I. Drive Motors
| Type | Characteristics | Applications |
|---|---|---|
| Servo motor | AC permanent magnet synchronous motor, closed-loop control, 23-bit encoder, torque density 30N·m/kg | Mainstream industrial choice |
| Stepper motor | Low cost, controlled by pulse signals, risk of step loss | Low-cost solution |
| RC servo | DC motor + reduction gear set, positioning accuracy ±1° | Entry-level |
| Dedicated joint module | Integrated motor, harmonic reducer, dual encoder, torque sensor, accuracy ±0.01° | High-end solution |
II. Reducers
Type Comparison
| Type | Characteristics | Transmission Efficiency | Accuracy |
|---|---|---|---|
| Harmonic reducer | Rigid wheel + flexspline + wave generator, backlash <1 arcmin | 60-90% | ±5µm |
| RV reducer | Two-stage reduction, higher torque capacity | - | Long life 20,000h |
| Planetary gear reducer | Lower cost, compact structure | - | Has backlash |
| Synchronous belt transmission | No metal contact, completely no backlash | - | Vibration reduction, noise reduction |
Harmonic Reducer
- Typical reduction ratio: 30:1 to 320:1
- Repeat positioning accuracy: ±5µm
III. Mechanical Structure and Materials
Material Selection
- Carbon fiber composite: density only 1/5 of steel
- 7075 aerospace aluminum alloy
- Titanium alloy
Accuracy Levels
| Type | Repeat Positioning Accuracy |
|---|---|
| Industrial grade | ±0.02mm |
| Collaborative | ±0.1mm |
| DIY | ±1mm |
Bearing System
- Crossed roller bearings
- Harmonic reducer integrated precision bearings
- Magnetic levitation bearings
IV. Sensors
Sensor Types
| Type | Equipment | Description |
|---|---|---|
| Position sensor | Incremental/absolute encoder | 17-bit can achieve 0.0027° resolution |
| Force/torque sensor | 6-axis sensor | Safety protection threshold <150N |
| Vision sensor | 2D camera, 3D depth camera, laser scanner | - |
| Auxiliary sensor | IMU, temperature sensor, collision detection | - |
V. Controllers and Drive Circuits
System Architecture
Layered design:
- Task planning layer
- Motion control layer
- Servo drive layer
Industrial-grade Controllers
- Typical control cycle: 0.5-2ms
- Position control accuracy: better than ±0.1mm
Communication Protocols
- EtherCAT
- Profinet
- CANopen
Open Source Solutions
- Arduino, Raspberry Pi, STM32, with ROS system
VI. End Effectors
Types
- Mechanical grippers: two-finger parallel grippers, three-finger grippers, pneumatic/electric/hydraulic drive
- Vacuum cups: vacuum generator + cup + sensor
- Welding guns: spot welding gun, arc welding gun, laser welding head
- Mounting standard: ISO 9409 standard flange