Lotte is built in the same way as P2. Instead of a push button, an IR photoreflector is attached to her hand.
Franz is a robot controlled by accelerometer.
Franz rolls back and forth to Lotte’s.
The IR photoreflector on Lotte’s hand detects Franz, then raises and lowers her hand.
When Franz reaches her for the 5th time, Lotte does not raise her hand but turns her head away.
The dog is a tracking robot. It is equipped with 1 sound sensor, 2 IR photoreflectors and 1 servo motor.
It will start on paw, tracking its way to Lotte’s. When its IR photoreflector detects Lotte, it stops, wags its tail, then continues tracking and moves away from Lotte.