PRT Vehicle Movement Envelope Control
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Solution Overview
Problem
In personal rapid transport (PRT) systems, there is a need for a method to control the movement of driverless vehicles within stations to avoid collisions and ensure safe transfer between main transport lanes and berthing areas without disrupting traffic flow.
Innovation Solution
A method that selects a path for a land vehicle between nodes, determines a desired movement envelope that does not conflict with other vehicles, communicates the path and start time, and adjusts vehicle movement to avoid conflicts, including stopping all vehicles if necessary, using positional information and conflict avoidance criteria to ensure safe operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If vehicles are allowed to move freely within the station between main transport lane and berthing area, then ease of operation is improved, but collision risk increases
Solution Approach 1:
The station space is segmented into discrete movement envelopes for different vehicles. Each vehicle is assigned a specific three-dimensional envelope (x, y, z coordinates with time component) that divides the shared space into non-overlapping zones. This segmentation allows multiple vehicles to operate simultaneously in different segments without collision risk.
Solution Approach 2:
The invention adds a time dimension to the spatial envelopes, creating four-dimensional movement envelopes (x, y, z, t). By considering temporal separation in addition to spatial separation, the system allows vehicles to use the same physical space at different times, maximizing utilization while preventing collisions.
2Adaptability or versatility
If vehicles transfer between main transport lane and berthing area, then adaptability is improved, but traffic flow disruption increases
Solution Approach 1:
The system pre-calculates and assigns movement envelopes to vehicles before they actually move. By determining collision-free paths and time windows in advance, vehicles can execute transfers predictably without causing unexpected disruptions to traffic flow. The preliminary assignment ensures that main transport lanes remain clear while allowing berthing area transfers.
3Reliability
If movement control is implemented to prevent collisions, then safety is improved, but system complexity increases
Solution Approach 1:
Instead of directly controlling each vehicle's physical movements, the system creates virtual copies called movement envelopes that represent each vehicle's intended path and time window. The control system operates on these simplified virtual models, determining envelope assignments algorithmically, then communicates only the essential start time and path information to vehicles. This copying approach simplifies the control logic compared to direct real-time coordination.
Data Source
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Figure 3
Figure 4a~5
AI summary
A method for controlling movement of a body within a system comprises: a) selecting a path for the body between a first node (B) and a second node (C), b) determining a desired movement envelope (20) for the body along the path that does not conflict with the movement envelope (23, 25) of any other body of the system, c) communicating the path and the start time of the desired movement envelope to the body, and d) causing the body to begin travelling over the selected path at the start time.