121,792 research outputs found
Comfort driven design of innovative products: A personalized mattress case study
No full textBACKGROUND: Human-centred design asks for wellbeing and comfort of the customer/worker when interacting with a product. Having a good perception-model and an objective method to evaluate the experienced (dis)comfort by the product user is needed for performing a preventive comfort evaluation as early as possible in the product development plan. The mattress of a bed is a typical product whose relevance in everyday life of people is under-evaluated. Fortunately, this behaviour is quickly changing, and the customer wants to understand the product he/she buys and asks for more comfortable and for scientifically assessed products. No guidelines for designing a personalized mattress are available in the literature. OBJECTIVES: This study deals with the experience of designing an innovative product whose product-development-plan is focused on the customer perceived comfort: a personalized mattress. The research question is: which method can be used to innovate or create a comfort-driven human-centred product? METHODS: Virtual prototyping was used to develop a correlated numerical model of the mattress. A comfort model for preventively assessing the perceived comfort was proposed and experimentally tested. Mattress testing sessions with subjects were organized, and collected data were compared with already tested mattresses. Brainstorming and multi-expert methods were used to propose, realize, and test an archetype of a new mattress for final comfort assessment. RESULTS: A new reconfigurable mattress was developed, resulting in two patents. The mattress design shows that personalized products can be tuned according to the anthropometric data of the customer in order to improve the comfort experience during sleep. CONCLUSIONS: A 'comfort-driven design guideline' was proposed; this method has been based on the use of virtual prototyping, virtual optimization and physical prototyping and testing. It allowed to improve an existing product in a better way and to bring innovation in it
A novel procedure for medial axis reconstruction of vessels from Medical Imaging segmentation
No full textA procedure for reconstructing the central axis from diagnostic image processing is presented here, capable of solving the widespread problem of stepped shape effect that characterizes the most common algorithmic tools for processing the central axis for diagnostic imaging applications through the development of an algorithm correcting the spatial coordinates of each point belonging to the axis from the use of a common discrete image skeleton algorithm. The procedure is applied to the central axis traversing the vascular branch of the cerebral system, appropriately reconstructed from the processing of diagnostic images, using investigations of the local intensity values identified in adjacent voxels. The percentage intensity of the degree of adherence to a specific anatomical tissue acts as an attraction pole in the identification of the spatial center on which to place each point of the skeleton crossing the investigated anatomical structure. The results were shown in terms of the number of vessels identified overall compared to the original reference model. The procedure demonstrates high accuracy margin in the correction of the local coordinates of the central points that permits to allocate precise dimensional measurement of the anatomy under examination. The reconstruction of a central axis effectively centered in the region under examination represents a fundamental starting point in deducing, with a high margin of accuracy, key informations of a geometric and dimensional nature that favours the recognition of phenomena of shape alterations ascribable to the presence of clinical pathologies
Posture prediction of a human on a chair: model validation
No full textOne of the aspects that influence the sitting comfort is the distribution of the pressure applied to the
skin by the seat surface. In the scientific literature, many studies show experimental activities in order to
evaluate the influence of pressure distribution at the seat-human interface on the comfort evaluation. The main
limitation in seat design is based on the difficulties to predict the contact pressures distribution without
prototypes because of the complex interaction among body muscles, wearing, human’s anthropometric
characteristics, shape and materials of the seat. Moreover, the same human can assume different postures on
the same seat, and different people, seated on the same chair, can assume different postures even if they have
the same anthropometric percentile. The aim of this study is to propose a mathematical model evaluating
interaction loads between human segments and seat segments. In this model a human body represented by 8
segments is placed on a 6 segments seat with posture dependent on seat segments and on position of the cocciyx
on seat and feet on floor. Human segments can be configured in length and weight and friction between body
and seat is considered. A model validation study based on an experimental comparison with contact pressures
is also presented
Assessment of ranges of rest postures of human lower limbs
No full textBACKGROUND: Several comfort perception models have proposed an objective method to evaluate 'effects in the internal body' and 'perceived comfort'. Postural comfort is one aspect of comfort/discomfort perception, and this current work adds to existing knowledge toward a more objectified posture evaluation for comfort. OBJECTIVE: The authors have used the concept of Range of Rest Posture (RRP), as proposed by Apostolico et al. The study focused on the identification of RRP within the Comfort Range of Motion (CROM) for lower limbs. METHODS: The proposed method is based on extensive experimental work involving 114 healthy individuals (59 males and 55 females) ranging from 20 to 40 years old. The age range was narrowed to avoid an age-clustering of results due to inhomogeneity of the statistical sample. Data were processed using statistical methods for identifying the RRP in the experimental CROM. Several Maximum Level of Comfort (MLC) positions were found within the RRP. RESULTS: RRPs for lower limbs of men and women have been identified and can be used for virtual comfort assessment. CONCLUSIONS: This paper shows a method to evaluate in a more objective way the subjective postural comfort perception and results allow researchers to improve models for the virtual preventive comfort assessment
