Vibration Energy Harvester Powers Train Sensors

Trains provide a sustainable source of vibration energy to power sensors, at least while they are moving. Testing has shown that the vibration spectra generated by train wheels was sufficient to allow Perpetuum’s energy harvester to generate 10s of mW of electrical energy – a level sufficient to power sensors to monitor the condition of wheel bearings.

Optimized to deliver the highest power output from vibration frequencies between 30Hz – 60Hz that are typical to the rail industry, Perpetuum’s PMG Rail operates in the temperature range from -40°C to 85°C (-40°F to 185°F) and has factory programmed voltage outputs from 3V – 10V.

Other monitoring and sensing applications for the PMG RAIL products include:

- Bearing Monitoring

- GPS Location Tracking

- Hazardous Cargo Monitoring (Temperature, Pressure, “Door Open”)

- Wheel Condition Monitoring (Flats, Cracks)

- Derailment

- Braking System Monitoring

For more information about Perpetuum’s PMG RAIL products vibration energy harvesters, click here.

Sense Acceleration with a 2 x 2-mm Package

Sensing acceleration in a space-constrained end product may result in the tradeoff of another feature if the accelerometer takes too much space. To avoid the conflict, STMicroelectronics introduced three-axis accelerometers in 2×2 mm packages. The tiny sensors have a quite a few features
of their own.

With full-scale ranges of ±2g/±4g/±8g/±16g, the LIS2DH and LIS2DM accelerometers include 4D/6D orientation detection and two programmable interrupt signals for motion detection, free fall and other conditions. The sensors also incorporate power saving features to improve battery life in portable applications that include power-down and sleep modes and a FIFO (first-in first-out) memory block for smarter power management.

The difference between the two sensors is the LIS2DH has more programmable sensitivity adjustments, a typical zero-g offset accuracy of ±40 mg versus ±100 mg for the LIS2DM and higher self-test output capabilities.

For more information about STMicroelectronics LIS2DH and LIS2DM triaxial accelerometers, click LIS2DH or LIS2DM.

Miniature Triaxial Accelerometer in 6.3-mm Cube

Measuring acceleration or vibration in small spaces poses problems for applications such as small component qualification, structural vibration and environmental stress screening. PCB Piezotronics, Inc., new miniature Integrated Circuit – Piezoelectric or ICP triaxial accelerometer addresses these space-constrained applications. With a 6.3 mm (0.25-in) cube form factor, the Model 356A03 delivers 10 mV/g sensitivity.

Other features of the piezoelectric sensor include a hermetic seal design with a low noise floor and high shock limit as well as a redesigned cable strain relief connection to provide improved shear and tensile strength. The CE certified 356A03 is compatible with any ICP signal conditioner or readout device that includes ICP power.

For more information about PCB Piezotronics Model 356A03 triaxial accelerometer, click here.

Electric Field-Based Sensor Detects Movement

Applications in security, switching and gaming have a new option for detecting movements with Plessey Semiconductors newest Electric Potential Integrated Circuit (EPIC) sensors. The company’s initial product addressed ECG products for the health monitoring markets. In contrast, the PS25401 was engineered for higher volume applications and can be used in both proximity mode or to detect specific kinds of movement as a limited gesture recognition device.

The sensor does not require line of sight and can even detect movement through walls. This allows its use to replace, or operate in conjunction with a passive infra-red (PIR) sensor in applications such as security motion detectors.

For more information about Plessey Semiconductors PS25401 EPIC sensor, click here.

MEMS IMU Delivers 10-Degree-of-Freedom Capability

Today, there are several sources for six degrees of freedom (DoF) sensors. However, when 6DoF is not enough, the newest solution from Analog Devices, Inc. (ADI) may be the answer. The ADIS16488 is a 10-DoF sensor that integrates a tri-axis gyroscope, tri-axis accelerometer, tri-axis
magnetometer and a pressure sensor into a single package. Based on microelectromechanical system (MEMS) technology, the four different sensors not only fit into a 66.04x 64.77×14-mm package, they provide high performance and stability.

With bias stability of less than 10 degrees/hr), other inertial measurement unit (IMU) parameters include:

• Triaxial, digital gyroscope with digital range
  scaling,  ±450°/sec dynamic range
• Triaxial, digital accelerometer, ±18 g
• Triaxial, delta-angle and delta velocity outputs
• Triaxial, digital magnetometer, ±2.5 gauss
• Digital pressure sensor, 300 mbar to 1100 mbar

For more information about Analog Devices ADIS16488 10-degree-of-freedom sensor, click here.

