## 1 Introduction  
Monitoring the short- and long-term deformation of large-span bridges, high-rise buildings, and other engineering structures, verifying whether their spectral characteristics are identical to those of the structure design, and checking whether the structure differs from its design due to external forces or design defects [1; 2] can enable the timely detection of structural damage and the assessment of a structure's safety. It can also help predict structural performance changes and facilitate maintenance decisions, which is very important for improving the efficiency of a structure. Over the past few years, researchers used accelerometers to obtain monitoring data, and they performed many experiments [3; 4]. However, accelerometers cannot directly measure structural deformation and are insensitive for slow-deformation monitoring [5; 6; 7]. Furthermore, the acceleration of the quadratic integral leads to error accumulation [8]. Thus, many researchers began using geodetic devices combined with accelerometers for deformation monitoring [9; 10; 11; 12], and the data are processed through optimization algorithms using computer technology [13]. Geodetic devices can directly measure the instantaneous three-dimensional coordinates of a specified point when the amplitude varies from a few millimeters to a few centimeters with a high frequency (<5 Hz) in a structure, independent of the structure itself [14]. They can perform quasi-static, semi-static, and dynamic measurements [15; 16]. These characteristics allow convenient monitoring of the spectral characteristics of a structure using geodetic equipment. Therefore, this became the main method used by geodetic researchers to monitor the health of engineering structures [17; 18; 19; 20]. Researchers recently began monitoring relatively rigid structures, such as pedestrian bridges [21; 22; 23]. Such bridges are subject to complex forces, and they are built on main roads with large traffic flows; thus, monitoring is necessary. Existing measurement methods are still based on global positioning systems (GPSs) and robotic total stations (RTSs) combined with accelerometer measurement [24; 25]. However, some structures exhibit small-amplitude and high-frequency motions, for which RTS and GPS cannot fully meet the requirements. The main reason is that the actual sampling frequency of an RTS is only 6-7 Hz (rated frequency 10 Hz) [11], and it cannot be used for measurements in parallel. A GPS can measure in parallel, but its dynamic accuracy is only \(\pm\)10 mm [26]. Even though an optimization algorithm can be used to obtain an amplitude of 5 mm or more, the accuracy of the results is difficult to verify. These shortcomings make it impossible for the current measurement methods to fully meet the requirements for monitoring small rigid structures. To overcome this problem, this paper discusses the feasibility of monitoring data acquisition with industrial measuring equipment. In recent years, the team at Tianjin University developed a space coordinate measurement technology called the workspace measuring and positioning system (wMPS) [27; 28; 29; 30; 31; 32]. The system's characteristics include high measurement precision, real-time measurements, and multi-task synchronization measurements. It can expand the working space by increasing the number of transmitting stations to avoid the contradiction between measurement ranges and accuracy. This approach is popular in large aircraft manufacturing, digital shipbuilding, and other fields. In this study, the feasibility of using the wMPS to monitor changes in rigid structure displacement was verified; moreover, the range of the inherent parameters of a rigid structure measured by the wMPS was explored, and the measurement-error rule was analyzed. The experiment was based on an oscillating device that produces known preset parameters. This is similar to an experiment designed by a geologist [19].