This paper addresses a design for an exoskeleton used for human locomotion purposes in cases of people with neuromotor disorders. The reason for starting this research was given by the development of some intelligent systems for walking recovery involved in a new therapy called stationary walking therapy. This therapy type will be used in this research case, through a robotic system specially designed for functional walking recovery. Thus, the designed robotic system structure will have a patient lifting/positioning mechanism, a special exoskeleton equipped with sensors and actuators, a treadmill for walking, and a command and control unit. The exoskeleton’s lower limbs will have six orthotic devices. Thus, the exoskeleton’s lower limbs’ motions and orthoses angle variations will be generated by healthy human subjects on the treadmill with the possibility of memorizing these specific motions for obtaining one complete gait cycle. After this, the memorized motions will be performed to a patient with neuromotor disorders for walking recovery programs. The design core is focused on two planar-parallel mechanisms implemented at the knee and ankle joints of each leg’s exoskeleton. Thus, numerical simulations for the design process were carried out to validate the engineering feasibility of the proposed leg exoskeleton.

This paper addressed attention to the design of a new lower limb exoskeleton that can be used for human gait assistance as based on kinematic considerations. The designed leg exoskeleton had on its own structure a combination of three mechanism types, namely a Chebyshev mechanism, a pantograph, and a Stephenson six-bar mechanism. The design core focused on inserting the Stephenson six-bar bar mechanism in order to obtain an imposed motion at the ankle joint level. Numerical simulations of the designed lower limb exoskeleton have been developed and the obtained results demonstrate the engineering feasibility of the proposed prototype, with a characterization of satisfactory operation performance.

This paper presents a new solution for an exoskeleton robotic system that is used for locomotor assistance in people with locomotor disabilities. As novel features of the present research, a novel structural solution of a plane-parallel kinematic chain, intended to be used as the leg of an exoskeleton robot, is proposed. A virtual prototype is made, on the basis of which kinematic and dynamic studies are carried out using ADAMS software for the dynamic analysis of multibody systems. The dynamic simulation of the exoskeleton is performed in two simulation situations: walking on a horizontal plane, as well as the simulation of motion assistance when climbing stairs. Following this analysis, it is noted that the robotic system achieves angular variations in the hip and knee joints similar to that of a human subject. As a result, the constructive solution is feasible, and the next stage of the study is to realize an experimental prototype by the rapid prototyping technique. The kinematic elements of the exoskeleton are designed to provide structural strength, to be easily manufactured by 3D printing and to be easy to assemble. For this purpose, the structural optimization is performed with the finite element method to eliminate stress concentrators. Finally, an experimental prototype of the exoskeleton robot is manufactured and assembled, whose motion is analyzed using ultrafast-camera-based video analysis.

This research addresses a feasibility study for validating an exoskeleton with kinematic considerations. The designed exoskeleton will be used for children with congenital disorders, especially for a case study characterized by Duchenne muscular dystrophy (DMD). The research core focuses on virtual simulations carried out through the multibody systems theory under an MSC Adams 2012 software environment, with an exoskeleton constructive solution. The designed exoskeleton mechanism is characterized by simplicity, low-cost, and easy-operation features criteria. The results obtained through a numerical processing analysis validate the feasibility study of the proposed prototype.

The current paper focuses on the impact phenomenon analysis, in the case of multi-body mechanical systems undergoing fast motion, due to the presence of some manufacturing and mounting errors or due to some accident during the transport mechanical systems. Thus, the impact phenomenon was analyzed in two cases, the first one consisting of a two bodies, namely, a free-fall body brought in contact with the other considered fixed in space and the second case, which is a complex one, when the analyzed bodies are components of a multi-body mechanical system. The research main objective is to analyze the impact generated between the two bodies through three methods, i.e., the analytical method, a virtual prototyping method accomplished with MSC Adams software and a method based on finite element analysis with Ansys and Abaqus software. A dynamic model of the impact force was developed, which allows to make a comparison of the numerical results obtained through the abovementioned methods. As a multi-body mechanical system, it was considered a mechanism from an internal combustion engine from which the radial clearance between the piston bolt and connecting rod head of the considered mechanism was analyzed.

The paper presents a comprehensive method for the elastodynamic analysis of mobile mechanical systems, based on the finite element method. Using Kane’s algorithm, which is employed in the dynamic analysis of mechanical systems with rigid bodies, a method is developed that, by superimposing the rigid body motion over the one of a deformable body, allows to identify the kinematic and dynamic components of the matrices involved in the motion equations namely, the mass matrix, stiffness matrix, damping matrix, and the force vector acting on the system. The method is applied to a high-speed mechanism used for actuating an internal combustion engine with three in-line pistons. Within this method, each kinematic link is considered as a finite element, with corresponding reference frames for which the kinematic and dynamic components of the matrices involved in the motion equations are determined. To solve the differential equations system, a modal superposition method is applied, which enables the decoupling of the equations and to identify the time-varying diagrams for nodal displacements, both longitudinal and transversal displacements, and consequently to determine the accelerations of the kinematic links, which are useful in vibration analysis. The strength force is considered the force exerted by the gas on the piston head, which was experimentally determined under laboratory conditions. The theoretical results obtained are validated through virtual prototyping and experimental tests.