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Realtime Merging Controller for Automated Guideways

IP.com Disclosure Number: IPCOM000085948D
Original Publication Date: 1976-Jun-01
Included in the Prior Art Database: 2005-Mar-03
Document File: 4 page(s) / 39K

Publishing Venue

IBM

Related People

Chu, KC: AUTHOR [+2]

Abstract

In merging two strings of high-speed vehicles it is important that each of the vehicles on two merging guideways be assigned to new nonconflicting positions, so that smooth merging occurs at the junction of the guideways. The described controller provides a rapid, realtime assignment of vehicles to nonconflicting positions moving at constant velocity, and works for any traffic densities up to the saturation capacity of the merged guideway.

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Realtime Merging Controller for Automated Guideways

In merging two strings of high-speed vehicles it is important that each of the vehicles on two merging guideways be assigned to new nonconflicting positions, so that smooth merging occurs at the junction of the guideways. The described controller provides a rapid, realtime assignment of vehicles to nonconflicting positions moving at constant velocity, and works for any traffic densities up to the saturation capacity of the merged guideway.

Referring to Figs. 1 and 2, the vehicles on each of the guideways are controlled by individual on-board controllers optimally designed so that the vehicles occupy fictitious moving reference cells. (See references). When the vehicles reach a decision point some distance upstream from the guideway junction, a new reference position is assigned whenever this is necessary to eliminate a merging conflict within the assignment block.

This assignment must be based on the status of vehicles within the assignment block containing L(2) cells, and this status can be represented by binary vectors A and B of length L(2) containing a 1 in position k, if a vehicle is present in cell k and a 0 if cell k is unoccupied. This information, however, is not enough to base an assignment on. In addition, the last assigned position of vehicles which have passed the decision point must be known, so that no other vehicles will be assigned to that position.

This information is summarized by the number N(1), which is the number of unoccupied cells between the decision point and the assigned position of the last assigned vehicle. If N(1) is negative, this means that a vehicle which has already passed the decision point has been assigned to a cell which is still in the assignment block, so it is slowing down to move to this reference position.

Letting m(A) and m(B) denote the number of cells the vehicles at the decision point on guideways A and B, respectively, must move, the following assignments can be used: m(A) = A(1) x m(A,B,N(1)) m(B) = B(1) x [m(A,B,N(1)) - A(1)] where m(A,B,N(1)) = min[N(1), max[0,L2 over epsilon over i=1 (A(i) + B(i)) - L(2)]] and A(i) and B(i) are the bits (0 or 1) in the i/th/ position of A and B.

This rule gives priority to an A vehicle to move in front of a B vehicle. Furthermore, since there is a practical limit to the number of positions that a vehicle can be required to advance the limitation m(A) and m(B) < or - L(1) is imposed. When N = min [N(1),L(1)] is used in the expression for m(A,B,N) this limit is imposed.

It is noted that the above rule makes assignments only to the vehicles at the decision point and is used each time that a new vehicle reaches this point. A cautionary warning will be issued when all conflicts between vehicles in the assignment block cannot be completely resolved. This occurs when: L(2) over Epsilon over i=1 (A(i) + B(i) > L(2) + N.

That is, the warning occurs when there are more vehicles than total unoccupied spac...