Robotic Tool Position Calibration Using Rotational Acceleration
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Solution Overview
Problem
Current robotic manipulator calibration techniques are inefficient and require visual data, physical targets, or human intervention, leading to increased production costs and frequent recalibrations due to difficulties in achieving precise calibration.
Innovation Solution
A technique that determines tool distance from the rotational axes of a robotic appendage using predicted and measured acceleration, eliminating the need for visual data and human intervention by correlating modeled and measured acceleration to estimate the tool's position, allowing for ongoing calibration during operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If visual data and physical targets are used for calibration, then measurement precision is improved, but device complexity and production costs increase
Solution Approach 1:
The patent extracts the calibration problem from complex visual target systems and reduces it to measuring only the distance between the rotation axis and tool center point. By using acceleration sensors and kinematic models, the system eliminates the need for visual data capture devices, physical calibration targets, and complex image processing systems, achieving accurate calibration with minimal hardware.
Solution Approach 2:
The patent replaces optical/mechanical calibration systems with an inertial measurement-based system. Instead of using cameras, visual targets, and mechanical measurement tools, the system uses acceleration sensors to measure tool acceleration during rotation and combines this with kinematic models to calculate calibration parameters, substituting a simpler sensor-based system for complex optical-mechanical systems.
2Ease of operation
If manual calibration techniques are used, then ease of operation is maintained, but productivity and time efficiency deteriorate
Solution Approach 1:
The calibration system performs self-calibration automatically without requiring human operators to manually manipulate calibration objects or interpret visual data. The system autonomously executes the calibration sequence by rotating the tool, measuring acceleration with sensors, processing the data through kinematic models, and computing calibration parameters, thereby eliminating manual intervention while maintaining operational simplicity.
Solution Approach 2:
The system performs preliminary calibration actions automatically during robot setup or maintenance periods. By pre-calibrating the robot-arm-tool system using the automated acceleration-based method, the system eliminates the need for repeated manual calibration operations, thereby improving productivity without compromising ease of operation when calibration is actually needed.
3Manufacturing precision
If frequent recalibration is performed, then manufacturing precision is maintained, but loss of time and productivity increase
Solution Approach 1:
The calibration system enables continuous or near-continuous calibration capability by using simple acceleration measurements that can be taken quickly during robot operation. The automated system can perform calibration sequences rapidly without requiring the robot to stop production for extended periods, maintaining manufacturing precision while minimizing calibration time through efficient sensor-based measurement and computation.
4Measurement precision
If complex calibration equipment is used, then measurement precision is improved, but ease of manufacture and cost increase
Solution Approach 1:
The system uses inexpensive acceleration sensors instead of expensive optical measurement equipment, cameras, and precision mechanical targets. The calibration approach relies on readily available inertial sensors and computational methods rather than costly specialized hardware, making the system easier to manufacture and implement while maintaining adequate calibration accuracy for industrial applications.
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
This method provides efficient, ongoing calibration without visual data or physical targets, reducing costs and improving precision by using accelerometers to track tool acceleration, thus simplifying the calibration process and reducing hardware wear.
Implementation Method 1
obtain acceleration measurements from a sensor affixed to the tool, the acceleration measurements taken during the rotational movement
Data Source
AI summary
System and techniques for tool position determination in a robotic appendage are described herein. A robotic appendage is put through a rotational movement to induce acceleration in a tool mounted to the appendage. A model for acceleration is created from positional kinematics of the appendage. A measurement of acceleration is taken at the tool and fit to the model to determine distance from the axis of rotation to the tool. The distance is provided for use in control or modeling of the robotic appendage.