Mobile Robot: Move to a Point

[Stephen Armah]

Hi,
I'm trying to run the sl_drivepoint simulink model, which depends on
the angdiff. When a run I get error message "Failed to find 'angdiff'
in library 'roblocks'. I try to locate the angdiff.m file located in
the common folder, and run it but also give me error message
initially, so I entered values for th1 and th2, which gave a value for
angdiff. But the simulink sl_drivepoint does not still pick up. In the
property of the angdiff block is source block roblocks/angdiff. Please
help me out.
Thanks

[Peter Corke]

Stephen,

sorry about the problem. I just ran it and it worked fine, so I need to ask what version of toolboxes and MATLAB you are running.

>> startup_rvc
Robotics, Vision & Control: (c) Peter Corke 1992-2011 http://www.petercorke.com
- Robotics Toolbox for Matlab (release 9.5)
- Machine Vision Toolbox for Matlab (release 3.2)
>> sl_drivepoint
>> xg=[5 5];
>> x0 = [8 5 pi/2];


peter.

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[Stephen Armah]

Version 9.5.
I just copy and past the above and it works, after i have run the
startup_rvc.m. I tought after I have to open and run the angdiff.m
file and before running the simulink model (sl_drivepoint).
I'm doing PhD student and my research topic is Image Recognision and
Tracking using Mobile Robot. There is a mobile robot platform from Dr
Robot to be used for this, and the documentation is in C-Sharp. Is
there a way to convert the MATLAB Code and/or Simulink Model into C-
Sharp or vice versa or can the MATLAB Code and/or Smulink Model be
implemented on the Robot instead of the C-Sharp.
Thanks, and hope to hear from you again.
Regards,
Stephen

On Jun 5, 8:32 pm, Peter Corke <peter.i.co...@gmail.com> wrote:
> Stephen,
>
> sorry about the problem.  I just ran it and it worked fine, so I need to ask what version of toolboxes and MATLAB you are running.
>
> >> startup_rvc
>

> Robotics, Vision & Control: (c) Peter Corke 1992-2011http://www.petercorke.com

[Peter Corke]

On 06/06/2012, at 12:12 AM, Stephen Armah wrote:

> Version 9.5.
> I just copy and past the above and it works, after i have run the
> startup_rvc.m.

Good

> I tought after I have to open and run the angdiff.m
> file and before running the simulink model (sl_drivepoint).

not sure why you would want to that, is there something in the documentation that says you should?

> I'm doing PhD student and my research topic is Image Recognision and
> Tracking using Mobile Robot. There is a mobile robot platform from Dr
> Robot to be used for this, and the documentation is in C-Sharp. Is
> there a way to convert the MATLAB Code and/or Simulink Model into C-
> Sharp or vice versa or can the MATLAB Code and/or Smulink Model be
> implemented on the Robot instead of the C-Sharp.

C-Sharp will be hard to integrate. MATLAB supports Java nicely or C/C++. There are lots of integration options but none of them easy. You could theoretically convert MATLAB code to C-Sharp but again far from easy.

[Stephen Armah]

Thanks again for the quick response.
I will be looking into how to go about with the conversion, if you
come across anything let me know.
My robot is 2-wheeled, and the one discussed in the textbook is 4-
wheeled. Do I have to change something in the bicycle model
(subsystem) to implement the matlab code/simulink to my robot. The
equation of motion of a 2-wheeled (from an article I came across) is
given by:
x_dot = vcos(theta)
y_dot = vsin(theta)
theta_dot = u u is the
rotational velocity (about its centre)
Similar to the one in the book, apart from the third equation which
looks slightly different.
Regards,
Stephen

[Peter Corke]

So it's differential drive rather than having a steered front wheel?

Can you join the group so I don't have to keep approving your messages.

peter

[Stephen Armah]

Thanks for the reply. So, how do go about with differential drive, any
materials out there?
How do I join the group?
Regards,
Stephen

[Peter Corke]

On 06/06/2012, at 10:16 AM, Stephen Armah wrote:

> Thanks for the reply. So, how do go about with differential drive, any
> materials out there?

The Siegwart book covers most drive geometries. Then you'd need to build a new Simulink block to implement the model and then integrate that with existing blocks.

> How do I join the group?

The "Sign in" button at the top of the page.

[Felipe]

Hello, Stephen.

You might want to try the unicycle-like blocks that I made for Peter's Robotics Toolbox:

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

These files allow the simulation of an unicycle-like mobile robot considering its complete dynamic model using Peter Corke's Robotics Toolbox. 

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 an example of use of the unicycle blocks.

The blocks were tested using Robotics Toolbox version 9.8 running on MATLAB R2012b and R2013a.

Best regards!

[Stephen Armah]

Hi Felipe,

Thanks for the information. Great work done.

I will look at it.

Regards,

Stephen

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[Uday Simha]

Hello sir,

I was trying to use the Diffsteer Kinematics block from the file you have posted here to generate my own steering angles trajectory etc.. for my project (i.e) try to create my own model, but when I simulate it, it gives an error that acceleratiion rate limit should be continuous or discrete . I didnot understand how to specify this.

Also, I tried with the bicycle model block from the new release tool box have the same problem.

could you kindly tell me what input should i give for the rate limiter block and how it should be.

Thanks in advance sir

[Felipe]

Hello, Uday.

Sorry it took me so long to give you a repply, but your message got lost in my inbox.

I made some updates, so I would recommend you to try the blocks that are available in Matlab Central:

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

Please, let me know if you still have the same problem.

Regards,

Felipe.