What are IMUs? Explanation of meaning and definition, what is measured and how it works

What are inertial measurement unit sensors(IMU sensors)

What are IMU sensors? Explanation of meaning and definition

Inertial Measurement Units (IMUs) are devices that measure the angular velocity and linear acceleration in three axes of motion. They are equipped with three-axis angular velocity (gyroscope) sensors, three-axis linear acceleration sensors, and a temperature sensor for measuring three-dimensional inertial motion (translational motion and rotational motion along three orthogonal axes). They measure linear acceleration and angular velocity with high accuracy to understand and enable control of attitude and trajectory for a moving body.

Inertial measurement units vs accelerometers

Inertial Measurement Units (IMUs) are equipped with three-axis angular velocity (gyroscope) sensors, three-axis linear acceleration sensors for measuring three-dimensional inertial motion (translational motion and rotational motion along three orthogonal axes). On the other hand, a single acceleration sensor only measures translational acceleration along one axis. Therefore, the difference between Inertial Measurement Units (IMUs) and acceleration sensors is the type of motion that can be measured. Inertial Measurement Units (IMUs) can measure both translational and rotational motion, while acceleration sensors can only measure translational motion.

How do inertial measurement units (IMUs) work

Inertial measurement units working principle

Inertial Measurement Units (IMUs) typically include three-axis gyroscopes (angular velocity sensors) and three-axis accelerometers. These components work together to measure both translational and rotational motion using the following process:

1. Angular Velocity Detection: Gyroscopes measure angular velocity (degrees per second, °/s) to detect rotational motion.
2. Acceleration Detection: Accelerometers measure linear acceleration (meters per second squared, m/s²) to detect translational motion.
3. Data Fusion: The IMU combines data from both sensors to allow a CPU to calculate orientation information and direction of movement in 3D space such as position, velocity, and attitude.
4. Central Processing Unit (CPU): The CPU processes sensor data to provide accurate motion information (translational and rotational motion).

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Inertial measurement units system (IMUs system) type

6 axis inertial measurement units

Inertial Measurement Units (IMUs) come in a variety of configurations, including 6-axis IMUs. These advanced IMUs combine three-axis gyroscopes and three-axis accelerometers to provide a comprehensive 6-axis sensing system for measuring the movement of a (rigid) body in 3D space.

Epson offers a range of 6-axis IMUs, including waterproof and dustproof models. These rugged IMUs can withstand harsh environments and operate with long cables, making them ideal for complex measurement systems that require multiple sensors. Epson's 6-axis IMUs are well-suited for a wide range of industrial and system applications.

What do IMUs measure

What data do the IMUs measure and output?

The IMU outputs the following data.

The IMU reads and processes this data to calculate its position, velocity, and orientation in 3D space.

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What are IMUs used for?

Automotive area(autonomous vehicle)

Inertial measurement units (IMUs) can precisely measure a vehicle's short-term movement and orientation. In recent years, along with the advancement of automotive technology, IMUs have been incorporated into various vehicle systems and play a crucial role in the following areas:

Vehicle dynamics control:

• High-precision positioning in combination with GPS: Even when GPS signal reception is poor, the vehicle's position can be estimated based on IMU data.
• Lane Departure Warning System (LDWS): Monitors vehicle tilt and yaw rate to detect the possibility of lane departure and alert the driver.
• Autonomous Driving System: In autonomous driving systems that perceive the surrounding environment and control the vehicle autonomously, IMUs play a vital role in supporting safe driving by measuring the vehicle's orientation and movement in real time.

Other applications:

• Airbag Control: Detects the vehicle movement in the event of a collision and deploys airbags at the optimal time.
• In-vehicle Entertainment System: Detects vehicle tilt and vibration and adjusts video and audio to provide a comfortable cabin environment.
• Vehicle Diagnostics: Detects abnormal vehicle vibration or tilt, which can be used for early detection of faults.

Industrial area

Inertial measurement units (IMUs) can precisely measure the movement and orientation of machinery. In recent years, along with the advancement of industrial machinery, IMUs have been incorporated into various types of industrial machinery, playing a crucial role in the following areas:

Agricultural machinery

• Autonomous Tractors: IMUs measure the tractor's orientation and movement, providing information to the autonomous driving system to enable high-precision autonomous operation.
• Pesticide Spraying Robots: IMUs measure the robot's orientation and movement to control and distribute pesticides evenly while minimizing waste.
• Harvesting Robots: IMUs measure the robot's orientation and movement to control and accurately harvest fruits and vegetables.

Construction machinery

• Excavator Control: IMUs measure the excavator's orientation and movement to precisely control the arm and bucket position.
• Bulldozer Control: IMUs measure the bulldozer's orientation and movement to control the dozer blade for efficiently creating flat or sloped terrain.
• Crane Control: IMUs measure the crane's orientation and movement to safely control and accurately lift and position loads.

Mining machinery

• Excavator Control: IMUs measure the excavator's orientation and movement to control and efficiently extract ore.
• Hauler Control: IMUs measure the hauler's orientation and movement to safely control and efficiently transport ore.
• Tunneling Machine Control: IMUs measure the tunneling machine's orientation and movement to enable precise tunnel boring.

Camera gimbals

• Action Cameras: IMU measurements are used to compensate for camera shake to enable stable video recording.
• Film Cameras: IMUs precisely measure camera movement to control the camera view for achieving high-precision video capture.

