Mobile Container Weighing System with Error Force Filtering
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Solution Overview
Problem
Existing mobile weighing systems face inaccuracies due to horizontal error forces caused by frame bending, particularly when measuring small weight increments, as conventional load cells are stressed by these forces, leading to inaccuracy in weight measurements.
Innovation Solution
A mobile apparatus with sensor assemblies that are non-resistive to horizontal error forces and a stabilizing assembly that inhibits shifting of the container relative to the frame, allowing accurate weight measurement by filtering out error forces and accommodating frame bending, while maintaining precise weight sensing in a vertical direction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional load cells are used in mobile weighing systems, then the system can measure weight, but horizontal error forces from frame bending cause measurement inaccuracy
Solution Approach 1:
The sensor assembly is segmented into multiple load cells arranged in a bridge configuration, where each load cell handles specific force components. This segmentation allows the system to isolate vertical weight forces from horizontal error forces, improving measurement accuracy by separating the measurement function from the stabilizing function.
Solution Approach 2:
A stabilizing assembly acts as an intermediary between the container and the sensor assembly. This stabilizing assembly absorbs and counteracts horizontal error forces from frame bending, preventing them from reaching the load cells. The intermediary structure protects the sensitive measurement elements from harmful external forces.
2Adaptability or versatility
If the mobile frame is made flexible to accommodate terrain, then mobility is improved, but frame bending generates horizontal error forces that stress load cells
Solution Approach 1:
The stabilizing assembly serves as a mediator between the flexible mobile frame and the rigid sensor assembly. It allows the frame to remain flexible for terrain adaptability while isolating the load cells from the resulting horizontal error forces, thus maintaining measurement reliability despite frame bending.
Solution Approach 2:
The system separates the mobility function (flexible frame) from the measurement function (rigid sensor assembly) through structural segmentation. The stabilizing assembly creates distinct zones: one that accommodates frame flexibility and another that maintains measurement stability, allowing both terrain adaptability and measurement reliability.
3Stability of the object's composition
If the load cell is rigidly mounted to the frame, then structural stability is improved, but horizontal forces from frame bending are transmitted to the load cell causing measurement error
Solution Approach 1:
The mounting structure is segmented into a rigid support framework and a flexible coupling mechanism. The rigid framework provides structural stability, while the flexible coupling (through the stabilizing assembly) prevents transmission of horizontal error forces to the load cell, maintaining both stability and precision.
Solution Approach 2:
Different parts of the mounting structure have different mechanical properties: the main support structure is rigid for stability, while the connection points to the load cell incorporate flexibility through the stabilizing assembly. This local differentiation allows the structure to be stable overall while protecting the sensitive measurement points from horizontal forces.
4Measurement precision
If the sensor assembly is made sensitive to detect small weight increments, then measurement precision is improved, but the system becomes more susceptible to error forces
Solution Approach 1:
The stabilizing assembly acts as a protective intermediary that filters out horizontal error forces before they reach the sensitive sensor assembly. This allows the load cells to be highly sensitive to small weight increments without being equally sensitive to harmful horizontal forces, as the intermediary selectively blocks the error forces.
Solution Approach 2:
The force transmission path is segmented into vertical weight force transmission (allowed through to the load cells) and horizontal error force transmission (blocked by the stabilizing assembly). This segmentation enables the sensor assembly to be highly sensitive to vertical weight changes while being protected from horizontal error forces.
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 accurate measurement of small weight increments, such as 20 kg, within a larger container load, by isolating horizontal error forces and maintaining the stability of the load cells, thus improving the overall accuracy of weight measurements.
Implementation Method 1
The load cell includes a plurality of strain gauges and coupling elements in a floating mount configuration
Data Source
AI summary
A mobile apparatus for carrying and weighing a load includes a mobile frame supported by a plurality of wheels. At least one container is supported on the mobile frame for carrying a load. A plurality of sensor assemblies are coupled between the frame and the container, the sensor assemblies resistive to a weight force exerted by the container towards the frame in a generally vertical sensing direction for sensing a weight of the load, and the sensor assemblies non-resistive to error forces exerted generally orthogonally to the sensing direction for filtering out the error forces from the sensed weight. A stabilizing assembly is coupled between the container and the frame, the stabilizing assembly freely accommodating transfer of the force exerted by the container towards the frame in the sensing direction, and simultaneously inhibiting shifting of the container relative to the frame in one or more shifting directions perpendicular to the sensing direction.