No description available.

Upper-limb myoelectric prostheses are controlled by muscle activity information recorded on the skin surface using electromyography (EMG). Intuitive prosthetic control can be achieved by deploying statistical and machine learning (ML) tools to decipher the user's movement intent from EMG signals. This thesis proposes various means of advancing the capabilities of non-invasive, ML-based control of myoelectric hand prostheses. Two main directions are explored, namely classification-based hand grip selection and proportional finger position control using regression methods. Several practical aspects are considered with the aim of maximising the clinical impact of the proposed methodologies, which are evaluated with offline analyses as well as real-time experiments involving both able-bodied and transradial amputee participants. It has been generally accepted that the EMG signal may not always be a reliable source of control information for prostheses, mainly due to its stochastic and non-stationary properties. One particular issue associated with the use of surface EMG signals for upper-extremity myoelectric control is the limb position effect, which is related to the lack of decoding generalisation under novel arm postures. To address this challenge, it is proposed to make concurrent use of EMG sensors and inertial measurement units (IMUs). It is demonstrated this can lead to a significant improvement in both classification accuracy (CA) and real-time prosthetic control performance. Additionally, the relationship between surface EMG and inertial measurements is investigated and it is found that these modalities are partially related due to reflecting different manifestations of the same underlying phenomenon, that is, the muscular activity. In the field of upper-limb myoelectric control, the linear discriminant analysis (LDA) classifier has arguably been the most popular choice for movement intent decoding. This is mainly attributable to its ease of implementation, low computational requirements, and acceptable decoding performance. Nevertheless, this particular method makes a strong fundamental assumption, that is, data observations from different classes share a common covariance structure. Although this assumption may often be violated in practice, it has been found that the performance of the method is comparable to that of more sophisticated algorithms. In this thesis, it is proposed to remove this assumption by making use of general class-conditional Gaussian models and appropriate regularisation to avoid overfitting issues. By performing an exhaustive analysis on benchmark datasets, it is demonstrated that the proposed approach based on regularised discriminant analysis (RDA) can offer an impressive increase in decoding accuracy. By combining the use of RDA classification with a novel confidence-based rejection policy that intends to minimise the rate of unintended hand motions, it is shown that it is feasible to attain robust myoelectric grip control of a prosthetic hand by making use of a single pair of surface EMG-IMU sensors. Most present-day commercial prosthetic hands offer the mechanical abilities to support individual digit control; however, classification-based methods can only produce pre-defined grip patterns, a feature which results in prosthesis under-actuation. Although classification-based grip control can provide a great advantage over conventional strategies, it is far from being intuitive and natural to the user. A potential way of approaching the level of dexterity enjoyed by the human hand is via continuous and individual control of multiple joints. To this end, an exhaustive analysis is performed on the feasibility of reconstructing multidimensional hand joint angles from surface EMG signals. A supervised method based on the eigenvalue formulation of multiple linear regression (MLR) is then proposed to simultaneously reduce the dimensionality of input and output variables and its performance is compared to that of typically used unsupervised methods, which may produce suboptimal results in this context. An experimental paradigm is finally designed to evaluate the efficacy of the proposed finger position control scheme during real-time prosthesis use. This thesis provides insight into the capacity of deploying a range of computational methods for non-invasive myoelectric control. It contributes towards developing intuitive interfaces for dexterous control of multi-articulated prosthetic hands by transradial amputees.

No description available.

