|Manipulability Based Hierarchical Control of Perturbed Walking
Behnam Miripour Fard* and Mohamad Mosadeghzad
International Journal of Control, Automation, and Systems, vol. 17, no. 9, pp.2343-2353, 2019
Abstract : In this paper, a novel manipulability based three-level hierarchical approach is suggested for control of perturbed bipedal walking. An appropriate postural strategy is selected to restore stability if a perturbation occurs during steady-state human walking. Previous experimental studies on the human walking suggest that the selection of stabilizing strategies can be related to the kinematic manipulability of swing foot. The proposed three-level structure consists of a low, middle, and high levels. The manipulability is at the high-level layer. Therefore, in case of disturbance it determines to lengthen the step (elevating strategy) or shorten the step length (lowering strategy). The middle-level layer determines the optimal desired trajectories for joints. Finally, a low-level controller tracks the desired optimal trajectory to maintain stability. The results show the success of the manipulability based adapted control scheme against pushing perturbation. A comparison between the optimal gait patterns obtained with and without consideration of manipulability is also presented in this study. The results show that the manipulability improves disturbance rejection capability. Positioning the manipulability in the high-level of our proposed method mitigates the possibility of singularity occurrence and configuration limits during postural response.
Bipedal walking, hierarchical control, manipulability, strategy selection.