The presence of sensory and motor deficits in upper and/or lower limb can negatively affect human's autonomy and independence during activities of daily living reducing the quality of life. Ambition of this thesis is to design and develop robotic systems for upper and lower limb rehabilitation and assistance of patients with sensori-motor deficit. The objective has been pursued in two different scenarios: i) prosthetics: a non-invasive electrical stimulation system for the restoration of sensory feedback and a novel, modular and compliant prosthetic wrist have been developed for the improvement of handling skills in patients with amputation; ii) rehabilitation: an in-depth analysis of literature on affordable rehabilitative robots and the development of an hybrid system combining non-invasive electrical stimulation and robotic assistance have been proposed. Notwithstanding the huge advancement aiming to develop anthropomorphic prostheses with functional performance similar to the physiological biomechanics; the current limb prostheses do not provide sensory feedback to the user. Several approaches have been proposed in literature to restore tactile feedback in amputees such as the use of invasive interface with Peripheral Nervous System (PNS). They have shown promising results thanks to their selectivity in the elicitation of somatotopic sensations (i.e., felt in phantom limb and not just locally in the stump) but they present disadvantages related to invasiveness due to surgery, the eventual onset of a fibrotic reaction and the weak long-term stability. The proposed sensory feedback restoration system was based on Transcutaneous Electrical Nerve Stimulation (TENS): it was able to evoke somatotopic sensation in a non invasive way using only electrical stimuli provided to the nerves by means of superficial electrodes. A full mapping protocol and new encoding algorithms for the elicitation of force and slippage sensations have been developed and tested on healthy participants and with transradial amputation. The obtained results showed TENS was able to elicit painless, superficial refereed tactile sensations mainly described as paresthesia (e.g., tingling and/or vibration). The results have shown the stimulus pulse amplitude modulation was a valid technique for the elicitation of refereed sensations with different levels of intensity as those ones experienced during object manipulation. Moreover, the presence of a 300 ms delay between the stimuli provided to the median and ulnar nerves was a good candidate for evoking an apparent moving sensation along the fingers like that one reported in slippage events that could occur during handling objects. Therefore the proposed TENS-based system represents an excellent trade-off between the non-invasiveness and the possibility to evoke somatotopic sensations. The good results of mapping protocol and force encoding algorithm have been confirmed in two case-studies involving participants with more proximal upper limb amputation (THA and shoulder disarticulation). The proposed TENS-based sensory feedback restoration system have been tested in lower limb prosthetics applications underlining its versatility. A mapping and stimulus intensity discrimination protocol have been tested on the tibial nerve of 15 healthy participants. The obtained results showed TENS was able to elicit painless and superficial tingling and/or vibration in the foot sole; moreover, the pulse amplitude modulation was a significant valid technique for ground reaction forces encoding. This is the first time in literature sensory feedback was restored in the lower limb in a non-invasive way and the promising results justified the testing of the proposed TENS-based system in participants with TTA or TFA evaluating its effect on deambulation, posture and equilibrium and post-amputation neuropathic pain. Notwithstanding the benefits achieved by the introduction of sensory feedback restoration, it has been demonstrated handling skills could be improved increasing the dexterity of the wrist, too. The prosthetic wrist proposed in this thesis was composed of two submodules: an active one for prono-supination (P/S) and a passive one for flexion/extension (F/E). The actuator of the P/S submodule was placed inside the socket along its major axis and the output shaft was connected to F/E submodule. F/E can work in two different modalities: compliant and fixed. In the first operating mode, the rotational motion was converted in a linear one with the consequent compression of a spring pack through two parallel Scotch-Yoke mechanisms: in this way, the module was able to elastically return to the neutral position when unloaded. Conversely, the fixed modality was implemented by means of a piston that can be engaged or not allowing or not firm and stables grasp during manipulation. The developed system fitted with human anthropometry in terms of mass and size and was designed to be used stand-alone way. Thanks to its adaptability, the system was able to work with different prosthetic hands available on the market still ensuring functional performance similar to the physiological biomechanics of the human wrist. One of the strength point of the developed system was represented by its modularity. As a matter of fact, the working principle on which the F/E compliant submodule was based (i.e., two parallel Scotch-Yoke mechanisms) could be potentially adapted in several other applications, such as ankle prosthesis and robotic joints, belonging to systems designed for other human–robot interaction applications (e.g., assistive, rehabilitation, or surgical robotics). As already stated, limb sensori-motor deficits can be caused not only by an amputation but also by neurological disorders due to stroke or brachial plexus injury. It has been extensively demonstrated that robotic devices may enhance motor recovery and neuro-plasticity, due to their ability to supply highly-intensive, repeatable, accurate and patient-tailored movement therapy, while guaranteeing patient safety and unloading therapist workload with respect to traditional methods. Nevertheless, the robot's high costs, sizes and technological complexity represent a barrier to their worldwide diffusion. Therefore, an in-depth analysis of literature low-cost upper limb rehabilitation robots and the different approaches that can be carried out to have affordable robotics that could be used in low resources clinical settings will be presented. The analysis pointed out different approaches for the improvement of robot's cost-effective in rehabilitation: i) developing end-effector and exoskeleton robots for the treatment of proximal and distal upper limb joints, respectively; ii) reducing the number of DoFs of the robots at the minimum (one or two); iii) avoiding the use of conventional materials exploiting additive manufacturing techniques; iv) implementing the modularity and reconfigurability principles during robot's design. An alternative approach could be the development of hybrid systems where the sinergic action of FES and robotic assistance could overcome their individual limitations and improve the rehabilitation effectiveness. The proposed FES-based system was able to generate muscular contractions and thus joints movements in a non-invasive way using as a reference for the stimulation modulation a dataset of healthy myoelectric and kinematic pattern. For the first time in literature, a kinetic and myoelectric dataset on healthy upper limb was used as reference for a closed-loop FES. On the base of the promising results obtained in terms of success rate, the use of the dataset could avoid the preliminary phase of myoelectric and/or kinematic signals recording to be used as a reference reducing the duration and complexity of the study. Two different FES modulation strategies were developed and tested on ten participants's non dominant arm during the execution of four ADLs. The obtained results have shown the two strategies presented similar performance during simple tasks (object reaching); conversely, the second modulation was better than the first one in task involving object interaction such as the lifting of a bottle of water or the lateral and pinch grasp of a spoon or a small object, respectively. In these tasks, the addition of kinematics information for the stimulation current modulation have obtained significantly better results than the exclusively use of EMG information.

