# Specify pose for inverse kinematics of 5 dof robot arm

I need to specify the pose for a 5 dof robot arm in order to calculate the inverse kinematics. Assuming I worked out the correct inverse kinematics solution for joint variables $$q_{1} \dots q_{5}$$, I now want to specify a (4x4) homogeneous transformation matrix from which get 3 position coordinates of the EE and the angle $$\phi$$ of $$z_{5}$$ from horizontal plane $$x_{0}-y_{0}$$ to use them for inverse kinematics. The kinematic scheme is the following: I don't really care about the orientation $$\phi = q_{2}+q_{3}+q_{4}$$ but I I need to specify it because of the form of the IK equations. I'm using Peter Corke Matlab Robotics Toolbox. Please give me some help, thank you

Edit: picture showing angle $$\phi$$

If I choose three coordinates x,y,z that the robot can reach, I'd like to reach that position without caring about orientation $$\phi$$. For one point maybe $$\phi$$ can be computed, but for a trajectory?

• Your question is vague. Do you need to compute the forward kinematics? If so, which method (i.e. DH, product of exponentials, dual quaternion,...,etc). Also, what is $\phi = q_2+q_3+q_4$? Jun 19 at 20:32
• @CroCo hi, look at the second picture I attached. This is a 3-link planar arm which corresponds to joints 2,3,4 of my robot, first picture. $\phi$ should be clear now. I need to impose the value of $\phi$ because it's used in the analytical solution of IK to solve for $q_{4}$ once I calculated $q_{2}$ and $q_{3}$ Jun 22 at 9:06
• Hi @newby_prog This looks like a homework question, and on stack exchange, questions asking for homework help must include a summary of the work you've done so far to solve/understand the problem, and a description of the difficulty you are having solving/understanding it. Please edit your question to add this information and take a look at How to Ask and tour for more information on how stack exchange works. For advice on how to write a good question, see the Robotics question checklist. Jun 22 at 17:32