Applying MEMS Inertial Technology to Reduce Injuries

Analyzing athletes’ reaction to the extreme physical requirements of their sport leads to improved performance and avoids injuries. For competitive rowing, Roessingh Research & Development (RRD), a Netherlands research center, uses the Xsens MVN system developed by Xsens Technologies B.V. for its kinematics analysis.

The Xsens MVN system is a motion capture solution that consists of inertial sensors attached to the body by a lycra suit. Analog Devices provides the iMEMS(R) inertial sensing technology for the suit. In the suit, 17 motion trackers (MTx) containing more than 80 high-performance ADI iMEMS inertial sensors and 17 ADI Blackfin digital signal processors to analyze the rower’s motion.

For more information about Analog Devices iMEMS inertial sensing devices click here.

For more information about Xsens MVN system, click here.

Small Vibration Monitor Delivers Exceptional Low-noise Performance

A vibration monitor can prevent a myriad of problems – if it can fit within the monitored system’s space constraints and has the right performance. For noise sensitive applications with limited space, Analog Devices’ ADIS16228 iSensor vibration monitor could be that solution.

An embedded programmable processor in the MEMS-based vibration analysis system provides directional sensing and spectral analysis to identify and classify specific sources of vibration.

The noise performance of the 3-axis vibration monitor is specified at only 248 µg/ √Hz, across a dynamic range of ±18g, and the unit is configurable to ranges of 0 g to 1 g 0 to 5 g/, 0 to 10 g and 0 to 20 g.

Footprint and pin-for-pin compatible with the ADIS16210, the ADIS16228 has an extended operating temperature range of −40°C to +125°C.

For more information about Analog Devices ADIS16228 vibration monitor, click here.

Sensing Three Axes of Linear and Angular Motion in a 20-mm Footprint

There seems to be an insatiable demand to sense motion in the latest portable electronic products. For those with limited space, STMicroelectronics LSM330DL Micro-Electro-Mechanical Systems (MEMS) sensor could satisfy their requirements. In its 4 x 5 x 1mm plastic land grid array (LGA) package, the 6 degrees-of-freedom (6DoF) inertial MEMS module is almost twice as small as anything else in production according to the company.

The accelerometer portion has a user-selectable full-scale acceleration range from 2 to 16g and the gyroscope portion has angular-rate detection from 250 to 2500 dps along the pitch, roll and yaw axes. The co-packaged sensors provide inherently precise alignment of the two sensors’ reference axes. In addition, the mechanical sensing structure’s design
delivers excellent thermal and mechanical stability. For example, the angular rate sensitivity change vs. temperature
from -40 to +85°C is ±2% (typically) and angular rate sensitivity with a full scale setting of ±250 dps is typically 8.75 mdps/digit.

The 6DoF  sensor is software-compatible with ST’s latest-generation 3-axis digital accelerometers (LIS3DH) and gyroscopes (L3GD20).

For more information about STMicroelectronics LSM330DL inertial module, click here.

Sensors Enable Portable Healthcare Innovations

Sensors as well as communication ICs and microcontrollers provide the enabling technologies for several new innovations in healthcare. A Kalorama Information Dec. 1, 2010 report estimates that the global market for medical mobile apps hit $84.M in 2010, increasing more than 2X its 2009 level of $41M. This is just the downloadable software portion of the market enabled by wireless sensing.

In spite of the difficulties in obtaining medical approvals for hardware, some companies are making definite progress in applying these advanced technologies.

Proteus Biomedical has developed a U.S. FDA 510K cleared and European Union CE Mark-certified personal patch-based wearable sensors for continuous physiologic sensing and monitoring. Proteus’ personal monitoring technology uses multiple sensors to monitor parameters including heart rate, physical activity, and sleep patterns. The figure shows an example of the types of measurements and monitoring system the company has developed.

This is just one example of how the pace is accelerating for healthcare monitoring. Lifecomm, a mobile health and wellness venture of Hughes Telematics, Qualcomm’s Health & Life Sciences Division, and American Medical Alert are working together to launch a 3G personal emergency response service (PERS) at the end of 2011. Lifecomm’s solution will include motion sensors and automatically initiate a call for help in the event of a fall.

Making High Temperature Rotation Measurements

Jeff Watson, a systems applications engineer in the High Temperature Strategic Marketing Group of Analog Devices, explains the high temperature measurements in ADI’s demo at Sensors Expo 2011 to Randy Frank.

With the 175°C rated ADXL206 accelerometer and the 210°C rated AD8229 instrumentation amplifier, rotation can be measured inside an oven.

For more information about Analog Devices ADXL206, dual-axis, high temperature accelerometer click here and for the AD8229 high temperature instrumentation amplifier, click here.

To watch the video, click here.

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