The positioning system will be driven to an arbitrary position on the travel path. An external measurement system (laser interferometer, measurement probe) will record this position. The positioning system drives to the same position repeatedly from the same direction whilst the measurement system is running. The external measurement system repeatedly measures this position. After a stipulated number of repetitions of this process there is a range of measured values available for this position, from which the two-fold standard deviation can be calculated. This value represents the unidirectional repetition accuracy for the respective position on the travel path.
In order to achieve a higher level of safety with the determination of this value, the unidirectional repetition accuracy is determined at multiple positions and the largest value arising from this is quoted as the characteristic value for the positioning system.