Compliant Robotic Tool Sensor for Normal and Shear Force Control
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Solution Overview
Problem
Existing robotic tactile sensors struggle to accurately measure and control contact forces, particularly on varying surfaces, due to issues with compliance and connection rigidity, which can lead to inadequate force application or damage.
Innovation Solution
A flexible tactile sensor with a conductive target and an array of induction coils, coupled by a pliable material, measures changes in inductance to determine force magnitude and direction, using a tool holder with sufficient rigidity to maintain accurate force measurement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the sensor is made more compliant to measure forces on various surfaces, then the sensor can adapt to rigid or non-rigid surfaces, but the robot cannot apply sufficient force to the contact surface via the tool
Solution Approach 1:
The sensor is divided into two distinct functional segments: a rigid tool holder for force application and a compliant sensing element for measurement. This segmentation allows each part to optimize its function - the rigid holder transmits force effectively while the compliant sensor adapts to surfaces.
Solution Approach 2:
A flexible coupling mechanism acts as an intermediary between the rigid tool holder and the compliant sensor element. This intermediary allows the tool holder to remain rigid for force application while enabling the sensor to be compliant for surface adaptation, resolving the contradiction through a mediating structure.
2Measurement precision
If connections are made rigid to transfer contact forces to the sensor, then force measurement accuracy improves, but tool replacement capability is reduced
Solution Approach 1:
The connection system is segmented into a rigid force transmission path and a modular tool interface. The rigid path ensures accurate force measurement while the modular interface enables easy tool replacement, allowing both requirements to be satisfied through functional separation.
Solution Approach 2:
The tool holder is designed with universal features that serve multiple functions: it provides rigid force transmission for accurate measurement, while also incorporating standardized interfaces for easy tool replacement. This multi-functionality resolves the contradiction by making the same structure serve both purposes.
3Adaptability or versatility
If the sensor is made too compliant, then the sensor can measure forces on various surfaces, but the sensor prevents the robot from applying sufficient force to the contact surface
Solution Approach 1:
The sensor system is segmented into a rigid force application component (tool holder) and a compliant measurement component (sensing element). This segmentation ensures that compliance is localized only where needed for surface adaptation, while the overall structure maintains sufficient rigidity for force application.
Solution Approach 2:
Compliance is applied locally only at the sensor element that contacts the surface, while the tool holder and force transmission path maintain high rigidity. This localized quality allows the sensor to be compliant where needed for measurement while remaining rigid where needed for force application.
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
Enables precise measurement and control of normal and shear forces, allowing robots to apply appropriate forces effectively without damaging surfaces.
Implementation Method 1
an electronic device electrically coupled to each of the at least three coils, the electronic device configured to induce an AC signal within each of the at least three coils and measure a change in inductance in the at least three coils in response to movement of the conductive target
Data Source
AI summary
In accordance with one embodiment of the present disclosure, a flexible tactile sensor includes a conductive target positioned in a first plane, a tool holder coupled to the conductive target configured to receive a tool, at least three coils forming an array within a second plane, the second plane spaced apart from the first plane, a pliable material coupling the conductive target to the at least three coils, and an electronic device electrically coupled to each of the at least three coils, the electronic device configured to induce an AC signal within each of the at least three coils and measure a change in inductance in the at least three coils in response to movement of the conductive target.