The "subject" of the participle

The doer of the action expressed by the participle is usually the subject of the sentence or the main clause:

A dog was barking in the distance.
How often do you go swimming?
Grumbling to himself, Ted left the room.
Having seen the film before, I didn't feel like going to the cinema.
The car was parked outside the building.
Taken daily, these pills can be highly effective.
Have you ever tried skiing?

In participle clauses, it can lead to confusion if the understood subject of the participle is not the subject of the main clause. This is called a misrelated participle:

?While going home, a bus almost ran over me.

This suggests that the bus was going home. If we mean that I was going home, we have to make the first person singular pronoun I the subject of the main clause:

While going home, I got almost run over by a bus.

In some cases, however, the subjects can be different without the chance of misunderstanding:

Considering what she has been through, she is doing well. (If we consider what she has been through...)
Judging from his accent, he is from New York. (As I judge from his accent...)

The doer of the action expressed by the participle can also be the noun or pronoun preceding it:

I heard him singing in the bathroom.
Who is the girl sitting next to you in class?
Our car having broken down, we had to take a taxi home.