A Variable Stiffness Actuator Module With Favorable Mass Distribution for a Bio-inspired Biped Robot

Achieving human-like locomotion with humanoid platforms often requires the use of variable stiffness actuators (VSAs) in multi-degree-of-freedom robotic joints. VSAs possess 2 motors for the control of both stiffness and equilibrium position. Hence, they add mass and mechanical complexity to the design of humanoids. Mass distribution of the legs is an important design parameter, because it can have detrimental effects on the cost of transport. This work presents a novel VSA module, designed to be implemented in a bio-inspired humanoid robot, Binocchio, that houses all components on the same side of the actuated joint. This feature allowed to place the actuator's mass to more proximal locations with respect to the actuated joint instead of concentrating it at the joint level, creating a more favorable mass distribution in the humanoid. Besides, it also facilitated it's usage in joints with centralized multi-degree of freedom (DoF) joints instead of cascading single DoF modules. The design of the VSA module is presented, including it's integration in the multi-DoFs joints of Binocchio. Experiments validated the static characteristics of the VSA module to accurately estimate the output torque and stiffness. The dynamic responses of the driving and stiffening mechanisms are shown. Finally, experiments show the ability of the actuation system to replicate the envisioned human-like kinematic, torque and stiffness profiles for Binocchio

A Variable Stiffness Actuator Module with Favorable Mass Distribution for a Bio-inspired Biped Robot

Achieving human-like locomotion with humanoid platforms often requires the use of variable stiffness actuators (VSAs) in multi-degree-of-freedom robotic joints. VSAs possess 2 motors for the control of both stiffness and equilibrium position. Hence, they add mass and mechanical complexity to the design of humanoids. Mass distribution of the legs is an important design parameter, because it can have detrimental effects on the cost of transport. This work presents a novel VSA module, designed to be implemented in a bio-inspired humanoid robot, Binocchio, that houses all components on the same side of the actuated joint. This feature allowed to place the actuator’s mass to more proximal locations with respect to the actuated joint instead of concentrating it at the joint level, creating a more favorable mass distribution in the humanoid. Besides, it also facilitated it’s usage in joints with centralized multi-degree of freedom (DoF) joints instead of cascading single DoF modules. The design of the VSA module is presented, including it’s integration in the multi-DoFs joints of Binocchio. Experiments validated the static characteristics of the VSA module to accurately estimate the output torque and stiffness. The dynamic responses of the driving and stiffening mechanisms are shown. Finally, experiments show the ability of the actuation system to replicate the envisioned human-like kinematic, torque and stiffness profiles for Binocchio

Study of design issues in a prototype lower-limb prosthesis - proof-of-concept in a 3D printed model

