A New Geometric Representation for Tree-Structured Robots

In order to solve the disaccord resulted from the existing frame assignment conventions, we propose a modified Denavit-Hartenberg parameters for tree-structured robots, which can be used for kinematic and dynamic modelling simultaneously. Then, the new frame assignment method is used to our designed rehabilitation robots which it has 17 freedoms and the whole body control is introduced to render the robot working in a corporative way such that the difficult leg-lifting rehabilitation is fulfilled. Numerical computation shows that, the derived kinematic and dynamic models are not only very useful to optimize the robot's mechanical structure in the early design stage, but also they can be used to implement motion control of the robot, to carry out intensity correction for key parts and to improve control performance in the future applications.