Feedback extension conversion device and method for encoder

Abstract

The invention discloses a feedback expansion conversion device and method for an encoder, the output end of the encoder is connected with the feedback expansion conversion device, the encoder outputs a differential signal, and the feedback expansion conversion device comprises a signal buffer circuit, a signal processing circuit and a feedback expansion conversion circuit, the input end of the driver is connected with the output end of the encoder so as to perform driving enhancement on the differential signal to generate an enhanced signal; and the interface expansion circuit comprises a plurality of groups of connectors, and the input ends of the connectors are respectively connected with the signal buffer circuit so as to realize expansion output of the enhanced signal. Through the design of signal buffering, multi-path expansion, impedance matching, overcurrent protection and electrical isolation, the transmission stability, the driving capability, the system expansibility and the anti-interference capability of feedback signals of the encoder are remarkably improved, multiple pain points in the prior art are solved, and the precision, the reliability and the maintenance convenience of the shaft control system are improved.

Description

Technical Field

[0001] This invention belongs to the field of servo control technology, specifically relating to a feedback extension conversion device and method for encoders. Background Technology

[0002] Against the backdrop of rapid development in intelligent manufacturing and industrial automation, high-precision axis control systems, such as CNC machine tools, industrial robots, and precision transmission equipment, are facing increasingly stringent requirements for the real-time performance and accuracy of position and speed feedback. As a core component for detecting axis position, speed, and zero position, the stable transmission of encoder feedback signals directly determines the system's control accuracy. However, in practical applications, the transmission and application of encoder feedback signals face a series of technical bottlenecks that urgently need to be addressed: On the one hand, the encoder's output circuit focuses on signal generation rather than strong drive design. This makes the feedback signal prone to amplitude attenuation and waveform distortion due to excessive load when long-distance transmission or simultaneous driving of multiple downstream control circuits is required. This distortion directly causes a decrease in the position detection accuracy of the axis control system, fluctuations in speed control, and even motion loss and oscillation, seriously affecting the processing accuracy or motion stability of the equipment. Currently, the mainstream solutions for encoder feedback signal transmission are "direct connection of the encoder to the control circuit" or "simple split-line extension". The former relies on the encoder's own driving capability. When the transmission distance exceeds 3 meters or the input impedance of the downstream load is low, the signal is prone to amplitude attenuation and pulse edge distortion due to cable loss and load tension, resulting in position counting errors. The latter uses a passive splitter to split one signal into multiple paths to meet the signal requirements of multiple devices. However, after splitting, the driving capability of each signal is further weakened, and there is a lack of impedance matching design, which exacerbates the signal reflection problem and significantly increases the high-frequency pulse loss rate.

[0003] On the other hand, traditional encoders are mostly single-channel signal outputs, meaning that one encoder can only transmit feedback information to one control device. However, modern shaft control scenarios often require multi-system collaboration. In this case, a single-channel encoder cannot meet the requirement of "one signal being transmitted in parallel to multiple control circuits." If the signal is forcibly split through additional circuits, it will further exacerbate the "insufficient driving capability" dilemma, creating a vicious cycle.

[0004] Meanwhile, the signal transmission cables and input impedance characteristics of subsequent control circuits in different axis control systems vary significantly. In existing technologies, encoders and control circuits are often directly hard-connected, lacking flexible impedance matching methods. This makes signal reflections during transmission prone to occur (especially in high-frequency differential signals A / B / Z phases). The superposition of reflected waves with the original signal degrades waveform quality and reduces timing and amplitude accuracy. Schemes using general-purpose operational amplifiers to enhance the drive require separate power supply and bias circuit designs, resulting in poor compatibility and the lack of integrated overcurrent protection. Short circuits in cables or subsequent stage failures can easily burn out the encoder.

[0005] Furthermore, the encoder feedback signal is a precise small signal, while the working environment of the subsequent control circuit is subject to strong electromagnetic interference. Moreover, load changes can affect the encoder in reverse through the lines. In the existing technology, the encoder and the subsequent circuit are directly electrically connected without intermediate buffer isolation links. The electromagnetic interference of the subsequent stage will "introduce" into the signal loop, reducing the signal-to-noise ratio. The current / voltage fluctuations of the subsequent load will also be coupled to the encoder side through the lines, interfering with its normal operation and even causing the operating point of the encoder's internal circuit to shift, affecting the signal generation accuracy.

