388 research outputs found
Trini the Stepladder - A helping device for in-home daycares: Trini the Stepladder - A helping device for in-home daycares
No full textSimulating the dynamics of a human-exoskeleton system using kinematic data with misalignment between the human and exoskeleton joints
Full text linkMusculoskeletal model-based simulation can be a powerful tool in the design and evaluation of exoskeletons. They are used extensively during the virtual prototyping stage using motion data of the human without the exoskeleton. An ideal exoskeleton model, perfectly aligned with the human joint axes, can be used to co-simulate the human and exoskeleton dynamics. However, misalignment between the human and exoskeleton joints is commonly observed during the use of an exoskeleton, potentially leading to a loss in the effective assistance received by the user. Motion data collected with the user wearing the exoskeleton should, normally, be able to capture the misalignment between the human and exoskeleton joints. Using misaligned motion data in the combined human-exoskeleton model can lead to complications in the virtual model and unrealistic outputs. One way to tackle these complications is to assume alignment between the human and exoskeleton joints in the model by kinematically constraining it.
This work presents a new method that facilitates the analysis of misaligned human-exoskeleton systems. This is achieved by introducing artificial segments between the human and exoskeleton models. These artificial segments, the so-called dummy segments, ensure kinetic alignment between the human and exoskeleton joints in the model without altering the observed kinematics from the actual trial. The method is demonstrated using an active lower-limb exoskeleton that aims to assist the elderly in stair negotiation. A single subject performed eight trials with the exoskeleton in a laboratory. Motion data of both the subject and exoskeleton were recorded using an optical marker-based motion capture system. Further, the measured ground reaction force and the exoskeleton assistive force were used as inputs in the combined human-exoskeleton model. The outputs from the inverse dynamics analysis of the model with the dummy segments were compared to those from a reference model, where the measured external forces were applied directly to the human model at the corresponding reference points, bypassing the human-exoskeleton interface model completely. The results of the knee compression force, knee flexion moment, and activation of vastus lateralis from the model with the dummy segments showed good agreement with the reference model. The use of the dummy segments allows the study of aligned kinetics and misaligned kinematics from the same model
A general marker-less motion capture approach for the Microsoft Kinect Sensor v2 using subject-specific articulated models within an iterative closest point algorithm for improved anatomical accuracy.
No full textJoint kinematics obtained by the Microsoft Kinect Sensors aremeasured based on a simplification of the human anatomy, which don’tinclude anatomically accurate estimations of the joint centers.Consequently the measured joint kinematics are not directlycompatible with the anatomically accuracy of musculoskeletal models.Accordingly, the purpose of the present study was to propose a newmarker-less tracking approach using the Microsoft Kinect v2 to obtainthe 3D movement of a single leg. A subject specific articulated modelof the right leg with anatomically correct joint centers was generatedusing the Microsoft Kinect v2 to scan the anatomical geometry of thesegments. The poses of the detailed articulated model was estimatedrelative to a dynamic depth recording of a 90 degree hip flexionmovement, using an iterative closest point algorithm to which aconstrained optimization problem was defined. The proposed approachwas compared to a marker-based system. Hip flexion/extension,abduction/adduction, external/internal, knee flexion/extension andankle plantar/dorsi flexion were measured for one subject. Theflexion/extension and internal/external rotation for the hip andflexion/extension for the knee showed good agreement with themarker-based results. The hip abduction/adduction and ankleflexion/extension showed poor results compared to the marker-basedsystem
Development of a Workflow for Wear And Functional Simulation of Total Knee Replacements
