Error With prismatic joint in RT10

[alessi...@gmail.com]

Hi,

I tried to create a S.C.A.R.A. manipulator with RT10, and I used this code:

%SCARA

%Parametri D-H:

d0=1;

a1=0.5;

a2=0.5;

a4=0.25;

%Definizione bracci:

L1 = Link('d',0,'a',a1,'alpha',0);

L2 = Link('d',0,'a',a2,'alpha',pi);

L3 = Link('d',1,'a',0,'alpha',0);

L4 = Link('d',0,'a',a4,'alpha',0);

scara=SerialLink([L1 L2 L3 L4], 'name', 'SCARA');

scara.plot([0 0 0 0])

But the 3rd joint of the resulting manipulator is not prismatic:

So I tried to change the code in this way:

L1 = Link([0,0,a1,0,0]);

L2 = Link([0,0,a2,pi,0]);

L3 = Link([0,d3,0,0,1]);

L4 = Link([0,0.1,a4,0,0]);

scara=SerialLink([L1 L2 L3 L4], 'name', 'SCARA');

scara.plot([0 0 0 0])

But the toolbox give me an error:

Error using RTBPlot.plot_options (line 772)

prismatic joint 3 has no qlim parameter set, set it or specify 'workspace' plot option

Error in SerialLink/plot (line 212)

    opt = RTBPlot.plot_options(robot, varargin);

Error in SCARA (line 19)

robot.plot([0 0 0 0])

 

Well, I tried to set qlim (L3.qlim=[0 2];), but it just reduces a1 and a2 arms (I really don't know why!!). Then I setted the workspace's limits (scara.plot([0 0 0 0],'workspace',[-2 2 -2 2 -2 2]), but in this way Matlab doesn't recognise "workspace" function.

How can I solve the problem???

[Erik van Oene]

Hi,

I changed line 97 in animate from:

set(h.pjoint(L), 'Matrix', diag([1 1 max(eps,q(L)) 1]))

to

set(h.link(L), 'Matrix', diag([1 1 max(eps, q(L)) 1]));

Erik

Don't now this is a valid fix of the prismatic joints should be displayed differently.

Erik

Op zondag 18 maart 2018 00:25:20 UTC+1 schreef ale....@gmail.com:

[alessi...@gmail.com]

Hi! I changed the cod that you said me, and I modified my code:

%Parametri D-H:

d0=1;

a1=0.5;

a2=0.5;

%Definizione bracci:

L1 = Link('d',0,'a',a1,'alpha',0);

L2 = Link('d',0,'a',a2,'alpha',pi);

L3 = Link('theta',0,'a',0,'alpha',0);

L4 = Link('d',0,'a',0,'alpha',0);

L3.qlim=[0 1];

scara=SerialLink([L1 L2 L3 L4], 'name', 'SCARA');

scara.plot([0 0 0 0])

But the manipulator is still wrong:

[Erik van Oene]

Hi,

Can you explain what us wrong about it. From te pictures I don't see anything wrong... try plotting nonzero configuration or the teach function.

Erik

Op zondag 18 maart 2018 22:42:17 UTC+1 schreef Alessia Adele:

C

[alessi...@gmail.com]

Yes, you're perfectly right! I used wrong parameters to plot the manipulator!
I'm sorry!
Thank you very much!! 

[Peter Corke]

I tried to create a S.C.A.R.A. manipulator with RT10, and I used this code:

%SCARA

%Parametri D-H:

d0=1;

a1=0.5;

a2=0.5;

a4=0.25;

%Definizione bracci:

L1 = Link('d',0,'a',a1,'alpha',0);

L2 = Link('d',0,'a',a2,'alpha',pi);

L3 = Link('d',1,'a',0,'alpha',0);

L4 = Link('d',0,'a',a4,'alpha',0);

scara=SerialLink([L1 L2 L3 L4], 'name', 'SCARA');

scara.plot([0 0 0 0])

But the 3rd joint of the resulting manipulator is not prismatic:

You didn't specify the 3rd joint to be prismatic, you have created an all revolute arm.   

