The application of encoders in automated equipment.

The application of encoders in automated equipment focuses on “precise position and speed control”, achieving the automation and intelligent operation of equipment by converting mechanical motion into electrical signals. The following analysis covers typical areas such as industrial automation, logistics warehousing, and medical equipment, examining the application scenarios, technical characteristics, and development trends of encoders:     

The core application of encoders in industrial automation equipment

1.CNC machine tools and machining centres: The encoder is installed on the machine tool spindle or feed axis, providing real-time feedback on rotational angle and displacement to form a closed-loop control system. For example, an incremental encoder outputs 2000 pulses per rotation, and with a ballscrew pitch of 5mm, positioning accuracy of 0.0025mm can be achieved (5mm/2000 pulses=0.0025mm/pulse).

 Application example: In a vertical machining centre during milling of moulds, the absolute encoder at the end of the X-axis servo motor continuously outputs position signals. When the controller detects that the deviation between the actual position and the programmed setting exceeds 0.01mm, it automatically adjusts the motor speed to compensate for the error. Connection diagram of the machine tool spindle encoder to the servo system: The encoder (such as a 17-bit absolute type) is directly installed at the rear end of the spindle, rotating synchronously via a coupling. The Gray code signal output is processed by the driver, then compared with the PLC program commands (for example, ”Target position 30000 pulses, current 29995 pulses, need to compensate 5 pulses“).

2.Principle of joint positioning in industrial robots: Each robot joint is equipped with an encoder to measure the joint rotation angle, achieving precise positioning of the end effector. For example, the first joint of a 6-axis industrial robot uses a multi-turn absolute encoder that can record positions from 0 to 360° multiplied by 4096 turns, ensuring a repeat positioning accuracy of ≤±0.02mm. Application example: When a welding robot welds a car chassis, it controls the welding gun's movement along the weld seam trajectory through the coordinated feedback from each joint encoder. When a joint encoder detects an angular deviation (e.g., target angle 45°, actual 45.1°), the controller immediately adjusts the angle of adjacent joints to compensate for the error.

 Schematic diagram of the robot joint encoder installation: the output shaft of the harmonic reducer is connected coaxially with the encoder, the code disc rotates with the joint, and the photoelectric transmitter-receiver pair generates a pulse sequence (for example, 100 pulses output per 1°), which is transmitted to the controller via a differential circuit.

3.Automated production line conveying system: encoders monitor the speed and displacement of the conveyor belt, achieving material sorting and positioning docking. For example, on a courier sorting line, an incremental encoder is installed on the driven roller shaft, calculating the conveyor belt's running distance through pulse counting (e.g., roller diameter 0.5m, 1000 pulses per revolution, 1 pulse = π×0.5m/1000≈1.57mm). When the parcel reaches the designated sorting outlet, the system triggers the push plate action. Application example: In the biscuit sorting equipment of a food production line, the encoder monitors the conveyor belt speed in real-time. When a speed fluctuation is detected (e.g., from 2m/s to 1.8m/s), the system automatically adjusts the triggering time of the sorting push rod to avoid biscuit stacking errors.

 Conveyor belt encoder and sorting control logic: Encoder pulse frequency (e.g., 1000Hz corresponds to 2m/s) → PLC calculates current position (e.g., “10,000 pulses have been run = 15.7m”) → Outputs high-level signal upon reaching the sorting point coordinate (16m) to drive the cylinder to push the plate.

4.Tension control in packaging machinery: An encoder measures the rotation speed of the unwind and rewind rollers, maintaining constant tension in the packaging material through closed-loop control. For example, when the diameter of the unwind roller decreases, causing the speed to increase, the encoder feedback pulse frequency rises, and the system automatically increases the torque of the unwind motor to prevent material tearing (tension control accuracy ±5N). Application example: In the production process of a plastic bag making machine, the magnetic encoder at the end of the rewind roller shaft monitors the speed in real time. When changes in material thickness cause tension fluctuations, the encoder signal drives the servo motor to adjust the rewind speed, ensuring that the bag length error is ≤ ±1mm.

 Layout of the tension control encoder for the packaging machine: the unwind roller (encoder A) and the rewind roller (encoder B) monitor the rotational speed respectively, and the controller calculates the tension deviation based on the pulse difference between the two (e.g. A=1000rpm, B=1005rpm) and outputs a current signal (4~20mA) to adjust the brake torque.

The application of encoders in special automation equipment.

1.Logistics storage AGV (Automatic Guided Vehicle): Encoders combined with gyroscopes measure the driving wheel speed and steering angle of the AGV to achieve path tracking. For example, a differential drive AGV is equipped with an incremental encoder on each of its left and right wheels, calculating the turning radius through pulse differences (for instance, left wheel 1000 pulses, right wheel 800 pulses, turning radius = vehicle width × (1000 + 800) / (1000 - 800)).

Application example: The warehouse sorting AGV monitors the wheel speed in real-time during operation using encoders. When it detects ground slipping (a sudden decrease in pulse count), the system automatically reduces motor power and triggers an alarm to prevent cargo from toppling. 

2.Medical CT scanner rotation control: An absolute encoder is installed on the CT machine's rotation axis, precisely recording the angle position of the X-ray tube (with a resolution of 0.001°), ensuring the stitching accuracy of the tomographic images. For example, during a 360° scan, the encoder outputs a position signal every 0.1°, in conjunction with detector data to generate high-resolution images. 

3.Semiconductor wafer handling robotic arm: Utilises high-precision magnetic grid encoders (resolution 0.1μm) to measure the displacement of the robotic arm, avoiding electrostatic interference and dust contamination. For instance, during wafer handling, the encoder provides real-time feedback on the Z-axis lift height, controlling the distance between the suction cup and the wafer within the range of 0.5mm±0.01mm to prevent collision damage.

Encoder types and their compatibility characteristics with automated equipment.

Technical challenges and cutting-edge development trends.

1.Challenges of adaptability in industrial environments: high temperatures (such as metallurgical equipment >200℃) and strong electromagnetic interference (such as near inverters) may cause encoder signal distortion. Solutions: - Use high-temperature resistant encoders (such as those using ceramic code disks, operating temperature -50℃ to 250℃); - Use twisted shielded pair cables for differential encoding (such as RS422 interface), enhancing anti-interference capability by 80%.

2.High precision and miniaturisation demand trends. Multi-sensor fusion: integration of encoders with LiDAR and vision cameras to achieve 'position-environment' synchronous perception (for example, AGV correcting positioning errors through encoder visual identification); Chip-level encoders: MEMS technology integrates encoders into chips (size<1mm³) for micro-robot joint control; AI intelligent diagnosis:

encoders with built-in machine learning algorithms that analyse vibration and temperature data in real time to predict bearing wear (for example, remaining life warning error<5%).

SummaryThe encoder, as the “nerve ending” of automation equipment, provides critical feedback to industrial robots, CNC machine tools, and other devices through precise measurement of mechanical motion parameters. Its technological evolution (such as high precision, resistance to harsh environments, and intelligent functionality) directly drives automation towards “flexibility and unmanned operation” In high-end fields such as semiconductors and healthcare, the resolution and reliability of encoders have become core indicators of equipment performance, while in general industrial scenarios, low cost and ease of maintenance are key to large-scale applications.