Epson IMU melds precision, low-cost
R Colin Johnson
6/6/2011 12:01 AM EDT
PORTLAND, Ore.—Epson Electronics America Inc. (EEA) aims to cash-in on a growing market for high-end inertial measurement units (IMUs) by cutting their cost by 50-fold with a high-precision model that combines the ultra-small size of micro-electro-mechanical systems (MEMS) with the ultra-low-power of piezoelectrics. Epson's IMU aspirations will be described this week at the Sensors Expo & Conference in Chicago.
High-end IMUs can cost as much as $75,000. The devices are well worth it if they keep ships, agricultural machinery and industrial robots safe and on-track. Growing at double digit rates, the market for industrial IMUs could reach a billion dollars by 2016, according to Yole Development.
"Our new IMU-G1 measures just an inch square, but its accuracy is comparable to those large, expensive military-grade fiber-optic gyro-based IMUs," said Bob Porooshani, general manager of EEA’s Sensing Systems business unit. "We have also gotten the power consumption down to about 1/10th of a watt, all for a cost of about $1,500 in volume."
Epson is currently test-marketing the new IMU—samples are $2,500—and is awaiting those test results before setting final price and specifications for production models. Epson's aim is to offer near mil-spec performance for industrial applications that need the precision, but have size, power and cost constraints in their application. Samples are currently being evaluated by industrial users for applications in precision farming, industrial robotics, mining and drilling, automobiles, elevators, theme park rides, motion capture for film and high-end sports training centers.
Double-T sensor element from Epson's oscillator chips was repurposed for this ultra-high precision gyro.
The 6-axis IMU combines a three-axis quartz-crystal-based gyroscope with a three-axis MEMS accelerometer from a third party, all in a package less than a half-inch high. Accuracy is six-degrees of gyro drift per hour which Epson claims is 100 times more accurate than the consumer-grade gyroscopes used in gaming controllers and smartphones.
Epson credits its high-precision in a small, low-power device to repurposing the quartz-MEMS (QMEMS) process it uses to craft oscillator chips that are as small as silicon MEMS, but which use the more stable vibration modes of piezoelectric materials. By retooling its most accurate double-T QMEMS oscillator structure to sense the gyroscopic rotational motions, Epson claims to have hit a price/performance point that its competitors will not be able to match.
"Not only is our drift a super-low six degrees per hour, but our bias instability is even more stunning at just 0.24 degrees per root-hour," said Porooshani. "And it is certified with factory calibration over its entire temperature range from minus 20 to plus 70 degrees Celsius."
The IMU can track motion as fast as plus or minus 300 degrees-per-second and can survive up to plus or minus 3-Gs. Communication is handled by industry standard SPI and UART interfaces.
Epson inertial measurement unit (IMU) combines a QMEMS gyroscope with a MEMS accelerometer to create the a high-precision that measures just 24-by-24-by-10 millimeters.