Hi Eitan,
Many thanks for the planner parameters--I already see an improvement in
the results. However, I am still getting velocities beyond the maximums
I set. I am using the latest Cturtle release (binaries) on a Ubuntu
10.04 LTS. In particular, the navigation version is:
ros-cturtle-navigation 1.2.2-36~lucid
I increased my max velocities to see if having them so low was a problem
but even with max_rotational_vel set to 1.0, I just now saw 2.5 when
asking the robot to move 1 meter in rviz.
If there is any other data I can provide, please let me know. Or
perhaps there is another way I can check the planner velocities besides
running the robot?
Thanks,
Patrick Goebel
Behavioral Sciences
Stanford University
> Patrick,
>
> I tried for awhile to get the commanded velocity from the
> base_local_planner
> to fall outside of the maximum limits using your configuration files in
> stage and failed. I can't get the commanded x velocity to go above 0.2
> m/s
> and the rotational velocity never goes above 0.15 rad/sec, both of
> which are
> within the specified limits. What version of navigation are you using?
> I've
> been testing on 1.2.2, which is the latest Cturtle release. Perhaps its a
> problem with a previous version?
>
> With that said, your velocity and acceleration limits are different
> enough
> from the defaults that it required tuning some parameters to get
> things to
> run smoothly. With the parameters you provided, the robot wouldn't go
> much
> of anywhere. I made a few modifications, which I'll include below to get
> things working in a reasonable manner. First, I upped the sim_time
> parameter
> to 2.0 seconds from the default of 1.0 second. I did this because you
> have a
> very low maximum linear velocity and trajectories are scored from their
> endpoints, so simulating them a bit further helps to differentiate
> between
> paths. Also, since you have a really low maximum for your angular
> velocity,
> I felt like it might be helpful for the robot to attempt to follow the
> global plan more closely. To this end, I upped the path_distance_bias
> weight
> and dropped the goal_distance_bias weight. I only spent about 2 minutes
> tuning the parameters, so I'm sure that you'd be able to get even better
> behavior by playing around some more (upping the sim_time even more,
> or the
> trade off between following the path and moving towards the goal... see:
> http://www.ros.org/wiki/base_local_planner for parameter
> descriptions), but
> this at least exhibits reasonable results for me in simulation. My
> changes
> can be found below:
>
> TrajectoryPlannerROS:
> max_vel_x: 0.2
> min_vel_x: 0.05
> max_rotational_vel: 0.15
> min_in_place_rotational_vel: 0.1
> acc_lim_th: 2.0
> acc_lim_x: 1.0
> acc_lim_y: 1.0
> yaw_goal_tolerance: 0.2
> xy_goal_tolerance: 0.2
> controller_frequency: 5.0
> holonomic_robot: false
> path_distance_bias: 0.8
> goal_distance_bias: 0.4
> sim_time: 2.0
>
> Hope this helps and that all is well,
>
> Eitan
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