Measurement methods for the position errors of a multi-axis machine. Part 1: Principles and sensitivity analysis

Accurate measurement of errors is an essential part of error compensation. By using telescoping ball-bars, two measurement methods, characterized by low cost, simplicity of setup, and quick measurements are developed to directly identify the total position errors at the tip of the tool of a multi-axis machine tool without the use of an error model. The first method uses the well known triangulation principle that requires three reference points. The second, referred to as the single socket method, utilizes a single reference point, offering thereby a higher degree of dexterity and flexibility. In addition, sensitivity analysis is used to investigate the accuracy of the two methods with respect to two error factors: errors of the ball-bar system, and location errors of the reference point.