Keep track of successfully hit and hit counts with this great work in progress shared by Lehmitz on Hackster.io:
How does it work?
This setup lights up the room whenever you take a hit and keeps track of the number of times you have been hit. The number of hits is displayed both via an LED system and a small OLED Screen numerically. It does this by placing piezoelectric sensors in the armor that detects pressure. Whenever the armor takes a hit in a region the pressure is picked up by the sensor and it triggers the lights to go on as well as a count change to the number of hits you have taken and number of hits you could still sustain.