Key Findings
KNR System has developed a high-torque QDD actuator specifically optimized for the lower-body joints of humanoid and quadruped robots. The actuator features a compact design with a diameter of 110mm and a height of 83mm, weighing 1.76kg. Despite its size, it delivers a rated torque of 121Nm and a peak torque of 308Nm.
Technical Details
To overcome the traditional trade-off between stiffness and backdrivability, KNR System implemented a Bi-Lateral Gear Drive (BGD) utilizing a compound planetary gear structure. This technical approach allows the actuator to maintain high backdrivability—essential for reacting to external shocks and navigating rough terrain—while providing the stiffness required for high-load operations.
- Design: Ultra-thin profile reducing axial thickness compared to conventional planetary gears.
- Performance: Achieves a gear reduction ratio 2 to 4 times higher than existing QDD actuators.
- Torque Capacity: The 308Nm peak torque is equivalent to a rotational force where a weight of 31.4kg is applied to the end of a 1-meter rod.
Background and Context
Standard QDD actuators typically employ low gear ratios to ensure shock absorption and backdrivability. However, this often leads to increased volume and heat generation when applied to hip, knee, or ankle joints due to the limitations of motor torque amplification. KNR System’s BGD technology resolves these constraints by allowing higher reduction ratios without sacrificing the ability to respond flexibly to external forces.
Significance and Outlook
KNR System is leveraging its existing expertise in hydraulic actuators—including a 1600Nm hybrid actuator—to expand its portfolio. The company is the only firm globally to have developed robot-specific hydraulic, electric, and hybrid actuators. KNR System plans to introduce additional electric actuators to establish a comprehensive “robot actuator full lineup” by 2027.
Source: https://www.livebiz.today/news/articleView.html?idxno=206186
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