The design of a new kind of hybrid-link coordinate measuring mechanism

Through the embedded analysis, the deficiencies of serial-link coordinate measuring machine, such as Cartesian CMM, have been revealed. The first is that the moving error of the probe is always the accumulation of all coordinate. And the second is that the flexibility of the probe posture is not sufficient. Clearly, the shortcomings of serial-link mechanism can be properly compensated by the characteristics of parallel-link mechanism. Aimed at the measurement of free-form surface, a new kind of hybrid-link coordinate measuring mechanism has been put forward. As the Y dimension is much larger than the dimension of X and Z, a three degree of freedom parallel-link mechanism has been designed to offer the movement of the probe in X-Z plane, and a linear guide way offer the movement in X direction. The influences of position error of joints and length error of legs on the kinematical accuracy of the probe are analyzed, and the mathematical model of the error of the probe is established.