Motion Platform With Mecanum Feet For Large Translational Range
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Solution Overview
Problem
Existing motion simulators, such as those using the Stewart platform, face challenges in simulating asymmetric motion scenarios like those of a sports car, requiring large translational motions in multiple axes while maintaining high-frequency response and minimizing weight and payload, which is difficult due to the restricted translational range of actuator technology.
Innovation Solution
A motion system with multiple feet, each capable of independent movement and equipped with rotatable elements like Mecanum wheels or Omniwheels, allows for six degrees of freedom and high-frequency response by using a combination of revolute and spherical joints, and optionally, planar electric motors or air-dynamic mechanisms for enhanced adhesion and control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a Stewart platform is used to simulate asymmetric motion with large translational ranges, then the motion coverage is improved, but the platform size becomes unfeasibly large
Solution Approach 1:
The system divides the motion generation function into two independent segments: a mobile platform carrying the load that handles large translational motions, and a separate Stewart mechanism that handles rotational motions. This segmentation allows each component to be optimized independently, avoiding the need for an oversized Stewart platform to cover both translation and rotation.
Solution Approach 2:
The mobile platform acts as an intermediary between the fixed ground and the Stewart mechanism. It carries the Stewart mechanism and enables the entire assembly to move freely in the horizontal plane, thereby providing large translational range without requiring the Stewart platform itself to be large.
2Volume of moving object
If the base of a Stewart platform is mounted on orthogonal tracks to enable large translational motion, then the workspace is improved, but the frequency response deteriorates due to large mass
Solution Approach 1:
The system separates the functions of large workspace and high frequency response into different components. The mobile platform with small wheels provides large workspace with low mass for high frequency response, while the Stewart mechanism provides rotational motions. This segmentation avoids the mass-frequency response tradeoff.
Solution Approach 2:
The system replaces the traditional heavy rail or track mechanism with mobile platforms equipped with small wheels that roll on the floor. This substitution dramatically reduces the mass of the moving components while maintaining large translational capability, thereby improving frequency response.
3Length of moving object
If linear motors are used to generate large translational motions, then the translational range is improved, but the system weight increases reducing high-frequency response
Solution Approach 1:
The system replaces heavy linear motors with a mobile platform mechanism using small rolling wheels. This substitution achieves large translational range through the mobility of the platform rather than through powerful linear actuators, thereby minimizing system weight and maintaining high-frequency response capability.
4Speed
If a Stewart platform is designed for high-frequency response, then the dynamic performance is improved, but the translational range is restricted
Solution Approach 1:
The system segments the motion functions: the mobile platform handles large translational displacements with high frequency response due to its low mass, while the Stewart mechanism handles rotational motions. This segmentation allows each component to be optimized for its specific function without compromise.
Solution Approach 2:
The system adds the dimension of platform mobility to the traditional Stewart mechanism. By making the entire Stewart mechanism mobile rather than fixed, the system achieves large translational range in the horizontal plane without compromising the high-frequency response characteristics of the Stewart mechanism itself.
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
Enables large translational motions in multiple axes with reduced weight and payload, improving the frequency response and immersion in motion simulations by allowing the motion platform to move freely within a large, unconstrained space.
Implementation Method 1
Each foot may comprise: at least one rotatable element such as a wheel, roller or turbine that engages the stage
Implementation Method 2
Such a wheel is known as an Omniwheel
Implementation Method 3
Planar linear motors can move a load in X and Y directions over a surface
Implementation Method 4
one or more of the feet may be configured to draw air so as to increase friction between the or each rotatable element and the stage
Data Source
Figure 1
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AI summary
A motion system operable on a substantially flat stage for imposing motion on a motion platform, the motion device comprising a plurality of feet coupled to the motion platform and capable of moving freely in two dimensions across the stage so as to impose substantially arbitrary three-dimensional motion on the motion platform relative to the stage.