Reachability Control for Safe Autonomous State Transitions
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Solution Overview
Problem
As autonomous systems become more complex and operate in unpredictable environments, it becomes increasingly difficult to ensure correct operation and safety, as current certification methods require analyzing all possible states, which is infeasible in complex scenarios.
Innovation Solution
The system incorporates a reachability controller that analyzes the current state and control signals to determine if a transition to a new state will result in a safe state, and if additional safe states can be reached from that new state, thereby blocking unsafe transitions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If all possible states are analyzed to ensure system safety, then system reliability is improved, but device complexity and testing requirements increase significantly
Solution Approach 1:
The reachability controller performs preliminary analysis of potential future states before the autonomous system actually transitions to them. By computing reachable sets and analyzing safety properties in advance, the system identifies unsafe states and prevents transitions to them, ensuring safety without requiring exhaustive testing of all possible states.
Solution Approach 2:
The reachability controller acts as an intermediary between the controller and the autonomous system. It receives control signals, analyzes their safety implications by computing reachable sets, and only allows safe transitions to proceed. This intermediary layer ensures safety without requiring the main controller to perform exhaustive state analysis.
2Reliability
If exhaustive state analysis is performed to certify autonomous systems, then system reliability is improved, but loss of time increases due to extensive testing requirements
Solution Approach 1:
Safety analysis is performed preliminarily and continuously during operation rather than through exhaustive post-deployment testing. The reachability controller computes reachable sets and verifies safety properties in real-time, allowing the system to be certified through operational analysis rather than extensive pre-testing.
Solution Approach 2:
The system implements continuous feedback through the reachability controller, which monitors control signals, analyzes their safety implications, and provides immediate feedback on whether transitions are safe. This continuous verification replaces the need for extensive external testing and accelerates the certification process.
3Adaptability or versatility
If the system allows all possible state transitions to maintain flexibility, then adaptability is improved, but system safety deteriorates due to increased risk of unsafe states
Solution Approach 1:
The reachability controller serves as an intermediary that receives control signals from the controller, analyzes their safety implications by computing reachable sets, and selectively permits or blocks transitions. This maintains the controller's flexibility in choosing actions while ensuring that only safe transitions are executed.
Solution Approach 2:
The system dynamically changes the parameter of state transition permission based on reachability analysis results. When reachable sets indicate safe transitions, the system allows full flexibility; when unsafe states are detected, transitions are blocked. This dynamic parameter adjustment maintains adaptability while ensuring safety.
Data Source
AI summary
An autonomous system includes a vehicle operable to travel from a first point to a second point, a first actuator operable to adjust a speed of the vehicle, and a second actuator operable to adjust a direction of travel of the vehicle. A controller is operable to send control signals to the first actuator and the second actuator to facilitate the transition of the system from a first state to a second state during travel between the first point and the second point. A reachability controller is coupled to the controller to receive the first state and the control signals and to analyze the first state and the control signals to determine if the second state is a safe state.