Himawari is a robotic sunflower that does not grow towards the sun, like a biological sunflower. That would be heliotropism. This robotic sunflower is homotropic, in the sense defined by Philip K. Dick; it turns toward people.
Created by Akira Nakayasu of Kyushu University, Japan, its impulse to follow the motion of a person's hand is brought about by the information streaming from an infrared camera in its head. The white and purple LEDs on the head, encircled by a shape memory alloy actuator, reflect light that corresponds to the hands waving close by. Servomotors turn the robot sunflower to follow your hand.
(Himawari sun flower robot video)
Philip K. Dick introduces the idea of robots that have the capacity to find and then follow human beings in his 1963 novel The Game Players of Titan.
At the door of the restaurant an automated news vending machine appeared, with a late edition of the Chronicle. It's Rushmore Effect bleated out "Special coverage of the Luckman murder case." The restaurant, with the exception of their party, was empty; the news vending machine, being homotropic, headed toward them, still bleating..
(Read more about Dick's Homotropic News Vending Machine)