Deformable Load-Bearing Plate Positioning with Reference Kinematics
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Solution Overview
Problem
High-accuracy positioning systems, such as those used in medical imaging and radiotherapy, face challenges due to deformations of load-bearing plates under heavy loads, which affect the precision of patient positioning and beam guidance.
Innovation Solution
A dual parallel kinematics system comprising a deformation-free reference plate with leg length measurement devices and distance sensors, connected to a position-calculating unit that generates a 3D position map of the load-bearing plate, allowing for deformation compensation and improved accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a load-bearing plate is used to support heavy loads in positioning systems, then the load-bearing capacity is improved, but the positioning precision deteriorates due to plate deformations
Solution Approach 1:
A reference plate is introduced as an intermediary element between the positioning system and the load-bearing plate. The reference plate remains undeformed while the load-bearing plate deforms under load. Distance sensors measure the deformation by comparing positions relative to the reference plate, enabling compensation for the deformations and maintaining positioning precision even when supporting heavy loads
Solution Approach 2:
The system implements feedback by continuously measuring the deformation of the load-bearing plate using distance sensors and leg length measurement devices. The measured deformation data is fed back to a control unit that calculates correction values, which are then applied to compensate for the deformations in real-time, maintaining accurate positioning despite load-induced deformations
2Measurement precision
If a reference parallel kinematics system is added to measure deformations, then the positioning accuracy is improved, but the device complexity increases
Solution Approach 1:
The reference parallel kinematics system is designed to perform multiple functions: it serves as both a measurement system for detecting deformations and as a reference frame for position calculation. The same structural elements (reference legs, platform, and control unit) are used for both supporting the load-bearing plate and measuring its deformation, reducing the need for separate measurement apparatus
Solution Approach 2:
The measurement function is merged with the support structure by integrating the reference parallel kinematics system into the existing positioning system architecture. The reference legs and platform are combined with the load-bearing mechanism, and the control unit processes both positioning control and deformation measurement functions, reducing overall system complexity despite enhanced measurement capabilities
Data Source
AI summary
The invention relates to an assembly for the positioning and position detection of a deformable load-bearing plate, having a driving parallel kinematics system with a plurality of drive legs, wherein the load-bearing plate forms a constituent part of the driving parallel kinematics system or is fixed rigidly on a platform thereof, a reference parallel kinematics system with a substantially deformation-free reference plate which is formed by the platform of the reference parallel kinematics system or is fixed rigidly thereto and which is positioned underneath the load-bearing plate, and a plurality of reference legs, a sensor assembly which comprises a plurality of leg length measurement devices arranged in the reference legs and also a plurality of distance sensors arranged on the reference plate for point-wise or region-wise detection of the distance of the reference plate from the load-bearing plate, and a position-calculating unit which is connected at the input side to the leg length measurement devices and to the distance sensors and which processes the output signals of the leg length measurement devices and distance sensors to give a position map of the load-bearing plate.