earlier. Besides, the overall traveling time of each engager
must be minimized to ensure the punctuality of congregate
activities. As most road conditions in a city are generally the
same, it can be hypothesized that traveling time is generally
equivalent to traveling distance here. Moreover, on many
occasions, congregate activities ought to temporarily change
plans due to unpredicted issues (rain during outdoor activities,
incomplete venue constructions, fire alarms, etc.). Thus, the
original place must change to ensure congregate activities
proceed, and so does the navigation destination.
As a summary of such a problem in navigation terms, DMS-
SD depicts a scenario in which multiple activity engagers need
to unite at a specified location, where each engager travels
equally and shortest distance. The intended destination may
change dynamically depending on real-time on-site situations.
Thus, route plans must be refreshed for every engager in cor-
respondence. Meanwhile, as Industry 5.0 emphasizes process
waste reduction, there are three additional requirements for
DMS-SD solutions: (1) DMS-SD solutions should emphasize
’dynamic’ so engagers can run the navigation system in real-
time software with reasonable computation time; (2) Com-
putation tasks of DMS-SD solutions should consume limited
resources to run in engagers’ mobile devices, rather than
introducing enormous loads to a central server; (3) DMS-SD
solutions should minimize the total distance to reduce power
consumption generated from traveling.
Conventionally, path planning algorithms simplify the prob-
lem into a point-to-point shortest time or shortest distance
problem, defined as a Single Source to a Single Destination
Problem (SS-SD). Based on this simplification, most existing
approaches seek optimal routes according to performance indi-
cators. For example, A* and Dijkstra algorithm can ensure an
optimal solution via exploitation of entire path computations
[7] [8]. However, these methods are not effective enough to
resolve DMS-SD problems as paths to all nodes must be
simulated to obtain the shortest path in iterations, especially in
a large-scale map. Besides, recent research also seeks solutions
via Q-learning-based reinforcement learning algorithms [9]
[10]. However, it is noticed to be challenging in DMS-SD
problems due to the complexity of reward design.
This paper proposes an innovative modified Dijkstra al-
gorithm to address the DMS-SD problem. This modified
algorithm introduces the Adjacent Matrix in classic Floyd’s
algorithm to store the shortest distance between nodes. Hence,
this storage method avoids the mass computation work in
Floyd’s algorithm about distance calculations for every pair
of nodes. On the base of adjustments brought by Adjacent
Matrix, a temporary destination could only associate with
the current locations of people in the DMS-SD problem.
Therefore, this algorithm possesses the capacity for the optimal
solution to the current state of people to navigate without a
pre-training model. More importantly, individuals keep their
personal preferences during decision-making. In this work,
considering individual preference an influential factor, multiple
preferences are provided to people, including distance, time,
and meeting place, to satisfy different meeting goals rather
than distance only. These beneficial changes enhance the
completeness of problem-solving and fortify its user-friendly.
The contributions of this paper lie in the following:
•Resolving the DMS-SD problem that has not been well
discussed in past studies.
•Proposing an efficient algorithm to address the DMS-SD
problem based on Dijkstra’s algorithm, which can effec-
tively compute an optimal solution without generating the
entire Adjacent Matrix. More importantly, the proposed
method can address a large scaled DMS-SD problem with
linearly increasing time.
The rest of the paper is organized as follows: Section 2 will
clarify the details of the modified Dijkstra algorithm. Section
3 will present evaluations of the modified Dijkstra algorithm
based on computation time, optimality, and dynamicity. Sec-
tion 4 will review related work about multi-agent path planning
to highlight the contribution and validation of this research.
Section 5 will conclude the paper and discuss future relevant
work.
II. THE MODIFIED DIJKSTRA’S(MD) ALGORITHM
Dijkstra’s algorithm was proposed by [8] in 1959. This
algorithm aims to search the shortest distance between a pair of
vertices. In our work, we record all shortest distances from the
source node to all other vertices using Adjacent Matrix, which
is typically used in Floyd’s algorithm. Then, by applying
several matrix calculations, we achieve our goal: every user
travels the shortest and equally distant to the destination based
on the current state. The proposed algorithm spends much less
time than Floyd’s algorithm on solving the DMS-SD problem
as well as efficiently generating an optimal solution.
A. Adjacent Matrix
The standard Adjacent Matrix (Madj ) is a 2-Dimensional
matrix used to represent the connection between vertices in a
graph. For example, provided a graph G= (V, E)where the
vertex set V={v1, v2, v3}and Eis the edge set, the initial
form of the Madj of Gcan be presented as in Eq. 1.
Madj =
v1v2v3
v10 2 4
v22 0 ∞
v34∞0
(1)
where the notation ∞means there is no direct road between
those two vertices. ∞can be updated to the actual number
later if the destination can be achieved via another vertex. In
our work, we use the Adjacent Matrix to present the shortest
distance from a person to all other nodes. This means the
matrix can be unsymmetric, as shown in Eq. 2
Madj =
v1v2v3v4
A0 2 4 1
B2 0 6 3
(2)
Where Aand Bare two people. Additionally, we use a tuple
(vx, vy)to represent the distance shown in the Madj . For
example, (A, v2)in Eq. 2 shows the distance from person