modified DH parameters

[Réda Hanifi]

Hello ,

I'm new with the use of the robotic toolbox

I've created a robot (FANUC LR Mate 200ib) using the standard Denavit Hartenberg parameters :

L(1) = Link([0        0       0.150   -pi/2   0  ]);

L(2) = Link([0        0       0.250    pi     0  ]);

L(3) = Link([0        0       0.075   -pi/2   0  ]);

L(4) = Link([0       -0.290   0        pi/2   0  ]);

L(5) = Link([0        0       0       -pi/2   0  ]);

L(6) = Link([0        0       0        0      0  ]);

q0 =[0   -pi/2   0   0   0   0];

R=SerialLink(L, 'name', 'Fanuc');

I want to create the same robot using the modified DH parameters and I need some help. 

[Peter Corke]

Have a look at pages 161-2 of the RVC book.

peter

[jok...@gmail.com]

when i used the modifed dh parameters,  the robot.plot  does not plot the right configuration.

as far as i know the modified dh  set  alpha(i-1) and a(i-1)   to alpha(i) and a(i).

i guess there is a problem in the robot.plot function.

在 2013年10月8日星期二UTC+8下午7时45分06秒，Peter Corke写道：

[Peter Corke]

Not enough information to debug this.

[Zhou K]

%                   th     d            a            alpha

% L(1) = Link([ 0     0             0             pi/2    0], 'standard');

% L(2) = Link([ 0     0             0.4318  0       0], 'standard');

% L(3) = Link([ 0     0.15005   0.0203     -pi/2   0], 'standard');

% L(4) = Link([ 0     0.4318     0             pi/2    0], 'standard');

% L(5) = Link([ 0     0             0             -pi/2   0], 'standard');

% L(6) = Link([ 0     0    0             0      0], 'standard');

L(1) = Link([ 0     0             0             0        0], 'modified');

L(2) = Link([ 0  0              0            pi/2    0], 'modified');

L(3) = Link([ 0     0.15005 0.4318     0        0], 'modified');

L(4) = Link([ 0     0.4318 0.0203     pi/2    0], 'modified');

L(5) = Link([ 0     0             0            -pi/2     0], 'modified');

L(6) = Link([ 0     0         0             pi/2    0], 'modified');

  

when use the modified dh parameters , the plot function  give the  axis1  coincide with axis2

在 2013年10月15日星期二UTC+8下午12时26分18秒，Peter Corke写道：

[Peter Corke]

There is indeed a bug in plot.  An assumption made for DH doesn't hold for MDH parameters.  Need to think the best way to sort this.  Thanks for picking it up.

peter

[Zhou K]

plot.m

%%%%%%%

....

function h = create_new_robot(robot, opt)

...

   if opt.jaxes

            % add a dashed line along the axis

            h.jointaxis(i) = line('xdata', [0;0], ...

                'ydata', [0;0], ...

                'zdata', [0;0], ...

                'color', 'blue', ...

                'LineWidth',2,...

                'linestyle', '-');

            h.jointlabel(i) = text(0, 0, 0, num2str(i), 'HorizontalAlignment', 'Center');

        end

When I was check out the plot.m,  I couldn't  figure out how the code above draws the axis for each joints and the way to control of the length of axis .

This function 'create_new_robot'  is very difficult to understand,  the parameters of robot doesnot show itself explicitly, but for 'sdh' the output is correct so far.

And the reason for not supporting 'mdh' parameters may be  the plot.m does not consider the 'mdh' situtation.

在 2013年10月16日星期三UTC+8上午5时26分49秒，Peter Corke写道：

[Zhang Tan]

Hi,

Have the Plot function been revised yet?

The current version seems to have some errors.

1) in the

[Zhang Tan]

Hello,

I am not sure if the plot function has bugs for both DH parameters and Modified DH parameters.

I set the DH parameters. However, the axis of the first joint cannot be changed, no matter how I change the parameters with DH or MDH.

Is that a bug?

If not, how to change the axis of the first joint?

Thanks.

Tandy

[tandy...@gmail.com]

What I mentioned was not a bug. By setting the 'base', the axis of frame {0} could be changed ;)

Tandy