The uncertainty of parallel model coordinate measuring machine
Tóm tắt
The Stewart platform is one of 6-DOF (6 degrees of freedom) parallel mechanism. A parallel mechanism is a mechanism to connect six actuators in parallel between the base and the stage. It is necessary to calibrate the kinematic parameters that compose the mechanism in order to use the parallel mechanism as the coordinate measuring machine. Additionally, it is necessary to estimate the uncertainty about the measurement results. In this study, the kinematics parameters are estimated by using the calibration point in one point, the uncertainty is estimated at several measurement coordinates from kinematic parameters and postures angle. The verification method is shown following; i) The amount of the actuator expansion and contraction in the parallel mechanism is assumed to be a value obtained with the sensor and, the kinematic parameters are estimated from the values by using the least squares method. ii)The coordinates of the stylus are calculated from the estimated kinematic parameters by forward kinematics. The uncertainty is estimated from the coordinates of the stylus. As a result, the influence of the uncertainty is reported when the target coordinates are measured.
Tài liệu tham khảo
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