Micro Electro-Hydraulic Actuator With Distributed Pump for Robot Grasping

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Solution Overview

Problem

Current robot power systems, particularly in humanoid robots, face limitations due to poor impact resistance, low power density, and insufficient grasping force, mainly because of their rigid connection structures and centralized hydraulic power sources, which result in large volumes, heavy weights, and complex hardware, restricting their application in bionic and quadruped robots.

Innovation Solution

A micro electro-hydraulic linear actuator integrating a spherical pump, motor, and hydraulic piston with a modular design, acting as a distributed hydraulic source, is developed to provide power for the robot's dexterous hand, featuring a compact structure and high power density, eliminating the need for directional valves and complex oil pipelines, and enabling flexible finger movement and increased grasping force.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Force

If a centralized hydraulic power source is used to drive multiple actuators, then the driving force is improved, but the system volume and weight increase significantly

Engineering Contradiction:
Improvedriving forceVSAvoidsystem weight
Core Design Contradiction:
ForceVSWeight of stationary object

Solution Approach 1:

The patent divides the centralized hydraulic power source into multiple distributed micro electro-hydraulic actuators, each containing its own integrated pump and motor. This segmentation allows each actuator to be independently sized for specific applications, reducing overall system weight while maintaining sufficient driving force for each individual actuator.

Inventive Principle:
Principle #1Segmentation

2Force

If a centralized hydraulic power source with complex pipelines is used, then the driving force is improved, but the device complexity increases

Engineering Contradiction:
Improvedriving forceVSAvoidhardware pipeline complexity
Core Design Contradiction:
ForceVSDevice complexity

Solution Approach 1:

The patent merges the hydraulic pump, motor, control valve, and actuator into a single integrated micro electro-hydraulic unit. This consolidation eliminates the need for separate hydraulic pipelines, connectors, and control components, dramatically reducing device complexity while maintaining full hydraulic functionality for force generation.

Inventive Principle:
Principle #5Merging (Combining)

3Stability of the object's composition

If a motor scheme with rigid connection structure is used, then the system stability is improved, but the impact resistance deteriorates

Engineering Contradiction:
Improvesystem stabilityVSAvoidimpact resistance
Core Design Contradiction:
Stability of the object's compositionVSReliability

Solution Approach 1:

The patent replaces rigid mechanical connections with dynamic hydraulic coupling through the integrated electro-hydraulic actuator. The hydraulic fluid acts as a flexible transmission medium that can absorb impact forces while maintaining system stability, allowing the system to adapt dynamically to varying load conditions and impact events.

Inventive Principle:
Principle #15Dynamics

4Force

If the robot loads hydraulic components for increased grasping force, then the grasping force is improved, but the effective load capacity decreases due to increased weight

Engineering Contradiction:
Improvegrasping forceVSAvoideffective load capacity
Core Design Contradiction:
ForceVSWeight of moving object

Solution Approach 1:

The patent changes the key parameter of power density by integrating the pump and motor within the actuator housing, creating a compact unit with high power-to-weight ratio. This allows the system to achieve high grasping forces through optimized hydraulic parameters while minimizing the weight penalty, thereby preserving effective load capacity.

Inventive Principle:
Principle #35Parameter changes

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 enhances the robot's grasping force, flexibility, and impact resistance, reducing system volume and weight, while allowing for convenient control and mass production, making it suitable for various robotic applications.

Implementation Method 1

a spherical pump unit and a reciprocating piston mechanism; the reciprocating piston mechanism is provided in the hydraulic cylinder

Methodology Applied
Scientific EffectHydraulic pressure: Hydraulic Press

Implementation Method 2

the spherical pump unit comprising a spherical pump and a motor

Methodology Applied
Scientific EffectElectromagnetic conversion: Electromagnetic Induction

Data Source

PatentEP4039987B1Micro electro-hydraulic linear actuator and electro-hydraulic actuated robot dexterous hand
Publication Date: 2024.09.25 SHENZHEN SPHERICAL FLUID POWER TECH CO LTD
  • EP4039987B1 patent drawingFigure 1~2
  • EP4039987B1 patent drawingFigure 3
  • EP4039987B1 patent drawingFigure 4

AI summary

Disclosed are a micro electro-hydraulic linear actuator and a dexterous hand of an electro-hydraulic driving robot, comprising an actuator base, a spherical pump unit and a reciprocating piston mechanism encapsulated in a closed elastic leather bag. The actuator base is provided with a hydraulic cylinder and a cylinder liner, both of which are cylindrical chambers with an open at one end. An open end of the hydraulic cylinder is provided with an end cover of the hydraulic cylinder, an open end of the cylinder liner is provided with an end cover of the motor, the reciprocating piston mechanism is provided in the hydraulic cylinder, and the spherical pump and motor are integrated in the cylinder liner to form a spherical pump unit; the present application adopts a distributed hydraulic source as the driving force and does not need a directional valve.