The workshop Measurement and Positioning System (wMPS) based on the rotary-laser scanning technology has been widely applied in the manufacturing industry to provide an accurate and robust coordinate measurement. However, some vibration-related problems in the rotating machinery inevitably exist. These problems influence the measurement accuracy of wMPS and even reduce its service life. In this paper, the rotating machinery vibration analysis of wMPS is introduced. Some significant factors causing vibrations, such as the mass imbalance of the rotor, are discussed. The vibration signals of rotating machinery are captured experimentally by the three-axis accelerometer. These raw vibration signals are processed by the data pretreatment, the time-domain analysis and the frequency-domain analysis. Based on these analyses, some evaluation criteria of rotating machinery vibration are introduced. These criteria provide guidance to the fault detection and ensure the ongoing operational condition of wMPS.
Large-scale dynamic three-dimension coordinate measurement technique is eagerly demanded in equipment manufacturing. Noted for advantages of high accuracy, scale expandability and multitask parallel measurement, optoelectronic scanning measurement network has got close attention. It is widely used in large components jointing, spacecraft rendezvous and docking simulation, digital shipbuilding and automated guided vehicle navigation. At present, most research about optoelectronic scanning measurement network is focused on static measurement capacity and research about dynamic accuracy is insufficient. Limited by the measurement principle, the dynamic error is non-negligible and restricts the application. The workshop measurement and positioning system is a representative which can realize dynamic measurement function in theory. In this paper we conduct deep research on dynamic error resources and divide them two parts: phase error and synchronization error. Dynamic error model is constructed. Based on the theory above, simulation about dynamic error is carried out. Dynamic error is quantized and the rule of volatility and periodicity has been found. Dynamic error characteristics are shown in detail. The research result lays foundation for further accuracy improvement.
The workshop Measurement Positioning System (wMPS) is a large-scale measurement system that better copes with the current challenges of dimensional metrology. However, as a distributed measuring system with multiple transmitters forming a spatial measurement network, the network topology of transmitters relative to the receiver exerts a significant influence on the measurement accuracy albeit one that is difficult to quantify. An evaluation metric, termed the geometric dilution of precision (GDOP), is introduced to quantify the quality of the network topology of the wMPS. The GDOP is derived from the measurement error model of wMPS and its mathematical derivation is expounded. Two significant factors (density and layout of the transmitter) affecting the network topology are analyzed by simulations and experiments. The experimental results show that GDOP is approximately proportional to the measurement error. More transmitters, and a relatively good layout thereof, can decrease the value of GDOP and the measurement error.
The workshop Measuring Position System (wMPS) based on intersection of optical planes is widely applied in large-scale metrology. However, in guidance areas concerning more about horizontal directions such as in the area of transporting with AGVs, the coordinate of z axis which represents the height of the vehicle is of no particular importance. Also, the installation and parameters calibration of wMPS is complex and time-consuming. In this paper, a new method with single transmitter measuring two dimensional coordinate to guide the moving object (except the vertical direction) is proposed and demonstrated. The three dimensional coordinate of receiver was calculated if its horizontal angle, vertical angle and the coordinate of vertical direction are given. In order to get the receiver’s horizontal and vertical angle, a serious of mathematical formulas was derived from a model of single transmitter with two rotating laser planes. The coordinate of vertical direction was obtained by the laser tracker and mapped from laser tracker coordinates to transmitter coordinates. Concerning that the coordinate of the vertical direction remains almost the same if the object moves in the level ground, a series of vertical-direction coordinates of moving object was measured beforehand and the average value of coordinates was the approximate vertical-direction coordinates of every point. To verify this method, the points acquired by the transmitter were remeasured by the laser tracker. Finally, the coordinates were compared and the results were analyzed. The experiment results show that the method’s measuring accuracy has reached 5mm.