How does Goku feel the Pirate Robot?

[SSJ2]

He is able to tell that it is lurking without it making them aware. How can he sense the ki of something with no ki?

 

[Papasmurf]

Vegeta could also sniff out Goku gathering the genkidama back when he couldnt sense ki. Just perception probably

 

[ahill1]

Yeah, but he even knew that wasn't a human thing. Weird.

 

[Papasmurf]

He might have smelled it maybe? Goku does say he has a canine sense of smell in part 1

 

[Let's Go Fearless!]

From early DB?