Parallel-Kinematic 4-Axis Positioner for Compact Shaft Alignment
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Solution Overview
Problem
Existing positioning systems for rotary test equipment fail to meet the requirements of precision, compactness, payload capacity, robustness, and cost-effectiveness for aligning rotating shafts, with existing technologies being either too bulky, expensive, or lacking in scalability and durability.
Innovation Solution
A 4-axis positioner utilizing parallel-kinematic principles with two 2-axis assemblies, allowing two linear and two rotational axes of motion, using four actuators and a platform connected via linear motion connections, which maintains stability and scalability without relying on magnets or point contacts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If linear and rotary stages are stacked to achieve multi-axis motion, then positioning precision is improved, but system size and complexity increase significantly
Solution Approach 1:
The patent combines multiple motion axes (two translational and two rotational) into a single integrated parallel-kinematic mechanism rather than stacking separate linear and rotary stages. The two 2-axis assemblies share a common frame and work together to provide all four degrees of freedom simultaneously, reducing overall system size while maintaining positioning precision through the parallel-kinematic architecture.
2Strength
If multiple actuators are added to increase payload capacity, then load-bearing capability is improved, but device complexity and cost increase
Solution Approach 1:
The patent divides the 4-axis positioner into two identical 2-axis assemblies, each capable of handling significant loads independently. This segmentation allows the system to achieve high payload capacity through the combined strength of two robust assemblies while avoiding the need for a single overly complex actuator system. Each assembly uses only two actuators, and together they provide the required four degrees of freedom with enhanced load-bearing capability.
3Ease of operation
If a lower profile design is implemented to improve accessibility, then ergonomic accessibility is improved, but structural stability may be compromised
Solution Approach 1:
The patent achieves a lower profile by reconfiguring the mechanism to utilize horizontal space more effectively. The two 2-axis assemblies are arranged side-by-side sharing a common frame, allowing the platform to be positioned lower while maintaining structural stability through the distributed support of multiple linkages and the rigid common frame structure.
4Reliability
If robust construction is used to withstand high loads and vibration, then reliability is improved, but system cost increases
Solution Approach 1:
The patent achieves robustness through optimized geometric parameters of the parallel-kinematic mechanism rather than simply using heavier materials. The predetermined angles of the linear motion connections and the specific configuration of the two 2-axis assemblies provide inherent stiffness and vibration resistance, allowing for cost-effective manufacturing while maintaining reliability under high loads and vibrational conditions.
Data Source
AI summary
A 4-axis positioner comprising two 2-axis assemblies sharing a common frame, with a platform connected between them. Each 2-axis assembly comprises a fixed assembly secured or integral to the common frame, two input assemblies secured to the fixed assembly by independently actuated linear motion connections, and a translation assembly secured to the input assemblies by additional linear motion connections. The connections between the input assemblies and the fixed assembly are parallel with one another, and the connections between the input assemblies and the translation assembly are both non-parallel from the connections to the fixed assembly, and non-parallel from one another. The translation assemblies move in two linear axes by common or opposing motion of the input assemblies. The platform is connected to each translation assembly by joints, and moves in two linear axes by common motion, and two rotational axes by opposing motion, of the translation assemblies.