TABLE 5.

Parameter table for training and simulation setup.

PPO	Description	Value
α	Learning rate	2.5e-4
γ	Discount rate	0.99
λ	GAE parameter	0.95
τ	Entropy bonus coefficient	0.001
T	Number of steps per policy updates	1,024
K	Number of epochs	4
M	Batch size	64
N	Number of parallel actors	4
Environment
$\text{Δ}$	Look-ahead distance	3
$n_w$	Number of training path waypoints	7
${\gamma }_a$	Sonar span apex angle	140
$s_r$	Sonar range	25
$-$	Sensor suite	(15, 15)
$-$	Sensor min. pool output	(8, 8)
$-$	Sensor update frequency	1
$\left[V_{\min },V_{\max }\right]$	Ocean current intensity limits	$\left[0.5,1\right]$
$d_a$	End-goal acceptance radius	1
$T_f$	Control fins time constant	0.2
Reward function
$c_{\chi }$	Course error penalty coefficient	$-1$
$c_{\upsilon }$	Elevation error penalty coefficient	$-1$
${\gamma }_c$	Obst. closen. penalty scaling	$-12.5$
${\mathit{ϵ}}_c$	Minimum obstacle penalty closeness	$-5e-3$
${\mathit{ϵ}}_{oa}$	Minimum vessel-relative scaling	$-0.05$
$c_{\varphi }$	Roll penalty coefficient	$-1$
$c_r$	Roll rate penalty coefficient	$-1$
$c_{{\delta }_r}$	Rudder action penalty coefficient	$-0.1$
$c_{{\delta }_s}$	Elevator action penalty coefficient	$-0.1$
${\lambda }_r$	path following/COLAV trade-off	$\left[0.9,0.5,0.1\right]$