Mobile Machine Stop Trajectory Control for Failure-Tolerant Braking
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Solution Overview
Problem
Existing mobile machine automation systems face challenges in accurately detecting failures, leading to potential delays or mission failures due to conservative or aggressive fault detection mechanisms, which can result in unexpected behavior or incomplete tasks.
Innovation Solution
An automation system that generates and manages stop trajectories for mobile machines, using sensors and computers to periodically update and control actuators, ensuring smooth deceleration and safe stopping even in failure scenarios, with an exception stop feature for late-revealed obstacles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the automation controller is too conservative and detects failure more often than failure actually occurs, then the mobile machine can be protected from potential failures, but the system exhibits unexpected behavior and payloads are delayed or disrupted
Solution Approach 1:
The system pre-calculates and stores multiple stop trajectories at different locations along the mission path before failure occurs. When failure is detected, the controller immediately switches to the appropriate pre-computed trajectory, eliminating the need for real-time trajectory generation during emergency stopping.
Solution Approach 2:
The system prepares multiple candidate stop trajectories in advance, cushioning against the uncertainty of where and when failure might occur. This allows the controller to select from pre-vetted safe stopping options rather than reacting to failure in real-time, reducing both false positives and missed detections.
2Productivity
If the automation controller is too aggressive and does not detect failure when failure actually occurs, then the system maintains continuous operation, but the mobile machine may be unable to complete its mission or may cause damage
Solution Approach 1:
The system pre-calculates and stores multiple stop trajectories at different locations along the mission path before failure occurs. When failure is detected, the controller immediately switches to the appropriate pre-computed trajectory, eliminating the need for real-time trajectory generation during emergency stopping.
Solution Approach 2:
The system continuously monitors system state and compares it against expected operational parameters, providing feedback to the controller. This allows for reliable failure detection without excessive conservatism, as the feedback mechanism distinguishes between normal variations and actual failures.
3Adaptability or versatility
If the automation controller generates and manages stop trajectories in real-time, then the system can adapt to current conditions, but the computational complexity and response time increase
Solution Approach 1:
The system pre-calculates and stores multiple stop trajectories at different locations along the mission path before failure occurs. When failure is detected, the controller immediately switches to the appropriate pre-computed trajectory, eliminating the need for real-time trajectory generation during emergency stopping.
Solution Approach 2:
The mission path is divided into multiple segments with pre-calculated stop trajectories for each segment. This segmentation allows the controller to quickly select from discrete trajectory options rather than generating continuous trajectories in real-time, reducing computational complexity while maintaining adaptability.
Data Source
AI summary
In an embodiment, an automation controller periodically generates stop trajectories and controls actuators to follow the stop trajectories. As long as new stop trajectories continue to be generated, the automation controller may follow a destination trajectory that is formed from the first portion of each stop trajectory. If stop trajectories are not generated for a period of time (e.g., due to failure in one or more computers generating the stop trajectories), the automation controller may continue to follow the most recent stop trajectory and bring the mobile machine to a stop.