# Selection of Optimal Path Control Algorithms for Probe Heads Used on Five-Axis Measuring Systems
## 3 Experiment and Results
Three available methods were tested: Guide point, guide curve, and fixed tilt and advance. In the guide curve option it was possible to specify the offset value for each point of the determined guide curve, in the direction from regarded point to the probing system's central point. The negative value of this parameter moves all points of the curve closer to the central point of the probing system, and the positive one moves them away. Three cases were tested during experiment: Guide curve with offset set to \(0\) mm, \(-5\) mm, and \(-10\) mm (denoted as GC \(0\), GC \(-5\), and GC \(-10\), respectively). Additionally, the fixed tilt and advance method was tested for different values of tilt and advance: With a fixed tilt value of \(30^{\circ}\) and three advance values, \(10^{\circ}\), \(20^{\circ}\), and \(30^{\circ}\) (denoted as FTAA \(30^{\circ}/10^  
FTAA 30\({}^{\circ}\)/20\({}^{\circ}\), and FTAA 30\({}^{\circ}\)/30\({}^{\circ}\), respectively); and with a fixed advance value of 30\({}^{\circ}\) and three changing tilt values, 10\({}^{\circ}\), 20\({}^{\circ}\), and 30\({}^{\circ}\) (denoted as FTAA 10\({}^{\circ}\)/30\({}^{\circ}\), FTAA 20\({}^{\circ}\)/30\({}^{\circ}\), and FTAA 30\({}^{\circ}\)/30\({}^{\circ}\), respectively). Measurements of the diameter and circularity deviation were repeated 10 times for all described methods and cases. Results of this part of the experiment are presented in Figure 6, which shows average deviations from nominal values (taken from the calibration certificate of the standard ring), and Figure 7, which gives information about the standard deviation for each measurement task. In the case of the standard ring measurements, the range of deviation produced by the different path control algorithms used for the determination of the diameter was equal to 6.3 \(\upmu\)m, whereas for the measurement of circularity the deviation was 2.8 \(\upmu\)m. What should be noticed, is that a slight change in parameter values for tilt and advance may cause significant changes in the results of both the diameter and circularity deviation measurements. Figure 6: The average deviations for the two chosen tasks, measured on the ring standard using nine different path control algorithms. Figure 7: The standard deviations for the two chosen tasks, measured on the ring standard using nine different path control algorithms. After completing the first part of the experiments, which involved gauges measurements, the obtained results (presented in Figures 4-7) were analyzed in order to find the inspection path planning methods that gave the best results for the measurement tasks included in the experiments. The main criterion for the selection of the most suitable method was the minimization of average deviation from nominal value. Additionally, the standard deviation was also taken into account during selection, as a secondary criterion. The result of this analysis is presented in Table 2.  
The second part of the experiments involved measurements of chosen dimensions and relations of the multi-feature check (MFC) gauge, and determination of the relationship of the results produced by the two methods used for inspection path control: the default option (suggested by the Modus software) and the option selected on the basis of results obtained in the first part of experiments. The multi-feature check standard allows for measurements of different geometrical features and the evaluation of the diversity of geometrical dimensions and tolerances, such as distances and angles between elements, perpendicularity, parallelism, flatness, cylindricity deviations, etc. The main element forming the standard's shape was a cylinder with a length of 200 mm (between front planes) and an outer diameter of 100 mm.