Research And Design Of The Protable Joint Coordinate Measuring Machine

The protable multi-joint coordinate measuring machine(PCMM), which basedon the coordinate measuring technology and the theory of the bionics, is a precisemeasuring instrument. Comparing with the traditional CMM, smaller, lighter, Port--able, flexible, infinite measure is its advantage. PCMM is widely applied in thefield of mechanical manufacturing, electronics, automobile, aeronautics andastronautics, army industry, mold and reverse engineering, particularly suitableto the on-the-spot mobile measure.Because the PCMM uses the whole serial revoluted-joint structure, the error ofthe tip is magnified severely. And the maths modle which made in thenon-cartesian coordinate system is complex, and its error is also complex, the erroris not easy calibrated and the compensated. How to guarantee that ultimateaccuracy is a critical technology. The paper surrounds how to increase the accuracyof the instrument, proceeding the following research:In the aspect of the mechanical structures design, I adopt the following methodto decrease the measuring errors: using carbon fiber carbon fiber to be the materialof the arms to reduce effect of the accuracy when temperature changes; In everyjoint, I adopt "back to back" precision shaft bearing in pairs and impress a littlepretightening force to increase the ragid of the rotating shaft, thus it can decreasethe measuring errors because of the joint shaken. In the aspect of the errorscalibration and compensation, with the experimental method to eliminate zeroerrors, and using the improved single-point calibration technich to calibrate thesystematical integrate measuring errors.