I am just thinking of making a rope skipping device (without a real rope ) with my limited Arduino skill.
As you can guess it should see if I am on the floor or I am at the air. There will be no rope. Just jumping.
When you increase your speed at rope skipping the space between you and the floor is decreases as you know. May be 1-2 cm space will be left.
What kind of sensor would you use for that kind of job?
Force sensor? Or kind of laser?