Encoders are vital to closed loop systems, so much so part of our logo reflects that (the top left part of the logo is similar to a rotary encoder track). How encoders may be used and in what form is application dependent.
Through the years there have been many forms of feedback, resolver, optical encoder, magnetic/hall, and more.
Typically, the type of feedback is chosen based on the application and commercial requirements; resolution, repeatability, harsh duty requirements (oil or water contamination, temperature range, etc), cost, and availability. While most motion engineers are familiar with these position generating encoder derivatives, there is a newer method of resolving position data based on tried and true technologies that offers the best of all options:
- IP67 Operation (water, oil, grease, dust tolerant)
- -10°C to +100°C standard
- High Resolution (better than .125um)
- High Speed (greater than 5M/sec)
- Single Count Repeatability
- Absolute encoding options
- Digital or analog and include:
- Incremental 1vp-p or TTL, with 1 zero signal or distance coding
- SSI + 1vp-p
- Endat 2.2
- Low price
This robust rated encoder technology is called “inductive”.
These systems operate on the principle of a transformer with a moving reluctance. The mutual inductance of the primary and secondary windings of a transformer changes depending on the relative position with respect to the core. These systems consist of a planar micro-coil structure and a measurement scale. The coil structure with a plurality of coils aligned in the direction of measurement (individual sets of micro-coils for Sine and Cosine), is incorporated on a substrate with micro-multi-layer flex circuit technology. The scale is a stainless steel scale with a high-precision photolithographic etched periodic graduation with variable reluctance.
The relative motion in the direction of measurement between the inductive sensor (encoder head) and measuring scale periodically changes the mutual inductance of each coil and generates two sinusoidal 90 ° phase-shifted signals (SIN and COS). With the excitation pure Sine wave signal, the resultant output is an excellent signal quality and stability against environmental influences so that after the signal conditioning in the evaluation electronics, the error is only 0.1% deviation from the ideal sinusoidal shape (harmonic content).
These inductive encoder devices come in two primary mechanical forms – linear and rotary ring. Linear options can be cut to length allowing OEM’s quick installation and easy form fit.
Comparing main feedback technologies:
We are positioned to help.
We have deployed thousands of encoders through the years and understand the challenges of choosing the appropriate feedback system that meets your application challenges and budgetary requirements. Give is a call and we’ll start providing “feedback” on what products may be appropriate for your needs!