A system comprises a first cannula comprising a proximal end and a cannula opening at the proximal end. The system further comprises a teleoperated surgical instrument, and a manually operated surgical instrument configured to be inserted into the cannula opening. The system further comprises a teleoperated manipulator, a controller, and a first position sensor coupled to the teleoperated surgical instrument, the first position sensor configured to provide a first sensor input to the controller. The system further comprises a second position sensor coupled to the manually operated surgical instrument, the second position sensor configured to provide a second sensor input to the controller, the second sensor input comprising an insertion depth of the manually operated surgical instrument into the first cannula. The system further comprises a reference fixture coupled to the first and second position sensors and to the teleoperated manipulator, the reference fixture being movable with the teleoperated manipulator.