Robot Leg Assembly Single Servo Transmission Design

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Solution Overview

Problem

Conventional humanoid robots require multiple servos to achieve human-like rotational degrees of freedom, which increases cost and complexity.

Innovation Solution

A leg assembly design that uses only one servo to drive the thigh, lower leg, and foot through a combination of transmission mechanisms, including a first transmission mechanism for rotating the thigh, a second transmission mechanism for flexing and extending the lower leg, and a third transmission mechanism for dorsiflexing the foot, allowing for cyclic movement with reduced servo requirements.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If multiple servos are used to provide rotational degrees of freedom for humanoid robot legs, then the robot can achieve human-like movement capabilities, but the cost and device complexity increase

Engineering Contradiction:

Improvehuman-like movement capabilitiesVSAvoidnumber of servos

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent combines multiple transmission functions into a single integrated transmission assembly that uses one servo motor to simultaneously control the thigh rotation, lower leg flexion/extension, and foot dorsiflexion/plantarflexion through coupled transmission mechanisms, thereby reducing the number of servos from three to one while maintaining human-like movement capabilities

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The single servo motor is designed to perform multiple functions by driving different parts of the leg assembly through the transmission mechanisms - it can rotate the thigh, flex and extend the lower leg, and dorsiflex and plantarflex the foot, making one servo component serve the role of multiple specialized motors

Inventive Principle:

Principle #6Universality (Multi-functionality)

2Adaptability or versatility

If multiple servos are used to drive thigh, lower leg, and foot independently, then each joint achieves full rotational freedom, but the manufacturing cost increases

Engineering Contradiction:

Improverotational degrees of freedomVSAvoidmanufacturing cost

Core Design Contradiction:

Adaptability or versatilityVSEase of manufacture

Solution Approach 1:

The patent merges the driving functions for the thigh, lower leg, and foot into a single servo motor and integrated transmission assembly, reducing the component count from three separate motors to one servo motor, which directly reduces manufacturing cost while maintaining all necessary rotational degrees of freedom

Inventive Principle:

Principle #5Merging (Combining)

Data Source

PatentUS10836032B2Robot and leg assembly thereof

Publication Date: 2020.11.17 UBTECH ROBOTICS CORP LTD

AI summary

A leg assembly of a robot comprising a waist includes a thigh rotatably coupled to the waist, a lower leg rotatably coupled to the thigh, a foot rotatably coupled to the lower leg, a servo fixe to the thigh, a first transmission mechanism configured to transmit motion from the servo to the thigh to drive the thigh to rotate with respect to the waist; a second transmission mechanism configured to transmit motion from the thigh to the lower leg to drive the lower leg to flex when the thigh move upward and extend when the thigh move downward; and a third transmission mechanism configured rotatably connected to the thigh and the foot in such a way that the foot dorsiflexes from an original position when the lower leg is flexing and rotates back toward the original position when the lower leg is extending.