Direct pose feedback control method and direct pose feedback controlled machine

A direct pose feedback control method applied to a direct pose feedback controlled machine, the direct pose feedback controlled machine comprising a machine body, a controller, a plurality of motors, a pose measuring mechanism and a tool, the pose measuring mechanism disposed between a workpiece-side and a tool-side of the machine body and comprising a tool platform disposed at the tool-side, a base platform disposed at the workpiece-side, at least six working double ballbars connected to the tool platform and the base platform, a reference plate and at least one reference double ballbar disposed on the reference plate, the direct pose feedback control method comprising a pose compensation control in addition to a position feedback control, the pose compensation control comprising:

• an initiation step, wherein a central distance function of the at least one reference double ballbar, a central distance function of each of the working double ballbars and a coordinate transformation between a tool platform coordinate system and a base platform coordinate system are built;
• a reference system step, wherein a coordinate transformation between the base platform coordinate system and a reference coordinate system is built according to setting parameters, loaded setting values or results of an on-machine measurement;
• an actual pose calculation step, wherein displacement values of the working double ballbars and the reference double ballbar and motor positions are read in real-time by the controller, thermal errors of the working double ballbars are compensated based on the displacement value of the reference double ballbar, a direct kinematic transformation of the pose measuring mechanism is performed and an actual pose and a pose error of the tool are calculated;
• and
• a position compensation step, wherein a position compensation value for each of the motors is obtained from a target pose for compensation and the actual pose;
• wherein for each of the motors, a compensation controller generates a compensation driving value according to the position compensation value, a position controller generates a primary diving value according to a setting value and an actual position value, the sum of the primary driving value and the compensation driving value is output to a corresponding driver, and the position compensation value is effective until updated by the pose compensation control.