Request #508 From Sarah

I can remember a book that I read in grade school very vaguely and it has been plaguing me for years. All I really can remember is that it was a kind of utopian/futuristic book with robots. There was a younger robot and an older robot that was kind of like a butler, who ‘died’ toward the end. I remember that it seemed like a pretty thick book for a 5th or 6th grader. I feel like the title was pretty simple, like one word or something. And it had a pretty simple and muted cover, maybe lots of light gray? I know this isn’t much to go off of, but I’ve tried searching everywhere!