Cable Pull Detection Using Dual Switch Tension Stages
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Solution Overview
Problem
Existing pulling detection devices for moving bodies, such as examination robots, are unable to reliably detect tension on control cables in stages, leading to potential damage and movement hindrance, and are often bulky, making them difficult to integrate and prone to environmental noise interference.
Innovation Solution
A compact pulling detection device with a movable rod and elastic compression spring system that uses two switches to detect tension levels, allowing for staged detection of tension magnitudes, thereby enabling precise control of moving body operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a displacement sensor, proximity sensor, or load cell is used to directly measure pulling amount or tension, then tension can be detected in stages, but the device size increases
Solution Approach 1:
The patent divides the tension detection range into multiple stages using a multi-level switch structure. The switch includes multiple contacts arranged at different positions along the pulling direction, allowing the system to detect different tension levels (first stage, second stage, etc.) without requiring complex sensing equipment. This segmentation approach enables staged tension detection while maintaining a compact device size.
2Measurement precision
If a large-sized tension measurement device is provided at the connection location between moving body and external cable, then tension can be detected accurately, but the device becomes difficult to integrate
Solution Approach 1:
The patent employs a nested structure where the switch operation body is housed within the switch body, and the entire assembly is integrated into the connection mechanism between the moving body and external cable. The movable rod moves within confined spaces, actuating switches that are nested within the structural components. This nesting approach enables accurate tension measurement while maintaining compact dimensions for easy integration.
3Reliability
If environmental noise protection measures are added to the wiring, then signal reliability improves, but device complexity increases
Solution Approach 1:
The patent uses the elastic body as an intermediary mechanical element that directly couples the pulling force to the switch operation body. This direct mechanical linkage eliminates the need for complex electrical wiring and signal conditioning circuits that would be required to protect against environmental noise. The elastic body transmits force reliably through its physical properties, providing inherent noise immunity without adding wiring complexity.
4Device complexity
If only a single switch is used to detect excessive tension, then the structure remains simple, but only a specific magnitude of tension can be detected
Solution Approach 1:
The patent segments the tension detection function into multiple discrete levels by providing a switch with multiple contacts at different positions. As the movable rod moves in response to increasing tension, it sequentially actuates different switches or different contacts on the same switch, enabling detection of multiple tension stages (first stage, second stage, etc.). This segmentation maintains structural simplicity while expanding the detection range.
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 device effectively detects tension on control cables in stages, preventing damage and movement hindrance, while maintaining a small size and simple structure, ensuring reliable operation and easy integration.
Implementation Method 1
an elastic body provided between the second wall portion opposed surface and the second wall portion so as to press the second wall portion opposed surface, the elastic body being extendable/contractible in the longitudinal direction of the foundation portion
Data Source
Figure 1
Figure 2
Figure 3A~3D
AI summary
This pulling detection device includes: a base (42) in which, on a plate-shaped foundation portion (42d) extending in a longitudinal direction, a first wall portion (42a), a projection (42b), and a second wall portion (42c) are provided in this order in the longitudinal direction; a movable rod (43) including a switch operation body (43e) and a pulling rod (43a), the switch operation body (43e) having a first wall portion opposed surface (43b) opposed to the first wall portion, a projection opposed surface (43c) opposed to a side of the projection opposed to the first wall portion, and a second wall portion opposed surface (43d) opposed to the second wall portion, the pulling rod (43a) extending from the second wall portion opposed surface so as to penetrate the second wall portion, the movable rod (43) being movable along the foundation portion in the longitudinal direction of the foundation portion, while movement of the movable rod (43) toward one side in the longitudinal direction is restricted by contact between the first wall portion and the first wall portion opposed surface and movement of the movable rod (43) toward another side in the longitudinal direction is restricted by contact between the projection and the projection opposed surface; an elastic body (46) provided between the second wall portion opposed surface and the second wall portion so as to press the second wall portion opposed surface, the elastic body (46) being extendable/contractible in the longitudinal direction of the foundation portion; a first switch (44) which operates by contact/separation between the first wall portion and the first wall portion opposed surface; and a second switch (45) which operates by contact/separation between the projection and the projection opposed surface.