Inertial Measurement Unit Targets Industrial Applications

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

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

"We believe we've created a new category of inertial measurement units," said Bob Porooshani, general manager of timing products, sensing devices and system solutions for Epson Electronics America, maker of the new sensing unit. "The high accuracy, small size and extremely low power consumption are unlike anything 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 1 cm, the device's enclosure is said to be the smallest package size ever for an IMU. In that tiny package, the six degree-of-freedom product incorporates a tri-axis gyroscope and a tri-axis accelerometer, which together allow it to measure and control motion in three dimensions. Using quartz-based MEMS (microelectromechanical systems) technology, the unit is said to offer extremely high accuracy: a six degree-per-hour gyro bias instability and 0.24 degree-per-root-hour of angular error.

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

Epson engineers say the product fits particularly well in applications such as agricultural machinery and heavy equipment, elevators, medical and military systems, and in downhole drilling, where it could help determine the size and angular direction of a hole.

Porooshani expects some markets, such as the agricultural equipment market, to gravitate toward the new technology because it could free engineers there from the task of developing their own IMUs and writing algorithms to make them work. Each of the S4E5A0A0 IMUs are individually calibrated to work to spec over the entire temperature range (-40 to +70C), he said.

"We take away the development from the customers," Porooshani said. "They can mount it in their product and they don't need to do any of the calibration on their own."