Inverse kinematics and pseudoinverse method for controlling movement of robotic arm is presented in this paper. For that task we used robotic arm DOBOT for which we made simulation model in Matlab environment and SimMechanics toolbox. We described in detail pseudoinverse method and problem solving of pseudoinverse for non-square matrixes. Because in future we will make implementation this method to movement control of robotic arm, we made simulation, how many digits we will need for correctly calculating of goniometrics functions in DSP.