Are today’s MEMS gyros “good enough”?

An article writen by Bryon Moyer for SEMICONDUCTOR ENGINEERING – Big improvements in precision may require new applications and market dynamics.

The gyroscope market is heating up, fueled by increasingly autonomous vehicles, robots, and industrial equipment, all of which are demanding greater precision and ever-smaller devices.

Gyroscopes historically have been a staple in navigation for years. However, classic designs are macro-mechanical, and high-performance units can be very expensive. For lower-performance applications, micro-electromechanical systems’ (MEMS) inertial measurement units (IMUs) have become increasingly popular due to their small size and lower cost. However, performance of these MEMS devices has been steadily increasing, allowing them to take on tougher roles. Most of them still need help from other sensors to cross-check their results, but they’re getting better.

“Academics have been for many, many years demonstrating all kinds of cool gyro architectures that could be used to create a low-drift gyro,” said Alissa Fitzgerald, founder and managing member at A. M. Fitzgerald and Associates. “But there haven’t been any commercial forces or market pull to bring that technology out of the academic world and into the real market.”

There are many tools available for navigation. IMUs, consisting of accelerometers and gyroscopes, are important, but less-expensive MEMS versions are assisted by global navigation satellite-system (GNSS) signals and other inputs from cameras, radar, and lidar – as well as magnetometers – to correct for drift. As performance improves, they need less correction. Still, it’s unlikely that they’ll be completely self-sufficient for critical applications anytime soon.

IMUs measure movement by tracking changes in both linear and rotational inertia. They consist of at least two different types of sensors, accelerometers and gyroscopes. These sensors can be built using either traditional macro-scale techniques or, increasingly, by using MEMS technology, where semiconductor techniques create sensors on a silicon chip.

Accelerometers provide a measurement of linear motion by sensing linear acceleration. That acceleration can be integrated to provide speed, and double integration provides position. A single accelerometer will measure changes along one axis. Combining three accelerometers with orthogonal axes can then measure 3D changes in the direction of motion.

Gyroscopes (or simply gyros) measure changes in orientation. This is distinct from the direction of travel, since one can change directions without changing which direction one is facing. Likewise, one can change orientation (effectively spinning) while moving in a straight line… Full article