Realidade Virtual em 3 Dimensões 3D virtual mirror for human Motion Learning and Therapy

Multibody System Dynamics and Virtual Reality.

O que é biomecanica?“A Biomecânica é a ciência que examina as forças internas e externas que actuam sobre o corpo humano os efeitos que elas produzem” (5, p.3). Hay, J. G. (1978). The biomechanics of sport tecniques. Prentice Hall, Inc., Englewood Cliffs.

São, porém, preocupações da Biomecânica os efeitos físicos das forças, internas ou externas que actuam sobre o sistema biológico considerado, bem como a capacidade e condições para que o sistema em causa possa produzir forças que actuem de determinada forma sobre outros corpos. Assim, para além de medir as forças em questão e os seus efeitos imediatos sobre os movimentos segmentares e os do “corpo todo”, a investigação Biomecânica deve lidartambém com os factores mecânicos que constrangem ou coadjuvam esses movimentos e com os efeitos biológicos das forças produzidas sobre os tecidos (crescimento, desenvolvimento, degenerescência, lesões de sobrecarga e sobreutilização, etc.).

The study of the human motion activities for health, sports, entertainment or for the design of supporting equipment requires the use of experimental and numerical tools that allow identifying the mechanisms of force transmission and their control inside the human body [1]. Sports sciences rely on the knowledge of the kinetics of the human body to devise better training practices and to help athletes to excel [2]. Designers of entertainment and health supporting equipment require that the structures and mechanisms of the human body are well understood and their limits identified so that the equipment can contribute to improve the human performance or that its functional specifications are compatible with safe limits. Also in medicine the biomechanics is supporting to devise new treatments and eventually helping to design surgeries [3].

A good example concerns the support that biomechanical models, analysed in the context of the human motion, provide to the understanding of pathological gait associated to cerebral palsy. Typical effects of the cerebral palsy are pathologic motion performances due to range restrictions caused by muscle shortening and/or constant muscle contraction and/or joint acampsia. Surgical interventions, such as tendotomy, myotomy or tendon transfer, all used to release a dynamical or fixed contraction of muscle tissue, neurotomy to relax a spastic palsy and ostetomy are chosen if classical therapies fail or are insufficient. Most of the surgical approaches are irreversible which creates the need for methods that help surgeons to assess a priori the consequences of changes in the biological system either leading to alternative therapy approaches avoiding a surgical intervention or, if intervention is unavoidable,

reducing stress for the patient by an optimized operation planning [3]. Current diagnosis methods have such a large tolerance interval (approx. 30%-40%), that computer simulations can provide a major contribution if dynamics can be predicted with tolerances of 10%-20%. This situation is illustrative of what aims to be achieved with more flexible, reliable and efficient tools for biomechanical analysis. The research work in biomechanics is typically multidisciplinary, requiring that knowledge in applied mechanics, physiology, experimental mechanics, and medical sciences or sports sciences is used simultaneously.

Biomechanics is a contraction of the words ‘biology’ and ‘mechanics’. In Biomechanics the application of the laws of physics and especially the laws of mechanics, on biological systems is studied Biomechanics has a number of application fields. In clinical applications it is attempted to improve the diagnosis, treatment and prevention of disorders to the musculoskeletal and cardiovascular system. In sport biomechanics the aim is to improve performance by a thorough understanding of the biomechanical principles of the movements. In ergonomic applications the behavior of human in interaction with the environment is studied, in order to prevent work-related diseases like RSI and to improve the performance. Biomechanics is a multidisciplinary field of research, in which medical researchers (orthopedics, neurology, rehabilitation, morphology, physiology) collaborate with mechanical, electrical and control engineers, and with researchers of biophysics and human movement science. Each of these research disciplines has their valuable contribution, and it is challenging to communicate results to researchers with another background.

