Robotic Arm Fault Isolation for Graceful Degradation Control
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Solution Overview
Problem
Robotic systems with multiple arms face challenges in handling faults, as existing methods either require costly redundancy or preventive maintenance, and often shut down entirely upon fault detection, failing to differentiate between system and local faults, which can lead to unnecessary system-wide shutdowns.
Innovation Solution
A method and system for fault reaction, isolation, and graceful degradation, where faults in robotic arms are detected, isolated, and managed by placing failed arms into a safe state, with a supervisor processor determining whether the fault is system or local, and only affecting non-failed arms if it's a system fault, allowing for continued operation in a degraded state if safe.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the entire robotic system is turned off upon fault detection for safety reasons, then system safety is improved, but system productivity is worsened due to unnecessary shutdowns
Solution Approach 1:
The robotic system is divided into independent functional modules (robotic arms, processors, sensors). When a fault is detected, only the affected module is isolated and shut down, while other modules continue to operate. This segmentation allows the system to maintain partial functionality rather than complete shutdown, resolving the contradiction between safety and productivity.
Solution Approach 2:
A supervisor processor acts as an intermediary between fault detection and system response. It analyzes fault information, determines the scope of impact, and coordinates the isolation of only affected components. This intermediary enables intelligent decision-making that prevents unnecessary system-wide shutdowns while maintaining safety.
2Reliability
If redundant components are provided to prevent fault loss, then system reliability is improved, but system cost is worsened
Solution Approach 1:
The robotic system implements self-diagnosis and self-isolation capabilities through distributed sensors and processors. Each component can detect its own faults and trigger isolation protocols automatically. This self-service approach provides fault tolerance without requiring redundant backup components, reducing system cost while maintaining reliability.
Solution Approach 2:
The system performs preliminary fault detection and classification before taking isolation actions. By detecting faults early and determining their scope in advance, the system can prepare appropriate responses without needing redundant components. This preliminary action enables cost-effective fault tolerance through intelligent control rather than hardware redundancy.
3Reliability
If non-failed arms are placed in safe state for system faults, then system safety is improved, but system adaptability is worsened due to loss of degraded operation capability
Solution Approach 1:
The safety response is made local rather than global. The supervisor processor determines whether a fault is local (affecting one arm) or system-wide (affecting multiple arms). For local faults, only the affected arm is isolated, allowing other arms to continue operating. This local quality approach maintains adaptability while ensuring safety by matching the isolation scope to the actual fault scope.
Data Source
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AI summary
A robotic system has arms, arm processors, arm supervisor, and system supervisor. Each arm includes nodes for controlling motors in the arm. Each node, including each arm processor, detects faults affecting the node, places the node into a safe state upon detecting a fault, propagates a fault notification, diagnoses the fault and classifies it, and sends an error message to the supervisor processor. The arm supervisor may detect faults affecting an arm and also perform fault reaction activities. The system supervisor handles the fault as either a system or local fault depending upon its class. For system faults, a fault notification is sent to the arm processors of non-failed arms so that the non-failed arms are placed in the safe state. For local faults, a degraded operation option is provided to a user and if the fault is classified as recoverable, a recovery option is provided to the user.