A force-displacement hybrid control method for a three-degree-of-freedom loading system

Abstract

The invention relates to the technical field of anti-seismic structures, and discloses a force-displacement hybrid control method for a three-degree-of-freedom loading system. It includes the following process: issue the target displacement, target rotation angle and target axial force commands to the three-degree-of-freedom loading system, obtain the target displacements of the three actuators through nonlinear transformation, and act on the specimen; Set the LVDT displacement sensor, collect the displacement of the LVDT displacement sensor, and collect the displacement and output of each actuator at the same time; obtain the actual displacement and rotation angle of the test piece through the nonlinear transformation of the displacement of the LVDT displacement sensor, and convert the actual displacement of the actuator to The actual axial force of the specimen is obtained through nonlinear transformation with the output force; the actual displacement, rotation angle and axial force are transmitted to the loading system for feedback control, and the above process is repeated through the correction of the PI controller to achieve the target command of the specimen. This scheme adopts LVDT displacement sensor, and considers the geometric nonlinearity of the loading system at the same time, which improves the accuracy of the test system.

Description

technical field [0001] The invention relates to the technical field of anti-seismic structures, in particular to a force-displacement hybrid control method for a three-degree-of-freedom loading system. Background technique [0002] As we all know, earthquake is one of the most common natural disasters. Its occurrence has caused immeasurable economic losses and casualties to human society. It is particularly important to study the seismic performance of structures. However, how to accurately evaluate the seismic capacity of structures or components is The primary problem currently facing. Therefore, the quasi-static test is studied. Among them, due to the significant technical and economic advantages of the quasi-static test, and through the test, important information such as the strength, stiffness, and energy consumption of the structure or component can be obtained, which provides an important basis for structural design, so it has always been a very important field in t...

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Problems solved by technology

[0005] The existing control method is to feed back the displacement and the obtained rotation angle of the actuator itself as the actual displacement and rotation angle. It can be seen from previous tests that although the displacement and rotation angle obtained by the feedback of the actuator itself can realize the control of the specimen. Target displacement, but there is a certain difference between the rotation angle measured by the LVDT high-precision displacement sensor and the target rotation angle, especially for the bending-shear type test, it will produce a large error, which will affect the actual measured performance of the structure or component

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