What is an REV IMU?

The REV Expansion Hub has a built-in IMU, or Inertial Measurement Unit. This is a sensor that can measure acceleration (movement) in several axes. It can be used in place of an external gyro. The IMU is not used in quite the same way as the gyro but is similar.

How does an inertial measurement unit work?

How Does an IMU Work? IMUs can measure a variety of factors, including speed, direction, acceleration, specific force, angular rate, and (in the presence of a magnetometer), magnetic fields surrounding the device. IMUs combine input from several different sensor types in order to accurately output movement.

What is an expansion hub?

The REV Robotics Expansion Hub (REV-31-1153) is a low-cost education device that can communicate with any computer (Commonly the REV Robotics Control Hub or an Android Phone) to provide the interfaces required for building robots and other mechatronics.

What causes IMU drift?

Gyroscopes are subject to bias instabilities, in which the initial zero reading of the gyroscope will cause drift over time due to integration of inherent imperfections and noise within the device. Bias repeatability can be calibrated across the known temperature range of the IMU.

What is difference between IMU and accelerometer?

Gyroscope: While accelerometers can measure linear acceleration, they can’t measure twisting or rotational movement. As you’ve seen, IMUs are used to measure acceleration, angular velocity and magnetic fields, and, when combined with sensor fusion software, they can be used to determine motion, orientation and heading.

Does an IMU measure velocity?

An IMU measures the linear accelerations (three-axis accelerometer) and rotational velocities (three-axis gyroscope), which can be numerically integrated to obtain 3-D position/orientation of an object.

How many sensors does the Rev expansion hub have?

The IMU incorporates three sensors: a 3-axis accelerometer, a 3-axis gyroscope, and a 3-axis geomagnetic sensor. This sensor can be used to determine orientation and location of the robot.

How accurate is IMU?

The IMU is a key dynamic sensor to steer the vehicle dynamically, moreover the IMU can maintain a better than 30cm accuracy level for short periods (up to ten seconds) when other sensors go offline.

How does an IMU know which way is down?

The answer is that it senses gravity. In physics, we often use this term “acceleration due to gravity” when we talk about gravitational forces. That’s because gravity is measured in acceleration. On our phones, usually, an IMU with a 3-axis accelerometer is used to sense the direction on which the gravity is acting on.