Motion Platform Linkage Spherical Joint Yaw Torsion
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Solution Overview
Problem
Existing motion platforms with three degrees of freedom are inefficient in terms of stiffness per unit mass when subjected to yaw torques, leading to distortion and reduced positional accuracy due to torsion in crank and wishbone members, which increases mass and cost when attempting to mitigate these issues.
Innovation Solution
A motion platform apparatus with linkages comprising spherical and revolute joints, including a first linkage with a fork structure and an actuator system that allows independent control of roll, pitch, and heave movements, reducing the need for supplementary elements and minimizing mass while enhancing stiffness and accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the size of existing elements (crank and wishbone members) is increased to counteract torsion effects, then stiffness is improved, but mass increases which increases cost and reduces dynamic performance
Solution Approach 1:
The linkage is divided into two separate arms (first arm and second arm) connected by a spherical joint, allowing each arm to be optimized independently for stiffness while maintaining overall lightweight design. This segmentation enables the first arm to be optimized for resisting torsion from yaw torques while the second arm connects to the payload platform, reducing the need to oversize the entire linkage.
Solution Approach 2:
The invention introduces a new dimensional degree of freedom by allowing the first arm to rotate independently about an axis perpendicular to the plane defined by the spherical joint centers. This additional rotational freedom enables the linkage to accommodate yaw torques without requiring increased size, as the arm can rotate to absorb the torsional stress rather than resisting it through increased stiffness.
2Strength
If additional mechanism elements are added to the motion platform arrangement to counteract torsion, then stiffness is improved, but mass, motion complexity, and inventory increase thereby increasing cost
Solution Approach 1:
The first arm serves multiple functions: it transmits motion from the actuator to the spherical joint, resists torsion from yaw torques through its structural design, and provides an additional degree of rotational freedom to accommodate payload platform movements. This multi-functionality eliminates the need for separate compensating mechanisms, reducing overall system complexity while maintaining stiffness.
Solution Approach 2:
The linkage transitions from a static rigid structure to a dynamic system where the first arm can rotate independently about an axis perpendicular to the spherical joint plane. This dynamic capability allows the linkage to adapt to varying torque conditions and payload positions in real-time, providing stiffness when needed without the complexity of active control systems or additional actuators.
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 provides improved positional accuracy and high-frequency movement control under yaw conditions, reducing the need for additional measures to counter torsion, thus lowering the overall mass, complexity, and cost of the motion platform.
Implementation Method 1
a first arm operably coupled at a first end thereof by a spherical joint to a second arm at a first end
Implementation Method 2
the first arm is operably coupled at a second end thereof to an anchoring site by a first revolute joint; and the second arm is operably coupled at a second end thereof to an elevation site by a second revolute joint
Data Source
AI summary
A motion platform apparatus (100) for vehicle simulation comprises a payload platform (134) having peripheral elevation sites (136, 138, 140). The apparatus (100) also comprises abase stage (102) having peripheral anchoring sites, and linkages (110, 112, 114) configured to couple the peripheral anchoring sites to the peripheral elevation sites (136, 138, 140) respectively, the linkages (110, 112, 114) comprising a first linkage (110). The first linkage (110) comprises a first arm (116) operably coupled at a first end thereof by a spherical joint (128) to a second arm (122) at a first end thereof. The first arm (116) is operably coupled at a second end thereof to an anchoring site of the peripheral anchoring sites by a first revolute joint (132). The second arm (122) is operably coupled at a second end thereof to an elevation site (136) of the peripheral elevation sites (136, 138, 140) by a second revolute joint (146).