A system for controlling a medical device includes a shaft rotatable about a longitudinal axis and a plurality of arms extending radially outwards from the shaft. Each arm includes an inward end positioned near the shaft and an outward end. The system also includes a collapsible pulley formed from a plurality of pulley pieces. At least one of the pulley pieces is slidably mounted on at least one of the plurality of arms and has a surface configured to receive at least one control element. The system further includes at least one biasing member located between the shaft and the at least one slidably-mounted pulley piece.
