Hexapod Actuator Vibration Reduction via Linear Axis Substitution

Resolve Bottlenecks,
Find Innovative Solutions
Generate Solutions

Solution Overview

Problem

Existing hexapod actuators for flight and driving simulators are inflexible, expensive, and generate significant vibrations and noise, limiting adaptability and increasing costs due to fixed configurations, and require additional power sources for safety features like uninterrupted power supplies and shock absorbers.

Innovation Solution

A hexapod actuator with six legs, each with a ball joint at the upper end and a linear axis at the lower end, allowing independent inter-distance variation and different fixed lengths, which can be secured to a ground or ceiling support, using motorized guide rails or toothed belts to minimize vibrations and noise, and incorporating standard end-of-travel dampers for enhanced safety.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Force

If electric screw jacks are used for hexapod actuation, then the device can handle loads of less than fourteen tons, but vibrations and noise increase significantly

Engineering Contradiction:
Improveload capacityVSAvoidvibrations and noise
Core Design Contradiction:
ForceVSObject-generated harmful factors

Solution Approach 1:

The patent replaces traditional electric screw jacks with a novel actuation mechanism using linear axes with carriages that move along guide rails. This substitution eliminates the ball-screw mechanism that generates vibrations and noise, while maintaining the ability to handle loads under fourteen tons through direct linear motion actuation.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

2Force

If hydraulic cylinders are used for hexapod actuation, then loads greater than fourteen tons can be handled, but the device complexity and cost increase

Engineering Contradiction:
Improveload capacityVSAvoidsystem complexity
Core Design Contradiction:
ForceVSDevice complexity

Solution Approach 1:

The patent substitutes hydraulic cylinders with electrically-driven linear axis systems. This replacement maintains sufficient load capacity for applications under fourteen tons while dramatically reducing system complexity by eliminating hydraulic fluid systems, pumps, and associated safety infrastructure.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

3Length of moving object

If the stroke of a cylinder is changed in existing hexapod designs, then the position range is adjusted, but a new design and revalidation of the entire hexapod system is required

Engineering Contradiction:
Improvecylinder strokeVSAvoiddesign flexibility
Core Design Contradiction:
Length of moving objectVSEase of manufacture

Solution Approach 1:

The patent implements dynamic adjustability of the linear axes, allowing the stroke length to be modified without redesigning the entire hexapod structure. The linear axes with adjustable travel ranges enable flexible reconfiguration of the hexapod's working envelope, maintaining geometric validity while adapting to different application requirements.

Inventive Principle:
Principle #15Dynamics

4Reliability

If standard shock absorbers are integrated into existing hexapod designs, then safety in case of control failure is improved, but the cost increases significantly due to specific design and certification requirements

Engineering Contradiction:
ImprovesafetyVSAvoidcost
Core Design Contradiction:
ReliabilityVSEase of manufacture

Solution Approach 1:

The patent incorporates shock-absorbing elements at the extremities of the linear axes that provide passive safety cushioning. These elements are designed to absorb impact energy in case of uncontrolled motion or power failure, returning the mobile platform to a stable horizontal position without requiring expensive specialized shock absorbers or additional backup power sources.

Inventive Principle:
Principle #11Beforehand cushioning (Prior cushioning)

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 reduces production costs, enhances the reliability and efficiency of simulator mobilization systems, minimizes vibrations and noise, and simplifies safety certifications by allowing flexible geometry adaptations and using commercially available components.

Implementation Method 1

The upper end of each of the six legs is mounted on a ball joint having three degrees of rotational freedom

Methodology Applied
Scientific EffectBall joint: Ball

Implementation Method 2

The lower end of each of the six legs is movable along a corresponding linear axis

Methodology Applied
Scientific EffectLinear constraint: Axle

Implementation Method 3

each first end of each leg resting on a carriage guided on one of the rails, the carriage being driven by a motor meshing on a rack

Methodology Applied
Scientific EffectRack and pinion: Rack and Pinion

Data Source

PatentEP2407954B1Hexapod actuator device
Publication Date: 2018.06.27 THALES SA
  • EP2407954B1 patent drawingFigure 1~2
  • EP2407954B1 patent drawingFigure 2bis
  • EP2407954B1 patent drawingFigure 3~4

AI summary

The device (20) has six legs (21-26) respectively comprising lower ends (212-262) movable in translation along straight segments (210-260). The straight segments are coplanar or inclined with respect to ground, and formed by rails. Each straight segment has an end and another end whose projections on a plane of a flat support belong to a ring (201). Upper ends of the legs are mounted on balls (211-261), respectively. Each ball has three degrees of freedom in rotation, and is firmly connected with a mobile platform (203). The legs are moved by a linear electromagnetic motor.