Systems and methods for guiding an instrument using haptic object with collapsing geometry

A method for guiding an instrument, comprising:

• establishing, by a processor associated with a computer, a target axis;
• determining, by the processor, a current orientation angle of the instrument based on orientation of the target axis;
• comparing, by the processor, the current orientation angle with a previous orientation angle of the instrument;
• establishing, if the orientation angle is less than the previous orientation angle, a virtual haptic surface relative to the target axis, the virtual haptic surface having a surface angle less than the previous orientation angle.

A method for guiding an instrument, comprising:

• establishing a target axis that comprises a target point;
• defining a virtual haptic volume based, at least in part, on the target point and the target axis;
• and
• determining a position of a reference point of the instrument;
• wherein upon determining that the position of the instrument reference point is within the virtual haptic volume, decreasing the virtual haptic volume based on a detection of a corresponding decrease in an orientation angle of the instrument axis relative to a plane normal to the target axis.

A computer-assisted surgery system comprising:

• a surgical device for performing at least one task associated with a surgical procedure;
• a processor, operatively coupled to the surgical device and configured to:
• determine an orientation angle of an instrument axis based on orientation of a target axis;
• and
• apply a haptic force to the surgical device based on the determined orientation angle of the instrument axis, the haptic force configured to constrain the instrument axis from being moved to an angle substantially greater than the orientation angle.