Cable Actuator Nut Sensing for Accurate Force Measurement
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Solution Overview
Problem
Existing cable actuators with force sensors are bulky, expensive, and lack accuracy due to the need to withstand impacts and vibrations, leading to increased volume and decreased sensitivity.
Innovation Solution
A cable actuator design that includes a distance sensor with a thread to sense distance, where the thread changes curvature at a specific point, improving the accuracy of angular movement estimation and force measurement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If force sensors are mounted directly on the outlet of the actuator, then force measurement is enabled, but the sensors become bulky, expensive, and less accurate due to the need to withstand impacts and vibrations
Solution Approach 1:
The invention extracts the force measurement function from the direct outlet location and relocates it to the nut component. By measuring the angular position of the nut and calculating force from this measurement, the system eliminates the need for bulky force sensors at the outlet, achieving accurate force measurement without the volume and robustness penalties of direct mounting
Solution Approach 2:
The invention replaces the mechanical force sensor system with an angular position measurement system. Instead of using physical force sensors that directly measure force at the outlet, the system uses an angular sensor to measure the nut's rotation angle and calculates force through mathematical relationships, substituting a more compact and sensitive measurement approach
2Measurement precision
If force sensors are mounted directly on the outlet of the actuator, then force measurement is enabled, but manufacturing and maintenance costs increase
Solution Approach 1:
The invention extracts the force measurement function from expensive outlet-mounted sensors and relocates it to the nut, where angular position sensors are more economical. This extraction enables force measurement capability while significantly reducing manufacturing and maintenance costs by using less expensive sensor technology in a more accessible location
Solution Approach 2:
The invention creates a virtual copy of the force measurement function through mathematical calculation rather than physical sensing. By measuring angular position and calculating force from this data, the system achieves force measurement capability at lower cost, effectively copying the measurement function through computation rather than expensive hardware
3Length of moving object
If the thread changes curvature at a point closer to the extreme position, then the sensor can measure the full stroke, but the signal-to-noise ratio decreases
Solution Approach 1:
The invention optimizes the geometric parameter of the thread's curvature change point location along the stroke. By positioning this point at 30-70% of the stroke distance from the extreme position, the system achieves an optimal balance between measurement range and signal-to-noise ratio, improving measurement precision while maintaining adequate measurement capability
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 enhances the accuracy of force measurement and reduces manufacturing and maintenance costs by providing a more sensitive and compact sensor system.
Implementation Method 1
the thread changes curvature at a first point situated in a first plane orthogonal to the first axis
Data Source
AI summary
A cable actuator (100) having a frame (10); a screw (2) rotatably mounted on the frame (10) and extending along a first axis (Ox); a nut (4) cooperating with the screw (2); a mechanism (30) for estimating the angular movement of the nut (4) about the first axis (Lx) relative to the frame (10); and a distance sensor (30) secured to the frame (10) and having a winder (33) for winding a thread (32), one end (32.1) of the thread (32) connected to the nut (4) at a connection point (4.1). The distance sensor (30) is arranged in such a manner that the thread (32) changes curvature at a first point (34) situated in a first plane (P1) orthogonal to the first axis (Ox).