Translational motions in human knee joint model

Different authors are dealing with description of motion components of human knee joint. The relative motion between femur and tibia realized by knee joint is ensured by complicated condyle surfaces and ligaments. Main part of authors focus merely on rotational displacement of human knee joint such as flexion-extension, abduction-adduction, tibial rotation. In order to achieve implanted prostheses we have to recognize not only the rotational but also translational kinematical parameters of human knee joint. Authors of this paper for description of motion of knee joint joined coordinate-systems on the basis of anatomical landmarks to the femur and tibia moreover joined a threecylindrical mechanism as mechanical model to the axes of coordinate-systems. In 2nd phase authors determined the six independent kinematical parameters of tibia compared to the fixed femur during flexion and extension. The experimental examinations were carried out on cadaver knees. The positioning was tracked by optical positioning appliance

Simple Numerical Method for Kinetical Investigation of Planar Mechanical Systems with Two Degrees of Freedom

The aim of this article is to demonstrate the application of a simple numerical method which is suitable for motion analysis of different mechanical systems. For mechanical engineer students it is important task. Mechanical systems consisting of rigid bodies are linked to each other by different constraints. Kinematical and kinetical analysis of them leads to integration of second order differential equations. In this way the kinematical functions of parts of mechanical systems can be determined. Degrees of freedom of the mechanical system increase as a result of built-in elastic parts. Numerical methods can be applied to solve such problems. The simple numerical method will be demonstrated in MS Excel by author by the aid of two examples. MS Excel is a quite useful tool for mechanical engineers because easy to use it and details can be seen moreover failures can be noticed. Some parts of results obtained by using the numerical method were checked by analytical way. The published method can be used in higher education for mechanical engineer students

Synthesis of some Mechanisms using Natural Coordinates

The aim of this article is to demonstrate the kinematical synthesis of some mechanisms applied in agricultural machineries. The applied method based on the use of natural coordinates for this reason the method is simple and efficient. The mechanical system is described by a set of geometric constraints. The design requirements are handled by a set of functional constraints. By the aid of objective function it can be obtained the values of design parameters of the mechanism. Finally two characteristically examples are presented that illustrate the application of the method