High-performance quasi-direct-drive (QDD) motors and integrated modules, including 105Nm configurations, designed for legged robotics, humanoids, and active force control.
Adjust target joint requirements below to estimate reflected inertia, gear ratios, and matched actuator models.
The 105nm integrated quasi-direct drive motor module features a lightweight 9:1 planetary reducer nested within the rotor core. This design optimizes coaxial space and heat dissipation.
A dynamic robot designer must determine when to buy standard catalog modules versus committing to winding customization.
A 105Nm QDD module can deliver its peak torque during high-impact jumps, but will thermal-trip if continuous static holding exceeds 35Nm for more than 4 minutes.
Ratio choice controls torque transparency. The 9:1 ratio has a reflected inertia of 0.0486 kg·m², which allows high-bandwidth current-loop force control without direct load-side torque sensors.
Running 48VDC on 105Nm windings ensures peak speeds of 24 rad/s under load. Running at 24VDC limits top speed and introduces back-EMF saturation early in gaits.
How QDD modules (105Nm class) compare with high-ratio Harmonic Drive and Series Elastic Actuator (SEA) systems.
| Parameter | QDD Motor Module (105Nm target) | Harmonic Drive Actuator | Series Elastic Actuator (SEA) |
|---|---|---|---|
| Reduction Ratio | Low (6:1 - 10:1) | High (50:1 - 160:1) | Medium (30:1 - 80:1) + Spring |
| Backdrivability (Hand-driven) | < 0.8 Nm (Excellent) | Non-backdrivable / > 12 Nm | Compliance backdrive |
| Reflected Rotor Inertia | Very Low (0.03 - 0.05 kg·m²) | Very High (5.0 - 15.0 kg·m²) | Filtered by spring elasticity |
| Torque Control Loop Bandwidth | High (50 - 150 Hz via FOC current) | Low (< 10 Hz, needs strain gauges) | Medium (15 - 40 Hz, spring-limited) |
| Shock / Collision Tolerance | High (Gears backdrive to absorb energy) | Fragile (Flexspline teeth shear) | High (Spring deflection absorbs shock) |
| Mechanical Backlash / Stiffness | 3 - 6 arcmin / Medium stiffness | < 0.5 arcmin / High stiffness | High backlash / Physical low stiffness |
Reflected inertia is calculated by multiplying the motor rotor inertia by the square of the gear ratio. In traditional high-ratio harmonic systems, a 100:1 ratio multiplies rotor inertia by 10,000. Under high-speed collisions, this inertia causes high destructive forces before the controller can react. In a 9:1 QDD system, the multiplier is only 81, allowing the output shaft to rotate backward and safely absorb impact.
Yes. Because QDD gearboxes have high efficiency (90%+) and low friction, the motor-side current (measured via FOC shunt resistors) has a highly linear relationship with the output torque. Current-based torque estimation is sufficient for walking robots, saving weight, cost, and cabling complexity.
Include these parameters in your inquiry to accelerate quotation and engineering review:
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