A method is provided for detecting a disturbance as an energy applicator of a surgical instrument traverses a cutting path. The method includes determining actual torques for each active joint of an actuated arm mechanism and calculating expected torques for each active joint of the actuated arm mechanism, wherein the expected torques are calculated based on an angular position of each active joint and a commanded joint angle for each active joint. The method further determines estimated backdrive torques based on the expected torques and the actual torques, wherein the estimated backdrive torques indicate a disturbance along the cutting path.