Linear Motion Table Force Stabilization for Position Repeatability
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Solution Overview
Problem
Existing linear motion systems suffer from backlash, non-repeatability due to non-uniform friction in rail bearings, and thermal expansion, leading to inaccurate and imprecise position measurements.
Innovation Solution
Implementing force stabilization components on the table to exert opposing forces on the rails, using low-CTE linear encoders to compensate for thermal expansion, and employing software correction with fiducials and high-resolution cameras to calibrate and correct position errors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional linear motion systems use standard rail bearings and ball screws, then the system structure is simple and easy to manufacture, but position repeatability is poor due to backlash, non-uniform friction, and thermal expansion
Solution Approach 1:
The patent introduces force stabilization components as intermediary elements between the table and rails. These components include springs that apply stabilizing forces to reduce the effects of non-uniform friction and backlash, thereby improving position repeatability without fundamentally changing the core linear motion mechanism
Solution Approach 2:
The patent employs low-CTE (coefficient of thermal expansion) materials for critical components to change the thermal expansion parameter. This reduces thermal expansion effects during operation, maintaining position accuracy and repeatability even as the system heats up from repeated actuation
2Measurement precision
If rail bearings are manufactured with uniform properties, then manufacturing complexity increases, but position repeatability improves; however, non-uniform friction still causes table rotation and measurement inaccuracy
Solution Approach 1:
The patent applies preliminary counteracting forces through the force stabilization components with springs. These components are pre-configured to exert forces that counteract the non-uniform friction effects before they can cause significant table rotation or positioning errors
Solution Approach 2:
The system performs preliminary calibration using fiducials and high-resolution cameras to detect and correct position errors. This preliminary measurement and correction action compensates for manufacturing non-uniformities in the rail bearings
3Productivity
If the ball screw is repeatedly actuated in different directions, then the system becomes more versatile and productive, but thermal expansion increases causing measurement errors
Solution Approach 1:
The patent changes the thermal parameter of critical components by using low-CTE materials. This reduces the thermal expansion parameter during repeated actuation cycles, maintaining measurement precision even as productivity and actuation versatility increase
Solution Approach 2:
The system performs preliminary calibration and error mapping using fiducials and cameras before production use. This preliminary action creates correction data that compensates for thermal expansion effects during subsequent high-productivity operation
4Measurement precision
If force stabilization components are added to mitigate backlash and friction effects, then position repeatability improves, but device complexity and manufacturing cost increase
Solution Approach 1:
The force stabilization components serve as intermediary elements that can be added to existing linear motion systems without completely redesigning the core mechanism. The springs and mounting components use standard mechanical elements that are relatively easy to manufacture and integrate
Solution Approach 2:
The patent applies force stabilization at critical locations rather than throughout the entire system. The number and placement of force stabilization components are optimized to provide sufficient correction for position repeatability without excessive complexity
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
Ensures consistent rotational forces and accurate position measurements by mitigating backlash and thermal expansion errors, achieving high precision and repeatability in linear motion systems.
Implementation Method 1
the force stabilization component exerts a force on an associated rail. The force exerted on the rail tends to push the table location where the force stabilization component is secured to the table away from the rail
Implementation Method 2
thermal expansion. During use, as the ball screw is repeatedly actuated in different directions to move the ball nut (and whatever is secured to the ball nut) back and forth, the ball screw, ball nut, and/or other components may heat up and undergo thermal expansion
Data Source
AI summary
A linear movement system may comprise a base having two parallel rails, a table comprising two rail bearings configured to move in one dimension relative to the table and along the rails, and two force stabilization components secured to the table and configured to exert and aggregate rotational force on the table relative to the base. The force stabilization components may each comprise a fixed block secured to the table and a free-moving block in contact with the fixed block through a spring configured to push the fixed block and the free-moving block apart so that the free-moving block is in contact with one of the rails and pushes the rail away from the table location at which the fixed block is secured. This system may provide an aggregate rotational force that is stronger than other rotational forces resulting from mechanical imperfections in the system, thereby guaranteeing that the rotational force is always in the same direction.