University of Twente Student Theses


Simultaneous optimization of contacts and smooth movements for control of humanoid robotics

Gils, H. van (2022) Simultaneous optimization of contacts and smooth movements for control of humanoid robotics.

[img] PDF
Abstract:Robotic exoskeletons have the potential to greatly improve the quality of life for paraplegic patients by providing them with greater independence and fewer negative health effects compared to wheelchairs. This study focuses on developing a control strategy for exoskeletons that allows them to mimic the natural behavior of a healthy individual as closely as possible. The current state-of-the-art method available at the Biomechanical Engineering department for doing this uses direct collocation with explicit contact constraints. This has limitations when it comes to tasks with unpredictable contact sequences, limiting it to the generation of gait. This thesis contributes by developing a new framework; which uses direct collocation with implicit contact constraints. This method does not require the user to specify a contact sequence, but only requires an objective function, a dynamic model, a time span over which to optimize and an initial guess. It then simultaneously optimizes the contacts and smooth movements. Four scenarios were tested with a biped model: gait, resisting perturbations, safe falling, and getting up. It is able to converge to a locally optimal solution in around 30 minutes for all tasks. However, for producing gait and safe falling trajectories, more task specific initial guesses were required. Additionally, the collocation errors were large and the mode sequences did not mimic human behaviour. Despite these limitations, the results of this framework demonstrate that this direct implicit method can be used to mimic human behaviour of different balance control related tasks. This makes it interesting for the application in lower limb exoskeletons and walking robots. There is still room for improvement in terms of fully realizing the potential of these devices to improve the mobility and quality of life of paraplegic patients. This framework represents an important step forward in the development of trajectory optimization for exoskeletons.
Item Type:Essay (Master)
Faculty:TNW: Science and 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