Unicycle-like (differential-drive) blocks: kinematics and dynamics

[Felipe]

Hello all,

I have built two blocks to simulate the kinematics and the dynamics of differential drive robots (unicycle-like) using Peter Corke's Robotics Toolbox. They can be downloaded here:

https://dl.dropboxusercontent.com/u/24875984/unicycle_model_for_Robotics_Toolbox.zip

One important feature is that the dynamic model accepts velocity commands. That is, you can use these blocks to simulate the complete robot model (kinematics+dynamics) directly connected to a controller that generates linear and angular velocities (not torques). 

Some sets of parameters to represent the following types of robots are provided (please, see the "help" of the dynamic block).

- Pioneer 3 with Sick LASER sensor

- Pioneer 3 without LASER sensor

- Pioneer 2 without onboard computer (no LASER sensor)

- Pioneer 2 with onboard computer (no LASER sensor)

- Robotic wheelchair carring a 55kg person

- Robotic wheelchair carring a 125kg person

After unzipping, you should copy all files, specially "unicycle_model.mdl" to the ...\rvctools98\simulink folder. Run the scripts "sim_unicycle_dynamics.m" and "sim_unicycle_kinematics.m" to see examples of use of the unicycle blocks.

The blocks were tested using Robotics Toolbox version 9.8 running on MATLAB R2012b and R2013a. If you have any doubts, please, let me know.

I hope this is useful for you!

[Erik van Oene]

Thanks, I will look into it just out of curiosity.

Always nice to share some code!

Erik

Op donderdag 23 mei 2013 01:24:59 UTC+2 schreef Felipe het volgende:

[Felipe]

OK, Erik.

If you have any questions, please le me know!

Felipe.

[Erik van Oene]

Felipe,

here a few questions:

Isn't the input "steering angle" in fact the steering velocity?

Further I am curious how the vector parameters is build up.

And is it correct that the files does not use anything of the Robotics Toolbox? It looks like I can run it all without the toolbox loaded.

Thanks for sharing... I was looking for a simulation (for velocity control) of a segway like robot. Maybe some of this will be helpful.

Erik

Op maandag 3 juni 2013 00:13:48 UTC+2 schreef Felipe het volgende:

[Felipe]

Hello, Erik.

You are right: the input is steering velocity (angular velocity). I have to correct that. 

The dynamic parameters depend on several physical aspects, as mass, moment of inertia, wheel radius, etc. Access the block help to see parameter sets that already have been identified for different robot models. You can get more information on the dynamic parameters in this paper:

http://www.sciencedirect.com/science/article/pii/S0967066108000373

It is true that you can use the blocks without the Robotics Toolbox. But, I have built them to be used with the robotics toolbox tools. In fact, the kinematics block can be used as a direct replacement of the Bycicle block.

I hope it helps you!

Best regards,

Felipe.

[Felipe]

Dear all,

I finally had the opportunity to finish my work on the velocity-based dynamic model for the differential steered mobile robot. I tried my best to make the blocks compatible with the Robotics Toolbox.

The files are in Matlab Central:

http://www.mathworks.com/matlabcentral/fileexchange/44850-velocity-based-dynamic-model-and-adaptive-controller-for-differential-steered-mobile-robot

I would very much appreciate your evaluation!

Best regards,

Felipe.

[Erik van Oene]

Hi Felipe,

Thanks for sharing!

I'm quite busy at the moment but I will take a look at this.

Erik

Op dinsdag 28 januari 2014 21:02:11 UTC+1 schreef Felipe:

[Felipe Nascimento Martins]

OK, Erik.

Please, contact me if you have any questions.

Att.,

Felipe Nascimento Martins

felipe.n...@gmail.com

http://about.me/felipe.n.martins

http://twitter.com/f_n_martins
Blog sobre robótica: http://nossosrobos.blogspot.com

2014-02-03 Erik van Oene <erik...@gmail.com>:

[yani.mu...@gmail.com]

Dear Felipe
Thank you for your information, it is very useful for me.
my question is How to add visual feedback to steering mobile robot ? do you have any example simulation?

[Felipe Nascimento Martins]

Hi, Yani.

I don't have examples of simulation of visual feedback to steer a mobile robot. But, on a related topic, I recommend you join Peter Corke's course on Robotic Vision that is about to begin:
https://www.qut.edu.au/study/short-courses-and-professional-development/short-courses/robotic-vision

I think you are going to learn just what you need. ;-)

Cheers!

Att.,

Felipe Nascimento Martins

felipe.n...@gmail.com

http://about.me/felipe.n.martins 

Blog sobre robótica: http://nossosrobos.blogspot.com 

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[Felipe]

Dear all,

I've corrected a small bug on the dynamic model block that was causing the dynamic compensation to be non-perfect. The new corrected block is available on the link bellow. 

http://www.mathworks.com/matlabcentral/fileexchange/44850-velocity-based-dynamic-model-and-adaptive-controller-for-differential-steered-mobile-robot

Cheers!

Felipe.

[Peter Corke]

Thanks Felipe,

with respect to what I had in that draft chapter (figs + text), is that bug present?

peter

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[Felipe Nascimento Martins]

Hi, Peter.

No. The draft is fine. The bug was not in the model itself, but only on the Simulink block that I built. 

Felipe.

Att.,

Felipe Nascimento Martins

felipe.n...@gmail.com

http://about.me/felipe.n.martins 

Blog sobre robótica: http://nossosrobos.blogspot.com 

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