The following is an analysis of the technical path for automatic doors to achieve precise control, combining sensor fusion, closed-loop algorithms and electromechanical collaborative design:
I. Multi-sensor fusion positioning
1. Target detection layer
- Microwave radar (24GHz frequency band): detection distance 10m, dynamic capture of moving object speed (accuracy ±0.1m/s) and azimuth (resolution 0.5°), to achieve predictive start
- TOF laser sensor: measure target distance through flight time, accuracy of ±2mm, compensate for radar's close-range blind spot
- Pressure sensing mat: detect static obstacles within 0.5m² of the door area, pressure trigger threshold ≤10kg
2. Door positioning layer
- Magnetic encoder: embed magnetic scale in the door track, cooperate with Hall sensor to achieve 0.05mm level real-time position feedback
- Photoelectric switch: set reference point at fully open/closed position to eliminate encoder cumulative error
II. Closed-loop control algorithm
1. PID dynamic adjustment
- Proportional term (P): adjust the motor speed in real time according to the position deviation, with a response time of ≤50ms
- Integral term (I): eliminate the steady-state error caused by track friction (such as 0.5° deviation caused by wind pressure)
- Differential term (D): predict the risk of inertial overshoot and decelerate in advance (acceleration control accuracy reaches 0.01m/s²)
2. Motion trajectory optimization
- S-curve planning: divide the door movement into 7 speed changes (acceleration → uniform speed → deceleration), and the impact force is reduced by 60%
- Load adaptation: monitor the motor torque through the current loop and automatically compensate for abnormal resistance such as heavy snow pressing the door
III. High-precision drive system
1. Servo motor
- Permanent magnet synchronous motor with 17-bit absolute encoder, angular position resolution of 0.0015°, supports 0.01mm micro-step control
- Equipped with a planetary gearbox (reduction ratio 30:1), converting the motor speed into a door linear speed of 0.1-1.2m/s
2. Transmission mechanism optimization
- Synchronous belt drive: pre-tensioning structure ensures transmission error <0.1mm, life of 1 million cycles
- Linear guide: V-type roller guide system controls the running yaw angle within ±0.1°
IV. Real-time safety feedback mechanism
1. Infrared light curtain array
- 64 infrared rays (wavelength 950nm) are arranged on both sides of the door frame, the minimum detection object diameter is 5mm, and the response time is ≤0.3 seconds
- Trigger the reversal program after encountering an obstacle: retreat 15cm at a deceleration of 0.2m/s² to prevent secondary collision
2. Torque limiter
- When the drive current exceeds the threshold (such as 12A), the power supply is automatically cut off and the mechanical brake is activated to protect the motor and transmission structure
V. Intelligent prediction and learning
1. Frequency of use learning
Statistics on the traffic volume during peak hours every day (such as 8:00-9:30 in the morning of office buildings), and adjust the door opening speed and waiting time in advance
2. Fault prediction model
Vibration sensors monitor the characteristic frequency of gear wear and provide 200-hour advance warning of maintenance needs
