Stop Trajectory Automation for Mobile Machine Safety
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Solution Overview
Problem
Existing automation systems for mobile machines face challenges in accurately detecting failures and transitioning to stop trajectories, which can lead to unexpected behavior, delayed or disrupted payloads, and potential collisions.
Innovation Solution
The implementation of an automation system that generates and manages stop trajectories in conjunction with destination trajectories, using sensors and computers to detect failures and initiate smooth stops, while also considering traffic conventions and obstacle avoidance.
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 safety is improved, but unexpected behavior and payload delays occur
Solution Approach 1:
The system pre-generates multiple stop trajectories at different locations along the destination trajectory before failure occurs. When failure is detected, the controller can immediately switch to an appropriate pre-planned stop trajectory, eliminating the need for real-time trajectory generation during emergency stops. This preliminary preparation enables rapid response to failures without disrupting payload delivery schedules.
2Productivity
If the automation controller is too aggressive and does not detect failure when failure actually occurs, then productivity is maintained, but the mobile machine may be unable to complete its mission
Solution Approach 1:
The failure detection system is divided into multiple independent monitoring modules that track different aspects of system health (sensor functionality, computer operations, actuator responses). Each module can independently detect specific failure modes, allowing the controller to identify failures with high sensitivity while maintaining overall system productivity through selective response to actual failures.
3Reliability
If the automation controller stops the mobile machine immediately upon failure detection, then safety is improved, but complex failure detection and smooth stopping become difficult
Solution Approach 1:
Multiple stop trajectories are pre-calculated and stored in memory at various locations along the destination trajectory, each representing a safe stopping path for different failure scenarios. When failure is detected, the controller simply selects the appropriate pre-computed trajectory and executes it, avoiding the need for complex real-time calculations while ensuring safe stopping behavior.
4Loss of time
If multiple stop trajectories are pre-calculated and stored, then response time to failure is reduced, but memory requirements and computational load increase
Solution Approach 1:
Instead of storing complete stop trajectories for all possible failure locations, the system generates and stores only the critical segments of trajectories that are most likely to be needed. The stop trajectories are segmented into manageable portions, with full trajectories generated on-demand for less critical scenarios. This local optimization reduces memory requirements while maintaining rapid response capability for the most probable failure modes.
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.