# US 10,441,364 B2 · Systems and methods for guiding an instrument using haptic object with collapsing geometry > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 10,441,364 B2 - Document ID: US10441364B2 - Status: Granted - Kind: B2 - Application number: 15/074,827 - Filed: 2016-03-18 - Published: 2016-07-14 - Granted: 2019-10-15 - Earliest claimed: 2011-12-29 - Assignees: MAKO Surgical Corp. - Applicants: MAKO Surgical Corp. - Inventors: Radu Iorgulescu; Dennis Moses - Web page: https://patentgrep.com/patent/US10441364B2 ## CPC - A61B 34/20: Surgical navigation systems; Devices for tracking or guiding surgical instruments, e.g. for frameless stereotaxis - A61B 17/17: Guides {or aligning means} for drills {, mills, pins or wires} - A61B 34/30: Surgical robots - A61B 34/76: {Manipulators having means for providing feel, e.g. force or tactile feedback} - A61B: DIAGNOSIS; SURGERY; IDENTIFICATION (usefulness limited to only animals A61D) ## Abstract A computer-implemented method for guiding an instrument, comprises determining, by a processor associated with a computer, a current orientation angle of an instrument axis relative to a target axis. The method also comprises establishing, by the processor, a haptic boundary associated with the instrument based on the determined orientation angle of the instrument axis relative to the target axis. The haptic boundary is configured to constrain the instrument axis from being moved to an angle substantially greater than the current orientation angle. ## Claims ### Claim 1 A computer-implemented method for guiding an instrument, comprising: determining, by a processor associated with a computer, a current orientation angle of an instrument axis based, at least in part, on orientation of a target axis; establishing, by the processor, a collapsing haptic boundary associated with the instrument based on the current orientation angle of the instrument axis, the collapsing haptic boundary configured to be modified so as to collapse as the instrument axis is brought into alignment with the target axis, and configured to constrain the instrument axis from being moved to an angle greater than the current orientation angle; and generating a control signal to constrain the instrument within the haptic boundary. ### Claim 2 (depends on 1) The computer-implemented method of claim 1, determining the current orientation angle of the instrument axis based on orientation of the target axis includes: determining whether the instrument axis is coplanar with the target axis; and if the instrument axis is coplanar with the target axis: measuring orientation of the instrument axis relative to the target axis; if the instrument axis is not coplanar with the target axis: identifying a line parallel with the target axis and coplanar to the instalment axis; and measuring orientation of the instrument axis relative to the identified line. ### Claim 3 (depends on 2) The computer-implemented method of claim 2, wherein the line parallel with the target axis is normal to a plane that is normal to the target axis. ### Claim 4 (depends on 1) The computer-implemented method of claim 1, wherein the haptic boundary is further configured to constrain the instrument axis from being rotated to an angle greater than the current orientation angle. ### Claim 5 (depends on 1) The computer-implemented method of claim 1, wherein establishing the haptic boundary associated with the instrument comprises: establishing, by the processor, a virtual haptic volume based on the target axis, wherein the virtual haptic volume comprises a surface at which a haptic force is applied to the instrument; and determining, by the processor, a position of a reference point of the instrument; wherein upon determining that the position of the reference point of the instrument is within the boundary defined by the virtual haptic volume, decreasing the virtual haptic volume based on a detection of a corresponding decrease in the current orientation angle of the instrument axis relative to a previous orientation angle. ### Claim 6 (depends on 5) The computer-implemented method of claim 5, wherein decreasing the virtual haptic volume includes decreasing a distance of the surface of the virtual haptic volume from the target axis. ### Claim 7 (depends on 6) The computer-implemented method of claim 6, wherein the haptic volume is funnel-shaped and decreasing a distance of the surface of the virtual haptic volume from the target axis includes decreasing a base radius of the funnel-shaped haptic volume. ### Claim 8 (depends on 6) The computer-implemented method of claim 6, wherein at least a portion of the haptic volume is cone-shaped, and decreasing the distance of the surface of the virtual haptic volume from the target axis includes decreasing a boundary angle of the haptic cone. ### Claim 9 (depends on 5) The computer-implemented method of claim 5, further comprising determining, by the processor, a distance between the reference point of the instrument and the target axis, the haptic force configured to constrain the reference point of the instrument from being positioned at a distance greater than the distance between the reference point of the instrument and the target axis. ### Claim 10 (depends on 1) The computer-implemented method of claim 1, further comprising: determining, by the processor, a position of a reference point of the instrument; determining, by the processor, a distance between the reference point of the instrument and the target axis; establishing a second haptic boundary configured to constrain the reference point of the instrument from being positioned at a distance greater than the distance between the reference point of the instrument and the target axis. ### Claim 11 (depends on 10) The computer-implemented method of claim 10, further comprising applying, if the distance between the reference point of the instrument and the target axis is less than a threshold distance, a haptic force configured to urge the reference point to a position along the target axis.