Compact Precision Drives for Humanoid Robots - Backlash-free strain wave gears and actuators from Nabtesco

Humanoid robots must stand securely, react dynamically to their environment, and perform a wide variety of tasks with precision. The gearboxes in the joints play a key role in this. There is a demand for drive systems that combine high power density, a small footprint, and intelligent functions for capturing gear, application, and status information.

Backlash-free strain wave gears and actuators for humanoid robots

Nabtesco’s strain wave gears and actuators are suitable for various joints in humanoid robots, particularly the shoulders, elbows, hips, and legs. Different levels of integration offer flexibility in design and allow for system integration tailored to specific needs. These drive solutions operate with zero backlash, offer high reduction ratios in a compact design, and are characterized by high rigidity, low transmission errors, and a slight increase in driving torque during reverse operation. This enables precise and sensitive movements with low power loss, supports the stable maintenance of joint positions, and reduces control requirements.

High power density in a compact space

In humanoid joints in particular, every millimeter of installation space counts. Actuators combine a strain wave gear, motor, and other components into a single compact unit, thereby simplifying design and integration. Hollow shafts also allow for space-saving routing of cables and components. For particularly compact drive designs, Nabtesco offers short gears that deliver 20% more torque and a 40% longer service life compared to strain wave gears of the same size.

Digital Functions Directly in the Gearbox

The digital strain wave gear expands backlash-free gearbox technology to include sensors, analytics, and digital functions integrated without affecting installation space. Position, torque, temperature, and vibration can be measured directly within the drive; meta-data and analytical data are also available. This allows the robot to better account for loads and external influences and execute its movements in a manner more suited to the situation.

The introduction of additional functions is planned for the future: Gear Boosters, for example, enable dynamic adjustment of the load limit, allowing the gearbox to be operated beyond its rated values when necessary. Using Anomaly Detection, the gearbox checks for signs of wear or damage based on AI-driven models and summarizes the results in a condition index. Furthermore, Overload Detection identifies and logs overload events, triggers alarms in the event of overloads, and statistically evaluates the load.

Advantages Over Planetary Gears

Planetary gears are frequently used in humanoid robots. They are usually less expensive to purchase but require additional design or control measures when high precision is required. Strain wave gears offer advantages in terms of precision, zero backlash, control complexity, energy efficiency, and installation space. Because they require less re-adjustment, energy can be used more efficiently, which contributes to longer operating times. Even at high reduction ratios, strain wave gears require less installation space, whereas planetary gears often require multiple stages to achieve the same reduction.

Cost-Effective Scaling for High-Volume Production

For manufacturers of humanoid robots, mass-production capability is just as crucial as technical performance. Nabtesco possesses extensive development and mass-production expertise from the automotive industry and supports manufacturers in design, integration, and scaling—even for high production volumes. The IATF-certified production of strain wave gears in Germany stands for high quality standards in industrial mass production.