Vibrating motor and angled bowl should do the job. Some electronics nerd with a box full of microcontrollers should be able to throw a concept together pretty easily, but sadly I'm not that nerd.
I want a Samuel L Tracksun robot pet bed with an adjustable attitude dial following the sunlight around the room and yelling:
Oh, I'm sorry. Did I break your concentration? I didn't mean to do that. Please, continue. You were shining... something about ultraviolet rays? Oh, y-you were finished? Oh, well, allow me to retort. What does the animal on my back look like? [angrily rolls back into the sunlight] What solar system are you from!? Silence ain't no country I ever heard of! They send photons in "Silence"!? [rolls up on the sunlight again] PHOTONS, MOTHERFUCKER! DO YOU SEND THEM!? MOVE AGAIN! I DARE YOU! I DOUBLE-DARE YOU, MOTHERFUCKER!! MOVE YOUR HELIOCENTRIC ASS ONE MORE GODDAMN TIME!