University of Twente Student Theses


Design of a control strategy for obstacle crossing in a lower limb exoskeleton for SCI patients

Opheusden, L.M.E. van (2017) Design of a control strategy for obstacle crossing in a lower limb exoskeleton for SCI patients.

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Abstract:Every year, tens of thousands of people worldwide are struck by the disastrous effects of spinal cord injury (SCI) [1]. Due to a lesion in the spinal cord, many patients suffering from SCI are paraplegic, making them unable to walk. A person’s quality of life is determined greatly by their self-sufficiency. Loss of mobility makes SCI patients very dependent on their environment and the health care system, which in turn greatly diminishes their quality of life. In recent years, scientists have put great effort into curing and treating SCI [2]. However, many SCI patients remain confined to a wheelchair after their rehabilitation period. Recent developments in the field of robotics have given birth to a new range of assistive devices. Through the use of powered exoskeletons, patients with SCI can be given back the ability to walk independently. The term ”exoskeleton” in this context is defined as a mechanical device that fits around the human body and moves in parallel with it, as if the patient is wearing a mechanical suit [3]. Powered exoskeletons distinguish themselves by the fact that they can, through the use of active elements, provide a net effort to the wearer. They can be used to augment the physical capabilities of an able-bodied person, like the BLEEX exoskeleton (Figure 1.1a), or to provide assistance to patients with a limb pathology, like the Ekso (Figure 1.1b). Even though powered exoskeletons carry the promise to become invaluable assistive tools, the current state of the art provides people suffering from SCI with limited functionality. The devices are tailored to flat grounds or shallow slopes, which hinders the wearer to move freely outside of a laboratory setting. In order to help SCI patients regain their mobility and self-sufficiency, exoskeleton technology must be taken out of the laboratory environment and into daily life scenarios. Our natural environment is highly unstructured terrain, as it is filled with obstacles, such as doorsteps, curbs and stairs. Powered exoskeletons are mechanically capable of overcoming these obstacles, but the design of their controllers falls short in this regard. Therefore, there is a need to improve upon currently available control strategies, to help SCI patients function in our unpredictable and three-dimensional world. The aim of this research is to design a control strategy that allows the wearer of an exoskeleton to step over an obstacle. This makes it possible for exoskeleton users to traverse doorsteps and uneven terrain and will allow the exoskeleton to help its wearer to successfully navigate daily life.
Item Type:Essay (Master)
Faculty:EEMCS: Electrical Engineering, Mathematics and Computer Science
Subject:30 exact sciences in general, 31 mathematics, 33 physics, 42 biology, 44 medicine, 50 technical science in general
Programme:Systems and Control MSc (60359)
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