Is "actuators used in humanoid robots" the same intent as "humanoid actuator"?
Yes for this site architecture. The phrase "actuators used in humanoid robots" asks which actuator roles, architectures, and validation evidence matter inside a humanoid. That is the same decision cluster as "humanoid actuator", so it is answered on this canonical page instead of a separate near-duplicate URL.
What actuators are used in humanoid robots?
Most modern humanoids combine rotary joint actuators for legs, waist, arms, and wrists with smaller hand actuators or tendon drives for fingers. The exact mix depends on torque density, backdrivability, brake strategy, cooling, and available package space.
Is one actuator family enough for a humanoid robot?
Usually no. Legs, arms, wrists, and hands face different torque, speed, impact, and contact requirements. A single-family choice can simplify sourcing but often creates mass, thermal, or force-control compromises.
What torque range should humanoid robot actuators target?
There is no universal range. Official Unitree references show smaller knee axes around 90-120 N.m on G1 and full-size leg-class peak torque around 360 N.m on H1/H2-class pages. Other OEMs often publish robot-level payload rather than joint torque, so continuous duty, speed, and cooling must be validated separately.
How does this canonical page cover "actuators used in humanoid robots"?
It answers the phrase as a planning workflow, not a duplicate glossary page: first map leg, waist, arm, wrist, and hand actuator roles, then compare QDD, compact geared, series elastic, linear, and hand-actuator paths with evidence and RFQ gates.
When should we choose quasi-direct drive?
Choose it when torque transparency, impact tolerance, and force-control behavior are more important than the smallest possible package. It still needs thermal and brake validation.
When is a compact geared actuator better?
It is often better for compact holding axes, wrists, elbows, and waist modules where static torque and package size dominate. The tradeoff is lower transparency and higher need for shock/backlash evidence.
Do humanoid robots need series elastic actuators?
Not always. Series elasticity helps with compliance, shock absorption, and force sensing, but it adds package length, resonance management, and spring fatigue validation.
Can public robot specs be used for final actuator selection?
No. Public specs are useful benchmarks, but they rarely disclose continuous torque, thermal boundary, lifecycle test setup, or exact safety case. Use them to frame RFQ questions, then require supplier evidence.
What should be included in an actuator RFQ?
Include robot mass, payload, joint axes, duty cycle, target torque/speed, package envelope, cooling assumptions, brake behavior, control interface, validation tests, quantity, destination, and timeline.
How should safety be handled for humanoid actuators?
Treat safety as robot and application-level work. Actuator selection must support braking, stops, force limiting, and contact measurement, but standards and risk assessment apply to the integrated machine and task.
What if our result is inconclusive?
Send the computed inputs with your CAD envelope and intended motion cases. The minimum next path is a dual-track RFQ: one catalog-like joint route and one custom architecture route with explicit validation gaps.
Can Humanoid Joint support a custom actuator stack?
Yes. The fastest path is to share joint-by-joint torque/speed targets, duty cycles, package constraints, and expected prototype quantity so feasibility feedback can be specific.
Why do some humanoid robots use linear actuators instead of all rotary actuators?
Linear actuators can fit along limb links and turn high motor speed into high axial force, which is useful for knees, ankles, or other high-load axes. Public Apptronik/TI material confirms custom linear and rotary actuator work, but exact joint placement and ratings should be treated as supplier-confirmation items unless they appear in a formal specification.
Why are leading humanoid manufacturers shifting to custom-designed motors?
Leading humanoid programs often need custom actuator packages because each joint has a different torque-speed, envelope, cooling, brake, and cable-routing problem. Apptronik/TI references custom actuator development, while other OEM public pages often stop at robot-level payload or system statements. Exact motor constants and continuous ratings still need RFQ evidence.
How does internal cabling affect actuator design?
With dozens of powered axes, exposed cables can become wear, snagging, and maintenance risks. Internal or protected routing can help, but it affects hollow-shaft geometry, bearing selection, connector access, bend radius, serviceability, and actuator housing design.
What cooling strategies are used for humanoid actuators?
Humanoid joints operate in compact, sealed environments. Passively cooled configurations rely on high thermal conductivity pathways to the outer aluminum chassis. High-performance or high-duty-cycle setups may utilize active air routing, liquid cooling channels, or phase-change thermal interface materials to prevent winding overheating.
