What is the encoder resolution, the resolution and accuracy of the encoder introduction

The resolution of the encoder refers to the number of positions output by the encoder shaft rotating one revolution, the more commonly used is the incremental photoelectric encoder, its resolution is also called the number of lines, such as 2500 lines 4 times the frequency, then its The resolution is 2500*4=10000 pulses. The higher the resolution of the encoder, the smaller the minimum scale of the motor, the smaller the angular displacement of the motor rotation, and the higher the control accuracy.

Resolution and accuracy

The accuracy of the encoder refers to the accuracy of the signal data output by the encoder to the actual angle measured. The corresponding parameters are arc minutes (') and arc seconds ("). Resolution: line, which is the encoder's The optical marking of the encoder, if the encoder is directly square wave output, it is the number of pulses per revolution (PPR), but if it is a sin/cos signal output, it can be electronically subdivided by signal analog changes , Get more square wave pulse PPR output, the square wave output of the encoder has A phase and B phase, A phase and B phase difference 1/4 pulse period, through the rising edge and falling edge judgment, you can get 1/ The change step of 4 pulse periods (4 times the frequency), this is the minimum measurement step (Ste p), so strictly speaking, the minimum measurement step is the resolution of the encoder.

The difference between encoder accuracy and resolution

For the understanding of the resolution and accuracy of the sensor, you can take the micrometer as an example. The resolution means that the micrometer can read up to a few decimal places, but the accuracy is also related to the processing accuracy of the ruler and the measurement method.

Similarly, in the use of rotary encoders, resolution and accuracy are two completely different concepts.

The resolution of the encoder refers to the smallest angle change that the encoder can read and output. The corresponding parameters are:

The number of lines per revolution (line), the number of pulses per revolution (PPR), minimum step (Step), bit (Bit), etc.

Encoder accuracy calculation formula:

Wheel circumference (mm) ÷ encoder resolution (P/R) × gear ratio =? mm/P How many millimeters send a pulse

P/R: Number of Pulse/Run pulses/turn, how many pulses are sent out per turn Circumference length=diameter Φ×circumference rate 3.14

The relationship between resolution and accuracy can be proved by the following figures:

The above four pictures are the same area, let us look at the border between the grass and the corn field (please pay attention to the border grid in the black box).

Figure A has 12 grids, and the boundary grid is 2 grids, so these two grids are uncertain, so the uncertainty is 2/12.

In the same way, there are 48 grids in Figure B and four boundary grids, so the uncertainty is 4/48.

Figure C is the uncertainty of 7/192. Figure D is the uncertainty of 12/768.

When the uncertainty is reduced, the natural accuracy is increased. The proof is completed

General literacy on A/D accuracy, resolution and LSB error

The accuracy we are talking about usually refers to its accuracy, but this is actually wrong.

Precision is also called precision, which is a concept corresponding to accuracy.

Just like shooting a target, it is accurate, that means its accuracy is relatively high;

The smaller the offset that can be hit between every two targets, the higher its precision.

Precision + accuracy = precision.