Multi-axis Load Cell Body with Integral Flexures
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Solution Overview
Problem
There is a need for an improved compact load cell that is easy to manufacture, capable of transmitting and measuring linear forces and moments along three orthogonal axes, while existing solutions like the Swift transducer are well-suited but require enhancements for manufacturing simplicity.
Innovation Solution
A compact load cell body with a rigid central hub, a concentric annular ring, and radial members, each featuring a center body with an aperture and flexures that include strain sensors connected in Wheatstone bridges to measure forces and moments, fabricated from a single unitary block of material for integral formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a multi-axis load cell body is designed to measure forces and moments along three orthogonal axes, then measurement capability is improved, but device complexity increases
Solution Approach 1:
The patent combines multiple measurement functions (forces and moments along three orthogonal axes) into a single integrated load cell body. The central hub, radial members, and annular ring work together as one unified structure to simultaneously measureFx, Fy, Fz, Mx, My, and Nz, eliminating the need for separate sensors for each measurement axis.
Solution Approach 2:
The load cell body serves multiple functions within a single device: it measures all three force components (Fx, Fy, Fz) and all three moment components (Mx, My, Nz) simultaneously. The radial members and flexures are designed to respond to multiple types of loading, making each component multi-functional rather than dedicated to a single measurement.
2Adaptability or versatility
If a compact load cell body is designed for wheel force transducer applications, then adaptability to specific applications is improved, but manufacturing complexity increases
Solution Approach 1:
The load cell body is segmented into distinct functional components: a central hub, multiple radial members extending outward, and an annular ring. Each radial member contains flexures at specific locations, creating a modular-like structure that is optimized for wheel force transducer applications while maintaining manufacturing feasibility through systematic design.
Solution Approach 2:
The patent implements local quality variations within the load cell body, specifically placing flexures with different characteristics at different radial members. Some radial members have first flexures, others have second flexures, with sensors positioned at specific locations to measure specific components. This localized differentiation optimizes the structure for its specific application while keeping the overall design manufacturable.
3Measurement precision
If strain sensors are positioned on flexures to measure bending, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The flexures are designed to naturally bend and deform in response to applied forces and moments, and strain sensors are positioned to directly measure this self-generated deformation. The structure itself provides the measurement mechanism through its elastic deformation, eliminating the need for additional active sensing elements or complex measurement systems.
Solution Approach 2:
The patent replaces complex mechanical measurement mechanisms with strain sensors that directly measure flexure bending. Instead of using mechanical linkages, levers, or other mechanical amplification systems to detect forces and moments, the design uses electrical strain sensors positioned on the flexures to directly measure the deformation, simplifying the overall measurement system.
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 enables precise measurement of forces and moments in multiple directions with reduced manufacturing complexity, providing accurate output signals indicative of six degrees of freedom, suitable for applications like wheel force transducers.
Implementation Method 1
The sensor may include a strain sensor. The sensor may include a first strain sensor on a first side of the at least one of the first flexure and the second flexure of each radial member and a second strain sensor on a second side of the at least one of the first flexure and the second flexure of each radial member. Each of the first strain sensors and each of the second strain sensors can be connected in a Wheatstone bridge.
Data Source
AI summary
A load cell body for transmitting forces and moments in plural directions includes a rigid central hub having a central axis and a rigid annular ring concentric with the central hub about the central axis. At least three radial members extend radially with respect to the central axis along corresponding longitudinal axes from the central hub to the annular ring where each radial member includes a center body with an aperture extending there through along an aperture axis that is parallel to the central axis. A first flexure joins the center body to the central hub, while a second flexure joins the center body to the annular ring.