Spinal Cord Injured (SCI) individuals and stroke patients, suffering from movement disorders of the upper limb, are often severely impaired in their quality of life and independence in Activities of Daily Living (ADLs). Functional Electrical Stimulation (FES) and robotic rehabilitation are popular and well-known means for enhancing modern therapy settings. Both systems, FES and robots, each have their specific advantages and drawbacks as, e.g., endless endurance of robotic systems versus occurring muscle fatigue during FES-assisted therapy. On the other hand, in contrast to robots, FES actively involves the patient’s muscles in the generation of movement. The combination of both techniques, also called hybrid neuroprosthesis, reveals a lot of new possibilities. This thesis presents new methods toward an adaptive hybrid neuroprosthesis for the upper limbs that utilizes the benefits of both, robot and FES, and overcomes the disadvantages by the respective other one. The cable-driven end-effector-based robot Diego by the company Tyromotion is extended by a four channel stimulation to form a novel hybrid neuroprosthesis for the upper limbs. The hybrid neuroprosthesis features a magnetometer-free sensor fusion method that overcomes the limited measurement information of end-effector-based robots by augmenting them with wearable inertial sensors. The evaluation with five healthy subjects demonstrates that the shoulder position and the elbow angle are accurately tracked. Furthermore, the sensor fusion method successfully detects undesirable compensatory shoulder movements. Thus, the hybrid motion tracking is well suited for performance assessment, real-time biofeedback, and feedback control of robotic and neuroprosthetic motion support. The practice of functional movements such as ADLs is assumed to improve the transfer of learned skills to daily life. Two different strategies for such training sessions are presented: a virtual environment that includes motivational aspects in the context of gamification, and a patient-triggered method, in which the patient is fully in charge of the control of applied FES and can freely determine the conducted movement sequence. The concepts motivate the patients to participate actively in the training sessions. The proposed methods’ technical and clinical feasibility is exemplarily demonstrated in experiments with three SCI subjects. Two different counterbalance-based control strategies are presented for the assistive weight support within the hybrid neuroprosthesis. They automatically adapt to the performed motion and current arm posture. First, inverse human arm models are implemented to counterbalance proportions of the arm weight using the robot’s rope forces. Additionally, a combined weight relief method that shares and automatically adapts the support between the robot and FES is proposed. The technical and clinical feasibility of the approaches and their advantages against constant robotic weight support are demonstrated in experiments and simulations. The hybrid neuroprosthesis furthermore provides a module for the FES-support of repetitive arm horizontal movements. An Iterative Learning Vector Field (ILVF) adjusts the stimulation intensities to the individual patient’s needs. Compared to previous iterative learning controllers, the main feature is that the patient is facilitated to perform the motion at self-selected cadence. The proposed learning algorithm explicitly takes the artificially activated muscles’ dynamics into account and assures smooth stimulation intensity profiles. The approach’s feasibility is successfully demonstrated in simulations with a complex neuro-musculoskeletal model. In total, the presented hybrid system and methods within this thesis address several open research issues in hybrid neuroprostheses contributing to a better adaptability to the patient’s needs and an intelligent sharing of the support between FES and the robot. These developments can improve the application of hybrid neuroprosthesis in the future and thus enhance the therapy outcome.


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    Title :

    Hybrid systems for upper limb rehabilitation after spinal cord injury


    Additional title:

    Hybride Systeme für die Rehabilitation der oberen Extremitäten nach Rückenmarksverletzungen


    Contributors:

    Publication date :

    2021



    Type of media :

    Miscellaneous


    Type of material :

    Electronic Resource


    Language :

    English



    Classification :

    DDC:    607 / 629 / 610




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