MEMS motion sensors deliver acceleration, angular rate, and magnetic sensing in millimeter packages for vibration monitoring, attitude control, fall detection, and asset tracking. They beat traditional piezo sensors on cost and digitization but need careful range, noise, and bias planning. Senseiot integrates MEMS IMUs in predictive maintenance and smart terminals—this article covers the essentials.
How MEMS Motion Sensing Works
Capacitive accelerometers move a proof mass to change capacitance proportional to specific force; gyros use Coriolis deflection of driven masses under rotation.
Three-axis accel + gyro (+ optional magnetometer) form an IMU fused via complementary filters or EKF into roll/pitch/yaw.
On-chip ADC with I2C/SPI suits direct MCU reads—browse the Product Catalog.
Range, Resolution, and Bandwidth
Accel spans ±2g–±16g: ±2g for attitude; ±16g+ for industrial vibration—watch saturation.
Gyro spans ±250–2000 °/s: high rate trades accuracy; low rate for slow tracking.
Match ODR and onboard LPF to FFT goals—from Hz tilt to kHz bearing faults.
Noise, Allan Variance, and Bias Stability
Gyro angle random walk and bias instability drift integrated angles; accel fixes roll/pitch statically, yaw needs mag or GPS.
Allan plots guide filter time constants; machinery monitoring cares about RMS velocity and spectral peaks.
FIFO and wake-on-motion enable battery Industry Application asset tags.
Vibration Monitoring and PdM
Mount on motor/pump bearings, sample 1–10 kHz, FFT for shaft and bearing frequencies vs ISO 10816.
MEMS dynamic range is smaller than IEPE piezo but covers most general machinery—extreme shock/temp may need piezo or fiber.
Edge AI uploads features only—see Industry Applications.
Mounting, Frames, and Calibration
Rigid mounting avoids false low-frequency motion; define sensor-to-body rotation matrices with consistent right-hand frames.
Six-face accel calibration; static gyro bias average; magnetometer hard/soft-iron figure-eight.
Industrial IMU -40–85 °C with boot-time gyro bias update.
Interfaces, Sync, and Sensor Fusion
I2C for setup; SPI for high ODR; external sync pins aid multi-sensor alignment.
Fuse with pressure, temperature, GPS for container tilt + environment; sub-ms sync matters for phase analysis.
Senseiot gateways batch MEMS with OTA tuning—Product Catalog.
Selection Checklist
Define target (vibration/attitude/shock), bandwidth, range, temperature, IP, power, interface, safety rating.
Avoid long I2C near VFD EMI; split analog ground and shield if needed.
Evaluation boards and reference algorithms—Request a Quote from Senseiot.