What is a robot actuator?
An actuator is the 'muscle' of a robot: a motor plus transmission (gears, reducers or screws) that turns electrical energy into controlled motion at a joint.
Updated:
Definition
An actuator converts energy into motion. In robots it is usually an electric motor with a transmission (reducer, harmonic drive, ball or roller screw), plus encoders and drive electronics.
Types
- Rotary actuators for joints such as shoulders and elbows.
- Linear actuators (often roller screws) for legs and some arm joints.
Why it matters
Actuator supply chains are scaling fast. Thailand's 2026 humanoid parts hub is built around roller screws and actuators. See humanoid robot.
Frequently asked questions
What is a planetary roller screw?
A high-precision mechanism that converts rotation into linear motion with high load capacity, used in linear actuators of humanoids.
What is an RV reducer?
A compact, high-torque gear reducer common in industrial robot joints; large ones are critical for heavy-payload arms.
Why are actuators important for humanoid costs?
A humanoid needs dozens of them, and precision transmission parts are among its most expensive components.
Coverage
Thailand approves a 10-billion-baht hub for humanoid robot parts
Thailand's Board of Investment approved five Chinese companies to make roller screws, actuators and structural parts for humanoids in the Eastern Economic Corridor, naming Tesla's Optimus as a target market.
Astribot raises ~$149M as cable-driven humanoids hit a $2.1B valuation
Shenzhen's Astribot closed an RMB 1 billion round at about RMB 15 billion valuation — its fourth raise in six months — to scale cable-driven S1 and T1 robots.
Korea's bet on site-tailored robots: construction haulers, wall-climbing Spiders and pipe inspectors
While humanoids grab headlines, Kore, Didin and Kalman are shipping task-specific machines into construction sites, shipyards and nuclear plants — with Oct 2026 deployments already lined up.
Boston Dynamics gives Atlas a four-finger hand built for mass production
Atlas's new hand has 13 degrees of freedom, no pinkie and direct-drive joints designed for sim-to-real training, as Hyundai starts training Atlas in Georgia and Rohit Prasad becomes CEO.
Newsletter
Robrief Weekly
One email a week with the robotics news that matters. Free, unsubscribe anytime.