Drive Stage Speed Control via Air Bearing Weight Detection
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Solution Overview
Problem
Existing drive stage devices, such as rotary tables, face challenges in maintaining measurement accuracy and preventing damage due to overloading, as they are often operated at low speeds regardless of the work piece weight, leading to inefficient measurement times and potential damage.
Innovation Solution
A control method that uses air bearings to float the stage, measures the height difference with and without a work piece to calculate its weight, and adjusts the rotational or movement speed limits accordingly to prevent exceeding the maximum load capacity, ensuring safe and efficient operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the rotary table is driven with conservative speed limits to preserve rotation accuracy for maximum load capacity, then rotation accuracy is maintained, but measurement time increases unnecessarily for lightweight work pieces
Solution Approach 1:
The patent applies dynamics by making the speed limit variable rather than fixed. The control device dynamically adjusts the speed limit based on the actual work piece weight detected during operation. For lightweight work pieces, the speed limit is increased to reduce measurement time, while for heavy work pieces approaching maximum load capacity, the speed limit is reduced to preserve rotation accuracy. This dynamic adjustment resolves the contradiction between maintaining reliability and improving productivity.
2Reliability
If the rotary table accelerates and decelerates slowly to preserve rotation accuracy for maximum load capacity, then rotation accuracy is maintained, but measurement time increases
Solution Approach 1:
The patent dynamically adjusts acceleration and deceleration rates based on the detected work piece weight. For lightweight work pieces, higher acceleration and deceleration rates are applied to reduce measurement time. For heavy work pieces, lower rates are used to maintain rotation accuracy and prevent damage. This dynamic control resolves the time-loss contradiction.
3Reliability
If conservative speed control is applied to prevent damage to internal mechanisms, then device safety is ensured, but measurement efficiency decreases for lightweight work pieces
Solution Approach 1:
The patent implements feedback control by detecting the actual work piece weight during operation and using this information to adjust speed limits and acceleration rates. The control device continuously monitors operational parameters and adjusts control settings accordingly. This feedback mechanism ensures device safety for heavy work pieces while optimizing measurement efficiency for lightweight work pieces, resolving the contradiction between safety and productivity.
4Reliability
If the rotary table is operated at low speeds for all work pieces, then rotation accuracy is preserved, but measurement time increases unnecessarily
Solution Approach 1:
The patent applies local quality by implementing differentiated speed control based on local conditions (work piece weight). Instead of applying a uniform conservative speed limit to all work pieces, the control device adjusts speed limits locally according to the actual weight detected. Lightweight work pieces receive higher speed limits while heavy work pieces receive lower limits, optimizing both accuracy and time efficiency for each specific case.
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
This method allows for precise control of drive stage devices based on work piece weight, preventing damage and optimizing measurement efficiency by adjusting speed limits dynamically, thereby improving the accuracy and reliability of shape measurements.
Implementation Method 1
causing a stage to float on an air bearing
Data Source
AI summary
In a control method of a drive stage device, a stage is floated on an air bearing, then a height of the stage while floating on the air bearing is measured as a first height. A work piece is placed on the stage and a height of the stage while holding the work piece is measured as a second height. A difference between the first height and the second height is calculated as a drop amount, and a weight of the work piece is calculated based on the drop amount. An upper limit speed of one of rotational drive and horizontal movement of the stage is determined based on the calculated work piece weight. A speed of the one of the rotational drive and the horizontal movement of the stage is controlled so as to not exceed the upper limit speed.