An accelerometer is a kind of device for measuring acceleration, which is often used in vehicles, machinery, mobile phones, and other devices to measure the motion state of devices. This article will show you the three-axis accelerometer based on micro-electromechanical systems (MEMS) introduced by Murata to understand its functional characteristics and related applications.
MEMS accelerometers are widely used in the automobile market
Accelerometers are widely used and can be found embedded in the systems of various products that need to measure the motion state of the device itself. There are many kinds of accelerometers, and their common working principles are piezoelectric effect, piezoresistive effect, capacitive induction, etc. Among them, accelerometers based on the MEMS architecture have the characteristics of small size, high precision, and good stability, and are more widely used as inertial measurement units (IMU) of advanced driver assistance systems (ADAS).
MEMS accelerometers are most commonly used in the airbag systems of modern automobiles to detect the sudden deceleration of the vehicle when a collision occurs, and can also be used to measure the applicability of a millimeter wave radar beam angle when the vehicle is running, so as to detect the distance between the driving vehicle and the preceding vehicle more accurately. Besides, it can also be used to detect the inclination angle of the vehicle when climbing a hill, so as to adjust the gear and power of the engine/motor and improve the operational efficiency of the vehicle.
Accelerometers for use in harsh and vibrating environments
Common accelerometer components include the housing (fixedly connected with the object to be measured), reference mass, sensitive components, signal output devices, etc. Accelerometers based on different principles have different ranges (from several g’s to hundreds of thousands of g’s), and accelerometers in different applications have great differences in performance. High-precision inertial navigation systems require accelerometer resolutions as high as 0.001g, but the range is not large. The accelerometers which measure aircraft overload may require a 10g range, but their accuracy is not high.
Murata has developed acceleration sensors with different specifications according to different application requirements, and is an advanced enterprise in low-gravity acceleration sensors for automotive applications. The wide range of accelerometer products includes high-performance analog and digital accelerometers for safety-critical automotive and industrial applications.
Murata's accelerometer is based on its unique 3D MEMS technology and provides many excellent product features for the demanding applications. Sensing components and measuring ASIC are assembled in dual in-line or double flat lead plastic packages with pins for surface mounting and reflow soldering. They use silicone gel for environmental protection, so they have excellent performance and reliability in wet environments and temperature cycles. In addition, the robust sensor element design with over-damped frequency response can achieve excellent performance even in harsh and vibrating environments.
High-performance acceleration sensor component
Murata, which has many years of experience and advanced technology in the field of sensor technology, has introduced its SCA3300 sensor for accelerometer applications, which is a high-performance acceleration sensor component, a triaxial acceleration sensor developed based on Murata’s proven capacitive 3D-MEMS technology, and its signal processing is completed in a mixed-signal ASIC with flexible SPI digital interface. The sensor element and ASIC are packaged in a 12-pin pre-molded plastic housing, which can ensure reliable operation throughout the product life cycle.
Murata's SCA3300 sensor family is specially designed, manufactured, and tested to meet high stability, reliability, and quality requirements. This component has stable output in a wide temperature and vibration range. This component has many advanced self-diagnosis functions, which is suitable for SMD mounting and compatible with RoHS and ELV directives.
The SCA3300 sensor elements is manufactured using Murata’s proprietary 3D-MEMS with high aspect ratio (HAR) and used for manufacturing of robust, extremely stable, and low-noise capacitive sensors. The acceleration sensing element is consists of four acceleration sensitive masses, and acceleration will cause capacitance changes, which are converted into voltage changes in the signal conditioning ASIC to convert the output acceleration data.
Excellent performance meets various application requirements
The SCA3300 accelerometer is a 3-axis high-performance accelerometer with a user-selectable measurement range of ±1.5 to ±6g, wide self-diagnosis function, bias stability better than 10 mg, low noise level of 37g/√Hz, good vibration resistance and linearity, and its performance is significantly improved by adopting industry-proven technology. The size is only 7.6 x 8.6 x 3.3 mm (width x length x height) with unique mechanical over-damping, it can work in the temperature range of -40℃ to +125℃, with a power supply voltage of 3.0V to 3.6V and only 1mA of current consumption.
The SCA3300 sensor has been calibrated in the factory, so it does not need to be calibrated separately in application. The calibration parameters are stored in the non-volatile memory during the manufacturing process, and the parameters are automatically read from the internal non-volatile memory during startup.
The SCA3300 accelerometer features a robust MEMS design, which can have excellent high performance in harsh environments, good performance under mechanical vibration, and excellent mechanical shock resistance. The product platform conforms to AEC-Q100 standards, and can be used in various applications requiring high stability and strict environmental requirements, such as professional level measurement, angle measurement and control, tilt compensation, and IMU for heavy machinery, and automobile ADAS, motion analysis and control, navigation system and heartbeat detection and advanced anti-theft application fields.
Murata also introduced the sensor board for digital accelerometers/inclinometers – SCA 3300-D01-PCB, which is a 3-axis acceleration sensor board with an acceleration measurement range of ±6g, which can be applied to industrial and healthcare equipment. It does not include the interface board and needs to be connected to the MEMS interface board for evaluation.
Conclusion
Accelerometers are widely used, but there are different specification requirements for different applications. In the field of automobile, there are higher requirements for interference, temperature, and vibration in automotive environments. Murata's SCA3300 accelerometer still has excellent high performance in harsh automotive application environments and conforms to AEC-Q100 verification specifications, which will be the ideal choice for developing automotive ADAS applications.