Seismic Sensor Mass Positioning via Stepper Motor and Photo-Interrupters
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Solution Overview
Problem
Broadband seismometers require adjustable mass positioning apparatuses that can reliably report position information and diagnose issues without increasing the sensor's volume, as traditional systems are prone to jamming and lack feedback on available adjustment ranges.
Innovation Solution
A mass positioning apparatus with a pivotable boom, capacitive displacement transducer, photo-interrupters, and a stepper motor-driven actuator system that automatically adjusts the boom to a null point, providing position feedback and preventing jamming through discrete step control and photo-interrupter monitoring.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a traditional mass positioning apparatus with manual screw or electrical motor is used, then the boom can be positioned at the null point, but the apparatus is prone to jamming and difficult to diagnose without disassembly
Solution Approach 1:
The patent replaces the traditional mechanical screw-driven positioning system with a stepper motor-driven system that uses discrete angular steps to rotate a crank. This substitution eliminates the jamming issues associated with continuous-threaded mechanical systems while maintaining precise positioning capability through controlled discrete movements.
Solution Approach 2:
The patent incorporates photo-interrupters that detect the position of the adjustment assembly and provide feedback signals to a controller. This feedback mechanism enables real-time monitoring of the positioning status, allows diagnostic information to be reported without disassembly, and enables automatic adjustment to maintain the boom at the null point.
2Loss of information
If traditional mass positioning apparatus is used, then adjustment can be made within a defined range, but position information relative to operational range is not reported
Solution Approach 1:
The photo-interrupters are positioned to detect specific angular positions of the adjustment assembly corresponding to the operational range limits. When the assembly approaches these limits, the photo-interrupters generate signals that provide feedback about the remaining adjustment margin, enabling operators to monitor position information without disassembling the instrument.
Solution Approach 2:
The patent uses photo-interrupters as intermediary sensing elements that convert the mechanical position of the adjustment assembly into optical detection signals. These intermediaries enable non-contact, non-invasive monitoring of the positioning status and provide diagnostic information about the operational range without requiring direct mechanical connection or disassembly.
3Volume of stationary object
If compact mass positioning is implemented, then the sensor volume is maintained, but the apparatus must be economically realized without significant volume increase
Solution Approach 1:
The patent employs a crank mechanism that converts rotational motion from the stepper motor into oscillating linear motion to position the boom. This dimensional transformation allows compact packaging of the positioning mechanism within the existing sensor enclosure volume, as the crank mechanism efficiently packs the motion transformation function into a small spatial footprint.
Solution Approach 2:
The adjustment assembly serves multiple functions: it positions the boom along the arc, provides position feedback through photo-interrupters, and indicates remaining adjustment range. By consolidating these functions into a single integrated mechanism rather than separate components, the patent reduces the overall volume requirement and simplifies the manufacturing process.
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
Enables reliable, economic, and compact mass positioning within seismic sensors, allowing for real-time monitoring and adjustment to compensate for environmental changes, preventing jamming and ensuring the sensor operates within a safe adjustment range.
Implementation Method 1
A capacitive displacement transducer includes two metal plates 104 attached to the boom 101 and a center plate 105 fixed to the frame 102
Implementation Method 2
The means for determining position includes photo-interrupters 140 and 141
Data Source
AI summary
A mass positioning apparatus for use with seismic sensors is described. The seismic sensor includes axis mechanics including a pivotable boom with a defined null point. The mass positioning apparatus comprising: adjustment means for positioning the boom at the null point; actuator means for moving the adjustment means; and means for determining a position of the adjustment means relative to an operational range of travel.