Bench Talk

This past weekend my family and I went to the Fort Worth Zoo. It had been some years since I had last visited the zoo—seventeen to be exact—and I decided to rely on my smartphone and the Google Maps app to help me navigate. Early into the trip, I noticed that my phone was having problems navigating and keeping me on course. The phone’s display kept pointing in the wrong direction, and the problem did not seem to be with Google Maps or acquiring a good global positioning system (GPS) signal; instead, the problem seemed to be with the phone’s gyroscope. I eventually had to pull the car over and calibrate the gyroscope: With the Google Maps app open, I rotated the phone on each of the axes in a figure-eight motion a couple of times, and voilà! That seemed to fix the issue.

A gyroscope is a sensor that determines orientation based on the x, y, and z-axes. Gyroscopes are not exclusive to smartphones. Gyroscopes are also used in platform control and stabilization, navigation, medical instrumentation, robotics, wearables, automobiles, and avionics. For example, cameras and drones have gyroscopes that help them keep steady, and aircraft use altimeters that contain gyroscopes to help them keep steady and determine position.

To better understand how the gyroscope in my phone works, we must understand microelectromechanical systems (MEMS). MEMS are a semiconductor technology that converts very complex mechanical and electromechanical elements into microscopic structures, actuators, electronics, and sensors. MEMS sensors can be as precise as traditional sensors (often more so), but they are also exponentially smaller, require less power and are less expensive.

Using MEMS technology, manufacturers can integrate multiple disparate sensors into a single MEMS device. These multisensor MEMS devices combine their respective data to detect the sensors’ subject—in this case, the movement and orientation of my phone—more reliably and more accurately than a standalone sensor. Through this process, known as sensor fusion, MEMS devices are helping to revolutionize the way electronic sensors are used, from fueling the Internet of Things (IoT) and its subset, the Industrial Internet of Things (IIoT), to painting a “big data” picture of measurements that would otherwise go unmonitored.

The gyroscope in my phone is a MEMS sensor, part of an inertial measurement unit (IMU). In most phones, the IMU is a single multisensor module that combines a gyroscope with an accelerometer and a magnetometer. The gyroscope measures the phone’s angular rate to help determine the phone’s orientation, while the accelerometer measures the phone’s specific force (or g-force) to help determine acceleration and velocity. The magnetometer (or compass) detects the earth’s magnetic fields to help the phone determine true north. The collective output data from the phone’s IMU combined with the GPS signal helps Google Maps determine precise position and speed at any given moment.

While this all might sound complicated, when power is applied to these sensor devices, they automatically start up and begin sampling sensor data without requiring much more.

For more information on gyroscopes, visit Mouser’s Applications and Technology site and explore the  sensors and test and measurement topics .