No full textThis project deals with development of a workflowfor wear and functional simulation of totalknee replacement (TKR). All loads and drivenmotion of the knee joint are computed in themuscoloskeletal modelling program AnyBodyTMduring a gait cycle, and through MATLAB appliedto an FE model solved in FEBio. Thismodel, containing tibial implant, femoral implantand the major surrounding ligaments, is solvedwith boundary conditions in all six degrees offreedom.The FE analysis predicts the kinematics and internalcontact of the joint, of which the former iscompared to fluoroscopic data and the AnyBodymodel. This showed good agreement in the translationdirections, but the agreement of the rotationsvaried.The linear wear is estimated from the computedcontact pressure with a developed algorithm writtenin MATLAB, which is verified with experimentalresults reported in the literature. Thealgorithm predicted a very low maximum weardepth (76.3 % deviation), compared to the literature,but the wear contour was in good agreement.The MS model can solve both an idealised hingeconstrained model and a contact-based knee jointmodel, and in this project the wear during a gaitcycle is investigated for both methods to investigatethe difference in wear depth. The lattermethod uses the force-dependent kinematicsolver, and this method turned out to predict thehighest wear depth of the two methods
Extruza - Underwater Welding Gun
No full textFormålet med dette afgangsprojekt er at kaste lys på Erhvervsdykkerne og med en vision om at gøre arbejdet undervand nemmere at udfører. Som en niche industri, især i Danmark, er markedet ofte overset og overladt til sig selv. Det resulterer i få løsninger af udstyr og erhvervsdykkere må derfor improvisere hvis de vil se ændringer i arbejdsmetoder, tilbehør på værktøj eller værktøjet i sig selv. Oftest håndteres dette på “gør det selv ”-metoden, hvor et eksisterende produkt bliver modificeret til at kunne fungere til dykkerens job. Udfaldet er dog at produkterne bliver slidte af løsningerne og det ender med en investering i nyt udstyr da det ikke kan holde til den hårde kontekst. Her ses der særligt på svejsning, med en arbejdsform der er lang fra perfekt, i forhold til et ellers perfekt resultat der skal opnås. Endnu videre ses der et stort problem i “smid ud” kulturen hos erhvervsdykkerne, specielt i svejsehåndtaget, der trods at kunne skiftes i enkelte dele, vælges at skiftes helt da det er en billig løsning. Projektet arbejder med udviklingen af et produkt der placerer dykkeren tættere på sit arbejde og derved øger præcision, giver en øget arbejdsintensitet og en ikke-destruktiv tilpasning af produktet med div. gadgets.The purpose of this master thesis is to shed light on the commercial diversand with a vision of doing the work underwater easier to perform. As a niche industry, especially in Denmark, the market often is overlooked and left to themselves. It results in a few solutions of equipment and divers must, therefore, improvise if they want to see changes in working methods, accessories on tools, or the tool itself. Most often this is handled by“dothe self ”method where an existing product gets modified to work for a specific job. The outcome, however, the products are worn out by the solutions and it ends up investing in new equipment as it cannot survive in the harsh context.Here, special attention is paid to welding, with a working method there is far from perfect, compared to an otherwise perfect result there must be achieved. Still, there is a big problem in the "throw out" culture at the professional divers, especially in the welding handle, theredespite being switchable in individual parts, it is chosen to switch completely since it is a cheaper solution. The project is working on the development of a product there places the diver closer to his work, thereby increasing precision, provides increased work intensity and non-destructive customization of the product with gadgets
Ambient 1 - Sound of the future
No full textThis project has been about developing a speakerfor newly built houses. The vision for this project wasto design a suggestion for a speaker for Dynaudiothat can reposition and introduce them on themainstream market in the future.As technology evolves so does the devices usingthem. Conventional passive speaker systems aren’tas popular as they once were.They are deselected in the favor of soundbars andsmaller bluetooth speakers, as these type ofspeakers requires less effort to use and becausethey are less visible in the interior.By user studies and trend investigation of userdemands in regard to sound reproduction, wemanaged to create a solution space in which oursolution was developed.Dynaudio Ambient 1, is a multifunctional speakerthat hides the speakers in its other function as alamp canopy. The product requires installation butis easier to install than a normal ceiling lamp. As thespeaker is a canopy, it can be used as a retrofitsolution in existing interiors as well as new houses.It has a neutral aesthetic that, combined with thepossibility of exchanging hardware as it getoutdated, contribute to securing its relevance onthe market in the future as well.The project was made during the Corona pandemic,which caused a shutdown of interaction with peoplein public, nationally and globally. As such usertesting was restricted
Prediction of ground reaction forces and moments during sports-related movements
