**Albina Kamalova 1, Sergey Navruzov 1, Dianwei Qian <sup>2</sup> and Suk Gyu Lee 1,\***


Received: 25 June 2019; Accepted: 17 July 2019; Published: 22 July 2019

**Abstract:** In this paper, we used multi-objective optimization in the exploration of unknown space. Exploration is the process of generating models of environments from sensor data. The goal of the exploration is to create a finite map of indoor space. It is common practice in mobile robotics to consider the exploration as a single-objective problem, which is to maximize a search of uncertainty. In this study, we proposed a new methodology of exploration with two conflicting objectives: to search for a new place and to enhance map accuracy. The proposed multiple-objective exploration uses the Multi-Objective Grey Wolf Optimizer algorithm. It begins with the initialization of the grey wolf population, which are waypoints in our multi-robot exploration. Once the waypoint positions are set in the beginning, they stay unchanged through all iterations. The role of updating the position belongs to the robots, which select the non-dominated waypoints among them. The waypoint selection results from two objective functions. The performance of the multi-objective exploration is presented. The trade-off among objective functions is unveiled by the Pareto-optimal solutions. A comparison with other algorithms is implemented in the end.

**Keywords:** multi-robot systems; multi-objective optimization; grey wolf optimizer; waypoints; exploration; uncertainties; unknown environment; mapping; grid map occupancy
