Tham khảo tài liệu 'innovations in intelligent machines 1 - javaan singh chahl et al (eds) part 14', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | 254 J. Gaspar et al. Fig. 14. Left Bird s eye view of the corridor. Right Measurements used in the control law the robot heading Ỡ and distance d relative to the corridor centre. The controller is designed to regulate to zero the error measurements actuating on the angular and linear speeds of the robot To navigate along the topological graph we still have to define a suitable vision-based behaviour for corridor following links in the map . In different environments one can always use simple knowledge about the scene geometry to define other behaviours. We exploit the fact that most corridors have parallel guidelines to control the robot heading direction aiming to keep the robot centred in the corridor. The visual feedback is provided by the omnidirectional camera. We use bird s eye views of the floor which simplifies the servoing task as these images are a scaled orthographic projection of the ground plane . no perspective effects . Figure 14 shows a top view of the corridor guidelines the robot and the trajectory to follow in the centre of the corridor. From the images we can measure the robot heading with respect to the corridor guidelines and the distance to the central reference tra jectory. We use a simple kinematic planner to control the robot s position and orientation in the corridor using the angular velocity as the single degree of freedom. Notice that the use of bird s eye views of the ground plane simplifies both the extraction of the corridor guidelines . the corridor has a constant width and the computation of the robot position and orientation errors with respect to the corridor s central path. Hence the robot is equipped to perform Topological Navigation relying on appearance based methods and on its corridor following behaviour. This is a methodology for traversing long paths. For local and precise navigation the robot uses Visual Path Following as detailed in Sect. . Combining these behaviours the robot can perform missions covering .
