Table 6.

Summary of the reviewed sonar-based methods

Ref.	Equipment and approach	Main contribution
[101]	FLS and PS	Improve elevation degradation and narrow-data issues
[102]	Acoustic camera	Solve the missing elevation angles of imaging sonars
[103]	MFLS and PF	Good performance in both state estimation and suppressing divergence
[104]	RS and UKF	Low-power and real-time SLAM
[105]	PPO and DRL	The first mapless, low-cost, end-to-end underwater navigation method
[135]	FLS	Continuously accurate submarine pipeline tracking

FLS, Forward-Looking Sonar; PS, Profile Sonar; MFLS, Multi-Beam Forward-Looking Sonar; PF, Particle Filter; RS, Range Sonar; UKF, Unscented Kalman Filter; PPO, Proximal Policy Optimization; DRL, Deep Reinforcement Learning.