Dissertação de Mestrado Integrado em Engenharia Biomédica Ramo de Biomateriais, Reabilitação e BiomecânicaThe amputation of one or both lower limbs, which can be brought on by trauma, diabetes, or other vascular diseases, is an increasingly common occurrence, especially due to the increase in the number of cases of diabetes in the developed world. In Portugal alone 1300 amputations each year are attributed to diabetes. These amputations severely impact the mobility, self-esteem, and quality of life of the patients, a situation that can be alleviated via the installation of a lower limb prosthesis. Sadly, these prostheses are not yet capable of completely emulating a sound limb in an affordable fashion. In this dissertation, state-of-the-art research was carried out regarding the mechanics of human gait, both healthy and prosthetic. An investigation regarding the state-of-the-art research was also carried out regarding lower-limb prostheses, their evolution, mechanics, and prospects, as well as additive manufacturing techniques, and how they can be crucial to the development of affordable prostheses. Special attention was provided to the study of the leading edge of prostheses research, namely active prostheses, capable of generating and introducing energy into the human gait, rather than simply acting as passive devices. This dissertation follows up on previous work carried out in the BioWalk Project of Universidade do Minho’s BiRDLab: “Prosthetic Devices and Rehabilitation Solutions for the Lower Limbs Amputees”. This work consisted of the development of an active lower-limb prosthesis prototype, with the goal of providing an affordable, but functional, prosthesis for future testing with patients. However, the resulting prototype was laden with issues, such as excessive weight and an underpowered motor. As such, this work set out to identify these issues, design, implement and test modifications to the prosthesis to produce a satisfying prototype. Given the limited resources and facilities available, it was decided to work on a smaller model prosthesis installed in a bipedal robot, the DARwIn-OP, using it as proof-of-concept for modifications to be implemented in the BiRDLab prosthesis. Modifications were successfully implemented, chiefly among them a planetary gear-based reductor and a novel attachment mechanism built using additive manufacturing techniques. It is possible to conclude that there is a great potential in the implementation of additive manufacturing techniques in the development of affordable prosthesis.A amputação de um ou ambos os membros inferiores, que pode ser causada por trauma, diabetes, ou outras doenças vasculares, é um evento cada vez mais frequente, especialmente devido ao aumento do número de casos de diabetes no mundo desenvolvido. Em Portugal, 1300 amputações são atribuídas aos diabetes todos os anos. Estas amputações influenciam negativamente a mobilidade, autoestima e qualidade de vida dos pacientes, mas estes efeitos podem ser minimizados através da instalação de uma prótese de membro inferior. Infelizmente, estas próteses ainda não são capazes de emular completamente um membro saudável de forma económica. Nesta dissertação, um estado da arte do caminhar humano foi realizado, tendo em atenção o funcionamento deste, quer em sujeitos saudáveis ou amputados. Um estado da arte também foi realizado relativamente às próteses de membros inferiores, a sua evolução, funcionamento, e perspetivas futuras, e também relativamente a técnicas de fabrico aditivas e a forma como estas podem ser aplicadas em próteses acessíveis. Tomou-se atenção especial ao estudo das próteses ativas, capazes de gerar e introduzir energia no caminhar, ao invés das próteses passivas tradicionais. Esta dissertação baseia-se em trabalho prévio ao abrigo do projeto BioWalk do laboratório BiRDLab da Universidade do Minho: “Dispositivos prostéticos e soluções de reabilitação para amputados dos membros inferiores”. Este trabalho consistiu no desenvolvimento de um protótipo de prótese de membro inferior ativa, com o objetivo de criar uma prótese de baixo custo para testes em pacientes. No entanto, o protótipo produzido possuí vários problemas, tais como peso excessivo e um motor subdimensionado. Assim sendo, este trabalho propôs-se a identificar estes problemas e a desenhar, implementar, e testar modificações. Tendo em conta os limitados recursos disponíveis, decidiu-se trabalhar numa prótese modelo mais pequena, instalada num robô bipedal, o DARwIN-OP, e a usá-la para testar modificações a implementar na prótese do BiRDLab. As modificações foram implementadas com sucesso, especialmente um redutor de engrenagens planetárias e um novo método de conectar a prótese, usando técnicas de fabrico aditivas

A Variable Stiffness Actuator Module with Favorable Mass Distribution for a Bio-inspired Biped Robot

Achieving human-like locomotion with humanoid platforms often requires the use of variable stiffness actuators (VSAs) in multi-degree-of-freedom robotic joints. VSAs possess 2 motors for the control of both stiffness and equilibrium position. Hence, they add mass and mechanical complexity to the design of humanoids. Mass distribution of the legs is an important design parameter, because it can have detrimental effects on the cost of transport. This work presents a novel VSA module, designed to be implemented in a bio-inspired humanoid robot, Binocchio, that houses all components on the same side of the actuated joint. This feature allowed to place the actuator’s mass to more proximal locations with respect to the actuated joint instead of concentrating it at the joint level, creating a more favorable mass distribution in the humanoid. Besides, it also facilitated it’s usage in joints with centralized multi-degree of freedom (DoF) joints instead of cascading single DoF modules. The design of the VSA module is presented, including it’s integration in the multi-DoFs joints of Binocchio. Experiments validated the static characteristics of the VSA module to accurately estimate the output torque and stiffness. The dynamic responses of the driving and stiffening mechanisms are shown. Finally, experiments show the ability of the actuation system to replicate the envisioned human-like kinematic, torque and stiffness profiles for Binocchio