7.3.5 Mental transformation

Using mental transformation, the robot could determine whether it was standing in the middle of the circle (figure 7.13), and it could determine the distance to the obstacle in front (figure 7.14).

On the first test, figure 7.13 shows which locations were classified as being in the center and which not. Among the positions that were classified as center, the maximum distance to the center was 10 cm.

On the second test, the number of predicted steps toward the obstacles scaled with the real distance (figure 7.14). A line was fitted to the data. In all trials, the deviation from the line was less then one step. From the slope of the line the speed of the simulated movement can be estimated. The slope is 6.6±0.2 cm/step and corresponds to a speed of 33±1 mm/sec (the actual speed for the given velocity command was 33.5 mm/sec: 40mm/sec divided by a conversion factor for the wheels).

Figure 7.13: Performance based on mental transformation for detecting the center of the circle. Markers indicate the position of the robot's rotational axis and the direction the robot was facing. Markers surrounded by a circle represent trials in which the position was classified as center.

Figure 7.14: The number n of predicted steps toward an obstacle against the real distance to the obstacle. A line is fitted to the data.