[0006] These problems are intertwined, affecting multiple dimensions such as signal transmission reliability, system scalability, and equipment operation stability, and severely restrict the accuracy, reliability, and scalability of the axis control system. Summary of the Invention

[0007] The purpose of this invention is to provide a feedback extension conversion device and method for encoders, in order to solve the problems in the prior art such as insufficient driving capability of encoder feedback signal in long-distance transmission or multi-load scenarios, resulting in signal attenuation and waveform distortion; single encoder output cannot meet the needs of multi-system collaborative transmission; lack of flexible impedance matching means leading to signal reflection and distortion; lack of overcurrent protection that easily damages equipment; and lack of intermediate buffer isolation link leading to electromagnetic interference affecting signal accuracy.

[0008] To achieve the above objectives, a specific embodiment of the present invention provides a feedback expansion conversion device for an encoder, wherein the output terminal of the encoder is connected to the feedback expansion conversion device, the encoder outputs a differential signal, and the feedback expansion conversion device includes: A signal buffer circuit, the input of which is connected to the output of the encoder, drives and enhances the differential signal to generate an enhanced signal; The interface expansion circuit includes several sets of connectors, the input ends of which are respectively connected to the signal buffer circuit to expand the output of the enhanced signal.

[0009] In one or more embodiments of the present invention, the encoder output terminal has six sets of output pins, which are capable of outputting differential signals of A+ phase, B+ phase, Z+ phase, A- phase, B- phase and Z- phase.

[0010] In one or more embodiments of the present invention, the feedback extension conversion device further includes a signal matching circuit, the signal matching circuit including a resistor network connected in series between the input pin of the signal buffer circuit and the output pin of the encoder, the resistor network being a plurality of sets of resistors connected in series between the input pin of the signal buffer circuit and the output pin of the encoder for signal impedance matching or overcurrent protection.

[0011] In one or more embodiments of the present invention, the buffer circuit includes a buffer chip, the buffer chip including six sets of input pins respectively connected to the encoder output pins through the resistor network; the buffer chip also includes six sets of output pins respectively connected to the input pins of the connector.

[0012] In one or more embodiments of the present invention, the connector is provided in three groups, and the output end of each group of the connector is respectively connected to the main controller, the redundant controller and the monitoring terminal.

[0013] In one or more embodiments of the present invention, the connector is a connector with a 28-pin specification, including at least six sets of differential signal pins, two sets of power supply pins and several auxiliary signal pins, wherein the six sets of differential signal pins are connected to the six sets of output pins of the buffer chip.

[0014] In one or more embodiments of the present invention, the feedback extension conversion device further includes a power supply circuit that provides a +5V operating power supply to the signal buffer circuit, the encoder, and the interface extension circuit.

[0015] In one or more embodiments of the present invention, the buffer chip is a six-channel tri-state buffer chip of model SN74HCS367DR.

[0016] In another aspect of the present invention, a feedback extension conversion method for an encoder is provided, the method comprising the following steps: the encoder outputs differential signals of A+ phase, B+ phase, Z+ phase, A- phase, B- phase and Z- phase respectively, the differential signals being input to a signal buffer circuit through impedance matching or overcurrent protection by a signal matching circuit; The signal buffer circuit drives and enhances the input differential signal to generate an enhanced signal. The enhanced signal is transmitted to at least one external control circuit via the connector of the interface expansion circuit as a feedback signal.

[0017] Compared with existing technologies, the feedback extension conversion device for encoders in this invention improves signal carrying capacity by 3-5 times through a dedicated drive circuit for the signal buffer circuit, stably supporting cable transmission of over 10 meters and simultaneously driving three or more control circuits, completely solving the waveform distortion problem in multi-load scenarios. Simultaneously, the resistor network in the signal matching circuit can flexibly adapt to transmission lines with different impedances, effectively reducing signal reflection and lowering the high-frequency pulse loss rate from over 15% in existing technologies to below 1%, significantly improving position detection accuracy.

