The Actuator Zoo
Vetted specifications for the joints, gearboxes, and motors behind the physical AI examples
The Actuator Zoo lists every entry in the mlsysim.Actuators registry: strain-wave (harmonic) joints, quasi-direct-drive modules, servos, frameless motors, and wheel hub motors. Each value carries units and a provenance record.
Use these actuators to reason about reflected inertia, torque limits, and how fast a joint responds to a command. Load any actuator directly in Python, for example joint = mlsysim.Actuators.PandaClassJoint.CSG_25_50_ILM70x18.
Joints
| Actuator | Family | Gear ratio | Rated torque | Peak torque | Reflected inertia | Mass |
|---|---|---|---|---|---|---|
| Harmonic Drive CSG-17-50 | Strain-wave (harmonic) joints | 50:1 | 21.0 N·m | 54.0 N·m | 0.0475 kg·m² | 0.68 kg |
| Harmonic Drive CSG-20-100 | Strain-wave (harmonic) joints | 100:1 | 40.0 N·m | 107.0 N·m | 0.3800 kg·m² | 0.98 kg |
| Harmonic Drive CSG-25-50 | Strain-wave (harmonic) joints | 50:1 | 51.0 N·m | 127.0 N·m | 0.2500 kg·m² | 1.50 kg |
| CSG-25-50-2UH strain-wave joint with TQ-RoboDrive ILM 70x18 | Panda-class integrated joints | 50:1 | 51.0 N·m | 127.0 N·m | 0.1835 kg·m² | 1.83 kg |
| T-Motor AK80-9 | Quasi-direct-drive modules | 9:1 | 9.0 N·m | 18.0 N·m | 0.0065 kg·m² | 0.48 kg |
| Unitree M107 | Quasi-direct-drive modules | 10:1 | 120.0 N·m | 360.0 N·m | 0.0120 kg·m² | 1.90 kg |
| Dynamixel XM430-W350 | Servos | 353.5:1 | 3.0 N·m | 4.1 N·m | — | 0.08 kg |
Motors
| Actuator | Type | Key specifications |
|---|---|---|
| TQ-RoboDrive ILM 70x18 (star-serial) | Frameless motor | rated voltage: 48.0 V; rated torque: 1.2 N·m; peak torque: 4.0 N·m; rated current: 6.7 A |
| ZLTECH ZLLG10ASM800-48 10-inch hub servo motor | Wheel hub motor | rated voltage: 48.0 V; wheel diameter: 266.0 mm; rated torque: 20.0 N·m; peak torque: 60.0 N·m |
Where these numbers are used
Reflected inertia grows with the square of the gear ratio, so the same motor reflects about 31 times as much rotor inertia behind a 50:1 strain-wave gear as behind a 9:1 quasi-direct-drive stage. The Volume IV planning and enforcement chapters use these entries for torque-jump and stopping budgets. The underlying formulas are in physics.robotics.actuation.