ACO	ant colony optimization
AVG	average value of data set of optimal route length
CGA	conventional genetic algorithm
CPSO	conventional particle swam optimization
ESA	elephant search algorithm
FA	firefly algorithm
GA	genetic algorithm
GPS	global positioning system
GRASP	greedy randomized adaptive search procedure
GWO	grey wolf optimizer
IPSO	improved particle swam optimization
KOS	known optimal solution
MAX	maximum number of iterations
NGC	navigation, guidance and control
PSO	particle swam optimization
QUST	Qingdao University of Science and Technology
RPE	relatively percentage error
SD	standard deviation
TSP	traveling salesman problem
TSPLIB	a library of sample instances for traveling salesman problem
USV	unmanned surface vehicle