Inertial Measurement Unit Targets Industrial Applications

A new quartz-based inertial measurement unit (IMU) combineslower cost and high accuracy for industrial applications ranging fromagricultural and construction machinery to medical and military systems.

Introducedat the Sensors Expo last week,the new IMU is said to be about 100 times more accurate than the low-costsilicon IMUs employed in consumer products. At the same time, it's expected tobe a fraction of the cost of conventional fiber optic-based IMUs commonly usedin aerospace and military applications.

"We believewe've created a new category of inertial measurement units," said BobPorooshani, general manager of timing products, sensing devices and systemsolutions for Epson Electronics America, maker of the new sensing unit. "Thehigh accuracy, small size and extremely low power consumption are unlikeanything that's out there now."

Indeed,Epson's new IMU, called the S4E5A0A0,comes in a small package and offers high accuracy. Measuring just 2.5 x 2.5 x 1cm, the device's enclosure is said to be the smallest package size ever for anIMU. In that tiny package, the six degree-of-freedom product incorporates atri-axis gyroscope and a tri-axis accelerometer, which together allow it tomeasure and control motion in three dimensions. Using quartz-based MEMS(microelectromechanical systems) technology, the unit is said to offer extremelyhigh accuracy: a six degree-per-hour gyro bias instability and 0.24degree-per-root-hour of angular error.

Thecombination of accuracy and cost put the S4E5A0A0 smack dab in the middle ofits own market territory. Its accuracy is far greater than that of silicon MEMSsensors, but less than that of fiber optic units. At the same time, its $2,500per-piece cost is far more than that of silicon MEMS sensors, which can cost onlya few dollars apiece, and far less than that of high-end fiber optics, whichcan cost as much as $20,000 per axis.

Epsonengineers say the product fits particularly well in applications such asagricultural machinery and heavy equipment, elevators, medical and militarysystems, and in downhole drilling, where it could help determine the size andangular direction of a hole.

Porooshaniexpects some markets, such as the agricultural equipment market, to gravitatetoward the new technology because it could free engineers there from the taskof developing their own IMUs and writing algorithms to make them work. Each ofthe S4E5A0A0 IMUs are individually calibrated to work to spec over the entiretemperature range (-40 to +70C), he said.

"We takeaway the development from the customers," Porooshani said. "They can mount itin their product and they don't need to do any of the calibration on theirown."