© Springer Nature Singapore Pte Ltd. 2017 339 A. Badnjevic (ed.), CMBEBIH 2017, IFMBE Proceedings 62, DOI: 10.1007/978-981-10-4166-2_51 Simulation of kinematic behaviour of prosthetic devices Vesna Raspudiü Faculty of Mechanical Engineering and Computing University of Mostar Bosnia and Herzegovina Abstract. Beside the possibility to actively control the amount of damping in artificial joints, modern prosthetic devices should have the ability to generate power. This would enable persons with amputation to achieve biologi- cally realistic kinematics and dynamics of locomotion. Re- cent development in prosthetics is primarily influenced by new knowledge and research performed in the field of hu- man body biomechanics. Tracking of human body motion is based on the use of appropriate optical or magnetic markers, which are placed on specific landmark points, and real-time estimating of their spatial coordinates. With the improve- ments introduced in computer monitoring of human motion, it is important to lay emphasis on the significance of com- bining motion capture data with commercial CAD pack- ages, in order to conduct detailed motion analysis and evaluate the mechanical performance of prosthetic design using CAD virtual models. This paper presents a method of determining the functional dependence of relevant kine- matic parameters on prosthetic devices, in order to define a set of data for the development of appropriate control sys- tems for achieving the desired movement pattern. The func- tional dependence of change in length and velocity of linear actuators built into the knee and ankle joint of the powered transfemoral prosthesis has been analysed. These data can be used to enhance the control system during the stance period of stair ascent, in order to achieve biologically equivalent locomotion. Keywords: biomechanics, prosthetics, CAD, computer simulation 1 Introduction Despite numerous improvements in lower limb prosthetic design over the last few decades, there is still the problem of passive prosthetic joints and therefore the problem of ability to perform activities of daily living. The prosthesis that could generate power in the knee and ankle joint will sig- nificantly contribute to the achievement of normal biome- chanical locomotion. The generated power should be in line with the values achieved during normal locomotion, while ensuring stability and coordinated interaction with the user and the environment in which the movement is performed. People with a passive transfemoral prosthesis do not have the ability to control prosthetic knee and ankle joints, which is resulting in a change in the entire body kinematics as well as in increased activity of hip muscles. The walking speed is less, as well as the ground reaction forces on the prosthesis in comparison to the intact leg, which can cause the problem of overloading and development of degenera- tive joint disease of the intact leg [1,2]. The problem of normal locomotion is especially evident in the performance of energy-consuming movements, such as ascending stairs. The stair ascent task needs excessive muscle activity com- pared to the stair descent task and level walking and the muscle activity on the residual limb of amputees is greater than those of healthy individuals [3]. The usual way of stair ascent for a person with a trans- femoral prosthesis is that the person begins climbing with intact leg, and then raises the prosthesis on the same step. In addition, due to inability of bending the prosthetic knee and because of the possibility of hitting the step with the front part of the prosthetic foot, the result is very unnatural movement of the entire body. External power source would enable lifting of the body weight to the next step over the prosthetic leg too. At the same time, it is necessary to achieve more natural kinematics and dynamics of the pros- thesis movement. As part of previous studies [4, 5], the possibility of intro- ducing an external source of energy in the knee and ankle joints of transfemoral prosthesis Endolite, type SFEUK (Stanceflex Uniaxial Knee Chassis) was analysed, to resolve the problem of climbing stairs. The existing damper in the knee has been replaced with specially constructed hydraulic linear actuator, wherein the existing connecting points in the prosthesis structure have been used. To achieve prosthesis kinematics which resembles the normal human movement, this paper will analyse 3D CAD simulation of the kinematic behaviour of the knee actuator, to achieve biomimetic badnjevic.almir@gmail.com