Supported interfaces:
Required devices:
Supported configuration requests:
| Name | Type | Default | Meaning |
| position_index | integer | 0 | Index of the underlying position device. |
| laser_index | integer | 0 | Index of the laser device. |
| cell_size | length | 0.1 | Local occupancy map grid size (m). |
| window_diameter | integer | 61 | Dimensions of occupancy map (map consists of window_diameter X window_diameter cells). |
| sector_angle | integer | 5 | Histogram angular resolution, in degrees. |
| robot_radius | length | 0.25 | The radius of the robot (m). |
| safety_dist | length | 0.1 | The minimum distance the robot is allowed to get to obstacles (m). |
| max_speed | integer | 200 | The maximum allowable speed of the robot, in millimeters/second, the robot. |
| max_turnrate | integer | 40 | The maximum allowable turnrate of the robot. |
| free_space_cutoff | float | 2000000.0 | Unitless value. The higher the value, the closer the robot will get to obstacles before avoiding. |
| weight_desired_dir | float | 5.0 | Bias for the robot to turn to move toward goal position. |
| weight_current_dir | float | 3.0 | Bias for the robot to continue moving in current direction of travel. |
| distance_epsilon | length | 0.5 | Planar distance from the target position that will be considered acceptable. |
| angle_epsilon | angle | 10 degrees | Angular difference from target angle that will considered acceptable. |
The primary parameters to tweak to get reliable performance are safety_dist and free_space_cutoff. In general, safety_dist determines how close the robot will come to an obstacle while turning (around a corner for instance) and free_space_cutoff determines how close a robot will get to an obstacle in the direction of motion before turning to avoid. From experience, it is recommeded that max_turnrate should be at least 15% of max_speed.
To get initiated to VFH, I recommend setting robot_radius to the radius of your robot and starting with the default values for other parameters and experimentally adjusting safety_dist and free_space_cutoff to get a feeling for how the parameters affect performance. Once comfortable, increase max_speed and max_turnrate. Unless you are familiar with the VFH algorithm, I don't recommend deviating from the default values for cell_size, window_diameter, or sector_angle.
For more information on the VFH driver, ask Chris Jones: cvjones@robotics.usc.edu.