Incremental vs Absolute Rotary Encoders
If you are looking for a suitable rotary encoder for your boat or car, then you may be unsure whether to choose an Incremental or an absolute rotary encoder. A rotary encoder is a specialized sensor which can be used to count the measurements of movement. They both have positive and negative features, which will influence your final decision, and there are also different capacities on these encoders. When you are trying to choose between the different rotary encoder types, you should look to see what resolutions you get, what the accuracy is, and the methods of assessing the measurements.
The Incremental Rotary Encoder
This style of encoder does not use the absolute measurement, but instead counts according to the angle of the car when the encoder is turned on. The encoder then counts the turns in increments of movement (hence the name). These incremental encoders are quite precise, with only an error reading of a few arc seconds, not enough to cause an error in calculating the degree unless you spend all of your time in the car turning in a circle. The incremental rotary encoder uses one of four types of technology to calculate the distance travelled. These technologies are optical, mechanical, fiber optic and magnetic. The optical encoder counts via a light emitter/receiver. The mechanical encoder is achieved by using mechanical switches to indicate the movement. Fiber optic transmission is connected to optical sensing, and the magnetic rotary encoder allows you to use magnetic switches triggered by the relationship between magnetic fields which the car passes.
The Absolute Rotary Encoder
This is the other version of the rotary encoder, and is intended to note the rotational output using an absolute code. Unlike the incremental rotary encoder, they do not measure the position from the place where the car is turned on, but in fact never lose their position, even without the power. This means that the car can be moved without being turned on, and the absolute rotary encoder will still keep the perfect position. This makes them more suited for those who work with large vehicles, or who travel a lot in the machine that they already have. The absolute rotary encoder can use a magnetic form of the rotary encoder technology, as these are most resistant to any kind of shock or disabling halt. The type of magnet encoder that you get can affect how well the machine notes the changes, so you will have to find one which is most resistant to movement, temperature, and shock.
Choosing between the two types of encoder can be very difficult, and there is really very little between them. The main difference is the starting position of the incremental encoder, which is affected by power loss and voltage loss. If you need a precision instrument, then you would be better of looking at the many types of absolute rotary encoders available.