Precision Tilting Platform With Closed-Loop Angle Calibration
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Solution Overview
Problem
Current precision tilting platforms for seismometer calibration suffer from low positioning accuracy and efficiency due to transmission clearances and friction losses in worm drives, limiting their application and precision.
Innovation Solution
A precision tilting platform utilizing a linear motor, grating scale, and laser interferometer for closed-loop control, combined with a clump weight and spring balancing system to minimize transmission clearance and friction, enabling high accuracy and efficiency in measuring and adjusting the tilting angle.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If worm drives are used in the tilting platform, then the structure is simple and cost-effective, but transmission clearances limit positioning precision and friction loss reduces transmission efficiency
Solution Approach 1:
The patent replaces the traditional worm drive mechanical transmission system with a direct-drive structure combined with a laser interferometer measurement system. The linear motor directly drives the tilting platform without intermediate mechanical transmission components, eliminating transmission clearances and friction losses. The laser interferometer provides precise measurement of the tilting angle, enabling closed-loop control to achieve high positioning precision without relying on mechanical transmission accuracy.
2Measurement precision
If optional encoder with semi-closed loop control is mounted, then some control capability is achieved, but full-closed loop control is not realized and positioning accuracy is still affected
Solution Approach 1:
The patent implements full-closed loop control by using the laser interferometer to continuously measure the actual tilting angle and feeding this information back to the control system. The control system compares the measured angle with the target angle and adjusts the linear motor output accordingly to eliminate any deviation. This feedback mechanism ensures high positioning accuracy by constantly correcting errors, achieving true closed-loop control rather than semi-closed loop.
3Ease of operation
If tilting angle is figured out by stepper motor displacement without direct measurement device, then the system is simpler, but measuring error occurs
Solution Approach 1:
The patent replaces the indirect measurement method (calculating tilting angle from stepper motor displacement) with a direct measurement approach using a laser interferometer. The laser interferometer directly measures the tilting angle by detecting the position of a reflector attached to the tilting platform, providing accurate measurement without relying on mechanical transmission ratios or motor displacement calculations. This eliminates measuring errors while maintaining system simplicity through the use of non-contact optical 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
The solution achieves high positioning accuracy, high transmission efficiency, and reliability in static calibration of seismometers, with the laser interferometer providing precise tilting angle measurements and automatic control ensuring robust performance.
Implementation Method 1
The driving part includes a linear motor
Implementation Method 2
a grating scale that fixed on the sliding table to measure the linear displacement of the linear motor
Implementation Method 3
The measuring part is composed of a laser interferometer and a reflector that reflects the laser beam back to the laser interferometer
Implementation Method 4
a reflector that reflects the laser beam back to the laser interferometer
Implementation Method 5
the sliding table is pulled backward and the rotary part rotates toward the negative direction because of the gravity of the clump weight
Data Source
AI summary
A precision tilting platform used for static calibration of seismometers includes a base, a worktable, a rotary part, a driving part, a measuring part and supporting frames. The rotary part includes a shaft, a driving arm, a rotary table and a clump weight. The driving part includes a linear motor, a sliding table, a pair of linear guides and sliders and a grating scale. The readhead of the grating scale is fixed with the base and sends out a signal of zero position when the worktable is horizontal. The sliding table contacts the driving arm. When the linear motor is moving forward, the rotary part rotates toward the positive direction. When the linear motor is moving backward, the rotary part rotates toward the negative direction under gravity of the clump weight. The measuring part includes a laser interferometer and a reflector to obtain the tilting angle of the worktable.