Robotic systems and methods for sensori-motor recovery in rehabilitation and prosthetics / Andrea Demofonti - Università Campus Bio-Medico di Roma. , 2022 Nov 03. 34. ciclo, Anno Accademico 2018/2019.

Robotic systems and methods for sensori-motor recovery in rehabilitation and prosthetics

DEMOFONTI, ANDREA
2022-11-03

Abstract

The presence of sensory and motor deficits in upper and/or lower limb can negatively affect human's autonomy and independence during activities of daily living reducing the quality of life. Ambition of this thesis is to design and develop robotic systems for upper and lower limb rehabilitation and assistance of patients with sensori-motor deficit. The objective has been pursued in two different scenarios: i) prosthetics: a non-invasive electrical stimulation system for the restoration of sensory feedback and a novel, modular and compliant prosthetic wrist have been developed for the improvement of handling skills in patients with amputation; ii) rehabilitation: an in-depth analysis of literature on affordable rehabilitative robots and the development of an hybrid system combining non-invasive electrical stimulation and robotic assistance have been proposed. Notwithstanding the huge advancement aiming to develop anthropomorphic prostheses with functional performance similar to the physiological biomechanics; the current limb prostheses do not provide sensory feedback to the user. Several approaches have been proposed in literature to restore tactile feedback in amputees such as the use of invasive interface with Peripheral Nervous System (PNS). They have shown promising results thanks to their selectivity in the elicitation of somatotopic sensations (i.e., felt in phantom limb and not just locally in the stump) but they present disadvantages related to invasiveness due to surgery, the eventual onset of a fibrotic reaction and the weak long-term stability. The proposed sensory feedback restoration system was based on Transcutaneous Electrical Nerve Stimulation (TENS): it was able to evoke somatotopic sensation in a non invasive way using only electrical stimuli provided to the nerves by means of superficial electrodes. A full mapping protocol and new encoding algorithms for the elicitation of force and slippage sensations have been developed and tested on healthy participants and with transradial amputation. The obtained results showed TENS was able to elicit painless, superficial refereed tactile sensations mainly described as paresthesia (e.g., tingling and/or vibration). The results have shown the stimulus pulse amplitude modulation was a valid technique for the elicitation of refereed sensations with different levels of intensity as those ones experienced during object manipulation. Moreover, the presence of a 300 ms delay between the stimuli provided to the median and ulnar nerves was a good candidate for evoking an apparent moving sensation along the fingers like that one reported in slippage events that could occur during handling objects. Therefore the proposed TENS-based system represents an excellent trade-off between the non-invasiveness and the possibility to evoke somatotopic sensations. The good results of mapping protocol and force encoding algorithm have been confirmed in two case-studies involving participants with more proximal upper limb amputation (THA and shoulder disarticulation). The proposed TENS-based sensory feedback restoration system have been tested in lower limb prosthetics applications underlining its versatility. A mapping and stimulus intensity discrimination protocol have been tested on the tibial nerve of 15 healthy participants. The obtained results showed TENS was able to elicit painless and superficial tingling and/or vibration in the foot sole; moreover, the pulse amplitude modulation was a significant valid technique for ground reaction forces encoding. This is the first time in literature sensory feedback was restored in the lower limb in a non-invasive way and the promising results justified the testing of the proposed TENS-based system in participants with TTA or TFA evaluating its effect on deambulation, posture and equilibrium and post-amputation neuropathic pain. Notwithstanding the benefits achieved by the introduction of sensory feedback restoration, it has been demonstrated handling skills could be improved increasing the dexterity of the wrist, too. The prosthetic wrist proposed in this thesis was composed of two submodules: an active one for prono-supination (P/S) and a passive one for flexion/extension (F/E). The actuator