Hydraulic Actuator Force Sensor Layout for Position-Independent Measurement
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Solution Overview
Problem
Existing linear force measuring devices for hydraulic actuators in orthopedic devices face issues with varying installation positions leading to different measured values for the same load, lack of modular structure, and poor signal quality.
Innovation Solution
A linear force measuring device with a base and bearing holder connected via two opposing webs, allowing for a modular and cost-effective structure, with sensors attached to the webs to ensure high signal quality and even force transmission, and a stiffening element to prevent bending effects, utilizing strain gauges or piezo elements for precise force measurement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If strain gauges are attached directly to the linear actuator for force measurement, then force measurement is enabled, but different installation positions lead to different measured values under the same load and signal quality is poor
Solution Approach 1:
The device is segmented into a base, bearing holder, and two opposing webs. The sensors are attached specifically to the webs rather than directly to the actuator, creating distinct functional zones. This segmentation allows the webs to serve as dedicated force transmission elements that channel loads uniformly to the sensor attachment points, eliminating position-dependent measurement variations.
Solution Approach 2:
The webs act as intermediary elements between the bearing holder and the base. They transmit tensile and compressive forces from the actuator to the base while providing a standardized, rigid attachment surface for the sensors. This intermediary structure ensures that all loads are transmitted through the same path regardless of installation position, guaranteeing measurement consistency.
2Adaptability or versatility
If a modular design is implemented for the force measuring device, then cost-effectiveness and adaptability improve, but structural rigidity and signal quality may deteriorate
Solution Approach 1:
The device is divided into separable modular components: a base, a bearing holder, and two webs that can be manufactured independently and then assembled. This segmentation enables modular design and mass production of individual components while maintaining the structural integrity of the complete assembly through precise connection interfaces.
Solution Approach 2:
The modular components (base, bearing holder, webs) are designed to be assembled into a unified structure that provides rigid force transmission. The webs connect the bearing holder to the base in a configuration that merges the functional advantages of modularity with the structural requirements of rigidity, allowing the sensor attachment points to remain stable and precise.
3Measurement precision
If the bearing holder is connected to the base via two opposing webs, then symmetrical force transmission and reduced bending moments are achieved, but device complexity increases
Solution Approach 1:
The device uses symmetrical geometry (two opposing webs) to achieve asymmetrical force distribution cancellation. By positioning identical webs opposite each other, the structure ensures that loads are distributed evenly across both webs, preventing bending moments while maintaining a relatively simple overall configuration compared to multi-element alternatives.
Solution Approach 2:
The two opposing webs serve multiple functions simultaneously: they provide structural support, transmit tensile and compressive forces, reduce bending moments through symmetrical load distribution, and provide standardized attachment surfaces for sensors. This multi-functionality reduces the need for additional separate components, thereby limiting the increase in device complexity.
4Stability of the object's composition
If a stiffening element is added between the webs, then bending effects and buckling are eliminated, but manufacturing complexity and cost increase
Solution Approach 1:
The stiffening element is integrated with the webs to form a unified structural assembly. Rather than being a separate attached component, the stiffening element is combined with the web structure during manufacturing, creating a single rigid unit that resists bending and buckling while minimizing the number of assembly steps and manufacturing operations required.
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 signal quality and linear force transmission with reduced bending moments, enabling precise force measurement independent of installation position, and allows for the efficient control of hydraulic actuators in orthopedic devices.
Implementation Method 1
The sensor or sensors are designed in particular as strain gauges or piezo elements
Implementation Method 2
The sensor or sensors are designed in particular as strain gauges or piezo elements
Data Source
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AI summary
The invention relates to a linear force-measuring device for a hydraulic actuator of an orthopedic device, having a base (10), a bearing receptacle (20) and at least one sensor (30) for detecting changes in length between the basis (10) and the bearing receptacle (20), wherein the bearing receptacle (20) is connected to the base (10) via two opposing connecting parts (40), and the at least one sensor (30) is secured to one of the connecting parts (40).