[0018] This invention achieves a "one-channel input, multiple-channel parallel output" architecture through the design of multiple industrial connectors in the interface expansion circuit, meeting the needs of multi-system collaborative control, and ensuring no signal strength attenuation during the expansion process. Furthermore, the overall modular design is compatible with various encoder models, including incremental and absolute encoders, eliminating the need to redesign circuits for different devices. Compared to the poor compatibility of dedicated drive circuits in existing technologies, this significantly reduces equipment upgrade and maintenance costs.

[0019] The high-impedance characteristic of the preferred three-state buffer in this invention achieves electrical isolation between the front and rear stages, improving the signal-to-noise ratio by 10-15 dB. Simultaneously, the configurable resistor network in the signal matching circuit also provides overcurrent protection, quickly interrupting excessive current in the event of a short circuit in the rear stage, preventing encoder damage. Compared to the over 30% failure rate caused by the lack of protection mechanisms in existing technologies, this reduces the system failure risk to below 5%, significantly improving the long-term operational stability of the axis control system. Attached Figure Description

[0020] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0021] Figure 1 This is a schematic diagram of the overall structure of the feedback extension conversion device according to one embodiment of the present invention; Figure 2 This is a circuit diagram of a signal buffer circuit according to one embodiment of the present invention; Figure 3 This is a circuit diagram of the original encoder in one embodiment of the present invention; Figure 4 The circuit sun of the connector in one embodiment of the present invention; Figure 5 This is a flowchart of feedback extension conversion in one embodiment of the present invention. Detailed Implementation

[0022] To enable those skilled in the art to better understand the technical solutions of this invention, the technical solutions of the embodiments of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are merely some embodiments of this invention, and not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of this invention.

[0023] like Figures 1-4As shown, the present invention is a feedback extension conversion device for encoders, which aims to solve many technical problems faced by shaft encoders in the field of industrial automation, such as insufficient driving capability, difficulty in multi-device collaborative transmission, inflexible impedance matching, and lack of overcurrent protection and electrical isolation during the transmission of feedback signals.

[0024] like Figure 1 The overall functional module architecture diagram shown illustrates that the core function of this device is to receive differential signals from the shaft encoder, process and enhance them, and then extend and transmit them to multiple downstream control or monitoring devices. For example... Figure 2 As shown, the encoder serves as the input source, and its output differential signal typically includes three-phase differential signals of A, B, and Z, namely A+, A-, B+, B-, and Z+, Z-, which are connected to the expansion conversion board through an interface.

[0025] like Figure 2 The diagram shows the signal buffer circuit of the expansion conversion board in this device. The input of this circuit is directly connected to the output of the encoder. Its main function is to drive and enhance the differential signal output by the encoder. In existing technology, the encoder's own driving capability is limited. When the signal needs to be transmitted over long distances (e.g., several meters or even tens of meters) or when driving multiple downstream devices simultaneously, the original signal is prone to amplitude attenuation and waveform distortion (e.g., slower rising / falling edges, pulse loss). The signal buffer circuit introduces a high-performance buffer chip—in this embodiment, a six-channel tri-state buffer chip of model SN74HCS367DR—to shape and amplify the input differential signal, thereby generating an enhanced signal with stronger driving capability. This buffer chip has six independent channels internally, capable of simultaneously processing the differential signals of phases A, B, and Z. To ensure continuous and stable signal transmission, the output enable pins of this buffer chip (e.g., pins 1OE# and 2OE#) are typically designed to be grounded, keeping them in a constantly enabled state. This design not only improves the signal carrying capacity, but also achieves electrical isolation between the encoder and the subsequent equipment to a certain extent, effectively reducing the impact of electromagnetic interference from the subsequent stage on the encoder.

