Capacitive Force Torque Sensor Miniaturization via Nesting
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Solution Overview
Problem
Existing force/torque sensors, particularly capacitive types, face challenges in miniaturization, complexity in assembly, and reduced sensitivity when attempting to reduce size, making them unsuitable for applications like humanoid robots.
Innovation Solution
A capacitive force/torque sensor design featuring a ground unit with a deformable part and a sensor unit positioned within an internal space, utilizing rectangular electrodes that generate capacitance variations in response to 3-axis or 6-axis forces and torques, allowing for easy assembly and miniaturization while maintaining sensitivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If capacitive force/torque sensor size is reduced, then miniaturization is achieved, but measurement sensitivity is lowered
Solution Approach 1:
The sensor unit is positioned within the internal space of the ground unit, creating a nested configuration where the sensing electrodes are located inside the cavity of the ground unit. This nesting approach allows the sensor to achieve miniaturization while maintaining adequate sensing space for capacitance measurement, resolving the contradiction between small size and measurement sensitivity.
Solution Approach 2:
The patent utilizes three-dimensional space efficiently by positioning the sensor unit at different locations within the internal space of the ground unit. The deformable part extends in multiple directions to provide elastic deformation capability, allowing the sensor to detect forces in various orientations while maintaining a compact overall volume.
2Ease of manufacture
If capacitive force/torque sensor structure is simplified, then assembly ease is improved, but manufacturing precision requirements increase
Solution Approach 1:
The ground unit and sensor unit are integrated into a unified structure where the sensor unit is positioned within the internal space of the ground unit. This merging of components simplifies the overall assembly process while the deformable part provides a built-in mechanism for precise positioning and elastic deformation, reducing the need for separate precision assembly steps.
Solution Approach 2:
The deformable part is designed to automatically provide the necessary elastic deformation and positioning without requiring external adjustment mechanisms. This self-service capability simplifies assembly while maintaining precision, as the deformable part inherently provides the required geometric relationships between components.
3Measurement precision
If resistive type sensor is used, then measurement capability is achieved, but complexity of assembly and vulnerability to external impacts occur
Solution Approach 1:
The patent replaces the resistive type sensor with a capacitive type sensor that measures force and torque through capacitance variation. This substitution eliminates the need for separate strain gauge attachment procedures, significantly simplifying assembly while maintaining measurement capability. The capacitive sensor's integrated structure also reduces vulnerability to external impacts compared to resistive sensors with separate components.
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 design achieves miniaturization and high sensitivity, enabling effective detection of small forces and torques, suitable for use in compact applications such as humanoid robots, with a simple configuration that facilitates easy assembly and efficient capacitance measurement.
Implementation Method 1
a deformable part connecting the sensing part and the base part and elastically deformed
Implementation Method 2
a plurality of electrodes generating capacitances with the ground unit
Data Source
AI summary
A force/torque sensor includes a ground unit having an internal space, a sensor unit positioned within the internal space and including a plurality of electrodes generating capacitances with the ground unit, and a support unit combined with a portion of the ground unit and supporting the sensor unit.