Path Planning of Free-Floating Robot in Cartesian Space Using Direct Kinematics

ISSN 1729‐8806, pp. 17–26 17 Path Planning of Free-Floating Robot in Cartesian Space Using Direct Kinematics Wenfu Xu1, Bin Liang1, Cheng Li1, Yangsheng Xu2 and Wenyi Qiang1 1Dept. of Control Science and Engineering Harbin Institute of Technology, Harbin, P.R. China 2 Dept. of Automation and Computer‐Aided Engineering The Chinese University of Hong Kong, Hong Kong, P.R.China {wfxu, bliang,cli}@robotsat.com, [email protected] Abstract: Dynamic singularities make it difficult to plan the Cartesian path of free‐floating robot. In order to avoid its effect, the direct kinematic equations are used for path planning in the paper. Here, the joint position, rate and acceleration are bounded. Firstly, the joint trajectories are parameterized by polynomial or sinusoidal functions. And the two parametric functions are compared in details. It is the first contribution of the paper that polynomial functions can be used when the joint angles are limited(In the similar work of other researchers, only sinusoidla functions could be used). Secondly, the joint functions are normalized and the system of equations about the parameters is established by integrating the differential kinematics equations. Normalization is another contribution of the paper. After normalization, the boundary of the parameters is determined beforehand, and the general criterion to assign the initial guess of the unknown parameters is supplied. The criterion is independent on the planning conditions such as the total time tf. Finally, the parametes are solved by the iterative Newtonian method. Modification of tf may not result in the recalculation of the parameters. Simulation results verify the path planning method.