Antennas

• Satellite Communication Antennas: IMU measurements are used to precisely control antenna orientation to stabilize and maintain reliable satellite communication.
• Radar: IMUs precisely measure the short-term motion of the radar system to control the radar orientation to enable accurate processing of the radar signals.

Drone area

Inertial measurement units (IMUs) have revolutionized drone technology, enabling precise movement and orientation control, which are essential for their safe and effective operation in various industries. IMUs play a crucial role in enhancing drone performance and safety, as drones continue to find applications in diverse fields. Here are some specific examples of how IMUs are utilized in drones:

Stabilizing flight control

For stable drone flight, continuous measurement of rotation and acceleration along the three axes and the transmission of appropriate control signals are crucial. IMUs provide this information in real-time, enabling smooth and stable drone flight, reducing pilot workload. IMUs are particularly important in outdoor environments with fluctuating wind speeds and air currents, where they maintain drone stability and prevent crashes.

Enabling autonomous flight

For autonomous drone flight, IMU-based orientation information is essential in addition to GPS data. IMUs precisely capture the drone's heading and tilt, allowing it to autonomously follow pre-programmed flight paths. Drone autonomy proves to be highly valuable in various industrial applications such as pesticide spraying, surveying, and inspection.

Controlling camera gimbals

Camera gimbals mounted on aerial drones utilize IMU data to control camera movements to enable stable video capture. High-quality aerial cinematography relies on IMU-powered advanced image stabilization.

Obstacle detection and avoidance

Drones are increasingly equipped with obstacle detection and avoidance capabilities. IMUs, combined with the drone's movement and surrounding environment data, can enable detection of obstacles to prevent collisions. This enhances safety in indoor flights and areas with human presence.

Satellite area

Inertial measurement units (IMUs) play a crucial role in satellite technology, enabling precise measurement of object movement and orientation. IMUs contribute significantly to satellite stabilization, attitude control, and orbit control. Here are some specific examples of their applications:

Satellite attitude control

Maintaining a stable attitude is essential for satellites to reliably operate in their Earth orbits. IMUs measure the satellite's rotation rate and tilt, providing information to the attitude control system. This system then activates thrusters or torque wheels to maintain the satellite's desired orientation.

High-precision attitude control is particularly important for tasks like aligning solar panels with the sun's direction and maintaining a fixed orientation for Earth observation cameras. IMUs provide the necessary data for such precise attitude control.

Orbit control

The gravity of Earth and other celestial bodies, along with atmospheric drag, continuously affect satellite orbits, necessitating regular orbit corrections. IMUs measure the satellite's acceleration, providing information to the orbit control system. This system then controls the thrusters to maintain the satellite's desired orbit.

For instance, GPS satellites utilize IMUs in conjunction with atomic clocks to deliver highly accurate positioning information. <-- This sentence seems out of place and context. I think it can be deleted.

Establishing inertial reference frames

Earth observation and weather satellites require high-precision location data to monitor the global environment effectively. IMUs measure the satellite's movement and orientation, providing information for establishing an inertial reference frame. This reference frame serves as a basis for accurately determining the relative positions of satellites to enabling precise monitoring of the global environment.

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Epson as an inertial measurement units manufacturer

Overview and features of Epson's IMUs

Epson's inertial measurement units (IMUs) are compact, high-precision 6-axis (3-axis angular rate and 3-axis linear acceleration) sensing devices. Here's a detailed explanation of the key features of Epson's IMUs:

High stability temperature characteristics and high alignment accuracy

In real-world environments, output data accuracy can degrade due to various factors such as warpage of the internal PCBs, mounting errors, vibration, and temperature changes. Epson's IMUs incorporate correction functions to minimize errors and output high-precision, high-stability sensing data.

Correction functions include alignment compensation, sensitivity compensation, offset compensation, and temperature compensation.

High stability of IMU performance

The stability of gyroscope sensors is expressed by Allan variance. Epson's IMUs employ gyroscope sensors with a crystal-based double T-shaped structure, achieving bias stability below 1 (°/h), which is comparable to that of more expensive gyroscope sensors.

Compact and lightweight 1-inch platform

The 1-inch platform offers compatibility in form factor and interface, enabling easy performance upgrades. The compact, lightweight, and low-power design also contributes to the miniaturization and weight reduction of customer products.

Waterproof and dustproof unit

The M-G552 series is a waterproof sensor with CAN and RS422 interfaces that can operate in outdoor environments and is suitable for complex system configurations.

Epson's IMUs are ideal for a wide range of applications in industrial and commercial systems, including motion analysis of equipment and analysis of rotational and translational motion.

Epson IMUs accuracy

Epson's inertial measurement units (IMUs) are renowned for their exceptional precision, making them ideal for demanding industrial and commercial applications. Here's a detailed breakdown of Epson's IMU accuracy:

Gyroscope bias stability

Epson's IMUs employ gyroscope sensors with a crystal-based double T-shaped structure. This innovative design achieves bias stability below 1 (°/h), surpassing even high-end gyroscope sensors in terms of stability.

Compensation features

To minimize errors in real-world environments, Epson's IMUs incorporate a suite of correction functions, including temperature compensation, alignment compensation, sensitivity compensation, and offset compensation. These features ensure consistently accurate and reliable data output.

High stability temperature characteristics

Epson's IMUs exhibit exceptional temperature stability, maintaining consistent performance across a wide temperature range. This remarkable stability ensures accurate data delivery even in extreme temperature conditions.