Research On Disturbances Of Workshop Measurement Positioning System And Its Control Technology

The workshop Measurement Positioning System(wMPS)is a large-scale positioning measurement system based on multi-angle measurement fusion,and has distributed spatial network structures.wMPS exhibits abroad range of applications as it overcomes the shortfalls of traditional precision measurement methods which suffer from low efficiency and poor precision;it can also avoid the restriction of the limited measuring range of single-station measurement system,and rationally coordinate the contradiction between the range and precision of measurement.However,the distributed characteristics of the wMPS mean that it may be easily disturbed by its application environment,further leading to unreliable measurement results.Based on the spatial configuration of measurement networks,this research analysed the characteristics of interferences suffered by transmittering nodes and receiving nodes respectively,and we designed and developed interference control schemes.This research includes:(1)The development process and measurement demands of large-scale spatial measurement technology used in advanced equipment manufacturing industry are firstly summarised.By comparing single-station measurement systems with distributed measurement systems(such as the wMPS),we discuss marked advantages and key technologies of the wMPS.Furthermore,unresolved issues regarding the interference arising from the application environment in practical measurement using the wMPS are demonstrated.Additionally,the interference with signals measured by the wMPS at different measuring stages was investigated by taking shipbuilding as an example.The characteristics of interferences at different measuring stages were analysed and schemes for interference control corresponding to each of the measuring stages were adopted.(2)The influences of spatial configuration of the wMPS on measurement precision were investigated using a numerical simulation method based on the measurement model of transmitters.Moreover,this study defined the geometric dilution of precision(GDOP)so as to quantify the quality of the spatial configuration.We then presented discussion of two factors affecting the GDOP,and these factors were analysed and their effects validated.The results indicated that a reasonable spatial configuration can ensure high-precision measurement of the wMPS,which is also proven to be a precondition for the analysis of interference control technologies.(3)To solve the issues concerning the attitude change of transmittering nodes,hardware redundancy techniques were used to control and compensate for attitude interference.According to our design based on an inclinometer-based transmitter,external reference constraints and the precision mechanical adjustment were conducted to correlate the information of the transmitter with gravity datum information.Furthermore,a real-time algorithm for compensating the attitude of the transmitter was developed and the errors generated in the process of compensating the attitude were simulated.At last,a new type of hardware platform was constructed to verify the feasibility of this proposed algorithm and the model.(4)The interference signals were removed using a signal filtering approach aiming at the errors produced in measuring signals.Afterwards,time and frequency domains of the characteristics for time series signals of the wMPS were analysed based on the statistical theory describing time-variant behaviour.The results showed that there are common model errors existing between varying sequences of time series data.To eliminate the errors,this research proposed the corresponding filtering schemes.(5)Aiming at the measuring errors in the coordinates of receiving nodes,a redundancy algorithm for removing these errors was used to test,and separate interference data.By introducing an integrity detection mechanism into the receiving nodes,a fault detection and separation algorithm for the transmitter was analysed based on the least squares model and total least squares model.The reliability of fault detection results was analysed.By considering the interference of multi-dimensional errors,this study proposes an overall solution to ensure data integrity at receiving nodes.This was simulated and validated experimentally.