“…Some other examples of perceptually and computationally demanding input variables not confined to the area of visual navigation include the closest point on the obstacle boundary, the distance to this point, or the value of another function determined by the entire boundary; see, e.g., [24,41,75,112,165,174,178,188,230,306,307,312] for representative samples. Another such variable employed by many proposed controllers, see, e.g., [125,165,307], is the boundary curvature, which is particularly sensitive to corruption by measurement noises since this is a second derivative property.…”