Figure 24: Maxon sensor selection

Most of the time, even if an external sensing system exists, having a sensor on the motor is valuable for testing, if not for the full operation of your system. Assuming the need for a sensor attached to the motor has been decided, the sensor types can be reviewed in greater detail. There are three common types of sensors that are installed onto motors which are summarized in terms of their general properties below.

• 
  Encoder
  
  • 
    Information Output
    
    • 
      Speed
      
    • 
      Angular Position
      
    • 
      Rotation direction
      
  • 
    General Overview
    
    • 
      Digital output
      
    • 
      Very good accuracy possible
      
    • 
      Most common type (many sub categories)
      
    • 
      High speed possible
      
• 
  DC Tachometer
  
  • 
    Information Output
    
    • 
      Speed
      
    • 
      Rotation direction
      
  • 
    General Overview
    
    • 
      Analog output
      
    • 
      Output voltage proportional to speed
      
    • 
      Not acceptable for positioning tasks
      
• 
  Resolver
  
  • 
    Information Output
    
    • 
      Speed
      
    • 
      Angular Position
      
    • 
      Rotation direction
      
  • 
    General Overview
    
    • 
      Analog Output
      
    • 
      Less accurate position than Encoder
      
    • 
      Long service life (great for industrial use)
      
    • 
      Requires special signal evaluation