University of Twente Student Theses


Optimizing Trajectories of Bipedal Robots for Robustness Against Disturbances

Bruin, S. de (2023) Optimizing Trajectories of Bipedal Robots for Robustness Against Disturbances.

[img] PDF
Abstract:Walking is an activity that most people take for granted every day. However, not everyone is so fortunate. For instance, a large part of people who encounter a spinal cord injury have to rely on wheelchairs to move around. Even though wheelchairs are a reliable and cheap solution, they have numerous disadvantages such as restricted access to public transport and buildings, and health issues related to the sitting lifestyle. As an alternative or companion to wheelchairs, lower limb exoskeletons could be a solution. These devices show great potential to improve impaired people’s lives, but they need to be improved in multiple aspects as energy consumption and disturbance handling. This thesis focuses on the disturbance handling of exoskeletons. The user of an exoskeleton continuously exerts (disturbance) forces on the exoskeleton. These forces can cause the exoskeleton to slip or fall. This failure occurs due to the robot facing physical limits such as friction or motor torque limits. Therefore, it is useful to consider these limits when planning a trajectory and stay as far away as possible from them. This thesis presents a method to optimize trajectories of bipedal robots to withstand a force on the center of mass (CoM) that cannot be counteracted without changing the planned trajectory. These trajectories are obtained by transcribing the optimization problem to a direct collocation problem, which is solved as a non-linear problem via an interior point method. The trajectory optimization was performed on a planar 7-DoF walker model. This study shows that optimizing for robustness for bipedal robots leads to trajectories that are more robust against disturbances on the CoM. To implement the optimization algorithm in a real-world application, two shortcomings have to be overcome. First, the optimization needs to be applied and tested on a 3D model instead of a planar model. Second, the computational time should decrease to enable online implementation.
Item Type:Essay (Master)
Faculty:ET: Engineering Technology
Programme:Biomedical Engineering MSc (66226)
Link to this item:
Export this item as:BibTeX
HTML Citation
Reference Manager


Repository Staff Only: item control page