error in using 'ikine' command in 'twolink' robot

[javidx...@gmail.com]

Hello Peter,

I am using MATLAB 2017a;

In page 149 and 150 of the book, I am unable to use the code 

>> q = twolink.ikine(T, [0 0], [1 1 0 0 0 0])

And it does give an error in line 164 whose description is: "Number of robot DOF must be >= the same number of 1s in the mask

matrix".

I would appreciate if you solve the problem.

Regards

[Erik van Oene]

Hi Jarvid,

your mask parameter is not properly handled in this way....

please use:

q = twolink.ikine(T, [0 0], 'mask',[1 1 0 0 0 0])

This could be found quite easily by using:

help seriallink.ikine

OR

use the Matlab debugger next time you run into an error like this... You would have found that ikine() was using the default mask of [ 1 1 1 1 1 1 ].

Erik

Op woensdag 26 juli 2017 23:39:55 UTC+2 schreef javid rabbani:

[Bruce Liang]

I have the same problem as your!

>> q = twolink.ikine(T, [0 0], [1 1 0 0 0 0])

warning: Initial joint configuration results in a (near-)singular configuration, this may slow convergence 

> In SerialLink.ikine at 156 

warning: ikine: iteration limit 1000 exceeded (row 1), final err 0.523502 

> In SerialLink.ikine at 179 

q =

   1.0e+15 *

    2.9396    1.4698

[Peter Corke]

You don't specify the value of T.  As per the documentation this robot moves in the xz-plane so be sure to give a pose that is reachable.  Using RTB10:

>> T=SE3(.5, 0, .5)

T = 

         1         0         0       0.5

         0         1         0         0

         0         0         1       0.5

         0         0         0         1

>> q = twolink.ikine(T, [0 0], 'mask', [1 1 0 0 0 0])

q =

   -0.4240    2.4189