ANNALS of Faculty Engineering Hunedoara – International Journal of Engineering 133 | Fascicule 3 Tome XIII [2015] – Fascicule 3 [August] ISSN: 1584-2673 [CD-Rom; online] a free-access multidisciplinary publication of the Faculty of Engineering Hunedoara 1. Miljan RUPAR, 2. Remzo DEDIĆ, 3. Adisa VUČINA, 4. Haris ĐINDO MEASURING EQUIPMENT IN THE RESEARCH AND THE DEVELOPMENT OF HYDRAULIC ABOVE – KNEE PROSTHESIS 1-3. Faculty of Mechanical Engineering and Computing, Mostar, BOSNIA & HERZEGOVINA 4. DICGIM, University of Palermo, ITALY Abstract: Climbing the stairs in natural manner still presents a big problem for an amputee using commercial above-knee (AK) prosthesis. The main problem with common AK prostheses is the lack of knee and ankle joints, since climbing the stairs requires overcoming large forces and moments. The main aim of the project of developing the new hydraulic AK prosthesis is to find a way to enable unilateral trans-femoral (TF) amputees to climb the stairs in as much as possible natural manner by developing prosthesis with externally powered knee and ankle joints. In order to test prosthesis functionality, various experiments need to be conducted, and for that purpose motion measuring equipment is needed. The equipment at disposal is TrakSTAR WIDE-RANGE. As this measuring equipment will be used for the first time for testing the prosthesis, it is necessary to test it prior to using it in final experiments. For that purpose preliminary test was done by simulating climbing the stairs of sound person. Keywords: experiments, Hydraulic AK Prosthesis, measuring equipment 1. INTRODUCTION The aim of the Hydraulic Above-Knee (AK) Prosthesis project is to develop an AK prosthesis that would enable unilateral above- knee leg amputees to perform various activities that are integral part of their everyday’s lives. The main goal, and the hardest to achieve, is to enable amputees to climb the stairs using Hydraulic AK prosthesis and perform it with ease and as naturally as non- amputees. Advanced microprocessor controlled AK prostheses that are available on the market enable amputees to walk on levelled and inclined ground, to descend the stairs and even to ride a bicycle and to do various other activities. In order for amputees to climb the stairs in a way that would be, by its kinematics and dynamics, approximate to natural climbing of non-amputees, external power is needed to substitute large number of muscles needed to perform such an activity [1]. However, climbing the stairs can now be achieved, but it is usually performed in an unnatural “step by step”, where amputees (unilateral) mostly progress to the next step with their sound leg, followed by pulling their prosthesis to the same step. This means that progressing to a next stair is always made with same leg. The development of initial physical prototype of Hydraulic AK prosthesis with two hydraulic actuators, in the knee and in the ankle, is in a stage of testing in order to assess all assumptions from the research conducted up to now. Also, it needs to be determined if the chosen power unit has the appropriate to power to overcome forces while climbing the stairs and to determine if hydraulic actuators are adequately chosen and positioned within the prosthesis design. For that purpose, there is a need of conducting experiments of climbing the stairs in multiple phases, and adequate measuring equipment is needed in order to be able to measure achieved results. 2. PROJECT OF DEVELOPMENT OF HYDRAULIC AK PROSTHESIS Initial research and development of Hydraulic AK prosthesis has lasted for long period of time, starting at Faculty of Mechanical Engineering and Computing, University of Mostar, Bosnia and Herzegovina. It was carried out in several phases and each of these phases represented a new progress which demanded proving the results through the appropriate experimental testing. These phases were conducted mostly as a part of master or doctoral research under the mentorship of professor PhD RemzoDedic, who was the initiator of the project of Hydraulic AK Prosthesis. Since all the research was conducted by different researchers, and on different locations, with certain time period passed between them, in all phases and experimental testing different measuring equipment was used. The reason for that is not only that different aspects were tested, but also because of the unavailability of attaining the same equipment in each time-separated phase.