TABLE 4.

Characteristics of reinforcement learning based exploration.

Characteristic	Description
Objective	Discover unknown environment
State Representation	Environmental features, grid cells or frontiers
Action Space	Movement actions, sensing actions
Reward Function	Rewards for successful exploration, penalty for revisiting areas
Observation	Sensor data for map building or data collection
Challenges	Balancing exploration and exploitation, stopping conditions
Citations	Niroui et al. (2019); Hu et al. (2020); Chen et al. (Chen et al., 2020a; Chen et al., 2020b); Maciel-Pearson et al. (2019)