Robot Joint Fault Detection Using Multi-Sensor Control Signals
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Solution Overview
Problem
Existing robot joint control systems lack robust and cost-effective error detection methods during operation, which can lead to unreliable performance and safety issues.
Innovation Solution
A method and device for controlling an actuator-driven robot joint using multiple sensors (current, position, and torque sensors) with error detection through a combination of analytical and signal-based methods, including process model-supported and signal-based error detection, to identify deviations from predetermined limit conditions and trigger appropriate reactions such as braking or warning signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple sensors and error detection methods are implemented to improve reliability, then error detection capability is improved, but device complexity increases
Solution Approach 1:
The error detection system is segmented into multiple independent error detectors (first error detector for limit value conditions, second error detector for process model conditions, third error detector for signal-based conditions). Each detector operates independently on different aspects of sensor data, allowing comprehensive error detection while maintaining modular complexity that can be implemented incrementally
Solution Approach 2:
The control device is designed with multi-functional error detectors that can handle multiple types of error detection using the same sensor inputs. The first through third error detectors collectively provide limit value checking, process model validation, and signal-based error detection, making the system universally applicable to various error conditions without requiring separate dedicated systems for each detection method
2Reliability
If comprehensive error detection with multiple detectors is used to improve safety, then reliability is improved, but cost increases
Solution Approach 1:
The error detection system utilizes self-service by processing existing sensor measurements through multiple detection layers without requiring additional expensive hardware. The first error detector uses predetermined limit values, the second uses process models, and the third uses signal analysis - all leveraging the same sensor inputs to provide comprehensive error detection at minimal additional cost
Solution Approach 2:
The system employs computationally efficient error detection methods that can be implemented as software algorithms rather than expensive hardware components. The limit value checking, process model comparison, and signal-based detection are designed to run on standard control processors, avoiding the need for costly redundant sensor channels or specialized safety hardware
3Measurement precision
If multiple sensor signals are processed through multiple error detectors, then measurement precision is improved, but processing time increases
Solution Approach 1:
The control device performs preliminary error detection by first checking limit value conditions in the first error detector before proceeding to more complex process model validation in the second error detector and signal-based analysis in the third error detector. This hierarchical approach allows quick rejection of obvious errors while reserving more computationally intensive analysis for cases that require it, reducing overall processing time
4Reliability
If redundant error detection mechanisms are implemented to improve reliability, then safety is improved, but ease of operation becomes more difficult
Solution Approach 1:
The control device merges the outputs of the first, second, and third error detectors into a unified error detection response. When any of the error detectors detect an error condition, the control device triggers appropriate safety reactions, presenting a simplified operational interface despite the complex multi-layered error detection mechanisms working in the background
Data Source
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AI summary
The invention relates to a method and a device for the open-loop/closed-loop control of a robot joint driven by an electric motor, the robot joint having: a current sensor with a first sensor electronics system for detecting a first operating current i<sb /> k,1 (t)of the electric motor, where k = 1, 2,...; a first position sensor for detecting an input positionθ m (t) of a power train of the robot joint; a second position sensor for detecting a power take-off position q(t) of a power take-off train of the robot joint and a first torque sensor for detecting a torqueτ J ,l(t) in the power take-off train, the electric motor being open-loop/closed-loop controlled on the basis of a predefined target manipulated variable zm(t). The method disclosed comprises the following steps: provision*(101) of the measured values θ <sb /> m <sb /> (t),i <sb /> k, l(t),τ J (t),q(t), checking (102) for the presence of a fault by the first fault detector, which detects the presence of a fault if the measured valuesθ m (t),i k, l(t),τ J (t),q(t) and/or their time derivatives do not fulfil predefined first limit value conditions, and checking (103) for the presence of a fault by additional fault detectors.