In industrial automation, servo motor encoders are the basic components that act as the eyes and ears of a precision motion control system. They can provide the necessary feedback, which will allow the machinery to perform tasks with accuracy and repeatability. However, when selecting the right encoder the decision can be a bit tough to make. You might find yourself deciding between the two choices: single-turn and multi-turn.
For this choice, you need to understand the differences between their technology. In this blog, we will look at the difference between single-turn and multi-turn servo motor encoders and also compare these two essential service encoder technologies which will help you make an informed decision based on your needs.
What is a Single-Turn and Multi-Turn Servo Encoder?
If you wish to make the right choice then it is important that you first understand what each of these encoder types represent and how they function at their most basic level. Their names are a hint at their core capability which is how they track rotation. Let’s have a look at them:
Single-Turn Encoder
These encoders are made to measure the angular position within a single, complete 360-degree rotation of the motor shaft. You can think of them as having a highly accurate compass that always knows where it is within one full circle. While they can report the exact angle at any point, their count of total revolutions reset once the shaft completes a full turn. This makes them ideal for when the motor’s movement doesn’t exceed one complete rotation or where only the absolute position within that specific turn is the primary concern. It could be an orientation or limited rotation valve or a robotic joint with a restricted range of motion.
Multi-Turn Encoder
Multi-Turn encoders are built on the capabilities of a single-turn encoder and a step further. They can not only track the exact position within a single revolution but also accurately count and remember the number of full rotations that the motor shaft has completed. This means that they provide a true absolute position across a lot of turns which is often in thousands.
Also, a key feature of these encoders is their ability to maintain the total travel distance, or absolute position, even after the power is lost. This memory is necessary for linear movements which are extensive like a gantry system moving along a long track, or for complex rotational applications where the machinery can spin many times in one direction yet still needs to know its overall absolute position without recalibration.
What is the Difference between Single-Turn and Multi-Turn Servo Motor Encoders?
The distinction between single-turn and multi-turn encoders creates differences in their operational advantages and ideal use cases. If you understand these comparative points then you will be easily able to select the right servo motor encoder for your industrial setup. Here it goes:
- Scope of Positional Tracking: The biggest difference between them is their measurement range, single-turn encoders are limited to reporting absolute position only within one revolution, which is from 0 to 359.9 degrees. In contrast, multi-turn encoders extend this absolute measurement over numerous revolutions, where it counts each full turn. This capability is absolutely important for applications which involve large travel distances to ensure that the system always knows its exact overall position without considering the number of times it has spun.
- Power-off Position Memory: This is kind of a major advantage for the multi-turn encoders as they are made to retain their absolute positions even if the power to the system is unexpectedly lost. This memory is often achieved through internal mechanical gearing or battery-backed electronic counters. Single-turn encoders on the other hand lose their turn count when there’s power loss which means that the total system position becomes unknown. This also means that it requires a re-homing procedure after the power is restored.
(Also Read: How Incremental Encoders Play an Important Role in Robotics and Motion Systems)
- Complexity and Cost Considerations: Due to the additional mechanisms or advanced electronics which are required to track and store the multiple revolutions, the multi-turn encoders are generally more complex in construction. This means that it also has a higher manufacturing cost when compared to simpler single-turn encoders which are most cost-effective for applications which don’t require multi-revolution tracking.
- Homing Procedure Requirements: The operational benefit that comes with multi-turn absolute encoders is that they eliminate the need for a homing procedure. With a multi-turn encoder, the system knows its exact position immediately upon power-up, saving valuable time and simplifying the startup process. So, systems which rely on single-turn encoders for applications that exceed one revolution need to perform a homing sequence ( moving to a reference point) after a power cycle to establish their total position.
Bottom Line
The choice between single-turn vs. multi-turn servo motor encoder is a decision which will impact the performance, reliability and also the efficiency of your automated systems. It hinges on the clear understanding of your applications’ specific requirements which particularly concerns the total travel distance, the need for power-off memory, and the acceptable level of system complexity. You can carefully evaluate these factors and select the best servo motor encoder for multiturn positioning applications or simple tasks where precision is needed in every movement.
If you wish to find high-quality single-turn and multi-turn servo motor encoder solutions which are engineered for industrial automation requirements then you can reach us out at brt@briterencoder.com.
