Incremental vs. Absolute Position Feedback: Key Differences for Precision Control

In industrial automation, robotics, and manufacturing, precise position feedback is essential for accurate motion control. Incremental and absolute linear and rotary position feedback systems are two common types of position sensing used in various applications. Each system has its unique method of operation and is suited to different environments and requirements. Understanding their differences is crucial for selecting the right solution based on accuracy, reliability, and cost considerations.

Incremental position feedback: tracking movement relative to a reference point

Incremental position feedback systems provide information about a device's or a component’s position relative to its last zeroed or powered-on reference point. Instead of tracking or storing absolute position data, they generate signals as the device moves, counting pulses from a known reference point to determine position. If power is lost or the signal is interrupted, the system cannot recall its absolute position, requiring re-referencing or homing upon restart.

Incremental Encoder Track Examples

Incremental systems typically use encoders that output pulses, which an external counter or controller tracks to determine position. Their resolution depends on the number of pulses per unit of movement, while factors like mechanical slip or missed pulses affect accuracy.

Absolute position feedback: ensuring precise tracking even after power loss

On the other hand, absolute position feedback systems assign a unique value to each position within a device's range of motion. Even after a power loss, they immediately report the exact position upon power-up without requiring a reference point. While more complex and expensive than incremental systems, they are crucial for applications that demand constant, precise position tracking.

Absolute encoder track example

Absolute encoders are optical, magnetic, or other technologies that encode position data in a format, such as binary code, that directly represents position without counting pulses. This design makes them inherently more robust and reliable, ensuring accurate position tracking even after power loss or signal interruptions.

Comparison of key features

The choice between incremental and absolute linear position feedback systems depends largely on the specific application requirements, including precision, reliability after power loss scenarios, and budget constraints. Absolute systems ensure robust and reliable position data but at a higher cost, while incremental systems offer a cost-effective solution for less critical applications.