CAD, CAE and rapid prototyping methods applied in long bones orthopaedics

U radu su prikazane metode za analizu ljudskih koštanih zglobova. Prvo, upotrebom CT slika, definisani su 'čvrsti' delovi kao glavne komponente kosti i 'meki' delovi kao što su ligamenti ili meniskusi. Ove komponente uvoze se u modul za montažu parametrizovanog okruženja i dobija se biomehanički model ljudskog hoda, koji se izvozi u kinematsko simulaciono okruženje i koristi za analizu konačnim elementima, gde se prvo definišu kinematski parametri. Sa ovako definisanim parametrima može se izvršiti zamena kinematskih i dinamičkih simulacija podsistema klasičnim, normalnim kretanjem. Nakon interpretacije rezultata, mogu se modifikovati početni parametri biomehaničkih podsistema. U sledećoj fazi, komponente podsistema su podeljene sukcesivno i dobijena je struktura konačnih elemenata za ceo biomehanički sistem spojeva koji učestvuju u ljudskoj lokomociji.The paper presents some methods used to analyze human bone joints. First, there were defined the 'hard' parts as the main bone components and 'soft' parts as ligaments or menisci using CT images. These components are imported into a parameterized environment assembly module and a biomechanical model of human walking is being obtained, which is exported to a kinematic simulation environment and finite element analysis, where first the kinematic parameters are defined. With these defined parameters, the kinematic and dynamic simulation of the subsystems for classical, normal motion can be switched. Following the interpretation of the results, the initial parameters of the biomechanical subsystems may be modified. In the next phase, the components of the subsystems are divided successively and the finite element structure is obtained for the entire biomechanical system of the joints that participate in human locomotion

CAD, CAE and rapid prototyping methods applied in long bones orthopaedics

U radu su prikazane metode za analizu ljudskih koštanih zglobova. Prvo, upotrebom CT slika, definisani su 'čvrsti' delovi kao glavne komponente kosti i 'meki' delovi kao što su ligamenti ili meniskusi. Ove komponente uvoze se u modul za montažu parametrizovanog okruženja i dobija se biomehanički model ljudskog hoda, koji se izvozi u kinematsko simulaciono okruženje i koristi za analizu konačnim elementima, gde se prvo definišu kinematski parametri. Sa ovako definisanim parametrima može se izvršiti zamena kinematskih i dinamičkih simulacija podsistema klasičnim, normalnim kretanjem. Nakon interpretacije rezultata, mogu se modifikovati početni parametri biomehaničkih podsistema. U sledećoj fazi, komponente podsistema su podeljene sukcesivno i dobijena je struktura konačnih elemenata za ceo biomehanički sistem spojeva koji učestvuju u ljudskoj lokomociji.The paper presents some methods used to analyze human bone joints. First, there were defined the 'hard' parts as the main bone components and 'soft' parts as ligaments or menisci using CT images. These components are imported into a parameterized environment assembly module and a biomechanical model of human walking is being obtained, which is exported to a kinematic simulation environment and finite element analysis, where first the kinematic parameters are defined. With these defined parameters, the kinematic and dynamic simulation of the subsystems for classical, normal motion can be switched. Following the interpretation of the results, the initial parameters of the biomechanical subsystems may be modified. In the next phase, the components of the subsystems are divided successively and the finite element structure is obtained for the entire biomechanical system of the joints that participate in human locomotion

Dynamically Stable 3D Quadrupedal Walking with Multi-Domain Hybrid System Models and Virtual Constraint Controllers

Hybrid systems theory has become a powerful approach for designing feedback controllers that achieve dynamically stable bipedal locomotion, both formally and in practice. This paper presents an analytical framework 1) to address multi-domain hybrid models of quadruped robots with high degrees of freedom, and 2) to systematically design nonlinear controllers that asymptotically stabilize periodic orbits of these sophisticated models. A family of parameterized virtual constraint controllers is proposed for continuous-time domains of quadruped locomotion to regulate holonomic and nonholonomic outputs. The properties of the Poincare return map for the full-order and closed-loop hybrid system are studied to investigate the asymptotic stabilization problem of dynamic gaits. An iterative optimization algorithm involving linear and bilinear matrix inequalities is then employed to choose stabilizing virtual constraint parameters. The paper numerically evaluates the analytical results on a simulation model of an advanced 3D quadruped robot, called GR Vision 60, with 36 state variables and 12 control inputs. An optimal amble gait of the robot is designed utilizing the FROST toolkit. The power of the analytical framework is finally illustrated through designing a set of stabilizing virtual constraint controllers with 180 controller parameters.Comment: American Control Conference 201

In Silico Optimization of Femoral Fixator Position and Configuration by Parametric CAD Model

Structural analysis, based on the finite element method, and structural optimization, can help surgery planning or decrease the probability of fixator failure during bone healing. Structural optimization implies the creation of many finite element model instances, usually built using a computer-aided design (CAD) model of the bone-fixator assembly. The three most important features of such CAD models are: parameterization, robustness and bidirectional associativity with finite elements (FE) models. Their significance increases with the increase in the complexity of the modeled fixator. The aim of this study was to define an automated procedure for the configuration and placement of fixators used in the treatment of long bone fractures. Automated and robust positioning of the selfdynamisable internal fixator on the femur was achieved and sensitivity analysis of fixator stress on the change of major design parameters was performed. The application of the proposed methodology is considered to be beneficial in the preparation of CAD models for automated structural optimization procedures used in long bone fixation