOAD, the content of the Data Register is loaded to the Data Output Register. While command byte is shifted into the Command Register, Data Output is shifted out on MISO (MSB first). As long as LOAD=1, the MISO output is in a high-Z mode (tri-stated). A negative edge on LOAD initiates an SPI transfer. The new command is executed after a positive edge on LOAD. If a positive edge occurs on LOAD before at least 8 bits are shifted in on MOSI, the command will be ignored. MOSI is read on the positive edge of SCLK, and MISO is shifted out on the negative edge of SCLK.
A number of functions are available through the digital SPI interface of the device, including advanced self diagnostics. 6 error monitoring functions are employed to make sure an irregular output angular rate is detected. A status register contains rate overflow information (recoverable error), excitation and detection loop diagnosis bits, a supply voltage information bit etc. In case of any irregularities detected, a specific error code is reported. This error code cannot be misinterpreted as valid sensor data. If any of the monitoring functions detects an irregular condition the corresponding flag becomes a ‘0’, otherwise a ‘1’. The Status Register flags are available to the application via the RSR SPI command. It is assumed that a flag can signal an “error” for any length of time. To make sure short error (‘0’) pulses are visible to the application, the ‘0’ pulses are "stretched" in time to between 1.5 and 2.0 ms.
Gyro sensors evaluation platform (EVP) provides rapid measurement and evaluation access to gyro sensors. Measurement results are presented in PC software and written to a file (optional). Power supply and communication is provided by USB. A number of signals are made available on header pin rows for the purpose of monitoring and test, such as for confirming SPI timing between the micro controller and sensor.
Thank you for taking the time to view this presentation on “ Medium Performance Gyroscopes” . If you would like to learn more or go on to purchase some of these devices, you may either click on the part list link right beside the play button on the TechCast portal, or simply call our sales hotline. For more technical information you may either visit the Sensonor Technologies AS site, or if you would prefer to speak to someone live, please call our hotline number, or even use our ‘live chat’ online facility. You may visit element14 e-community to post your questions.