3-Axis vs 6-Axis vs 9-Axis Gyro Sensors: Key Differences

This article compares 3-axis, 6-axis, and 9-axis gyro sensors, outlining the differences between 3-axis, 6-axis, and 9-axis gyroscopes. It also discusses the advantages, disadvantages, and manufacturers of each sensor type.

Introduction

A gyro sensor is a device that measures angular rate or angular velocity, defined as the change in rotational angle per unit of time, typically measured in degrees per second. Gyroscopes or gyro sensors are used in various applications, including:

• Motorboats
• Aircrafts
• Race cars
• Robots
• Toys
• Cameras
• Smartphones
• Video games
• Quadcopter/drones
• Health monitors
• Wearable electronics (smartwatches, fitness trackers)
• IoT applications

Gyro sensors come in different types, namely 3-axis, 6-axis, and 9-axis, and are chosen based on the required measurement accuracy under various conditions. They help determine the position and movement of a device, differentiating between activities like walking, running, and swimming. Gyroscopic data also aids in 3D gesture recognition, motion tracking, and relative positioning.

All these sensors utilize one or more of the following modules:

• Accelerometer: Measures linear acceleration in 3 axes. Gravity is a form of acceleration, allowing the determination of the system’s orientation relative to the “down” direction.
• Magnetometer: Measures magnetic fields. Used in compasses to identify Earth’s magnetic field, analyzing its magnitude, direction, and rate of change to find the “magnetic North.”
• Gyroscope: Measures rotational speed, which accelerometers cannot. While accelerometers can sense a device at rest, they cannot detect movement.

3-Axis Gyro Sensor

The 3-axis gyro sensor consists of three orientation sensors along the three standard axes: pitch, yaw, and roll. It’s also called a 3-axis gyroscope.

Example: The ITG-1010 is a 3-axis gyro sensor manufactured by InvenSense.

Technical Features:

• Supports functionalities of a 3-axis gyroscope sensor
• Supports I2C and SPI interfaces
• Contains 512-byte FIFO and programmable interrupts
• Houses ADCs to digitize sensor outputs
• Houses programmable digital filters and a precision clock with 1% drift
• Requires a VDD supply voltage in the range of 1.71 to 3.6 V

6-Axis Gyro Sensor

The 6-axis gyro sensor comprises three standard axes (yaw, pitch, and roll) along with a 3-axis accelerometer, totaling six axes. Some 6-axis sensors house an accelerometer and magnetometer instead of a gyroscope.

Example: The ICM-42605 is a 6-axis gyro sensor manufactured by InvenSense.

Technical Features:

• Supports configurable host interfaces like I2C, I3C SM, and SPI
• Houses a 2 KB FIFO
• Supports two programmable interrupts
• Offers high stability against temperature, shock, or SMT/bend-induced offset
• Houses user-programmable digital filters for accelerometer, gyroscope, and temperature sensor

9-Axis Gyro Sensor

The 9-axis gyro sensor integrates a 3-axis gyroscope, a 3-axis accelerometer, and a 3-axis compass, resulting in nine axes.

Example: The MPU-9250 is a 9-axis gyro sensor manufactured by InvenSense.

Technical Features:

• Combines functionalities of a 3-axis gyroscope, 3-axis accelerometer, and 3-axis magnetometer in a single module
• Has a built-in digital motion processor
• Supports I2C and SPI interfaces
• Houses nine 16-bit ADCs: three for gyroscope outputs, three for accelerometer outputs, and three for magnetometer outputs

Refer to the InvenSense datasheet for further product specifications on the MPU-9250.

Manufacturers of 3-axis, 6-axis, and 9-axis gyro sensors include Kionix, Inc., InvenSense, MICRO-HYBRID ELECTRONIC GMBH, Althen, and STMicroelectronics.