Considerando-se o atual estagio de desenvolvimento das máquinas elétricas, tanto em termos de ferramentas computacionais auxiliares nas simulações e nos projetos, quanto de materiais e sistemas eletrônicos de acionamento e controle, propõe neste trabalho a construção de um dispositivo eletromecânico, na classe dos motores elétricos lineares, que atenda as necessidades e se aplique a bioengenharia, mais propriamente as próteses de membro superior, na forma de acionador translacional. Este dispositivo deve substituir os sistemas que utilizam motores elétricos rotativos com mecanismos de adaptação mecânica (roldanas, vários fios, redutores), que convertem o movimento rotacional em linear. Também, os dispositivos híbridos, como atuadores eletro-hidráulicos e eletropneumáticos, que necessitam de fontes de energia de naturezas diferentes da eletroeletrônica, podem ser substituídos pelas maquinas elétricas lineares. Uma revisão dos conceitos relacionados a área de bioengenharia e feita, destacando-se os mecanismos de transmissão existentes. E apresentada uma analise comparativa entre os principais motores lineares, enfatizando-se as características construtivas, as vantagens e as desvantagens de cada um, relacionados a aplicação. A escolha da maquina a ser projetada e construída recaiu no motor linear síncrono, com imas permanentes na superfície da parte móvel, em uma estrutura tubular. Para esta maquina, e exposta uma metodologia de projeto, baseando-se nos seguintes tópicos: equacionamento do circuito magnético, cálculos de parâmetros utilizando-se o método dos elementos finitos e modelagem matemática por meio das equações por fase. Apos a etapa teórica, a construção da maquina e apresentada juntamente com os ensaios experimentais, possibilitando a comparação das características reais em relação ao projeto inicial. Por fim, o motor e aplicado ao dedo artificial, verificando-se a sua capacidade de substituição do motor rotativo. / By means of the latest technological advances of the electrical machines, both in terms of computational aids in simulations and designs, materials and electronic systems of drive and control, this work put forward the construction of an electromechanical device, in the class of the linear motors. It will be applied to bioengineering area, in particular in upper limb prostheses, in the form of a translational actuator. This linear motor must substitute the systems that use electric rotational motors with planetary gears and lead screw transmission, to convert the rotational movement into linear. The hybrid mechanisms, like electro pneumatic/hydraulic actuators, which need energy sources different from electronics, can be changed for the linear electric machines too. A review about bioengineering topics is done, where the existent mechanical mechanisms are highlighted. According to the application necessities, the advantages and disadvantages of different topologies of electric linear machines are compared and the constructive characteristics are emphasized. The tubular linear synchronous motor, with permanent magnets on the surface of the mobile part, was chosen to be applied to hand prostheses. To this machine, a design methodology is presented for calculating the motor dimensions, based on the following subjects: magnetic circuit equating, finite element analyses to evaluate parameters and machine dynamic modeling. After the theorethical stage, the construction of the machine is presented with the experimental results, allowing comparisons between the real characteristics and the initial design features of the motor. Finally, the machine is applied to an artificial finger to verify its capability to replace the rotational motor.

Considerando-se o atual estagio de desenvolvimento das máquinas elétricas, tanto em termos de ferramentas computacionais auxiliares nas simulações e nos projetos, quanto de materiais e sistemas eletrônicos de acionamento e controle, propõe neste trabalho a construção de um dispositivo eletromecânico, na classe dos motores elétricos lineares, que atenda as necessidades e se aplique a bioengenharia, mais propriamente as próteses de membro superior, na forma de acionador translacional. Este dispositivo deve substituir os sistemas que utilizam motores elétricos rotativos com mecanismos de adaptação mecânica (roldanas, vários fios, redutores), que convertem o movimento rotacional em linear. Também, os dispositivos híbridos, como atuadores eletro-hidráulicos e eletropneumáticos, que necessitam de fontes de energia de naturezas diferentes da eletroeletrônica, podem ser substituídos pelas maquinas elétricas lineares. Uma revisão dos conceitos relacionados a área de bioengenharia e feita, destacando-se os mecanismos de transmissão existentes. E apresentada uma analise comparativa entre os principais motores lineares, enfatizando-se as características construtivas, as vantagens e as desvantagens de cada um, relacionados a aplicação. A escolha da maquina a ser projetada e construída recaiu no motor linear síncrono, com imas permanentes na superfície da parte móvel, em uma estrutura tubular. Para esta maquina, e exposta uma metodologia de projeto, baseando-se nos seguintes tópicos: equacionamento do circuito magnético, cálculos de parâmetros utilizando-se o método dos elementos finitos e modelagem matemática por meio das equações por fase. Apos a etapa teórica, a construção da maquina e apresentada juntamente com os ensaios experimentais, possibilitando a comparação das características reais em relação ao projeto inicial. Por fim, o motor e aplicado ao dedo artificial, verificando-se a sua capacidade de substituição do motor rotativo. / By means of the latest technological advances of the electrical machines, both in terms of computational aids in simulations and designs, materials and electronic systems of drive and control, this work put forward the construction of an electromechanical device, in the class of the linear motors. It will be applied to bioengineering area, in particular in upper limb prostheses, in the form of a translational actuator. This linear motor must substitute the systems that use electric rotational motors with planetary gears and lead screw transmission, to convert the rotational movement into linear. The hybrid mechanisms, like electro pneumatic/hydraulic actuators, which need energy sources different from electronics, can be changed for the linear electric machines too. A review about bioengineering topics is done, where the existent mechanical mechanisms are highlighted. According to the application necessities, the advantages and disadvantages of different topologies of electric linear machines are compared and the constructive characteristics are emphasized. The tubular linear synchronous motor, with permanent magnets on the surface of the mobile part, was chosen to be applied to hand prostheses. To this machine, a design methodology is presented for calculating the motor dimensions, based on the following subjects: magnetic circuit equating, finite element analyses to evaluate parameters and machine dynamic modeling. After the theorethical stage, the construction of the machine is presented with the experimental results, allowing comparisons between the real characteristics and the initial design features of the motor. Finally, the machine is applied to an artificial finger to verify its capability to replace the rotational motor.