Humanoid robots require different joint characteristics across the shoulder, elbow, wrist, hip, knee, and ankle. Smaller joints prioritize low weight and fast response, while larger joints require higher torque density, load capacity, and reliability. A suitable robot joint module should therefore be matched to the specific torque, weight, range of motion, and control requirements of each joint. In this article, HONPINE uses the HPJM harmonic joint module series as an example to present a joint configuration solution for humanoid robot upper and lower limbs, covering torque requirements from small wrist and finger joints to high-load hip joints.

A hollow robot joint module provides an internal passage for power cables, signal lines, pneumatic tubes, and other end-effector connections. Compared with external cable routing, a hollow joint module can help reduce cable exposure, improve system integration, and create a cleaner motion path for robotic arms. This article explains why internal cable routing matters in robotic joints and what to consider when selecting a hollow joint module for robotic applications.

The humanoid robot waist joint is one of the most demanding motion joints in a humanoid robot. Unlike conventional robotic arm joints, it supports the upper body while handling bending, twisting, posture transitions, and continuously changing dynamic loads. At the same time, the limited internal space must accommodate power cables, signal lines, sensors, and structural components. These requirements make a large-bore harmonic joint actuator an important option for humanoid robot waist joints. This article explains how to select a suitable harmonic joint actuator by considering hollow bore size, dynamic torque, reduction ratio, mechanical rigidity, integration, and service life.

Selecting a robot joint actuator is not simply a matter of matching motor torque or achieving a suitable inertia ratio. In a real robotic system, reduction ratio, load spectrum, thermal performance, mechanical stiffness, transmission nonlinearity, encoder architecture, control bandwidth, and service life all interact to determine the final result. A joint may meet its peak torque requirement and still experience vibration, overheating, positioning errors, or premature wear in real operation. This article examines the engineering logic behind robot joint actuator selection and explains why moving from single-parameter matching to system-level optimization can lead to more reliable and predictable robotic joint performance.