Analysis and control of the step climbing control of a wheeled Inverted Pendulum Type Assistant Robot

In this paper the control of an Inverted PENdulum Type Assistant Robot (I-PENTAR) during climbing over of steps is discussed. A mobile robot must be able to traverse its environment with a certain degree of robustness otherwise the usability of the robot is compromised. As initial steps to solving the step climbing motion the modeling of the different phases involved was performed. In-depth analysis of the different phases show that parameter and model changes come into play and cause disturbances. These disturbances are estimated and compensated by using the extended state observer and so no model is used during the actual control. Both success and failure guidelines based on the models are determined and verified with tests. To improve the robustness of the control a trajectory based on information from the model is developed offline. Results show that using this trajectory, the response of step climbing is improved and the maximum step height can be increased.