With the help of feedback systems, various parameters can be measured in engines. An absolute feedback system always knows the absolute position of the axle, which makes a homing routine redundant. Relative feedback obviously shows the position of the axis opposite a certain point of departure. However, when the power is dropped, it will need to be rehomed to preserve the integrity of the system. Examples are encoders (absolute and incremental), tachometers, resolvers and potentiometers. An important aspect is the measurement method. For example, it can be linear or rotating and magnetic or optical.
- Absolute encoders;
Optical and magnetic, linear and rotating (Mechanical absolute encoders, optical absolute encoders, magnetic absolute encoders, capacitive absolute encoders)
- Incremental encoders;
Optical, both linear and rotary
Rotating, measure the speed of the shaft and generate a corresponding DC output voltage.
Rotating, measure the mechanical position/angle warp of the shaft and generate a corresponding sine/cosine output voltage. A resolver is an absolute feedback system.
Single or Multiturn potentiometers