Application / Humanoid Robotics

Joint actuator supply for humanoid OEMs.

A full-size humanoid needs 20–40 actuators, knee to shoulder. Every joint has different torque and bandwidth requirements. Tendonkindle supplies all three TK models with published torque-density specs, backdrivability curves, and ROS 2 firmware included.

Request Engineering Sample View Actuator Specs
Humanoid robot leg joint assembly with compact actuator modules visible at knee and ankle
42 Nm/kg
Peak torque density (TK-240)
0.08 Nm
Cogging torque RMS
19-bit
Encoder resolution
400 Hz
FOC control bandwidth

Joint Mapping

Which model for which joint

Torque requirements vary 5:1 between a finger joint and a hip actuator. We designed three models so every joint in your design can be matched to the right spec without over-buying.

Wrist / Elbow / Ankle

TK-120 — 18 Nm continuous

120mm OD. Lowest mass at 0.43 kg. Ideal for distal joints with high-cycle but lower torque requirements. Backdrivability spec: 1.8 Nm reflected backdrive torque.

Elbow, wrist, ankle — < 20 Nm requirement
6-DOF arm, 3 TK-120 units per arm
TK-120 Specs

Shoulder / Knee

TK-240 — 42 Nm continuous

240mm OD. 42 Nm/kg peak torque density. The most popular model for full-size humanoid shoulder and knee joints. Peak torque: 105 Nm.

Shoulder, knee, hip abduction — 20–60 Nm
Most common bipedal locomotion joint
TK-240 Specs

Hip / Lumbar / Load-bearing

TK-480 — 95 Nm continuous

IP67 sealed, EtherCAT-native, industrial grade. Peak 220 Nm. For load-bearing hip flexion and lumbar rotation joints that must handle payload-plus-bodyweight torques during locomotion on uneven terrain.

Hip flexion, lumbar — > 80 Nm requirement
IP67 for outdoor / industrial environments
TK-480 Specs

Supply chain approach

Single-vendor actuator supply

All three TK models run identical firmware. Same ROS 2 package, same EtherCAT profile, same impedance control API. One firmware update propagates to every joint in the robot. One engineering sample program, one NDA.

Uniform firmware across all joint sizes
Volume pricing for 50+ unit evaluation orders
Talk to Engineering

What we are not: Tendonkindle is not a drop-in replacement for a general industrial servo arm. We do not make single-axis rotary stages, SCARA arms, or delta robots. We design specifically for applications requiring high torque density in a compact package — humanoid joints, exoskeleton frames, and dexterous manipulation — where backdrivability and sub-millisecond torque bandwidth are required by the control architecture, not optional.

Building a humanoid? Let's talk joint specs.

We'll send you a mapping table for your DOF count, torque requirements, and estimated power budget — no NDA required for initial scoping.

Request Engineering Sample