I think what you have is a circular link.    That means a
parallelogram type geometry.      I have a robot arm like this too but mine
is MUCH smaller and lower cost.

Mine is nearly identical to this arm on Amazon.

Notice that these are two motors on the shoulder and the "elbow" is pushed
by a link.  I think we have the same geometries, except for scale.
The way to model it using DH is to re-draw the robot arm.   Make a paper
drawing of an equivalent arm that has a motor on each axis and no
circular links and no passive links.    You WILL need to transform the
shaft angle of the moved motor.

I don't use MK for this.  I like "move it" but still DH parameters really
only work for serial links so the trick is to model your arm as a serial
link arm, just pretend the elbow motor is on that elbow and it's shaft
angle is a function of the base motor shaft angle.   This geometry is VERY
common and yes there are names for it but most people call them palletizing
robots.    THese robots need to lift heavy loads, like bags of dog food off
belts and place them on wood pallets so the motors are plased in the base
and force transmitted to push rods.   Most are only 4-DOF   A Google search
for "palletizing robot kinematics" will ,give tons of information.    But
"cheating" works.  Remove the pushlinks and move the motor and make DH
parms for that.  The later "fix" the elbow motor shaft angle. .

The arm in the above link is like mine in that it uses model airplane
servos.   These are very inaccurate and are open loop.   So the plan is to
close the control loop with a video cameras.  This is not something MK was
designed for hence using Moveit. moveit.ros.org    Then I find I need to
sychronize the video shutters so that is on hold for now.

On Thu, Mar 21, 2019 at 6:45 AM yomin estiven jaramillo munera <
yejm...@gmail.com> wrote:

>  Hi guys is me again, our kinematics problem have progressed, this is
> because we are sure that our D-H  parameters were correctly extracted, but
> seems that our robot couldn't be defined with this parameters.
> I'm saying this 'cause our robot is a miller MR 2000  and is very old, it
> is moving how you can see in the follow link
> https://www.youtube.com/watch?v=Hp0gVXj5u-I&feature=youtu.be
> the D-H parameters could define the kinematics but when a joint depend of
> the before one, but in this case our joint 2 is not changing the
> orientation of our joint 3. The joint 2 is able to change the position on
> the space of the final tool, but is unable to change its orientation on the
> space. this kinematics is obviously very different to PUMA kinematics and
> we are doubting about DH parameters can solve this.
> is there any name for this kind of kinematics?
> could i solve this using D-H parameters?
> could i solve this using genserkins?
> All my axes are set like angular joint, could that involved in a possible
> solution?
> <https://www.youtube.com/watch?v=Hp0gVXj5u-I&feature=youtu.be>
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Chris Albertson
Redondo Beach, California

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