Patent ID: 11959743
Assignee: GUANGDONG UNIVERSITY OF TECHNOLOGY
Field: Measurement (Instruments)
Classification: CPC G  Y | IPC A  G

Claim 3:
4. A dimensionless kinematics calibration apparatus based on a virtual point, comprising:
a first establishment unit for establishing a kinematics model of a motion mechanism, wherein a tail end of the motion mechanism is clamped with a reflecting head;
a second establishment unit for arranging a plurality of virtual points at the tail end of the motion mechanism, and establishing a dimensionless kinematics model and a dimensionless error model based on the virtual points and the kinematics model;
a conversion unit for converting a measurement coordinate system of a measurement device into a motion mechanism coordinate system according to a spatial relationship between the measurement device and the tail end of the motion mechanism to obtain a new measurement coordinate system;
a measurement unit for acquiring a rotation matrix and a translation matrix of a target virtual point measured by the measurement device in the new measurement coordinate system, and calculating actual coordinates of all virtual points according to the rotation matrix and the translation matrix of the target virtual point to obtain a measured value of the dimensionless kinematics model, wherein the target virtual point is an origin of a reflecting head coordinate system;
a calculation unit for acquiring a spatial relationship between the reflecting head and the tail end of the motion mechanism, and calculating a theoretical value of the dimensionless kinematics model according to the spatial relationship between the reflecting head and the tail end of the motion mechanism; and
an optimization unit for performing model optimization on the dimensionless error model according to the measured value and the theoretical value of the dimensionless kinematics model to obtain a dimensionless kinematics calibration result of the motion mechanism;
wherein, the conversion unit is specifically configured for:
tracking and measuring the motion mechanism by the measurement device to obtain a reflecting head track rotating in a B-axis and a reflecting head track rotating in a C-axis;
acquiring a center of circle of the B-axis and a center of circle of the C-axis respectively according to the reflecting head track rotating in the B-axis and the reflecting head track rotating in the C-axis, and performing circle fitting based on the reflecting head track rotating in the B-axis and the center of circle of the B-axis to obtain a radius of the B-axis;
moving the center of circle of the C-axis downward by a numerical value corresponding to the radius of the B-axis to obtain an origin of the motion mechanism;
acquiring a plurality of points on an X-axis and a Y-axis by point measurement, and obtaining straight lines on which the X-axis and the Y-axis are located by straight line fitting; and
establishing a coordinate system based on the origin of the motion mechanism and the straight lines on which the X-axis and the Y-axis are located to obtain the new measurement coordinate system;
the calculation unit is specifically configured for:
resetting the motion mechanism, and measuring current rotation matrix and translation matrix of a first virtual point by the measurement device, wherein the first virtual point is an origin of the reflecting head coordinate system;
acquiring the spatial relationship between the reflecting head and the tail end of the motion mechanism according to the current rotation matrix and translation matrix of the first virtual point; and
calculating a theoretical value of the dimensionless kinematics model according to the spatial relationship between the reflecting head and the tail end of the motion mechanism.