Tri-Axis Force Sensor Using Hall and Piezoresistive Sensing
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Solution Overview
Problem
Existing tactile sensing technologies in robotics fail to provide high-resolution force sensing and dimensionality, are bulky, and face size and weight constraints, limiting their applicability in complex environments.
Innovation Solution
A force sensor incorporating a deformable substrate with a magnet and Hall effect sensors, utilizing a multilayer structure to measure both normal and tri-axis contact forces, combining piezoresistive and Hall effect sensing principles to estimate contact force magnitude, location, and direction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If known sensor arrays are used for tactile force sensing, then force sensing capability is provided, but the sensors are bulky and subjected to physical size and weight constraints
Solution Approach 1:
The patent replaces traditional mechanical force sensing elements with a magnetic field-based sensing system. Magnets are embedded in the deformable substrate, and Hall effect sensors detect magnetic field changes caused by substrate deformation under force. This substitution eliminates bulky mechanical components while maintaining force sensing capability, directly resolving the contradiction between measurement precision and weight.
Solution Approach 2:
The patent employs a deformable substrate that acts as a flexible thin film structure. This substrate deforms under applied force and transmits the deformation to the embedded magnets, which in turn modulate the magnetic field detected by Hall effect sensors. The flexible substrate enables high-resolution force sensing across a large area without adding significant weight, addressing both the precision and weight constraints.
2Measurement precision
If known sensor arrays are used for tactile force sensing, then force sensing capability is provided, but the sensors are bulky and subjected to size constraints
Solution Approach 1:
The patent replaces traditional mechanical force sensing elements with a magnetic field-based sensing system. Magnets are embedded in the deformable substrate, and Hall effect sensors detect magnetic field changes caused by substrate deformation under force. This substitution eliminates bulky mechanical components while maintaining force sensing capability, directly resolving the contradiction between measurement precision and weight.
Solution Approach 2:
The patent transitions from direct mechanical contact sensing to magnetic field-based sensing, adding a dimensional shift from physical mechanical interaction to electromagnetic field interaction. This allows the sensing system to be distributed across a large two-dimensional area of the deformable substrate without increasing volume, as the magnetic field penetrates through the substrate thickness without requiring additional space.
3Measurement precision
If high-resolution force sensing is implemented, then tactile sensing sensitivity is improved, but device complexity increases
Solution Approach 1:
The deformable substrate serves multiple functions simultaneously: it acts as the sensing element that deforms under force, as the embedding medium for the magnets, and as the transmission medium that couples mechanical deformation to magnetic field modulation. This multi-functionality reduces device complexity by eliminating the need for separate components for each function, while still achieving high-resolution force sensing.
Solution Approach 2:
The patent merges the force transmission function and the sensing function into a single integrated structure. The deformable substrate with embedded magnets combines mechanical deformation capability with magnetic field generation, and the Hall effect sensors simultaneously detect both the substrate position and the magnetic field changes. This merging reduces the number of separate components and simplifies the overall device structure while maintaining high sensing resolution.
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 sensor provides improved tactile sensing with high sensitivity, robustness, and form factor, enabling precise estimation of contact information for enhanced safety and stability in robotic interactions.
Implementation Method 1
a deformable substrate that deforms under the contact force
Implementation Method 2
a second sensor for sensing, and producing an output from, a relative displacement of the body relative to the second sensor, wherein the second sensor is one or more Hall effect sensors
Implementation Method 3
The first sensor may comprise one or more sensors each being one of a matrix piezoresistive sensor
Data Source
AI summary
A force sensor comprising a contact arrangement for transmitting a contact force to a force sensor assembly. The force sensor assembly comprising a first sensor sensing, and producing an output from, a normal contact force component of the contact force; and a body moveable on transmission of the contact force to the force sensor assembly; and a second sensor for sensing, and producing an output from, a relative displacement of the body relative to the second sensor, the a tri-axis contact force being determined from the relative displacement.