Human muscular effort characterizationThe ability of humans to move and coordinate their limbs in theperformance of common tasks is remarkable. When holding a heavy object or applying a force to the environment through a tool, thearms and body of a skillful human are configured in the most effective fashion for the task. The human selection of specific posturesamong the infinity of possibilities is the result of a long and complex process of learning. Through learning, humans seem to cometo discover the properties of their bodies and how best to put themto use when performing a task. Exploiting the body kinematic characteristics, humans are effectively using the body mechanicaladvantage to improve the transmission of the tension of muscles into task required forces. However, the efficiency of this transmission is also affected by the human muscle actuation physiology. Byalso adjusting the body configurations to maximize this transmission of muscle tensions to resulting task forces, humans are in factexploiting what can be termed the physiomechanical advantage oftheir musculoskeletal system. If confirmed, this would correspondssimply to the overall minimization of the human muscular effort

O que sistemas multi corpos

The mechanical systems included under the definition of multibodies compriserobots, heavy machinery, spacecraft, automobile suspensions and steering systems, graphic arts and textile machinery, packaging machinery, machine tools, and others. Normally, the mechanisms used in all these applications are subjected to large displacements, hence, their geometric configuration undergoes large variations under normal service conditions. Moreover, in recent years operating speeds have been increased, and consequently, there has been an increase in accelerations and inertia forces. These large forces inevitably lead to the appearance of dynamic problems that one must be able to predict and control

The analysis programs simulate the behavior of a multibody system once allof its geometric and dynamic characteristics have been defined. The analysisprograms are certainly very useful. At the present time they are the only generalpurpose tools available for the largest number of applications.

We define a multibody system as an assembly of two or more rigid bodies (alsocalled elements) imperfectly joined together, having the possibility of relativemovement between them

Porque utilizar

O que é realidade virtual

The analysis of human gait is a complex task, relies mostly the use of the multibody formulations applied as kinematic and dynamic tools. The human body can also be considered a multibody system, composed by rigid bodies and connected by joints

Answering "what is virtual reality" in technical terms is straight-forward. Virtual reality is the term used to describe a three-dimensional, computer generated environment which can be explored and interacted with by a person. That person becomes part of this virtual world or is immersed within this environment and whilst there, is able to manipulate objects or perform a series of actions.

Virtual reality also acts as a problem solving device in that it enables us to explore various options as a means of finding an answer to a problem.

Virtual reality has been adopted by the military – this includes all three services (army, navy and air force) – where it is used for training purposes. This is particularly useful for training soldiers for combat situations or other dangerous settings where they have to learn how to react in an appropriate manner.A virtual reality simulation enables them to do so but without the risk of death or a serious injury. They can re-enact a particular scenario, for example engagement with an enemy in an environment in which they experience this but without the real world risks. This has proven to be safer and less costly than traditional training methods.

Military uses of virtual realityThese include:

Flight simulation Battlefield simulation Medic training (battlefield) Vehicle simulation Virtual boot camp

Virtual reality is also used to treat post-traumatic stress disorder. Soldiers suffering from battlefield trauma and other psychological conditions can learn how to deal with their symptoms in a ‘safe’ environment. The idea is for them to be exposed to the triggers for their condition which they gradually adjust to. This has the effect of decreasing their symptoms and enabling them to cope to new or unexpected situations.

This is discussed further in the virtual reality treatment for PTSD (post traumatic stress disorder) article.

Use of computer modeling and SIMULATION  to enable a person to interact with an artificial three-dimensional visual or other sensory environment. A computer-generated environment simulates reality by means of interactive devices that send and receive information and are worn as goggles, headsets, gloves, or body suits. The illusion of being in the created environment (telepresence) is accomplished by motion sensors that pick up the user's movements and adjust his or her view accordingly, usually in real time. The basis of the technology emerged in the 1960s in simulators that taught how to fly planes, drive tanks, shoot artillery, and generally perform in combat. It came of commercial age in the 1980s and is now used in games, exhibits, and aerospace simulators. It has potential for use in many fields, including entertainment, medicine and biotechnology, engineering, design, and marketing.