Sensorized Gripper Finger for Decoupled Force and Moment Sensing
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Solution Overview
Problem
Existing robotic fingers struggle to accurately detect both axial loading force and bending moment over a wide range of forces, often having bulky structures and limited sensor integration, which complicates their performance and robustness.
Innovation Solution
A sensorized finger with a two-axis load cell and tactile sensor array, utilizing strain gauges in a Wheatstone half-bridge configuration, decouples force and moment measurements, allowing precise detection of axial force and bending moment, and integrates multiple sensors for compact and robust operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple sensors are integrated into the finger structure, then measurement precision and functionality are improved, but device complexity increases
Solution Approach 1:
The patent combines multiple sensing functions (force detection and moment detection) into a single integrated load cell structure. The load cell simultaneously measures axial force through strain gauges on the stem and bending moment through strain gauges on the gripping head, reducing the number of separate sensor components needed while maintaining high measurement precision
Solution Approach 2:
The load cell is designed as a multi-functional sensor that performs both force measurement and moment measurement capabilities. By making the load cell universal in its sensing functions, the patent reduces overall device complexity while achieving comprehensive measurement of mechanical interactions
2Ease of operation
If the finger structure is made compact, then ease of operation and integration are improved, but manufacturing precision requirements increase
Solution Approach 1:
The strain gauges are pre-positioned and pre-wired onto the load cell structure during manufacturing, with connection cables routed through predefined channels in the finger structure. This preliminary arrangement of sensing elements and their connections simplifies subsequent assembly operations while ensuring precise sensor positioning is achieved during the initial manufacturing process
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 sensorized finger achieves accurate detection of axial force and bending moment, enabling safer and more complex robotic interactions with high precision and flexibility, suitable for medium-heavy industrial applications.
Implementation Method 1
The stem is provided with a load cell sensitive to the axial force (FZ) acting on the gripping head along the force application axis (Z) and to the bending moment (MY) acting along a finger bending axis (Y) orthogonal to the stem axis (X) and to the force application axis (Z). The load cell comprises a first pair of strain gauges positioned on the first stem surface and aligned along the stem axis and a second pair of strain gauges positioned on the second stem surface and aligned along the stem axis.
Implementation Method 2
One of the first and the second pair of strain gauges is connected so as to form a Wheatstone half-bridge; the other one of the first and the second pair of strain gauges is connected so as to form a Wheatstone half-bridge with a diagonal configuration.
Data Source
Figure 1
Figure 2~3
Figure 3a~3b
AI summary
A sensorized finger for a gripper, in particular for robotic applications, comprises a stem terminating in a gripping head, wherein the stem is provided with a load cell sensitive to the axial force ( Fz) acting on the gripping head and to the bending moment (My) acting along a finger bending axis (Y). The load cell comprises two strain gauges, one of the first and the second pair of strain gauges being connected so as to form a Wheatstone half-bridge, and the other one of the first and the second pair of strain gauges being connected so as to form a Wheatstone half-bridge with a diagonal configuration.