Best practice for Ackermann car to follow a path

Question

Hi all,

I have built a MIT-Racecar which has Ackermann and VESC. The car can be driven with ackermann_msgs/AckermannDriveStamped type messages in ROS.

Now I would like to drive the car along a particular path to collect some videos with the camera on the car. The path consists of straight and curved segments. You can imagine the path as in a shape of "8" in a 30x30 yard region. Please note this is NOT autonomous driving. I can drive the car with teleop, an customized ROS node, etc. All I want is that the car follows the path accurately.

I am not very good in using teleop. So my first idea is to write a ROS node. I can collect some measurements of the path and calculate a serial of speed and steering parameters and let the ROS node send them out as AckermannDriveStamped message. The advantage of this method is that I can continue improve my speed/steering numbers and make the control more and more accurate. But I have two questions:

1. Is this approach the best practice to make the car follow a pre-defined path?

2. If this is the best way, is there any existing method to convert a known path to a serial of speed and steering numbers for ackermann? I think this may be a part of Path Planing, but I am not sure.

Thank you very much.

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Originally posted by AutoCar on ROS Answers with karma: 102 on 2018-07-04

Post score: 0

Answer 1

I am also working on the predefined path problem for the navigation stack.

Here are some questions available:

Question 1

Question 2

Question 3

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Originally posted by aarontan with karma: 135 on 2018-07-05

This answer was ACCEPTED on the original site

Post score: 0

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Original comments

Comment by AutoCar on 2018-07-05:
Thank you very muh

Comment by AutoCar on 2018-07-05:
@aarontan could you please let me know the approach you used?

Comment by aarontan on 2018-07-05:
From Question 2, I wrote a custom global planner plugin with a predefined path, in this case a circle with a fixed radius. From the video attached with the question, you can see that my robot is able to follow this global path; however, no obstacle avoidance. You can customize the code for any path.

Comment by aarontan on 2018-07-05:
If you give me your email address, I can send you my files?

Comment by AutoCar on 2018-07-05:
thank you. userstyles at artlystyles dot com

Comment by aarontan on 2018-07-06:
i have sent you an email. if you are satisfied with this answer, please mark it as the correct one. thank you.

Comment by KSWang on 2019-04-02:
@aarontan Hi, may I get your files too. I also have the same problem. email: [email protected] appreciated for your help.