👉 In mathematics, a capstan is a type of closed loop system where the output is directly proportional to the input. It is named after the mathematician Sir William Rowan Hamilton, who discovered it in 1842. Capstans are used in the design of many scientific instruments and in various fields such as robotics, control systems, and signal processing. They are particularly useful for controlling mechanical devices that can be subjected to a large range of variations due to their closed loop structure.