A harness for inhibiting an animal from straining against a leash and inducing the animal to come to a halt or to a walk or run at a pace acceptable to the animal handler is provided. The controller compares the pressure measured to a predetermined target pressure and varies the speed of the motor to minimize deviation of the measured pressure from the target pressure. The retrieving paths share the beam splitter and the photo-detector commonly at the returning route. Related ancillary terrestrial networks are also described.