Forward kinematics and inverse kinematics

if i have this following dh parameter how can i draw the robot using matlab ?

[darova]

Do you have a picture?

Answer 1

[Aastav Sen]

As an example, take a look at the following:

(the DH parameters are different, but procedure for creating and showing the final robot as a rigidbodyTree is the same)

Lets say (for a 3DOF robot with 4 bodies (final body being a fixed tool)...

The arrangement for creating a rigidbodyTree with DH parameters is <a, alpha, d, theta> (unlike your table which is <theta, alpha, a, d> (just rearrange it).

% cols: a, alpha, d, theta
dhparams = [0   	pi/2	0   	0;
            0.65	0       0.156   0;
            0.435	-pi/2	0.069	0;
            0       0	    0   	1];
        
% create rigidbody tree
myrobot = rigidBodyTree('MaxNumBodies', 4, 'Dataformat', 'col');

% add first link
body1 = rigidBody('body1');
jnt1 = rigidBodyJoint('jnt1','revolute');
jnt1.PositionLimits = [-1.01 +0.26]; % this is additional...
jnt1.HomePosition = 0.0;
dhparams(1,:)  % this is the row corresponding to link 1 (in DH)
% this is how you use the corresponding DH row
% to define a fixed transform between rigidbodies
setFixedTransform(jnt1,dhparams(1,:),'dh');
body1.Joint = jnt1;

body1.Mass = 0.5;  
% NOTE: inertial components also optional for simply
% showing the final robot
body1.CenterOfMass = [0 0 0];
body1.Inertia = [1 1 1 0 0 0];
addBody(myrobot,body1,'base')

% add the rest of the bodies
body2 = rigidBody('body2');
jnt2 = rigidBodyJoint('jnt2','revolute');
jnt2.PositionLimits = [-0.96 +0.96]; 
jnt2.HomePosition = 0.0;
body3 = rigidBody('body3');
jnt3 = rigidBodyJoint('jnt3','revolute');
jnt3.PositionLimits = [+0.40 +2.84]; 
jnt3.HomePosition = 0.5;
tool = rigidBody('tool');
jnt_ee = rigidBodyJoint('jnt_ee', 'fixed');
% add the rest of the transforms betwn the bodies
setFixedTransform(jnt2,dhparams(2,:),'dh');
setFixedTransform(jnt3,dhparams(3,:),'dh');
setFixedTransform(jnt_ee,dhparams(4,:),'dh');

body2.Joint = jnt2;
body3.Joint = jnt3;
tool.Joint = jnt_ee;

body2.Mass = 1.0;
body2.CenterOfMass = [0.325 0 0];
body2.Inertia = [1 1 1 0 0 0];
body3.Mass = 1.0;
body3.CenterOfMass = [0.2175 0 0];
body3.Inertia = [1 1 1 0 0 0];
tool.Mass = 0.01;
tool.CenterOfMass = [0 0 0];
tool.Inertia = [1 1 1 0 0 0];

addBody(myrobot,body2,'body1')
addBody(myrobot,body3,'body2')
addBody(myrobot,tool,'body3')

And to finally draw the robot in a 3D figure:

% verify that the myrobot was built correctly
showdetails(myrobot)
% and set the home configuration...

Happy coding.

[RoBoTBoY]

Dear, I have these successive transformations that appear in the attached file jpg. I have found the kinematic chain A07 with matlab but the final 4x4 matrix is too big.

How do I find the inverse kinematics from these transformations where q_1 q_2 q_4 are active, q_3 = q_5 = q_7 = 0 and q_6 = 0.75(rad)?

Also, how do I find the pseudoinverse of the Jacobian where here all joints are active?

Thanks in advance