High performance MEMS vibration sensor modularized ADcmXL 3021

Vibration is one of the most important information for achieving condition-based monitoring (CbM) of motors, pumps, and the bearings and encoders that make up them.

Measuring vibration makes it easier to isolate mechanical noise from electrical noise and provides additional information about the state of the machine, improving diagnostic accuracy. Also, it is valid to bring sensors closer to the source of vibration with the miniaturization of sensor size and overall form factors in improving diagnostic accuracy and real-time mechanical control.

Here we introduce the following 3 features of the high-performance 3 axis MEMS sensor ADcmXL 3021 that can be installed with standard mechanical screws, provided from Analog Devices.

1. Complete vibration detection system accelerates development of state reference maintenance
2. Various signal processing functions by built-in embedded processing
3. High performance MEMS vibration sensor that realizes state reference maintenance
    

1. Complete vibration detection system accelerates development of state reference maintenance

ADcmXL3021 is a complete vibration detection system that combines high-performance vibration detection (using a MEMS accelerometer) with various signal processing functions.

The following features simplify the development of smart sensor nodes in state based maintenance systems :

• Small, mountable form factors optimized for performance in dynamic environments
• Full-function signal conditioning for vibration measurement
• Application preprocessing reduces data flow injected into control loops
• SPI data output for industrial networking flexibility
• Electrical and mechanical tested to meet industrial performance requirements

Highly integrated vibration detection system

ADcmXL3021 Function Block Diagram (Source : Extracted from ADcmXL3021 Datasheet)

2. Various signal processing functions by built-in embedded processing

ADcmXL3021 contains the following embedded processing, which can be accessed by the Serial Peripheral Interface (SPI).

• Fast data sampling (220 kSPS)
• Sample record length of 4096
• Filtering
• Window processing
• Fast Fourier transform (FFT)
• User-configurable spectrum alarms
• Error flag

These embedded processings enable the acquisition of information in the time domain and frequency domain.

Time domain and frequency domain

3. High performance MEMS vibration sensor that realizes state reference maintenance

Analog Devices offers the ADXL354/355, an ultra-low-noise 3 axis accelerometer that can be used to monitor aging infrastructure, and the ADXL100x series of ultra-low-noise, broadband accelerometers. The ADcmXL3021 also supports excellent resolution with an ultra-low-noise density of 25 µg/√Hz.

The sensing bandwidth is as wide as DC to 10 kHz with a flatness of 5%, enabling us to track the main vibration characteristics of many devices.

The main features of ADcmXL 3021 are as follows:

• MEMS vibrational sensing module of 3 axis / digital power output.
• Measurement range : ± 50 g
• Ultra low noise density  25 μg/√Hz
• Broadband : DC to 10 kHz (5% flatness)
• Embedded high-speed data sampling 220 ksps
• FIR filter, 32 taps (coefficient)
• High-pass filter cutoff frequencies : 1 kHz, 5 kHz, 10 kHz
• Low-pass filter cutoff frequencies : 1 kHz, 5 kHz, 10 kHz
• User-configurable filter bank (32 coefficients)
• Spectral analysis by FFT
• Long record length : 2048 bins per axis
• Manual or timer-based (automatic) triggers
• Window Options : Rectangle, Hanning, Flat Top
• Multi-record averaging, up to 255 records
• Alarm monitoring with defined spectrum, 6 alarms per axis
• Capturing Time Domains with Statistical Indicators
• Long record length : 4096 points per axis
• Mean, standard deviation, peak, crest factor, skewness, kurtosis
• Real-time data streaming - 220 ksps per axis
• Burst mode communication with CRC-16 error checking
• 10 data records on each axis
• Status Flag On-Demand Self-Test
• Sleep mode with external and timer-driven wake-up
• Digital measurement of temperature and power supply
• SPI-compatible serial interface
• Identification register : serial number, device ID, user ID
• Single Power Operation : 3.0 V ～ 3.6 V
• Operating temperature range : −40°C ～ +105°C
• Automatic shutdown at 125 °C (junction temperature)
• 23.7 mm × 26.7 mm × 12 mm23.7 mm x 26.7 mm aluminum package
• 34.5 mm flexible 14 pin connector interface

Package of ADcmXL3021

Target applications

• Vibration analysis
• State reference maintenance system
• Machine state monitoring
• Measuring instruments and diagnostic functions
• Detection of a safety interruption

This "ADSP-CM408F EZ-Board" is equipped with the ARM Cortex-M4 and can be used as a microprocessor evaluation board.

In particular, it can be used not only for assessment of motor control, but also for other applications, with

• Floating-point manipulable 240 Mhz ARM-Cortex - M4
• High precision dual 16bit ADC
• 384KB SRAM memory
• 2Mb Flash memory
• CAN, SPI, UART, USB, Ethernet
• Quadrature encoder interface