Magnetic Tactile Sensor Calibration via Offset Parameter Derivation
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Solution Overview
Problem
Magnetic tactile sensors require time-consuming calibration due to inconsistencies in magnet placement and deformation, making it difficult to accurately measure external forces, especially on curved surfaces where sensors are disposed at different attitudes.
Innovation Solution
A detection device and calibration method that use a relational expression to associate sensor output values with physical quantities, involving a function derivation unit to calculate parameter values from offset values, allowing for quick and accurate calibration of multiple sensors on varying surfaces by measuring offset values and applying known external forces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional calibration methods using testing devices are used for each tactile sensor, then measurement precision is improved, but productivity deteriorates due to extremely time-consuming calibration work
Solution Approach 1:
The invention creates a virtual model (copy) of the robot's surface geometry and sensor positions, and performs calibration calculations in this virtual space rather than requiring physical testing for each sensor. The coordinate transformation relationships are computed based on the geometric model, eliminating the need for time-consuming physical calibration procedures while maintaining accuracy.
Solution Approach 2:
The invention replaces the mechanical calibration process (using physical testing devices to apply forces) with a computational approach. By using coordinate transformation algorithms and geometric modeling, the calibration is performed through mathematical calculations rather than physical mechanical testing, dramatically reducing calibration time.
2Adaptability or versatility
If tactile sensors are disposed at predetermined spots on curved surfaces, then adaptability is improved, but measurement precision deteriorates due to magnet position displacement from elastic body deformation
Solution Approach 1:
The invention compensates for magnet position displacement by introducing coordinate transformation parameters. The calibration process calculates transformation relationships between the sensor coordinate system and the robot coordinate system, accounting for the actual positions of magnets even when displaced from ideal locations. This allows the system to adapt to curved surfaces while maintaining measurement accuracy through parameter adjustment.
3Adaptability or versatility
If many tactile sensors are disposed at different attitudes on various surfaces, then adaptability is improved, but device complexity increases making calibration difficult
Solution Approach 1:
The invention creates a universal calibration framework that handles sensors at different positions and orientations through a unified coordinate transformation approach. The same basic calibration algorithm and geometric modeling techniques are applied regardless of sensor location or attitude, making the calibration process systematic and manageable even for complex multi-sensor configurations.
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 rapid and precise calibration of tactile sensors on different surface shapes by determining parameter values for each sensor, reducing the need for extensive calibration procedures and allowing accurate measurement of external forces across multiple sensors.
Implementation Method 1
a magnetic tactile sensor using changes in a magnetic field due to the action of an external force. The magnetic tactile sensor is provided with an elastic body having a surface on which the external force acts, a magnet secured inside the elastic body, and a magnetic sensor that detects the state of a magnetic field generated by the magnet.
Data Source
AI summary
A detection device 12 according to the present invention is provided with a calibration means 14 that specifies a relational expression between an output value from a force sensor 11 when an external force is applied and the magnitude of the external force. The relational expression contains a formula that includes a predetermined parameter and with which it is possible to calculate, according to an offset value obtained as the output value when the sensor is free of contact and not acted upon by the external force, the magnitude of the external force from the actual output value. The calibration means 14 is provided with a function derivation unit 17 that derives a function for calculating the parameter value from the offset value, and a parameter value determination unit 18 that uses the function to determine the parameter value. The function derivation unit 17 generates the function from the output value when a known external force is applied and an offset value from a preceding step, and the parameter value determination unit 18 calculates the parameter value from the offset value acquired in a state in which the force sensor 11 is disposed on a predetermined site where the external force is to be measured.