I'm trying to remember a book I read in the 90's about a group (3 maybe?) of siblings who are alone on an alien planet. The book starts with them fleeing a hostile group of aliens through a rubbery alien jungle, they are separated at some point, and one of the boys is forced to live in a cage???
Also, there are robots, and possibly an alien queen.
The cover had an abstract drawing of a girl and a boy standing on a box, almost like a wind-up toy.
I have been looking for this book for years and any help would be appreciated.