You could make it Prismatic by writing either of

L3 = Link('d',1,'a',0,'alpha',0, 'jointtype', 'P');

or

L3 = Prismatac('d',1,'a',0,'alpha',0);

So I tried to change the code in this way:

L1 = Link([0,0,a1,0,0]);

L2 = Link([0,0,a2,pi,0]);

L3 = Link([0,d3,0,0,1]);

L4 = Link([0,0.1,a4,0,0]);

scara=SerialLink([L1 L2 L3 L4], 'name', 'SCARA');

scara.plot([0 0 0 0])

OK, now you have specified the 3rd joint to be prismatic

 

But the toolbox give me an error:

Error using RTBPlot.plot_options (line 772)

prismatic joint 3 has no qlim parameter set, set it or specify 'workspace' plot option

Error in SerialLink/plot (line 212)

    opt = RTBPlot.plot_options(robot, varargin);

Error in SCARA (line 19)

robot.plot([0 0 0 0])

 

Well, I tried to set qlim (L3.qlim=[0 2];), but it just reduces a1 and a2 arms (I really don't know why!!).

I don't understand what you mean here.

 

Then I setted the workspace's limits (scara.plot([0 0 0 0],'workspace',[-2 2 -2 2 -2 2]), but in this way Matlab doesn't recognise "workspace" function.

Can you show me the error message?   I don't understand what you mean by "doesn't recognise"

[Erik van Oene]

Peter is correct.

I tried your original code again after re-installing the latest version of the Toolbox, the original line in animate works fine now! So no need to change that line! (the pjoint field exists in h).

The following code runs fine now:

clear all
close all
clc

%Parametri D-H:
d0=1;
a1=0.5;
a2=0.5;
a4=0.25;

d3=0.5

L1 = Link([0,0,a1,0,0]);
L2 = Link([0,0,a2,pi,0]);

L3 = Link([0,d3,0,0,1]); L3.qlim = [0 2];

L4 = Link([0,0.1,a4,0,0]);

scara=SerialLink([L1 L2 L3 L4], 'name', 'SCARA');
scara.plot([0 0 0 0])

scara.teach

So my advice is to reinstall the toolbox and try it again. It should work with the code above.

Erik


Op zondag 25 maart 2018 00:51:02 UTC+1 schreef Peter Corke:

[mina199...@gmail.com]

Le dimanche 18 mars 2018 00:25:20 UTC+1, alessi...@gmail.com a écrit :

l1=link([0   1 0 0   0],'standard')

l2=link([0   1 0 0   0],'standard')

l3=link([-pi 0 0 1   1],'standard')

 

r=robot ({l1, l2, l3},'robot 3ddl')

plot(r, [0 0 0])

 

drivebot(r)

ecrire les instruction une par une dans le workspace  

[Peter Corke]

What's the question?  This code is written against a very old version of the toolbox, there are no classes/functions called link, robot or drivebot.  Therefore this code example can't be tested.

[Ankit Kumar]

%SCARA

%Parametri D-H:

d0=1;

a1=0.5;

a2=0.5;

a4=0.25;

%Definizione bracci:

L1 = Link('d',0,'a',a1,'alpha',0);

L2 = Link('d',0,'a',a2,'alpha',pi);

L3 = Link([0,d3,0,0,1]);

L4 = Link('d',0,'a',a4,'alpha',0);

scara=SerialLink([L1 L2 L3 L4], 'name', 'SCARA');

scara.plot([0 0 0 0])

I tried this code but it's giving me error as follows :

Error using RTBPlot.plot_options (line 768)

prismatic joint 3 has no qlim parameter set, set it or specify 'workspace' plot option

Error in SerialLink/plot (line 213)

    opt = RTBPlot.plot_options(robot, varargin);

Error in Untitled3 (line 17)

scara.plot([0 0 0 0])

[valeria leto]

 You must  add this line in your code, to limit the extension of the prismatic joint
L3.qlim=[0 0.18];