What Is the Difference Between Absolute and Incremental Angle Sensors?

Angle sensors are used to measure the rotation of an object and provide information about its position. There are two types of angle sensors: absolute and incremental. While both types of sensors measure angles, they differ in how they provide information about the angle.

Absolute Angle Sensors

Absolute angle sensors provide the exact angle of rotation of an object. They can be implemented in many different ways. One type uses a code disk with a unique pattern of binary code that corresponds to each angle. When the sensor reads the code, it can determine the exact angle of rotation. Another type uses inductive sensing which is great in environments with oil, dirt, etc.

Absolute angle sensors are ideal for applications where the angle at power-on is critical.

Incremental Angle Sensors

Incremental angle sensors provide information about the change in the angle of an object. They may use a code disk with holes spaced equally around the perimeter. Each hole represents a change in angle when it passes a sensing element. They can also be implemented using a magnet ring or ring of magnets with a Hall-effect type sensor to detect each step. Using two Hall sensors offset by half a step a quadrature signal can be generated, from which the direction of rotation can also be detected. Adding a 3rd sensor element and an index hole/magnet on the disc, the absolute angle can be calculated once this index point has been passed for the first time.

Incremental angle sensors are simpler and can be used in situations where absolute angle is not required, or where angle at power-up is not needed.

In conclusion, the main difference between absolute and incremental angle sensors is the type of information they provide. Absolute angle sensors provide the exact angle of rotation, while incremental angle sensors provide information about the change in angle. The choice between the two types of sensors depends on the specific application.