Abstract
Abstract
In recent years, the 4th generation synchrotron radiation
light sources have gradually emerged. However, the accumulated
errors in Laser Tracker multi-station measurements make it
challenging to meet the accuracy requirements for the control
network measurement, especially in the direction of elevation. To
address this issue, this paper proposes to utilize the Hydrostatic
Leveling System (HLS) to provide high-precision external constraints
for the control network measurement. Firstly, based on the
measurement principle of capacitive HLS sensor, a system is designed
and constructed which was used to optimize the measurement accuracy
of the HLS for level difference between difference points and to
obtain the external reference. Comparison of the HLS measured values
with the nominal values measured by the CMM shows that the optimized
HLS can achieve a level difference measurement accuracy of
5 μm. On this basis, some constraint methods are proposed,
which have been verified by simulations and measurements. The
results show that the error accumulation in the elevation direction
is suppressed compared with the classical adjustment. For the 70 m
linear tunnel control network of Hefei Light Source, the maximum
error of the measurement is reduced by 90 μm (23%
improvement in accuracy) and the standard deviation of the error is
reduced by 26 μm (35% improvement in accuracy) after adding
constraint.