i am designing a sumo robot... but i am having trouble with the ring edge detection... i am using LDR to detact the ring (i can get LDR for free) but the response is not so good... the edge is a 5cm white line... my robot can speed up from 10cm/s to 25cm/s and weigh almost 1.8 kg... so the momentum is high to stop or reverse from about 2 cm from the edge... without any supporting calculation i think if i could make the detaction faster could help my robot to stay in the ring... so can any of u help me over here...?