Surgical instrument including housing, a cutting accessory that extends from the housing and actuators that establish the position of the cutting accessory relative to the housing

1. A system comprising:

an instrument adapted to be manually supported and moved by a user, the instrument including a hand-held portion, a working portion including a cutting accessory movably coupled to the hand-held portion with a plurality of actuators, a plurality of actuators operatively coupled to the working portion for moving the working portion in a plurality of degrees of freedom relative to the hand-held portion, and a plurality of sensors for sensing positions of the working portion relative to the hand-held portion, the plurality of actuators configured to preventing backdriving; and

a control system in communication with the actuators to control the actuators to move the working portion relative to the hand-held portion, the control system operable in both a passive mode and a manual override mode, the system monitoring a position of the cutting accessory relative to a work course along which the working portion of the instrument should travel while in the passive mode, and the control system operable to control the instrument to become a fixed and stiff tool while in the manual override mode.

2. The system of claim 1 , wherein the control system is further configured to establish a home position of the working portion relative to the hand-held portion, and track deflection of the working portion from the home position as the working portion moves in one or more of the plurality of degrees of freedom relative to the hand-held portion to maintain the work course, the control system controlling the plurality of actuators to default to the home position while in the manual override mode.

3. The system of claim 1 further comprising a trigger coupled to the control system and the hand-held portion, the trigger operable to control a speed of the cutting accessory while in the manual override mode.

4. The system of claim 1 , wherein the cutting accessory comprises a saw blade.

5. The system of claim 1 , further comprising a navigation system and determine a position of the working portion relative to a target volume.

6. The system of claim 5 further comprising a display in communication with the navigation system for indicating the position of the working portion relative to the target volume.

7. The system of claim 6 , wherein the display provides visual instructions to inform the user where to position the hand-held portion relative to the target volume.

8. The system of claim 1 , wherein the control system is configured to:

define a virtual boundary;

evaluate a position of the working portion and cutting accessory relative to the virtual boundary; and

stop movement of the cutting accessory when the cutting accessory reaches or crosses the virtual boundary.

9. A system comprising:

an instrument adapted to be manually supported and moved by a user, the instrument including:

a hand-held portion;

a working portion including a cutting accessory movably coupled to the hand-held portion;

a plurality of actuators operatively coupled to the working portion for moving the working portion in a plurality of degrees of freedom relative to the hand-held portion, each of the plurality of actuators including a motor; and

a plurality of sensors for sensing positions of the working portion relative to the hand-held portion; and

a control system in communication with the actuators to control the actuators to move the working portion relative to the hand-held portion, the control system configured to:

determine whether the cutting accessory is within a snapping radius of a location where a void space is to be formed; and

controlling the motors of the plurality of actuators to position the cutting accessory so that a distal end of the cutting accessory is positioned above a location at which the void space is to be formed when the cutting accessory is within the snapping radius, the snapping radius being less than a maximum deflection radius of the cutting accessory relative to the hand-held portion.

10. The system of claim 9 , wherein each of the plurality of actuators are configured to move between a first position and a second position to move the working portion relative to the hand-held portion, wherein a home position is a midpoint between the first position and the second position of each of the plurality of actuators, and the working portion has a maximum range of motion when the plurality of actuators are at their home position.

11. The system of claim 10 , wherein the cutting accessory moves from the home position to the positioned above the location at which the void space is to be formed when the cutting accessory is within the snapping radius.

12. The system of claim 9 , wherein the cutting accessory comprises a saw blade.

13. The system of claim 9 , further comprising a display in communication with a navigation system for indicating a position of the working portion relative to the void space.

14. The system of claim 13 , wherein the display provides visual instructions to inform the user where to position the hand-held portion relative to the void space.

15. A system comprising:

an instrument adapted to be manually supported and moved by a user, the instrument including a hand-held portion, a working portion movably coupled to the hand-held portion, a plurality of actuators operatively coupled to the working portion for moving the working portion in a plurality of degrees of freedom relative to the hand-held portion, and a plurality of sensors for sensing positions of the working portion relative to the hand-held portion;

a control system in communication with the actuators to control the actuators to move the working portion in a plurality of degrees of freedom relative to the hand-held portion, the control system being configured to establish a home position of the working portion relative to the hand-held portion and track deflection of the working portion from the home position as the working portion moves in one or more of the plurality of degrees of freedom relative to the hand-held portion; and

wherein the control system is configured to control a cutting speed of the working portion based on the deflection into the deflected position.

16. The system of claim 15 , wherein the control system determines the deflection of the working portion from the home position, the deflection is based on comparison of a necessary deflection to a maximum possible deflection of the working portion; and

wherein the necessary deflection is a first deflection and a second deflection, the first deflection corresponding to a first cutting speed of the working portion, and the second deflection corresponding to a second cutting speed of the working portion, the first cutting speed is greater than the second cutting speed.

17. The system of claim 15 , wherein the working portion comprises a saw blade.