Medical system and method for controlling the same

1. A medical system comprising:

a multi-joint slave arm;

a master arm that has a joint structure structurally similar to the multi-joint slave arm and is operated by an operator; and

a controller that controls the multi-joint slave arm on the basis of an operation applied to the master arm,

wherein the controller is configured to switch between a first control mode for controlling a rotational motion of each joint of the multi-joint slave arm on the basis of an amount of rotation of each joint of the master arm so that the multi-joint slave arm takes a shape similar to the master arm and a second control mode for controlling the rotational motion of each joint of the multi-joint slave arm on the basis of a displacement of a predetermined region of a distal end section of the master arm so that a predetermined region of a distal end section of the multi-joint slave arm follows a movement of the predetermined region of the distal end section of the master arm; and

a ratio of an amount of motion of the multi-joint slave arm to an amount of operation applied to the master arm is a predetermined constant value in the first control mode and is smaller than the predetermined constant value in the second control mode.

2. The medical system according to claim 1 , wherein the controller is further configured to control the multi-joint slave arm so as to minimize an amount of change in a shape of the multi-joint slave arm in the second control mode.

3. The medical system according to claim 1 , wherein the controller is further configured to control a rotational motion of any number of joints starting from a distal end of the multi-joint slave arm so that said joints take a shape similar to the master arm in the second control mode.

4. The medical system according to claim 1 , wherein

in the second control mode, the controller is configured to calculate reverse kinematics of the multi-joint slave arm on the basis of a position of the predetermined region of the distal end section of the master arm and select, from among an obtained plurality of solutions, a solution that causes the shape of the multi-joint slave arm to be closest to the shape of the master arm.

5. The medical system according to claim 4 , wherein the controller is configured to select a solution that minimizes a total of differences between an amount of displacement of each joint of the master arm and an amount of displacement of each joint of the multi-joint slave arm in the second control mode.

6. The medical system according to claim 5 , wherein the controller is configured to change the ratio of the amount of motion to the amount of operation.

7. The medical system according to claim 4 , wherein if four spaces defined by two planes that pass through a central axis of a basal part of each of the multi-joint slave arm and the master arm and that are orthogonal to each other on the central axis are assumed, the controller is configured to select a solution that causes the multi-joint slave arm to be positioned in a space corresponding to a space in which the master arm is positioned.

8. The medical system according to claim 7 , wherein the controller is configured to change the ratio of the amount of motion to the amount of operation.

9. The medical system according to claim 4 , wherein in the second control mode, the controller is configured to control the multi-joint slave arm so as to place a most distal joint of the multi-joint slave arm at a position and an orientation corresponding to a position and an orientation of a most distal joint of the master arm.

10. The medical system according to claim 1 , wherein the controller is configured to change the ratio of the amount of motion to the amount of operation.

11. The medical system according to claim 1 , wherein the controller is configured to receive an instruction from the operator to select one of the first control mode and the second control mode.

12. The medical system according to claim 1 , wherein the controller is configured to switch between the first control mode and the second control mode depending on a condition, circumstance, or environment of use of the multi-joint slave arm.

13. The medical system according to claim 12 , wherein the controller is configured to switch between the first control mode and the second control mode depending on a type of the multi-joint slave arm.

14. The medical system according to claim 1 , wherein when switching from the second control mode to the first control mode, the controller is configured to perform a reset flow for moving at least one of the master arm and the multi-joint slave arm before the first control mode is started so as to match the amounts of displacements of individual joints of the master arm and the multi-joint slave arm.

15. A method for controlling a medical system including a multi-joint slave arm and a master arm that has a joint structure structurally similar to the multi-joint slave arm and that is operated by an operator,

wherein a control mode for controlling the multi-joint slave arm can be switched between a first control mode for controlling a rotational motion of each joint of the multi-joint slave arm on the basis of an amount of rotation of each joint of the master arm so that the multi-joint slave arm takes a shape similar to the master arm and a second control mode for controlling a rotational motion of each joint of multi-joint slave arm on the basis of a displacement of a predetermined region of a distal end section of the master arm so that a predetermined region of a distal end section of the multi-joint slave arm follows a movement of the predetermined region of the distal end section of the master arm; and

a ratio of an amount of motion of the multi-joint slave arm to an amount of operation applied to the master arm is a predetermined constant value in the first control mode and is smaller than the predetermined constant value in the second control mode.

16. A medical system comprising:

a multi-joint slave arm;

a master arm that has a joint structure structurally similar to the multi-joint slave arm and is operated by an operator; and

a controller configured to control the multi-joint slave arm on the basis of an operation applied to the master arm,

wherein the controller is configured to switch between a first control mode for controlling a rotational motion of each joint of the multi-joint slave arm on the basis of an amount of rotation of each joint of the master arm so that the multi-joint slave arm takes a shape similar to the master arm and a second control mode for controlling the rotational motion of each joint of the multi-joint slave arm on the basis of a displacement of a predetermined region of a distal end section of the master arm so that a predetermined region of a distal end section of the multi-joint slave arm follows a movement of the predetermined region of the distal end section of the master arm; and

the controller controls the multi-joint slave arm so as to minimize an amount of change in a shape of the multi-joint slave arm in the second control mode.

17. The medical system according to claim 16 , wherein the controller is configured to control a rotational motion of any number of joints starting from a distal end of the multi-joint slave arm so that said joints take a shape similar to the master arm in the second control mode.

18. The medical system according to claim 16 , wherein a ratio of an amount of motion of the multi-joint slave arm to an amount of operation applied to the master arm is a predetermined constant value in the first control mode and is smaller than the predetermined constant value in the second control mode, and

in the second control mode, the controller is configured to calculate reverse kinematics of the multi-joint slave arm on the basis of a position of the predetermined region of the distal end section of the master arm and select, from among an obtained plurality of solutions, a solution that causes the shape of the multi-joint slave arm to be closest to the shape of the master arm.

19. The medical system according to claim 16 , wherein the controller is configured to receive an instruction from the operator to select one of the first control mode and the second control mode.

20. The medical system according to claim 16 , wherein the controller is configured to switch between the first control mode and the second control mode depending on a condition, circumstance, or environment of use of the multi-joint slave arm.

21. The medical system according to claim 16 , wherein when switching from the second control mode to the first control mode, the controller is configured to perform a reset flow for moving at least one of the master arm and the multi-joint slave arm before the first control mode is started so as to match the amounts of displacements of individual joints of the master arm and the multi-joint slave arm.