Surgery assistive system and method for obtaining surface information thereof

A surgery assistive system, comprising:

• an instrument comprising a tool configured to contact or modify an anatomical surface on a body part of a subject, a parallel manipulator, connected to the tool and having a plurality of actuators, a force sensor for detecting at least one of force and torque sustained by the tool, an inertial measurement unit, a platform, and a plurality of joints mounted on the platform, wherein the force sensor is connected between the tool and the parallel manipulator;
• a spatial sensor system for detecting spatial information of the instrument;
• and
• a computer system electrically connected to the instrument, the spatial sensor system, and a user interface, for manipulating a kinematic state of the manipulator according to the spatial information of the tool as detected by the spatial sensor system, wherein the computer system comprises a non-transitory computer readable medium storing a program for obtaining surface information, the program is executable by at least one processor of the computer system and comprises instructions that, when executed by the processor, causes the surgery assistive system to perform actions comprising:
• assigning, by the computer system, matching spatial data of a plurality of fiducial markers on the subject into a virtual anatomical model, wherein the fiducial markers are readable by the spatial sensor system and radiopaque to a medical imager associated with the surgery assistive system;
• defining, by the computer system, a target region and a plurality of reference points in the target region on the virtual anatomical model of the subject, wherein the reference points are distributed in the target region where a plurality of key surface features are covered by the reference points;
• generating sampling information according to a plurality of sampling points on the subject corresponding to the reference points, wherein the tool is configured to sample the sampling points, the tool is a probe, and the computer system is further configured to manipulate the kinematic state of the parallel manipulator to control a tip of the probe to contact the sampling points for sampling the sampling points along a predefined sampling route formed by the sampling points;
• wherein a first piece of the sampling information comprises a coordinate of a first sampling point of the plurality of sampling points, a first angle of a contact of the tool at the first sampling point as detected by the spatial sensor system, and first parameters associated with the contact between the tool and the first sampling point;
• determining whether at least one of the first parameters does not meet a sampling criterion which requires a specific relationship between a normal force, a lateral force or a torque detected by the force sensor, an output power of the plurality of actuators of the parallel manipulator, or a duration of steady contact detected by the inertial measurement unit or the spatial sensor system and a threshold;
• wherein in response to determining that the at least one of the first parameters does not meet the sampling criterion, the tool is configured to contact the first sampling point from a second angle different from the first angle;
• designating, by the computer system, the sampling information as surface information of the sampling points that meet the sampling criterion;
• and
• determining whether to prompt the user to sample a next sampling point on the predefined sampling route according to the key surface features associated with the sampled sampling points, wherein the key surface features include a peak and a valley on the surface as determined according to at least one of a direction and an intensity of force sustained by the tool during sampling;
• wherein in response to sampling the next sampling point on the predefined sampling route, the computer system identifies the next sampling point by:
• deciding a direction that includes one or more of the key surface features, the key surface features being the peak and the valley on the surface as determined according to the at least one of the detected direction and intensity of force sustained by the tool during sampling, according to the parameter in a last sampling information and defining a sampling point in the direction as the next sampling point;
• or
• redefining the reference points or the sampling route and start sampling according to a newly defined sampling route;
• wherein each piece of the sampling information comprises a coordinate of one of the sampling points, an angle of a contact of the tool at the one of the sampling points as detected by the spatial sensor system, and parameters associated with a contact between the tool and the one of the sampling points as detected by the force sensor;
• and
• designating, by the computer system, the sampling information as surface information of the sampling points, and assigning the surface information as surface information of the sampling points, and assigning the surface information into the virtual anatomical model, thereby registering the virtual anatomical model into a coordinate system established by the spatial sensor system.