of the P/S submodule was placed inside the socket along its major axis and the output shaft was connected to F/E submodule. F/E can work in two different modalities: compliant and fixed. In the first operating mode, the rotational motion was converted in a linear one with the consequent compression of a spring pack through two parallel Scotch-Yoke mechanisms: in this way, the module was able to elastically return to the neutral position when unloaded. Conversely, the fixed modality was implemented by means of a piston that can be engaged or not allowing or not firm and stables grasp during manipulation. The developed system fitted with human anthropometry in terms of mass and size and was designed to be used stand-alone way. Thanks to its adaptability, the system was able to work with different prosthetic hands available on the market still ensuring functional performance similar to the physiological biomechanics of the human wrist. One of the strength point of the developed system was represented by its modularity. As a matter of fact, the working principle on which the F/E compliant submodule was based (i.e., two parallel Scotch-Yoke mechanisms) could be potentially adapted in several other applications, such as ankle prosthesis and robotic joints, belonging to systems designed for other human–robot interaction applications (e.g., assistive, rehabilitation, or surgical robotics). As already stated, limb sensori-motor deficits can be caused not only by an amputation but also by neurological disorders due to stroke or brachial plexus injury. It has been extensively demonstrated that robotic devices may enhance motor recovery and neuro-plasticity, due to their ability to supply highly-intensive, repeatable, accurate and patient-tailored movement therapy, while guaranteeing patient safety and unloading therapist workload with respect to traditional methods. Nevertheless, the robot's high costs, sizes and technological complexity represent a barrier to their worldwide diffusion. Therefore, an in-depth analysis of literature low-cost upper limb rehabilitation robots and the different approaches that can be carried out to have affordable robotics that could be used in low resources clinical settings will be presented. The analysis pointed out different approaches for the improvement of robot's cost-effective in rehabilitation: i) developing end-effector and exoskeleton robots for the treatment of proximal and distal upper limb joints, respectively; ii) reducing the number of DoFs of the robots at the minimum (one or two); iii) avoiding the use of conventional materials exploiting additive manufacturing techniques; iv) implementing the modularity and reconfigurability principles during robot's design. An alternative approach could be the development of hybrid systems where the sinergic action of FES and robotic assistance could overcome their individual limitations and improve the rehabilitation effectiveness. The proposed FES-based system was able to generate muscular contractions and thus joints movements in a non-invasive way using as a reference for the stimulation modulation a dataset of healthy myoelectric and kinematic pattern. For the first time in literature, a kinetic and myoelectric dataset on healthy upper limb was used as reference for a closed-loop FES. On the base of the promising results obtained in terms of success rate, the use of the dataset could avoid the preliminary phase of myoelectric and/or kinematic signals recording to be used as a reference reducing the duration and complexity of the study. Two different FES modulation strategies were developed and tested on ten participants's non dominant arm during the execution of four ADLs. The obtained results have shown the two strategies presented similar performance during simple tasks (object reaching); conversely, the second modulation was better than the first one in task involving object interaction such as the lifting of a bottle of water or the lateral and pinch grasp of a spoon or a small object, respectively. In these tasks, the addition of kinematics information for the stimulation current modulation have obtained significantly better results than the exclusively use of EMG information.
3-nov-2022
Robotic systems and methods for sensori-motor recovery in rehabilitation and prosthetics / Andrea Demofonti - Università Campus Bio-Medico di Roma. , 2022 Nov 03. 34. ciclo, Anno Accademico 2018/2019.
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/20.500.12610/70563
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