High-Precision Large-Displacement Measuring Method with Walking Pattern

A method for measuring large displacements >800 mm with a precision of 0.0094% and an accuracy of 0.0125%, realizing the principle of measurement with walking pattern and utilizing two analog high-precision small displacement sensors as the measuring unit is presented. A self-tuning fuzzy PID controller with high adaptability is used to make two identical measuring subsystems work coordinately for reaching a large displacement measurement. A series of tests are conducted to verify the effectiveness of the method. The results show that this method has a good performance. The influence of the mechanical deformation on measuring precision is discussed, and the functional relationship between mechanical structural deformation and measuring error is found in the experiment. A feasible compensation scheme is built to eliminate the error caused by mechanical deformation.