How to Choose an IMU for UGVs

An Inertial Measurement Unit (IMU) is an important sensor for unmanned ground vehicles (UGVs), autonomous mobile robots (AMRs), and research robots. It measures acceleration and angular velocity and is commonly used together with wheel encoders, LiDAR, cameras, GNSS, or RTK for localization and motion estimation.

However, choosing an IMU is not simply about selecting the most accurate sensor. The right choice depends on how the IMU will be used in the complete robotic system.

1. What Does an IMU Do on a UGV?

In a typical UGV, an IMU can support:

• Attitude and heading estimation

• Angular velocity measurement

• Wheel odometry correction

• LiDAR or visual SLAM

• GNSS/RTK sensor fusion

• Motion detection on slopes and uneven terrain

• Short-term localization during GNSS interruptions

For an indoor robot using LiDAR and wheel odometry, the IMU usually acts as one part of a multi-sensor localization system.

For an outdoor UGV, especially one using GNSS or RTK, better inertial performance becomes more important when satellite positioning is temporarily unavailable.

2. Five Key Specifications to Check

Gyroscope Bias Instability

Bias instability describes how stable the gyroscope's zero point remains over time.

A lower value generally means better long-term angular stability.

For many mobile robots using LiDAR, wheel odometry, vision, or GNSS corrections, an industrial MEMS IMU is usually sufficient. Applications relying heavily on inertial dead reckoning require much lower drift and therefore a higher-grade IMU or INS.

Measurement Range

The IMU should have enough accelerometer and gyroscope range to handle:

• Rapid turning

• Wheel slip

• Rough terrain

• Vibration

• Sudden impacts

A UGV normally experiences lower angular rates than a UAV, but sufficient measurement margin is still important.

Output Rate

Higher output rates are useful for dynamic motion, sensor fusion, and research applications, but they also increase communication and processing requirements.

For many UGV applications, tens to hundreds of hertz are sufficient.

Communication Interface

Check how the sensor connects to your onboard computer or controller.

Common interfaces include:

• USB

• UART

• RS485

• CAN

• I2C

For research robots, USB and UART are convenient. For industrial and outdoor robots, RS485 or CAN may be preferable depending on cable length and system architecture.

ROS and ROS 2 Compatibility

For ROS-based robots, software support can be just as important as sensor accuracy.

Before purchasing an IMU, check whether it provides:

• ROS 1 or ROS 2 drivers

• Raw accelerometer and gyroscope data

• Euler angles and quaternions

• Configurable output frequency

• Timestamps

• Documentation or SDKs

Good software support can significantly reduce integration time.

3. Indoor vs Outdoor UGV Requirements

Indoor UGVs

A common localization architecture is:

Wheel Encoders + IMU + LiDAR / Camera

Typical applications include:

• Research mobile robots

• Warehouse AMRs

• Educational UGVs

• Indoor SLAM platforms

In these systems, the IMU normally does not need to provide long-duration standalone navigation.

Outdoor UGVs

Outdoor robots may use:

Wheel Encoders + IMU + GNSS/RTK + LiDAR / Camera

The IMU becomes more important when operating:

• Near buildings

• Under trees

• Inside short tunnels

• In areas with GNSS multipath

• On uneven terrain

The longer the robot must operate without external position correction, the more important IMU stability becomes.

4. Consider the Complete Sensor Fusion System

The IMU should not be selected in isolation.

For example:

A robot continuously corrected by LiDAR or RTK may not need an extremely expensive inertial sensor.

By contrast, a robot expected to navigate for extended periods without external positioning requires significantly better inertial stability.

The goal is therefore not to purchase the most accurate IMU available, but to choose an IMU that matches the complete localization architecture.

5. A Practical ROS IMU for UGV Development

For ROS-based research UGVs and mobile robots, the H30 High-Precision ROS IMU is one practical option.

The H30 series integrates a 3-axis gyroscope, accelerometer, and magnetometer and provides acceleration, angular velocity, magnetic field, Euler angles, quaternions, and timestamp data.

Key specifications include:

• Gyroscope range: ±2000°/s

• Accelerometer range: ±16 g

• Gyroscope bias instability: 4°/h

• IMU output rate: up to 400 Hz

• Navigation output rate: up to 400 Hz

• Operating temperature: -40°C to 85°C

• Multiple form factors for different robotic platforms

The series includes H30 Mini, H30, and H30WP versions, allowing engineers to select different dimensions, interfaces, and environmental protection depending on the vehicle.

For UGVs using LiDAR, wheel odometry, vision, GNSS, or RTK as additional localization sources, this class of IMU provides a useful balance between performance, integration complexity, and cost.

For long-duration GNSS-denied inertial navigation, a higher-grade IMU or integrated INS should instead be considered.

6. Quick UGV IMU Selection Checklist

Before choosing an IMU, check:

• Gyroscope bias instability

• Accelerometer and gyroscope range

• Output frequency

• Communication interface

• ROS / ROS 2 compatibility

• Operating temperature

• Mechanical dimensions

• Environmental protection

• Documentation and SDK support

• Compatibility with your LiDAR, GNSS, RTK, or wheel odometry system

The best IMU is not necessarily the one with the highest specification.

It is the one that provides the right level of performance for your robot's localization architecture.

For ROS-based UGV development, you can view the H30 ROS IMU specifications and available versions here.