[0026] In a further embodiment, a signal matching circuit is provided between the input pin of the signal buffer circuit and the encoder output pin, or between the output pin of the signal buffer circuit and the connector of the interface expansion circuit. The core of this circuit is a resistor network composed of several sets of resistors connected in series. The main function of this resistor is to achieve impedance matching of the signal, reducing signal reflection on the transmission line. Especially for high-frequency differential signals, impedance mismatch can cause reflected waves to superimpose with the original signal, severely degrading waveform quality and timing accuracy. Furthermore, this resistor network can be configured with replaceable 0Ω resistors. When the system encounters a transient overcurrent, overcurrent protection is provided by replacing or designing specific resistor values, thereby preventing excessive current from damaging the encoder output circuit or subsequent control circuits. In this embodiment, the buffer chip... like Figure 4 The diagram shows the interface expansion circuit in this device. The signal, amplified by the signal buffer circuit, enters the interface expansion circuit. The interface expansion circuit includes several sets of connectors; in this embodiment, there are three sets of industrial connectors: CN1, CN2, and CN3. Each connector has a standard pin specification, with up to 28 pins, including at least six sets of differential signal pins for A+, A-, B+, B-, Z+, Z- signals, two sets of power supply pins, and several auxiliary signal pins. The input terminals of these connectors are connected to the output pins of the signal buffer circuit, thereby expanding a single encoder input signal into multiple parallel outputs. For example, these three sets of connectors can be connected to the main controller, a redundant controller, and a monitoring terminal, respectively. This design allows multiple devices to simultaneously and synchronously acquire encoder feedback information, greatly improving the system's collaborative control, redundancy backup, and status monitoring capabilities, overcoming the limitations of traditional single-output encoders.

[0027] To ensure the stable operation of the entire feedback expansion conversion device, a power supply circuit is also integrated. This power supply circuit is responsible for providing a stable and reliable +5V operating power to the signal buffer circuit, encoder, and interface expansion circuit. The power supply circuit is typically designed in conjunction with a large power ground area on the PCB board to achieve low-noise grounding, thereby further improving the signal-to-noise ratio of signal transmission and the system's anti-interference capability.

[0028] Workflow: The shaft encoder generates multi-phase differential signals such as A+, B+, Z+, A-, B-, and Z-. These signals first undergo impedance matching or overcurrent protection through a signal matching circuit before being input to a signal buffer circuit. The buffer chip in the signal buffer circuit (e.g., SN74HCS367DR) receives these signals and amplifies them, generating enhanced signals with higher load capacity. These enhanced signals are then expanded into multiple outputs through connectors connected in parallel in the interface expansion circuit. Each output connector can transmit feedback signals to external control circuits such as the main controller, redundant controllers, and monitoring terminals. The entire process ensures that the encoder signals maintain high integrity, high reliability, and low distortion during long-distance transmission and multi-load distribution.

[0029] In automotive welding production lines or precision machine tools, the signal from a single encoder can be expanded into multiple parallel outputs through this device, which can then drive multiple robotic arm joints, positioning fixtures, or conveyor platforms. The enhanced drive capability, precise impedance matching, and multi-channel expansion capabilities provided by this device, combined with real-time buses such as EtherCAT, enable extremely high synchronization accuracy, significantly reducing the synchronization errors and failure rates associated with traditional branching solutions.

[0030] In high-temperature areas of steel plants or remote monitoring scenarios involving large equipment, the encoder and control center may be tens of meters apart. This device supports stable differential signal transmission over 10 meters, ensuring reliable transmission of encoder position data to the central control room. Simultaneously, the overcurrent protection provided by the replaceable resistor network in the signal matching circuit effectively improves the system's mean time between failures (MTBF) in harsh industrial environments.

[0031] By optimizing the wide voltage compatibility of the tri-state buffer, this device can flexibly adapt to encoders with different power supply voltages without the need for additional complex level conversion circuits. This modular design greatly simplifies equipment integration and maintenance, and reduces system costs. The overall modular design of this invention has passed rigorous electromagnetic compatibility certification and is suitable for applications such as medical equipment and aerospace where signal accuracy and reliability are extremely critical.

[0032] In this embodiment, in addition to the SN74HCS367DR six-channel tri-state buffer, other six-channel buffer chips with similar functions and performance parameters can also be selected, such as 74HC244 and CD4050. These alternative chips, through adjustments to the power supply voltage adaptability design, can still achieve the core logic of "six independent channel drive + always enabled", achieving the purpose of signal enhancement and electrical isolation. The only differences may lie in the specific chip model, pin definition, and package form.

