Background knowledge

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• Measured differently for linear and rotary encoders 

Resolution - Linear (μm): The length of one measured step 

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• Even if all the measurements are wrong, if they are all wrong in the same way (so they are in a similar place at every revolution) it is repeatable.

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Types

For our purposes: It has been decided by the other sub-teams to go with absolute rotary encoders for the sake of narrowing the scope of the first revision. In future revisions it might be worth considering to use incremental encoders in addition to the absolute rotary encoders.

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Mounting 

• Source: https://www.manufacturingtomorrow.com/article/2020/04/best-practices-for-encoder-mounting/15149#:~:text=Encoders%20are%20sensors%20used%20to,%2C%20environmental%2C%20and%20mechanical%20factors.
• Mounting practices depend on the type of encoder

Types of Rotary Encoders

Shafted Rotary Encoders

Required

1. Encoder Mount - Usually a mounting flange or a foot mount attaching encoder to a fixed surface (typically bracket or adapter) 
2. Connection from encoder shaft to motor shaft or load - Typically a flexible coupling or a belt drive 
   1. Flexible coupling
      1. Advantages: Compensates for shaft misalignment, isolates encoder from shock, vibration, noise and movement in the shaft/motor
      2. Disadvantages: Add space in line with the motor shaft, increases instillation time/complexity

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In this example a mounting flange is used (1) and a flexible coupling is used (2)

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Hollow Shaft Rotary Encoders - Direct Mounting 

• Have hollow bores that allow them to be mounted directly on to the shaft of the motor with a concentric clip
• How to install 

Required

1. Concentric clip - fixes the encoder to the shaft
2. Flexible tether or torque arm - Prevents the encoder from rotating with the shaft

In the example a concentric clip is used with a flexible tether to mount a hollow shaft rotary encoder

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Hub Shaft Rotary Encoders - Direct Mounting

• Similar to hollow shaft but the encoder caps the end of the shaft

Required

1. Plastic sleeve or insert - isolates encoder from motor shaft current (can alternatively use other grounding equipment)

Bearingless Rotary Encoders - Ring or C-Face Mounting

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