Robbie was the name of a multi-purpose machine created by scientist Carl Readon. Carl had spent years attempting to build the robot, working on the project with his assistant Jane Francis, who was often accompanied by her dog Scruff.
Carl Readon attempted, through micro-wave cycles and frequencies, to make the machine respond to affection and emotion; giving it a personality. This also lead to Robbie often following and imitating his actions. When the Third Doctor was invited to look over Readon's notes, he eventually concluded that there was nothing wrong with the machine.
However, after Readon insisted Scruff stay out of his laboratory, Robbie escaped by crashing through a wall. Despite the attempted intervention of the police and military, Robbie could not be stopped. The Doctor eventually deduced that Readon was unhappy due to missing Scruff, and the two were reunited. (COMIC: Doctor Who and the Robot)