1. A method for controlling operator commanded movement of a distal tip of a robotic endoscope while maintaining a roll orientation at the tip, the method comprising: receiving a control input from an operator manipulatable input control device; determining a current commanded state of the tip of the robotic endoscope from the control input, wherein the commanded state includes a current commanded roll position and velocity; modifying the current commanded state by constraining the current commanded roll position and velocity to be a modified current commanded roll position and velocity according to a roll angular adjustment indicated by a prior process period commanded state of the tip and a setpoint indicative of the roll orientation to be maintained at the tip; and commanding the tip of the robotic endoscope to be driven to the modified current commanded state.