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Tham khảo tài liệu 'motion control theory needed in the implementation of practical robotic systems 2 part 11', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | Chapter 10 A Novel Navigation Technique Figure 10.3. A map of obstacles and line segments. Figure 10.4. The potential field created by Mexican Hat Navigation. 73 Chapter 10 A Novel Navigation Technique Figure 10.5. The path of least resistance through the potential field. Figure 10.6. The resulting path through the course. 74 Chapter 10 A Novel Navigation Technique There are several simple variations to Mexican Hat Navigation. The first ones involves smoothing the path. This can be done by calculating the same path and then going back and applying an averaging filter to each point. Significant smoothing can be added by eliminating excursions where the path goes sideways for a single step and then returns to its original path. A more sophisticated method of smoothing the path is to assume a sphere has to roll down the path of least resistance instead of a point and then adjusting the radius and momentum of the sphere to gain the desired smoothness. Another variation is to change or increase the number of objects allowed in the universe beyond line segments and obstacles. New potential fields must then be contrived to describe the new objects. Contrived fields with more general geometric shapes are known as artificial potential fields and are also used for obstacle avoidance and approach by Khosla and Volpe 49 . A wide variety of alternate navigation strategies is available in the literature. Kim and Khosla in 50 and Akishita et. al. in 51 use an artificial potential function to get around an obstacle to a goal sink. In 52 Megherbi and Wolovich use potential fields and complex conformal mapping to do obstacle avoidance in 3D. Nam et. al. 53 use artificial potential fields to do collision planning and avoidance when multiple objects are moving. In 54 Joarder and Raviv exploit another characteristic of the human retina to perform obstacle collision. They mimic the looming reflex where objects close to the eye that change texture suddenly cause one to flinch in the .
