Tilt Sensor Using Optical Fiber for Surveying Instruments
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Solution Overview
Problem
Prior art tilt sensors in total stations are slow due to damping times required for fluid settlement or movement-induced disturbances, affecting measurement accuracy and reliability.
Innovation Solution
A tilt sensor with a gravity-sensitive gradient indicating element fixed to a non-rotating base, eliminating damping time by maintaining orthogonality to the gravitational field during instrument movement, using a detecting device to measure deviations between the rotational axis and true vertical axis.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a fluid-filled tilt sensor is used to determine vertical deviation, then measurement accuracy is improved, but the response time deteriorates due to fluid settling time
Solution Approach 1:
The patent replaces the mechanical fluid-based tilt sensing system with an optical system using a laser beam, optical fiber, and detector. The laser beam defines a fixed vertical reference without requiring physical settlement, eliminating the damping time while maintaining measurement accuracy through optical detection of the beam's position relative to the target point.
Solution Approach 2:
The patent extracts the gravity reference function from the mechanical fluid system and implements it through a laser beam that inherently defines the vertical direction. This separates the reference establishment (laser beam) from the measurement detection (optical fiber and detector), allowing instantaneous reference availability without fluid settling delays.
2Measurement precision
If a balance plate with capacitive sensors is used for tilt measurement, then measurement precision is improved, but the device complexity increases
Solution Approach 1:
The patent replaces the mechanical balance plate and capacitive sensor system with an optical system comprising a laser emitter, optical fiber, and position detector. This substitution simplifies the device by eliminating complex mechanical balancing components and capacitive sensing arrangements while achieving tilt measurement through optical path analysis.
Solution Approach 2:
The patent uses an optical fiber to copy and transmit the laser beam position information to the detector. The optical fiber acts as a flexible transmission medium that replicates the beam's angular position without requiring rigid mechanical connections, thereby reducing device complexity while maintaining measurement precision.
3Measurement precision
If an element suspended by wires is used for tilt sensing, then measurement accuracy is improved, but the reliability deteriorates due to wire-induced disturbances during movement
Solution Approach 1:
The patent replaces the wire-suspended mechanical element with an optical system where the laser beam defines the vertical reference without physical suspension. This eliminates wire-induced disturbances during instrument movement while maintaining tilt sensing accuracy through optical detection, thereby improving reliability during dynamic operations.
Solution Approach 2:
The patent segments the tilt sensing function into independent optical components: the laser emitter establishes the vertical reference, the optical fiber transmits the positional information, and the detector measures the angle. This segmentation eliminates the need for physical suspension wires and their associated disturbances during movement.
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 faster and more accurate deviation measurements, allowing for efficient on-site calibration and improved reliability of surveying instrument results.
Implementation Method 1
a gravity sensitive gradient indicating element arranged such that a surface of the element is positioned orthogonally to the true vertical axis during movements of the measuring instrument
Implementation Method 2
a deviation between the rotational axis and the true vertical axis can be detected using the at least one response signal
Data Source
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AI summary
The present invention relates to a position-determining apparatus such as measuring or surveying instruments. More particularly, the present invention relates to a tilt sensor for a measuring instrument having a movable housing (240) that is controllably rotatable around a rotational axis (290), wherein the rotational axis may be positioned so that it deviates from a true vertical axis (222) being parallel with a gravitational axis. The tilt sensor comprises a gravity sensitive gradient indicating element (285) arranged such that a surface of the element is positioned orthogonally to the true vertical axis (222) during movements of the measuring instrument, wherein the gravity sensitive gradient indicating element is arranged in connection to the non- rotating base (80); and a detecting device adapted to produce at least one detecting signal and to receive at least one response signal, wherein a deviation between the rotational axis and the true vertical axis can be detected using the at least one response signal.