Classification of servo motor encoders

We have previously understood the principle of the servo motor encoder. It can be seen that the working principle of this device is relatively complex, but it has many functions and has attracted much attention from various industries. So what are the classifications of servo motor encoders? Next, the editor will introduce the classification of this device one by one!

The classification of servo motor encoders is as follows:

In addition to the ABZ signal of general encoders, incremental coding also has UVW signals for incremental servo encoders. Most domestic and early imported servos use this method, which has more lines.

The incremental encoder outputs pulses when it rotates, and its position is known through the counting device. When the encoder does not move or has a power outage, it relies on the internal memory of the counting device to remember the position. In this way, when there is a power outage, the encoder cannot move. When the power is turned on, there can be no interference and loss of pulses during the encoder output pulse. Otherwise, the zero point recalled by the counting device will shift, and this shift There is no way to know the quantity. It can only be known after the wrong production results appear.

The solution is to add a reference point. Every time the encoder passes the reference point, the reference position is modified into the memory position of the counting device. Before the reference point, the accuracy of the orientation cannot be guaranteed. For this reason, in industrial control, there are methods such as finding the reference point for each operation and finding change when turning on the machine.

For example, the positioning of the printer scanner uses the incremental encoder principle. Every time it is turned on, we can hear a crackling sound as it searches for the reference zero point before working.

This method is more troublesome for some industrial control projects, and does not even allow the machine to be turned on to make change (you need to know the location after turning on the machine), so the appearance of the absolute encoder has emerged.

Positive rotary photoelectric encoders are increasingly used in angle, length measurement and positioning control in various industrial systems because each position is unique, anti-interference, and does not require power-off memory.

Make sure there are many engraved lines on the encoder code disk. Each engraved line is arranged in order of 2 lines, 4 lines, 8 lines, 16 lines, etc. In this way, in every position of the encoder, by reading each engraved line The pass and dark are used to obtain a set of only binary codes (Gray codes) from 2 to the n-1 power. This is called an n-bit positive encoder. Such an encoder is determined by the mechanical position of the code disk and is not affected by power outages and interference.

It determines the uniqueness of each position of the servo encoder determined by the machine position. It does not need to remember, does not need to find a reference point, and does not need to count all the time. When you need to know the position, you can read its position. In this way, the anti-interference characteristics of the encoder and the reliability of data are greatly improved.

Because positive encoders are significantly better than incremental encoders in positioning, they are increasingly used in servo motors. Because of its high precision, the positive encoder has a large number of output digits. If parallel output is still used, each of its output signals must ensure a good connection. For more complex working conditions, it must be isolated, and the number of connecting cable cores is large. This brings a lot of inconvenience and reduces reliability. Therefore, multi-digit output type positive encoders generally use serial output or bus type output. The serial output of positive type encoders produced in Germany is commonly SSI (synchronous serial output). line output).

Rotate the single-turn positive encoder from a single-turn positive encoder to a multi-turn positive encoder, and measure each engraved line of the optical code disk while rotating to obtain the unique code. When the rotation exceeds 360 degrees, the code is Back to the starting point, this does not comply with the only principle of positive encoding. Such an encoder can only be used for measurement within a rotation range of 360 degrees, and is called a single-turn positive encoder. If you want to measure rotation beyond 360 degrees, a multi-turn positive encoder is used.

Encoder manufacturers use the principle of wall clock gear machinery. When the central code disc rotates, another set of code discs (or multiple sets of gears, multiple sets of code discs) are transmitted through the gear, and the number of turns is added to the single-turn encoding. Encoding to expand the measurement range of the encoder, such a certain encoder is called a multi-circle certain encoder. It also determines the encoding by mechanical position. Each position code is unique and does not need to be memorized.

Another advantage of the multi-turn encoder is that due to its large measurement scale, it is often more abundant in actual use. In this way, there is no need to work hard to find the zero point during installation, and a certain center position can be used as the starting point, which greatly simplifies the difficulty of installation and debugging. Multi-turn positive encoders have significant advantages in length positioning. New servo motors in Europe basically use multi-turn positive encoders.