Integrated Robot Actuator Layout for Reduced Axial Length

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Solution Overview

Problem

Existing actuators for robots are too large in axial length, making them unsuitable for commercial applications where space is limited, due to the separate design of motors, motor drivers, and reducers, which hinders miniaturization and compactness.

Innovation Solution

An integral actuator design with a motor, position encoder, and reducer, where the motor rotor is rotatably connected to the housing, covering the motor stator, and the motor driver is externally connected, allowing for a compact, flat, and high-torque density structure with reduced axial length.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If the motor, motor driver and reducer are separately designed with the motor having an inner rotor, then the actuator can achieve functional separation and ease of manufacture, but the axial length becomes very great

Engineering Contradiction:
Improvefunctional separationVSAvoidaxial length
Core Design Contradiction:
Ease of manufactureVSLength of moving object

Solution Approach 1:

The patent merges the motor driver with the motor assembly, integrating the control electronics directly into the motor structure. This eliminates the need for separate mounting space for the motor driver, thereby reducing the overall axial length while maintaining functional separation for manufacturing purposes

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The patent transitions from an inner rotor configuration to an outer rotor configuration, fundamentally changing the spatial arrangement of motor components. This dimensional reorganization allows the motor driver to be mounted on the housing rather than requiring axial space, thus reducing axial length while preserving manufacturing flexibility

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

2Device complexity

If the motor is designed with an inner rotor configuration, then the motor structure is simplified, but the axial length increases which affects miniaturization of the entire robot

Engineering Contradiction:
Improvemotor structureVSAvoidrobot volume
Core Design Contradiction:
Device complexityVSVolume of moving object

Solution Approach 1:

The patent inverts the traditional motor rotor configuration by using an outer rotor design instead of an inner rotor. This inversion places the rotor outside the stator, which fundamentally changes the spatial distribution of magnetic fields and allows for a more compact axial profile, enabling robot miniaturization while maintaining structural simplicity

Inventive Principle:
Principle #13The other way round (Inversion)

3Power

If the actuator is designed for industrial production with separate components, then the functionality is optimized for high-strength work, but the actuator occupies more space making it unsuitable for commercial applications

Engineering Contradiction:
Improvehigh-strength work capabilityVSAvoidoccupied space
Core Design Contradiction:
PowerVSArea of stationary object

Solution Approach 1:

The patent combines the motor driver circuit board with the motor housing, integrating control functions directly into the actuator assembly. This merger eliminates the need for separate mounting space for the driver, reducing the occupied area while preserving the high-strength work capability through maintained functional integrity

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The patent designs the housing to serve multiple functions: it provides structural support, houses the motor components, and mounts the motor driver circuit board. This multi-functionality allows the actuator to maintain industrial-grade power output while occupying less space, making it suitable for both industrial and commercial applications

Inventive Principle:
Principle #6Universality (Multi-functionality)

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

The solution results in a compact actuator with high torque density, moderate speed, easy installation, precise control, and intelligent load sensing, suitable for commercial applications by reducing the axial length and volume while maintaining high performance.

Implementation Method 1

a motor, including a housing, a motor stator and a motor rotor, wherein the motor stator is disposed to the housing, the motor rotor is rotatably connected to the housing

Methodology Applied
Scientific EffectElectromagnetic induction: Electromagnetic Induction

Data Source

PatentEP3530414B1Actuator, robot arm and robot
Publication Date: 2023.11.29 CLOUDMINDS SHENZHEN HLDG CO LTD
  • EP3530414B1 patent drawingFigure 1
  • EP3530414B1 patent drawingFigure 2
  • EP3530414B1 patent drawingFigure 3~4

AI summary

An actuator, a robot arm and a robot are disclosed. The actuator includes: a motor, including a housing, a motor stator and a motor rotor, wherein the motor stator is disposed to the housing, the motor rotor is rotatably connected to the housing, and the motor rotor covers the motor stator; a position encoder, disposed to the motor rotor; a reducer, connected to the motor rotor, and configured to adjust a rotation speed output from the motor rotor; and a motor driver, disposed on the housing, and electrically connected to the motor. According to embodiments of the present disclosure, integral design of the actuator may be practiced, and the actuator has an smaller length in an axial direction and is flatter.