Research On Articulated Coordinate Measuring Machine (ACMM)

The articulated coordinate measuring machine(ACMM) has been increasing given attention due to the advantage of low cost, easy installation, agile action, low weight and no dead zone measurement.The paper take theories in robotics called Deravit-Hartenberg(D-H) method as reference to give the model of three-joint ACMM prototype, this model express the coordinate of probe in ACMM's coordinate system. In the model of ACMM, there are four parameters to express joint's character.Turing angle was acquired by the optical gratings which were fixed on joints. So the designing of data acquisition system is very important. The paper design the communication method of the data acquisition circuit and introduce measuring software of three-joint ACMM.The paper analyzes measuring space, draw up it in measuring space and designs the algorithm for how to calculate reasonable structure parameter, so as to avoid measuring dead zone.The most difficult of research on ACMM are measuring error classify and measuring error compensation, that is calibration of ACMM. Stochastic error analysis has the follow usage, one is to know the best compensation condition, the other one is to design better expenrimental space of ACMM. The paper analyzes stochastic error diatribution. Error distribution is discussed by two ways:single parameter fluction and four-parameter fluction. The paper design the stochastic error analysis algorithm and draw up stochastic error distribution in measuring space.Because stochastic error analysis propose the better experiment space, the paper propose six experiments based on stochastic error analysis and implement them in the above space. In every experiment, the paper propose calibration principle, parameter compensation algorithm and compensation result.