Rotary Encoders: Applications, Accuracy, Microcontroller Interfacing and Troubleshooting

You often find yourself needing to know how far a shaft has actually turned, how fast it’s going, or even what its exact angular position is in just about any modern machine, automation system, or robot, and that’s where rotary encoders come into play. It converts the rotation or angle of a shaft into electronic signals, allowing controllers, microcontrollers, and computer systems to monitor and control motion with pinpoint accuracy. Whether you’re building a robotic arm or just a basic motorised camera mount, a reliable rotary encoder from Brite Encoder can help your system capture data and act accordingly.

In this blog, we’ll be taking a walk through the key use cases for rotary encoders in robotics, how to make sense of all the different encoder types, what to expect when it comes to resolution and accuracy, how to hook an encoder up to a microcontroller, and how to ensure these things keep running smoothly over time. So, stick with us until the end to learn everything you need to know.

What are the top use cases of rotary encoders in robotics?

Commonly, you’ll find Rotary Encoders playing a pretty key role in many robotics & automation applications out there. Now, how do you actually use one in robotics? Let’s break it down:

• Joint-angle feedback/position sensing in robot arms
  In robotics, especially in industrial robots, encoders provide a super-precise, real-time readout of joint positions. And that’s no small deal – it means the robot can keep track of exactly where each joint is at all times & that’s a must for all sorts of tasks like welding, assembly, machining, or just pick and place.
  
• Velocity and acceleration control
  By keeping an eye on how fast that shaft is spinning, encoders give you the low down on motor speed and acceleration – which is a total game changer for smooth, accurate motion control in robotics.
  
• Multi-axis coordination and synchronisation
  With robots that have multiple joints or axes, these encoders provide feedback from each axis, enabling coordinated movement, precise trajectory planning, & even complex motion sequences.
  
• Compensation for gear backlash and mechanical errors
  When you place encoders after gear trains or at the joints, they let you measure the actual position rather than just what the intended motion was. All this helps reduce errors caused by sloppiness or backlash.
  
• Repeating tasks reliably with high precision
  For operations like welding, printing, pick-and-place, and machining, where repeatability is super important, these Briter Rotary encoders help ensure the robot returns to the same spot over and over again with zero misses.
  
• Feedback in servo-motor or brushless-motor control
  Lastly, in systems that use brushless motors, these encoders provide rotor-angle feedback to enable electronic commutation, resulting in efficient, smooth motor control.

How to choose between incremental and absolute rotary encoders?

Both incremental and absolute encoders are commonly used in this industry, and determining which one is right for your needs is a pretty crucial step. Here’s a basic comparison to help you make up your mind:

• Incremental Encoder

The Incremental Encoder provides relative motion feedback by outputting pulses (most often labelled A and B, and sometimes an index pulse, Z, to mark a reference per revolution). This is usually pretty handy for tracking movement, speed, direction, or distance travelled, because you can just count the pulses over time to get a pretty good idea of where you are or how fast you’re going. They’re also pretty economical and easy to work with, and are often just what you need for jobs like controlling motor speed, positioning, and conveyor control. But the only real downside is that they don’t remember an absolute position. So if you power down or restart, the system will lose track of where it is, and you’ll need to find a way to get that reference back or re-initialize things to know where the shaft actually is.

(Also read from our previous blogs: How to Install an Incremental Rotary Encoder – A Friendly Step-by-Step Guide)

• Absolute Encoder 

The Absolute Encoder provides absolute position feedback. Which means each unique shaft position corresponds to a unique digital code. Immediately after power-up, this gives the exact shaft position, so no homing routine is required. It’s very useful in applications such as robotics, CNC machines, and safety-critical systems where the position must be known immediately. However, this is more complex and costly than incremental encoders, but the extra cost is justified for advanced and safety-critical systems.

So, which one to choose?

