Force Torque Sensor Self-Calibration via Actuator Dynamics
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Solution Overview
Problem
Current calibration methods for multi-axial force and torque measuring devices require precisely known external forces and torques, leading to measurement uncertainties due to vertical alignment constraints and lever uncertainties, with no official standards for multi-component sensors, resulting in relatively high uncertainties even with complex calibrations.
Innovation Solution
A device and method utilizing a mechanically rigid carrier with position and speed measuring systems, electrical actuators, and an evaluation unit to transmit and measure forces and torques in all degrees of freedom, allowing for self-calibration independent of external forces and spatial direction, using actuator parameters determined by induced voltages and movement speeds.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If external forces and torques are used for calibration, then calibration can be performed according to existing standards, but measurement uncertainties increase due to vertical alignment constraints and lever uncertainties
Solution Approach 1:
The measuring device calibrates itself by utilizing its own actuators to generate forces and torques. The actuators serve dual purposes: both as measurement actuators during normal operation and as calibration actuators during calibration, eliminating the need for separate external calibration forces and reducing measurement uncertainties
Solution Approach 2:
The actuators are designed to perform multiple functions: they serve as both measurement actuators for detecting forces and torques during normal operation and as calibration actuators for generating known forces and torques during calibration, thereby eliminating the need for separate calibration equipment
2Measurement precision
If reference measuring systems are used for calibration, then known external forces can be provided, but adverse measurement deviations arise from position changes between calibration and use
Solution Approach 1:
The system performs self-calibration using its own actuators and measurement systems, eliminating the need for external reference systems. This ensures that the calibration is always performed in the exact same position and configuration where the device will be used, preventing position-related measurement deviations
Solution Approach 2:
The control unit acts as an intermediary that coordinates the calibration process by controlling the actuators to generate calibration forces and torques, and by processing the measurement data to determine calibration parameters, ensuring consistent results
3Measurement precision
If levers are used for torque calibration, then torques can be generated using forces and lever arms, but the uncertainty of lever length significantly affects calibration results
Solution Approach 1:
The measuring device uses its own actuators to generate calibration torques directly, eliminating the need for external levers. The actuators apply forces at precisely known positions relative to the measurement point, eliminating uncertainties associated with mechanical lever length
Solution Approach 2:
The patent replaces the mechanical lever system with an actuator-based system. Instead of using physical levers with uncertain lengths, electromagnetic or piezoelectric actuators generate forces at precisely controlled positions, substituting mechanical precision requirements with controllable actuator positioning
4Adaptability or versatility
If multi-axis measuring devices are calibrated using uniaxial calibration methods, then existing calibration standards can be applied, but no official calibration procedures exist for multi-component sensors
Solution Approach 1:
The calibration method is designed to be universally applicable to multi-axial measuring devices by using multi-functional actuators that can generate forces and torques in all measurement directions. The same actuator system used for measurement serves for calibration in all axes, ensuring consistent and accurate multi-axial calibration
Solution Approach 2:
The calibration process dynamically activates different actuators to generate forces and torques in various directions as needed. The system can switch between different calibration modes (force calibration, torque calibration, or combined) by controlling which actuators are active, providing versatile calibration capability
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 traceable, high-accuracy calibration of force and torque measuring devices without external forces, reducing measurement uncertainties and allowing for simultaneous detection of multiple components, both statically and dynamically, with reduced parasitic movement effects.
Implementation Method 1
electrical actuators (3) which are designed and arranged so that a force and moment transmission to the beam (1) is possible in all degrees of freedom
Implementation Method 2
position measuring systems (2) for measuring all degrees of freedom of the spatial position and rotation of the beam (1) with respect to the frame
Implementation Method 3
at least one velocity measuring unit (4) for recording the movement velocity v of the support (1) relative to the frame
Data Source
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AI summary
The present invention proposes a method and an apparatus for traceably calibrating multi-axis force and torque measuring devices on the basis of the determination of an actuator parameter. According to the invention, the calibration is carried out by measuring the actuation and reaction magnitude and the speed of a relative movement. In contrast to known solutions, the calibration can be carried out independently of the spatial direction. Therefore, the proposed method can be used both for single-axis force and/or torque measuring devices and for multi-axis force and/or torque measuring devices.