Absolute vs Incremental Encoders: Which One Is Better for Robotics?

Introduction

Encoders are a fundamental component in any robotic system.

They provide real-time feedback on position, speed, and motion, making precise control possible.

When selecting an encoder for robotics, one key question always arises:

Should you use an absolute encoder or an incremental encoder?

This article explains the differences, advantages, and applications of both types, and why absolute encoders are becoming the standard in modern robotics.

What Is an Encoder?

An encoder is a sensor that converts mechanical motion into electrical signals.

In robotics, encoders are used to:

• Measure position

• Track rotation

• Provide feedback for motion control

They are essential for closed-loop control systems that require accuracy and repeatability.

What Is an Incremental Encoder?

An incremental encoder generates signals based on movement.

How It Works

• Outputs pulses as the shaft rotates

• Position is calculated by counting pulses

Key Characteristics

• Measures relative position only

• Requires a reference point

• Simple structure and lower cost

Advantages

• Cost-effective

• Simple design

• High-speed performance

Limitations

• Loses position after power-off

• Requires homing during startup

• Prone to accumulated error over time

What Is an Absolute Encoder?

An absolute encoder provides a unique position value for every shaft angle.

How It Works

• Each position corresponds to a unique digital code

• Position is known immediately, even after power-off

Key Characteristics

• Provides absolute position

• No homing required

• Supports multi-turn position tracking

Advantages

• Immediate position recognition

• High precision and repeatability

• Reliable for complex robotic systems

Limitations

• Higher cost

• More complex design

Absolute vs Incremental Encoders

Why Absolute Encoders Are Preferred in Robotics

No Homing Required

• Reduces startup time

• Eliminates positioning errors during initialization

Safer Operation

• Maintains position after power loss

• Prevents unexpected movement

Higher Precision

• High resolution output

• Better repeatability

Better Multi-Axis Coordination

• Supports complex robotic systems

• Ensures synchronized motion across multiple joints

Single-Turn vs Multi-Turn Absolute Encoders

Single-Turn Encoders

• Measure position within one rotation

• Simpler and cost-effective

Multi-Turn Encoders

• Track multiple rotations

• Maintain position across extended motion

Why Multi-Turn Matters

• Robotic joints often rotate continuously

• Maintains accurate long-term position tracking

Communication Interfaces in Robotics Encoders

Modern encoders support various communication protocols:

• RS485 for stable long-distance communication

• EtherCAT for high-speed real-time control

• CAN and CANopen for reliable automation systems

Select an encoder compatible with your control system and communication architecture.

The Role of Encoders in Robot Joint Modules

Encoders are essential in integrated robot joint modules:

• Provide real-time position feedback

• Enable closed-loop control

• Improve motion accuracy

Dual Encoder Systems

• Motor-side encoder

• Output-side encoder

Benefits include higher precision, compensation for transmission errors, and improved system stability.

When to Choose Each Type

Choose Incremental Encoder

• Lower cost requirement

• Simple applications

• Homing is acceptable

Choose Absolute Encoder

• High precision requirements

• Complex systems

• Safety-critical applications

• Multi-axis robotics

Conclusion

Incremental encoders are suitable for simple systems, while absolute encoders are preferred for modern robotics.

Absolute encoders provide immediate position feedback, higher accuracy, and reliable multi-axis coordination, making them essential for advanced robotic applications.

Need Help Selecting the Right Encoder?

If you are designing a robotic system or integrated joint module, selecting the right encoder is critical.

Provide your application details, and our team can recommend the most suitable encoder solution for your system.