No full textInverse dynamic analysis (IDA) on musculoskeletal models has become a commonly used method to study human movement. However, when solving the inverse dynamics problem, inaccuracies in experimental input data and a mismatch between model and subject leads to dynamic inconsistency. By predicting the ground reaction forces and moments (GRF&Ms), this inconsistency can be reduced and force plate measurements become unnecessary. In this study, a method for predicting the GRF&Ms was adopted and validated for an array of sports-related movements. The method uses a scaled musculoskeletal model and the equations of motion alone to predict GRF&Ms from full-body motion, and entails a dynamic contact model and optimization techniques to solve the indeterminacy during double support. The method was applied to ten healthy subjects performing e.g. running, a side-cut manoeuvre and vertical jump. Pearson’s correlation coefficient (r) was used to compare the predicted GRF&Ms and associated joint kinetics to the corresponding variables obtained from a traditional IDA approach, where the GRF&Ms were measured using force plates. In addition, peak vertical GRFs and resultant JRFs were computed and statistically compared. The main findings were that the method provided estimates comparable to the traditional IDA approach for vertical GRFs (r ranging from 0.96 to 0.99, median 0.99), joint flexion moments (r ranging from 0.79 to 0.98, median 0.93) and resultant JRFs (r ranging from 0.78 to 0.99, median 0.97), across all movements. Although discrepancies were identified for some variables and the majority of the peak forces were significantly different, the former were mainly contributed to noise while the differences in peak forces could potentially be overcome by adjusting parameters in the contact model. Considering these results, this method could be used instead of force plate data, hereby facilitating IDA in sports science research and providing valuable opportunities for complete IDA using motion analysis systems that does not commonly incorporate force plate data, such as marker-less motion capture
Effect of orthoses on lower extremity biomechanics associated with patellofemoral pain during running gait
No full textOrthoses are commonly prescribed in clinical treatment of various running-related injuries. However, the underlying mechanisms of orthoses are poorly understood. The purpose of the study was to determine the effect of anti-pronation orthoses on biomechanical parameters associated with development of patellofemoral pain during running. Eight healthy recreational runners participated in a cross over study. Each subject was instructed to run on a predefined track in six different configurations of an orthotic running shoe, containing adjustable medial wedge support, adjustable medial longitudinal arch support and adjustable midsole cushioning. Kinematic and kinetic data were obtained from motion capture and force plate system. A subject-specific lower extremity muskuloskeletal model was constructed based on functional joint trials. Inverse dynamics was applied to compute external moments and forces. The results obtained from the model displayed that anti-pronation orthoses significantly increased foot inversion moment, increased internal foot rotation moment, increased internal knee rotation moment, reduced hip adduction moment and reduced lateral knee shear force during stance phase in running. These findings supports the clinical application of orthoses as a prophylactic tool against development of patellofemoral pain. However, the orthotic effect was distally oriented with only small or no effect on local and proximal parameters, suggesting only subgroups with distal risk factors may benefit from anti-pronation orthoses.</p
Groa by Spire
No full textThis report illustrates the process of designing a product that can provide the right support for mothers during breastfeeding. This assignment is made as a master thesis project by two industrial design students at Aalborg University.During breastfeeding, the right position and support will help the mother to relax, which is necessary to make the milk flow. The market for products designed for this purpose is very limited, perhaps because it is mainly needed for the first six months, which is a short lifetime for that type of product. Designing a nursing chair that combined with a bedside crib can be transformed into a cot, will create a big business opportunity.The result is the product Groa. A simple furniture design consisting of a nursing chair and a bedside crib that can be transformed into a cot, and used until the child is seven, by adding an extension. The nursing chair is designed to create a support that fits the individual mother, with a nursing pillow that can be attached around the mother, and thereby create good support under the arms and for the lower back.<br/
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