Multi-Axis Kinematic Safety Setup Using Worst-Case Error Compensation
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Solution Overview
Problem
Conventional safety monitoring systems for multi-axis kinematic systems often fail to accurately account for errors caused by sensor inaccuracies and inertias, leading to overly conservative safety measures that reduce system availability and reliability.
Innovation Solution
A method that calculates compensation values based on specific error values and geometric parameters of the kinematic system, allowing for precise adjustments to safety functions, such as safe zone monitoring and speed limits, to account for sensor errors and run-on distances, thereby enhancing safety without unnecessary restrictions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional statistical error calculation methods are used for safety monitoring, then the safety function can be implemented, but the error compensation is insufficient because mean deviations are calculated instead of worst-case deviations
Solution Approach 1:
The patent changes the error calculation parameter from mean deviation (statistical average) to worst-case deviation (maximum possible error). This is achieved by calculating compensation values based on maximum error propagation through the kinematic chain, considering all possible combinations of axis errors. The compensation value is determined by evaluating the Jacobian matrix and error propagation equations to find the maximum possible deviation, ensuring safety monitoring accounts for the worst-case scenario rather than average conditions.
2Reliability
If general correction values are used without specific kinematic system knowledge, then safety-oriented operation can be ensured, but the availability of the multi-axis kinematic system is unnecessarily reduced
Solution Approach 1:
The patent applies local quality by tailoring the error compensation specifically to each kinematic system's unique characteristics. Instead of using universal conservative correction values, the system calculates compensation values based on the specific geometric parameters (link lengths, joint configurations), actual sensor error values, and operational trajectories of that particular kinematic system. This localized approach ensures safety while minimizing unnecessary restrictions on system operation, as the compensation is precisely matched to the actual error sources present in each specific application.
Solution Approach 2:
The patent performs preliminary calculation of compensation values during the setup phase, before actual operation begins. The system pre-calculates compensation values by analyzing the specific kinematic chain, sensor error characteristics, and planned trajectories. These pre-computed compensation values are then applied during operation, allowing the system to run with optimized safety parameters rather than conservative defaults, thereby maintaining high availability while ensuring safety.
3Reliability
If conservative safety margins are applied to account for sensor errors and inertias, then safety is improved, but system performance and efficiency are reduced due to unnecessary restrictions
Solution Approach 1:
The patent applies partial action by calculating compensation values that are sufficient to cover actual error sources without being excessively conservative. Instead of applying uniform large safety margins to all operations, the system calculates precise compensation values based on actual sensor error specifications and kinematic parameters. The compensation is applied selectively - only to the extent necessary to cover the calculated worst-case deviations - allowing the system to operate efficiently within accurately determined safety boundaries rather than being restricted by overly conservative general margins.
Data Source
AI summary
A method for setting up safe operation of a multi-axis kinematic system, a method for safely operating a multi-axis kinematic system, and to an input device for setting up safe operation of a multi-axis kinematic system and a corresponding computer program product. A method includes providing error values of respective axes and ascertaining a compensation value for at least one variable of the safety function on the basis of the error values, on the basis of geometric parameters of the multi-axis kinematic system and on the basis of axis values of the respective axes that are obtained from trajectories of the multi-axis kinematic system.