In short, if you only need relative motion, speed or direction and can live with or manage homing after power loss, you can go for an incremental encoder. Plus, if your budget is tight and requirements are modest. But if you need the exact shaft position all the time, reliable power-cycle recovery or multi-axis absolute positioning, choose an absolute encoder.

What resolution and accuracy are realistic for common encoders?

When choosing an encoder, you need to check two main specifications: resolution, which indicates how finely it can detect movement, and accuracy and repeatability, which indicate how well those detections reflect the real-world shaft position.

Let me explain:

1. Resolution

• For Incremental Encoders, resolution is typically expressed as PPR (pulses per revolution), which is the number of pulses the encoder generates per full 360° rotation. Many incremental encoders support up to 10,000 PPR. But some encoders and systems also use interpolation, especially optical or sine-wave–based encoders, to subdivide pulses and achieve much finer effective resolution. This is good for high-precision robotics or CNC.
  
• But for Absolute Encoders, resolution is often expressed in bits as an n-bit encoder can give up to 2ⁿ distinct positions per revolution. In fact, for Higher-end absolute encoders, even 16-bit or more can offer increasingly finer resolution.

2. Accuracy and repeatability

• For incremental encoders, accuracy is often described as deviations in arcminutes or arcseconds. Typical “good” incremental encoders have accuracy of around 20 arcminutes, though high-precision versions may reach 5 arcseconds.
• For absolute encoders with high bit resolution and good manufacturing, you can achieve very fine positional accuracy and high repeatability.

How to interface a rotary encoder with a microcontroller?

Now, while it may sound too complicated, hooking up a rotary encoder to a microcontroller isn’t so complex. Just follow these steps:

1. Know the three main pins

You need to know the three main pins. Basic rotary encoders, like the common KY-040, have three main pins: A (CLK/Signal A), B (DT/Signal B), and GND & VCC (power). Sometimes it also has an SW pin which is a simple push button built into the knob.

2. Connect the pins

Just connect the pins, follow this simple wiring:

• VCC → 3.3V or 5V
• GND → GND
• A → Digital Pin
• B → Digital Pin
• SW (optional) → Another Digital Pin

And…you are done!

3. What the microcontroller reads

When you rotate the knob, both Pin A and Pin B send quick pulses, and the microcontroller watches the pulse order. This tells it which direction you turned, whether it is clockwise or anticlockwise, and how much you turned.

4. Add a simple program.

Every microcontroller platform, such as Arduino, ESP32, STM32, and Raspberry Pi, has ready-made libraries that let you include them and read the encoder as a counter. And once it is connected, you can use it to change menu settings, adjust volume or speed, measure rotation in robots or wheels, and control position in DIY machines.

What are the common failure modes and maintenance tips for encoders?

Some of the common problems in Rotary encoders are:

• Dust and dirt build up quickly; this can cause the encoder to give incorrect or jumpy readings.
• Wires are loose, signals cut off or unstable.
• The bearings are worn out, rotation feels rough, and the encoder is noisy.
• Moisture or humidity builds up, causing rust or short circuits.
• Overloading the shaft causes the encoder shaft to bend or break.
• And electrical noise can cause false pulses or incorrect counts.

Don’t worry. Just follow these tips, and you’re good to go:

• Keep it clean, always. Wipe dust, avoid oily or dirty environments.
• Check cables regularly to make sure connectors are tight.
• Avoid moisture and use enclosures if the place is humid.
• Lubricate bearings when needed.
• Avoid excessive force on the shaft and never push or pull it too hard.
• Finally, use shielding for noisy environments. This will reduce false signals.

Bottom Line

Briter Encoder introduces the rotary encoders, which have clearly become the unsung heroes in the world of automation and robotics. They convert mechanical rotation into electronic feedback that allows the machines to know where they are, how fast they are moving, and where they are supposed to go next. So, whether you choose an incremental or an absolute encoder depends on the task type. 

Have more queries regarding the encoders? Get in touch.