Active Isolation End Stop Detection via Base Oscillation Feedback
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Solution Overview
Problem
Existing precision motion systems face challenges in accurately detecting and adjusting mechanical end stops during setup and maintenance, leading to potential damage and reduced accuracy due to tilting or height changes over time, especially in active isolation systems used in semiconductor processing and other precision equipment.
Innovation Solution
A method involving a six-degree-of-freedom active isolation system with actuators and inertial sensors to detect mechanical end stops by inducing oscillatory motion and using a process sensitivity matrix to determine forces for precise contact detection and offset positioning, preventing damage and ensuring accurate alignment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If shipping brackets are released to allow base movement on dampers, then the system can operate with vibration isolation, but the base may tilt or shift from horizontal position due to damper stiffness variations and equipment weight
Solution Approach 1:
The patent applies mechanical vibration by inducing oscillatory motion of the base in each translational degree of freedom and detecting mechanical contact with end stops through vibration analysis. Inertial sensors measure the oscillatory motion, and contact detection is achieved by analyzing changes in vibration characteristics when the base contacts the mechanical end stop, enabling precise position determination without manual measurement tools.
Solution Approach 2:
The system uses feedback from inertial sensors to continuously monitor base position and oscillatory motion. The sensors provide real-time data on base movement, and this information is fed back to the control system to detect end stop contact and determine the base's position relative to mechanical limits, enabling automatic adjustment and maintenance of proper positioning.
2Measurement precision
If manual adjustment with shims is used to check base position, then some position information can be obtained, but the operation is unprecise and cumbersome
Solution Approach 1:
The patent replaces the manual mechanical shim-based measurement system with an automated sensor-based detection system. Inertial sensors and vibration analysis substitute for physical shims, eliminating the need for manual insertion and measurement of shims. The system automatically detects base position and end stop contact through oscillatory motion analysis, providing precise measurements without cumbersome manual operations.
Solution Approach 2:
The system performs self-measurement by using its own actuators to induce oscillatory motion and its own inertial sensors to detect the resulting vibrations. The motion system tests itself automatically without requiring external measurement tools or manual intervention, enabling autonomous position verification and end stop detection.
3Measurement precision
If no automatic detection system is used, then the system structure remains simple, but the base position relative to mechanical end stops cannot be accurately determined
Solution Approach 1:
The inertial sensors serve multiple functions: they measure base position, detect oscillatory motion, identify mechanical contact with end stops, and provide data for control system adjustments. The actuators also serve dual purposes by both positioning the base and inducing oscillatory motion for detection. This multi-functionality reduces the need for separate dedicated detection components, minimizing system complexity while achieving accurate measurement.
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 detection and adjustment of mechanical end stops, preventing collisions and ensuring accurate positioning of the motion system, thereby maintaining high precision and preventing damage to the system components.
Implementation Method 1
several inertial sensors arranged to provide a six DOF measurement of the base's motion
Implementation Method 2
determining, using the process sensitivity matrix of the mechanical system comprising the base and the active isolation system, a force to be applied to the base by the actuators to cause an oscillatory motion of the base
Data Source
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AI summary
The present invention concerns a method for detecting a mechanical end stop of a motion system comprising a base designed to receive a motion stage for an equipment, a machine frame resting on the floor and an active isolation system therebetween, wherein said active isolation system comprises several actuators arranged to impart a six degree-of-freedom (DOF) motion to said base, several inertial sensors arranged to provide a six DOF measurement of the base's motion, and dampers to support the base, the mechanical end stop being arranged to limit the base's motion relative to the machine frame, the method comprising the steps of: (a) selecting a translational DOF among the six DOFs; (b) determining, using the process sensitivity matrix of the mechanical system comprising the base and the active isolation system, a force to be applied to the base by the actuators to cause an oscillatory motion of the base in the selected translational DOF the motion being of a predetermined amplitude; (c) applying the force to the base using the actuators to obtain the oscillatory motion of the base in the selected translational DOF; (d) detecting a mechanical contact between the base and the mechanical end stop using at least one inertial sensor from the several inertial sensors.