DWB_local_planner slows down while avoiding obstacles.

asked 2019-01-29 09:08:46 -0500

Mobile_robot gravatar image

updated 2019-01-29 09:15:54 -0500

Dear all,

While trying to avoid obstacle (dynamic and static) by the DWB_local_planner, the robot slows down to its min_vel_x.

I believe the problem comes from the way that I have configured the DWB_local_planner parameters (specially that I am not sure about the max_scaling_factor and scaling_speed).

Do you have any idea why it behaves like this?

Here you can find my current configuration:

acc_lim_x: 0.5
acc_lim_th: 0.5

# Robot Configuration Parameters
max_vel_x: 1.0
min_vel_x: 0.1 

max_trans_vel: 1.0
min_trans_vel: 0.1

max_trans_vel: 1.0
min_trans_vel: 0.0

max_rot_vel: 0.628 
min_rot_vel: 0.2 

# Goal Tolerance Parameters
yaw_goal_tolerance: 0.15 
xy_goal_tolerance: 0.5 
latch_xy_goal_tolerance: false

# Forward Simulation Parameters
sim_time: 4.0 
sim_granularity: 0.025
vx_samples: 6
vy_samples: 0 
vtheta_samples: 30
controller_frequency: 10
#meter_scoring: true
#penalize_negative_x: false

# Trajectory Scoring Parameters
path_distance_bias: 12
goal_distance_bias: 10
occdist_scale: 14.0
forward_point_distance: 0.325
stop_time_buffer: 0.2
scaling_speed: 0.25
max_scaling_factor: 0.2

# Oscillation Prevention Parameters
oscillation_reset_dist: 0.05 

# Debugging
publish_traj_pc : true
publish_cost_grid_pc: true
global_frame_id: map

# Global Plan Parameters
prune_plan: true

The test without inflation image description

The test with inflation (cost_scaling_factor: 0) image description

Thanks a lot,

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A) I'm not sure what your diagrams are showing B) What do you think it should do instead?

David Lu gravatar imageDavid Lu ( 2019-01-29 16:01:32 -0500 )edit

Thanks David for your comment.

A) In order to indicate that this behavior of the DWB_local_planner is not related to the distance between the footprint and the obstacle.

Mobile_robot gravatar imageMobile_robot ( 2019-01-30 02:39:01 -0500 )edit

B) I think the fact that it slows down is logical but I do not understand why the DWB sets the robot's velocity to the min_vel_x. The robot is too slow while detecting an obstacle and while avoiding it which leads to a not satisfying behavior.

Mobile_robot gravatar imageMobile_robot ( 2019-01-30 02:42:31 -0500 )edit

This is why I was wondering if I have done any mistake while configuring the parameters.

Mobile_robot gravatar imageMobile_robot ( 2019-01-30 02:43:25 -0500 )edit

Does it get better when you turn down sim_time?

David Lu gravatar imageDavid Lu ( 2019-02-11 12:07:44 -0500 )edit

I have tried that but unfortunately I saw no changes.

Mobile_robot gravatar imageMobile_robot ( 2019-02-18 07:09:01 -0500 )edit

Can you record the DWBLocalPlanner/evaluation topic and post it here?

David Lu gravatar imageDavid Lu ( 2019-02-19 15:50:58 -0500 )edit