Personal Rapid Transit - Part 3

The software.

SOFTWARE
What makes all the hardware of the  Morgantown / West Virginia University - Personal Rapid Transit System go, and go safely, is the software sub system set up 35 years ago. The operational software is broken up into three segments which reside in computers at separate locations. The passenger Station Segment resides at each of the five passenger stations. The Central Segment resides at Central Control and the Maintenance Station Segments resides at the Maintenance Station. Central Control as you might suspect collects all the data, logs the history of the systems operation, and is where the big picture of the entire system operation is displayed on a mimic display. Each of the Stations is involved in the tiny but critical details of making everything mesh. The Maintenance Station is involved in scheduled preventative maintenance and repair of the system to eliminate system breakdowns and unplanned outages.

The operating algorithms are:

1. Synchronous Vehicle Control
Numbered imaginary points circulate around the main guideway, which are 15 seconds apart. The vehicles are dispatched to the guideway so that they will merge with and closely follow an assigned moving point. Presence detectors monitor each vehicles position relative to its assigned point and adjust its speed if the vehicle is 1.1 seconds ahead or behind its assigned moving point. The speed of the moving points change along the guideway reaching as high as 30 mph in some sections and the vehicle has to change speed to keep up with the moving point. If the time between presence detectors built into the guideway is too short, the vehicle will be declared a "runaway,” which causes its brakes to be applied, and power to be shut off to the section it is traveling in.

2. Vehicle Dispatch Logic
Each vehicle leaving a station is commanded to start at a precise time calculated to accomplish a successful merge with its assigned (moving) point on the guideway. A check is made to make sure the assigned point is clear before merging.

3. Vehicle Arrival Logic
As vehicles approach their destination a switch command loop is set to cause the vehicle to enter the station entrance ramp. The presence detector on the ramp must be hit in order for the vehicles assigned point on the guideway to be cleared for another vehicle to use downstream of the station.

4. Channel Management
In the station each vehicle stops as an unloading berth first, then when empty, moves ahead to a loading berth from which it is dispatched to the main guideway moving towards its destination.

5. Demand Mode
Vehicles are assigned to groups of passengers based on the number of people waiting (1 to 21 people) for a particular destination and the length of time that they have been waiting (maximum of 5 minutes).

6. Schedule Mode
A master schedule, made up of series of sub schedules are run specific times of day between specific origin-destination pairs during very high, predictable, demand periods. These schedules are based on system traffic history and produce a slightly higher efficiency than the demand mode.

7. Transition Algorithm
Automatic redistribution of vehicles throughout the system takes place just before moving into Schedule Mode so that all the assets are in place for Schedule Mode to begin.

8. Anomaly Management
When there is an interruption of service caused by an equipment failure, automatic action is taken to protect passengers in the trailing vehicles. Demand mode is used to keep traffic flowing as much as possible, outside of the affected area, until maintenance crews can clear the fault and restore operation to the affected section.

9. Vehicle Redistribution
If a station is not capable of handling the passenger demand with the vehicles on hand plus the expected arrivals, vehicles are automatically redistributed throughout the system to meet the demand.

The original 1975 plans for the M/WVU - PRT command and control system.

C² PARTS
The three main parts of this diagram are the Vehicle, Typical Station, and Central Control. The vehicles communicate with the station in whose operating area they are, which in turn communicates with Central Control. Most of the communication traffic is in and around the stations and deals with the timing of arrivals and departures.

GO ROBOTS !

Paul F. Grayson - Chief Engineer
AMERICAN INDUSTRIAL MAGIC, LLC
Racing to build technology that saves soldier’s lives.
390 4-Mile Rd. S.
Traverse City, MI 49686-8411
(231) 946-0187, (231) 883-4463 Cell
pgrayson@aimagic.org
AIM: http://aimagic.org
Robot Club: http://tech.groups.yahoo.com/group/robotcluboftraversecitymi/
CE Magazine: /blog/1180000318.html
pfg: (s),(l), tt