An apparatus comprises a surgical instrument mountable to a robotic manipulator. The surgical instrument comprises an elongate arm. The elongate arm comprises an actively controlled bendable region including at least one joint region, a passively bendable region including a distal end coupled to the actively controlled bendable region, an actuation mechanism extending through the passively bendable region and coupled to the at least one joint region to control the actively controlled bendable region, and a channel extending through the elongate arm. The surgical instrument also comprises an optical fiber positioned in the channel. The optical fiber includes an optical fiber bend sensor in at least one of the passively bendable region or the actively controlled bendable region.