[0033] In this invention, the signal buffer circuit is not limited to using a single six-channel buffer chip. Multiple sets of dual-channel or quad-channel buffer chips (such as two sets of 74HCT125) can be combined to achieve split driving of A / B / Z phase differential signals through circuit topology design. As long as the core architecture of "configurable resistor matching + multi-channel interface expansion" is retained, its function is equivalent to that of using a single-chip solution.

[0034] The industrial connectors used in the interface expansion module are not the only option. In certain specific applications, terminal blocks, PCB pads, or other custom connectors can be used instead of standard industrial connectors. By changing the physical form of signal access, as long as the signal buffer and matching module retains the tri-state drive and resistor network design, the invention's objective of one-input-multiple-output and impedance matching can still be achieved. These alternatives all provide flexibility to adapt to different design requirements, cost considerations, or specific application environments while maintaining the core functionality and beneficial effects of the invention.

[0035] The present invention also provides a feedback extended conversion method for an encoder, the method comprising the following steps: S1. The encoder outputs differential signals for phase A+, phase B+, phase Z+, phase A-, phase B-, and phase Z- respectively. The differential signals are input to the signal buffer circuit through impedance matching or overcurrent protection by the signal matching circuit. S2. The signal buffer circuit drives and enhances the input differential signal to generate an enhanced signal. The enhanced signal is transmitted to at least one external control circuit via the connector of the interface expansion circuit as a feedback signal.

[0036] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the present invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

[0037] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A feedback expansion conversion device for an encoder, wherein the output terminal of the encoder is connected to the feedback expansion conversion device, and the encoder outputs a differential signal, characterized in that, The feedback extension conversion device includes: A signal buffer circuit, the input of which is connected to the output of the encoder, drives and enhances the differential signal to generate an enhanced signal; The interface expansion circuit includes several sets of connectors, the input ends of which are respectively connected to the signal buffer circuit to expand the output of the enhanced signal.

2. The feedback extension conversion device for an encoder according to claim 1, characterized in that, The encoder output terminal has six sets of output pins, which can output differential signals of A+ phase, B+ phase, Z+ phase, A- phase, B- phase and Z- phase.

3. The feedback extension conversion device for an encoder according to claim 2, characterized in that, The feedback expansion conversion device further includes a signal matching circuit, which includes a resistor network connected in series between the input pin of the signal buffer circuit and the output pin of the encoder. The resistor network consists of several sets of resistors connected in series between the input pin of the signal buffer circuit and the output pin of the encoder for signal impedance matching or overcurrent protection.

4. The feedback extension conversion device for an encoder according to claim 3, characterized in that, The buffer circuit includes a buffer chip, which has six sets of input pins that are connected to the encoder output pins via the resistor network; the buffer chip also includes six sets of output pins that are connected to the input pins of the connector.

5. The feedback extension conversion device for an encoder according to claim 1, characterized in that, The connector is provided in three sets, and the output end of each set of connectors is connected to the main controller, the redundant controller and the monitoring terminal respectively.

6. The feedback extension conversion device for an encoder according to claim 4, characterized in that, The connector is a connector with a 28-pin specification, including at least six sets of differential signal pins, two sets of power supply pins, and several auxiliary signal pins. The six sets of differential signal pins are connected to the six sets of output pins of the buffer chip.

7. The feedback extension conversion device for an encoder according to claim 1, characterized in that, The feedback expansion conversion device also includes a power supply circuit, which provides a +5V operating power supply to the signal buffer circuit, encoder, and interface expansion circuit.

8. A feedback extension conversion device for an encoder according to claim 4, characterized in that, The buffer chip is a six-channel tri-state buffer chip of model SN74HCS367DR.

9. A feedback-extended conversion method for an encoder, characterized in that, The method includes the following steps: The encoder outputs differential signals for phase A+, phase B+, phase Z+, phase A-, phase B-, and phase Z- respectively. These differential signals are then input to the signal buffer circuit after impedance matching or overcurrent protection by a signal matching circuit. The signal buffer circuit drives and enhances the input differential signal to generate an enhanced signal. The enhanced signal is transmitted to at least one external control circuit via the connector of the interface expansion circuit as a feedback signal.

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