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osrf / rmf_core

Provides the centralized functions of RMF: scheduling, etc.
Apache License 2.0
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how to set the starting motion time for individual robot? #195

Closed Jason-Zhou1 closed 3 years ago

Jason-Zhou1 commented 4 years ago

Hi all, I want to do a simulation about 2 robots: magni1 and magni2. I want magni2 to start motion 10 seconds later than magni1. Anyone can help me in this issue?

mxgrey commented 4 years ago

This question/issue might be better suited for the rmf_demos repo.

That repo provides a delayed_request_loop script which you can use from a launch script to give a rough timing to the robot motion start times.

This isn't meant to be a robust way of scheduling tasks, but it may be useful for demo and experimental purposes while we currently work on more rigorous task scheduling features.

Jason-Zhou1 commented 4 years ago

Hi mxgrey,

image

Thanks!

mxgrey commented 4 years ago

You're talking about completely changing the public API of rmf_fleet_adapter in a way that I don't think is sensible.

I don't believe a task request should specify the velocity that a robot uses. A robot's operational velocity is typically determined by the physical capabilities of the robot platform. It's not something that a human user (which is where a task request comes from) should be allowed to fiddle with in my opinion.

The way to change a robot's operational velocity for a demo involves two steps:

  1. Modify the nominal_drive_speed (edit: fixed link) value of the model you want to change, or create a new model with the nominal_drive_speed value that you want it to have.
  2. Modify the linear_velocity value in the launch file for the fleet adapter of the robot fleet you're using, or create a new fleet adapter launch file with the linear_velocity value that you want it to have.

Now launch the simulation with the modified (or newly created) model and fleet adapter launch file.

Jason-Zhou1 commented 4 years ago

Hi mxgrey, I have changed the values of linear velocity in both sides(nominal_drive_speed&linear_velocity), but the actual speed does not change in the simulation.

mxgrey commented 4 years ago

Sorry, it looks like I linked you to a deprecated repo.

If you want to modify the nominal_drive_speed of the existing model in the office, you need to change it here.

I just tested out setting that value to zero, and the robot is no longer able to drive forward (but it can still turn in place).

One thing I should note: Reducing the nominal drive speed in simulation should be fine, but using a higher speed (like the 1.0 that you've mentioned) might not actually work well because the wheels might start slipping. You can fix the slipping by tuning various simulation parameters like friction coefficients and the kp & kd values for ODE, but this requires either a lot of knowledge about physics simulation or a lot of patience. You can certainly try using a higher value, but don't be surprised if you find the robot slipping.

mxgrey commented 3 years ago

Closing as this is not an issue. To continue discussing this topic, please open a discussion.