Axis straightening measuring instrument refers to an instrument capable of measuring geometric shapes, lengths, and circumferential divisions within the spatial range of a hexahedron, also known as a coordinate measuring machine or coordinate measuring bed. A coordinate measuring instrument can also be defined as "an instrument with a detector that can move in three directions and can move on three mutually perpendicular guide rails. This detector transmits signals in a contact or non-contact manner, and a three-axis displacement measurement system (such as a grating ruler) calculates the various points (x, y, z) and functional measurements of the workpiece through a data processor or computer. The measurement function of a coordinate measuring instrument should include dimensional accuracy, positioning accuracy, geometric accuracy, and contour accuracy.

Axis straightening measuring instrument is a measuring device that has a guiding mechanism, measuring element, and digital display device in three mutually perpendicular directions. It has a worktable that can place workpieces (large and giant ones are not available), and the measuring head can be easily moved to the measured point by manual or motorized means. The coordinate values of the measured point are displayed by a reading device and a digital display device. Obviously, this is a simple and primitive measuring machine. With this measuring machine, the coordinate values of any point in the measured volume can be displayed through a reading device and a digital display device. The sampling and transmitting device of the measuring machine is a measuring head, which is equipped with a grating ruler and a reading head along the X, Y, and Z axes. The measurement process is that when the measuring head contacts the workpiece and sends out a sampling signal, the control system collects the coordinate values of the current three-axis coordinates of the machine tool relative to the machine tool origin, and then the computer system processes the data.