What is the definition of “absolute” for absolute encoders?
Rotary encoders are important mechanical position angle, length, speed feedback and control sensors in the industry. Rotary encoders are incremental encoders, absolute encoders and absolute multiturn encoders. On devices received from the outside (such as servo controllers, PLCs), the incremental value refers to a change in relative position information. The calculation of the increase and decrease of the signal from point A to point B is also called “ Relative value”, it requires uninterrupted counting of subsequent devices. Since each data is not independent, but depends on the previous readings, the error caused by power failure and interference in the previous data cannot be judged, resulting in error accumulation. “Absolute mode of operation” means that after the device is initialized, an origin is determined. All subsequent position information is the absolute position of the “origin”. It does not require the uninterrupted counting of subsequent devices, but directly reads the current The position value, the error that may occur for power failure and interference, is called “absolute” mode of operation of the receiving device because each reading is independent of the previous influence and thus does not cause error accumulation.
The definition of the “absolute value” inside the absolute encoder refers to all position values inside the encoder. After the encoder is manufactured, all positions in the range have been “absolutely” determined in the encoder. After initializing the origin, each position is independent and unique. Its internal and external data refresh reading does not depend on the previous data read, either inside the encoder or outside the encoder. There is an accumulative calculation of the “count” and the previous reading, because such data is not “independent” “unique” “all positions in the range have been pre-established in advance”, and thus does not conform to the meaning of the word “absolute”. Therefore, the definition of a true absolute encoder refers to the absolute correspondence between the pre-position and the origin position of all positions in the range, and it does not depend on the internal and external count accumulation and independent and unique absolute coding.
“Deliberate Confusion” and Misunderstanding of the Concept of “Absolute” Encoder
Regarding absolute encoders, many people still know that they should stay in the “blackout” position to save this concept. This is one-sided and limited. The “absolute value” encoder is not only a power outage problem, but also a receiving device. The meaning of “absolute value” is that its data is refreshed and read, whether inside or outside the encoder, the independence and uniqueness of each position, and the “absolute coding” that does not depend on the previous reading. For the definition of “absolute” The market is still ambiguous, for which some businesses will “deliberately confuse” this concept:
Confuse the “absolute mode of operation” of the receiving device with the “absolute” of the absolute encoder. The “absolute” of the receiving device means that the receiving device does not need to continuously count up, the “absolute” working mode of all the positions for the device origin, in fact, this mode passes the incremental encoder + its own counting accumulator + battery memory, The same “absolute” position information can be provided to the device. It is not a concept with the “absolute coding” of the absolute value encoder. It has the error of counting and the possibility of accumulating errors, the possibility of power failure of the counting device, and the high speed. The possibility that the count cannot respond.
The absolute value of the single-turn encoder + internal and external count accumulators is confused with the true absolute value of the true multi-turn encoder. Absolute value single circle + counting device, it is absolute within 360 degrees, but after more than 360 degrees, its position is not “independent” “unique”, it depends on internal or external counting to determine how much The internal or external “counting device” of the single-turn absolute position information in the circle is the same as the incremental encoder + counting device + battery memory, any counting error, or the power supply when the counting device is operating. The instantaneous failure will cause errors and accumulate and cannot be judged, resulting in deceptive false absolute information. The true absolute multi-turn encoder, except for the position within 360 degrees, is absolutely unique. After more than 360 degrees, the absolute value code wheel driven by the gear mechanism continues to provide “independent” “unique” and independent. The accumulated absolute code is read in the previous data refresh. In fact, from the definition of “absolute”, the “fake multi-turn absolute encoder” of the previous single-turn absolute + counting accumulator can no longer be called “absolute multi-turn encoder”, although Within 360 degrees is absolute, but the working range of more than 360 degrees is no longer “absolute value coding”.
In combination with the above definition of “absolute” for absolute encoders, the use of “absolute encoders” or “false absolute multi-turn codes” must be used in applications where high speed, security, etc. are required. “,” must use a true absolute encoder or an absolute multi-turn encoder, and any count-independent (internal or external, battery-free, all-independent, unique, Absolutely to ensure absolute reliability and high speed accuracy of the data. When selecting and using an absolute encoder, please determine whether it is “absolute code” as described above to ensure the absolute utility of the use.