Method and system for automatically maintaining an operator selected roll orientation at a distal tip of a robotic endoscope

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.

2. The method according to claim 1 , wherein a tip reference frame is defined at the tip of the endoscope so as to have a Z TIP axis indicative of a depth direction of a view captured at the tip, a X TIP axis indicative of a horizontal direction of the view, and a Y TIP axis indicative a vertical direction of the view, the method further comprising:

receiving a reference vector indicative of the setpoint;

projecting the reference vector onto a plane containing the Y TIP axis and the Z TIP axis; and

determining the roll angular adjustment as an angle between the reference vector and the projected reference vector.

3. The method according to claim 1 , where the current commanded roll velocity is modified by setting it to zero and the commanded roll position is modified by setting it to the prior process period commanded roll position as long as the roll angular adjustment is less than a threshold value.

4. The method according to claim 1 , wherein the current commanded roll velocity is modified by setting it to a fixed value and the commanded roll position is adjusted to a value consistent with the modified current commanded roll velocity whenever the roll angular adjustment is greater than a threshold value.

5. The method according to claim 1 , wherein the current commanded roll velocity is modified so as to be a function of the roll angular adjustment and the current commanded roll position is adjusted to a value consistent with the modified current commanded roll velocity whenever the roll angular adjustment is greater than a threshold value.

6. The method according to claim 1 , wherein the setpoint is established so as to be orthogonal to gravity.

7. The method according to claim 1 , further comprising:

receiving an indication of the setpoint from an operator manipulated input device.

8. The method according to claim 7 , wherein the setpoint is established by a roll orientation at the tip at the time that the indication of the setpoint is received from the operator.

9. The method according to claim 7 , further comprising:

displaying a graphical representation of the setpoint on a display screen viewable by the operator;

receiving an input from the operator manipulated input device;

adjusting an orientation of the graphical representation of the setpoint on the display screen according to the received input; and

determining the setpoint from the adjusted orientation of the graphical representation of the setpoint.

10. The method according to claim 1 , wherein the commanding of the tip of the robotic endoscope to be driven to the modified current commanded state comprises:

determining a combination of states for one or more joints of a manipulator that manipulates the robotic endoscope in corresponding degrees of freedom movement and bending angles for one or more bending segments of the robotic endoscope to bend a body of the robotic endoscope so as to achieve the modified current commanded state of the tip of the robotic endoscope; and

commanding the one or more joints of the manipulator to be driven to the determined joint states and the one or more bending segments of the robotic endoscope to be driven to the determined bending angles.

11. The method according to claim 10 , wherein the one or more joints of the manipulator includes a prismatic joint for moving a proximal end of the robotic endoscope forward and backward along a linear path and a rotary joint for rotating the proximal end of the robotic endoscope about the linear path.

12. The method according to claim 10 , wherein the determining of the current commanded state of the tip of the robotic endoscope from the control input comprises:

determining translational and angular tip states from the control input and stored information of control inputs for one or more prior process periods.

13. The method according to claim 10 , wherein the determining of the current commanded state of the tip of the robotic endoscope from the control input comprises:

transforming the control input to a desired state of the tip of the robotic endoscope relative to a fixed Cartesian reference frame.

14. The method according to claim 13 , wherein the determining of the states of the one or more joints of the manipulator and bending angles for the one or more bending segments of the robotic endoscope comprises:

applying the modified current commanded state to inverse kinematics of the combined serial kinematic chain composed of the manipulator and the robotic endoscope.