Sulle Procedure di Modellazione Tipizzata 3D per la Valutazione dei Fattori di Intensità delle Tensioni da Cricche Superficiali
No full textPosture prediction of a human on a chair: model description
No full textOne of the aspects that influence the sitting comfort is the distribution of the pressure applied to the
skin by the seat surface. In the scientific literature, many studies show experimental activities in order to
evaluate the influence of pressure distribution at the seat-human interface on the comfort evaluation. The main
limitation in seat design is based on the difficulties to predict the contact pressures distribution without
prototypes because of the complex interaction among body muscles, wearing, human’s anthropometric
characteristics, shape and materials of the seat. Moreover, the same human can assume different postures on
the same seat, and different people, seated on the same chair, can assume different postures even if they have
the same anthropometric percentile. The aim of this study is to propose a mathematical model evaluating
interaction loads between human segments and seat segments. In this model, a human body represented by 8
segments is placed on a 6 segments seat with posture dependent on seat segments and on position of the cocciyx
on seat and feet on floor. Human segments can be configured in length and weight and friction between body
and seat is considered. A model validation study based on an experimental comparison with contact pressures
is also presented
Cerebral Vessels Diagnostic Investigation: Vessel Classification from Medial Axis Evaluation
No full textA survey of methods to detect and represent the human symmetry line from 3D scanned human back
No full textAbstract This paper proposes a review of the methods to detect and represent the human symmetry line. In the last years, the development of 3D scanners has allowed to replace the traditional techniques (marking based methods) with modern methodologies that, starting from a 3D valid discrete geometric model of the back, perform the posture and vertebral column detection based on a complex processing of the acquired data. The purpose of the paper is a critical d iscussion of the state of the art in order to highlight the real potentialit ies and the limitations still present of the most important methodologies proposed for human symmetry line detection
"In vivo" validation of 3d-printed innovative surgical template for lumbar spinal arthrodesis
No full textThe most common type of spine instrumentation is the pedicle screw fixation. The recent literature shows how customized drilling templates help surgeons to perform the surgery better. This work aims to validate the design of a customized template for inserting lumbar pedicle screw via a procedure based on rapid prototyping and reverse engineering techniques and to show the benefits. The novelties of this template are its low-invasive sizes, its design based on a patented algorithm, which calculates the sizes of the screws and the optimal insertion direction, the engage/disengage system, and the adaptability to every kind of surgeon's kit. Accuracy of pedicle screw location, surgery duration, and X-ray exposition have been used to evaluate the performances of the template. Mono-centric in vivo trial was performed. Twenty patients (8 women and 12 men) were enrolled randomly corresponding to sixty vertebrae treated with spinal arthrodesis (30 with and 30 without templates). Accuracy of the screw positioning and reduction in both surgery duration and patients' exposure to X-rays achieved excellent results because the time spent on the insertion of pedicle screws via the surgical template was cut down by about 63%, while the number of X-ray shots was reduced by about 92%. The proposed template performed better than the standard approach and could be helpful both for skilled and novice surgeons
Multi-target driven design of a smart aircraft accessibility system for people with reduced mobility: the BEAIR® project
No full textThe number of persons with disabilities represents a significant part of world’s population. There
are more than 1 billion people with disability that is about 15% of the world’s population or one in seven people.
In Europe, there are around 80 million persons with disabilities (physical disabilities 72.5%). On the other
hand, population aging in Europe, along with the high correlation between age and disability, implies that the
share of the disables among the European citizens is bound to increase significantly. With regard to transport,
the lack of accessibility contributes to the disadvantages experienced by people with disability. The paper
shows a multi-target driven design of a smart aircraft accessibility system for people with reduced mobility
(the BEAIR®) in which the comfort assessment has been made through the explicit FEM simulation approach.
Obtained results have been compared with values coming from literature. The development of the
BEAIR® concept has been initiated by making use of the Quality Function Deployment (QFD) approach,
which has led to the identification of the key equipment characteristics, in fulfillment to the applicable regulations
and laws, as well as to the stakeholders needs (the PRM, Passenger with reduced mobility). Among the
needs, one of the most relevant is the mitigation of the bedsores problem, which occurs mainly when the PRM
is subjected to long haul flight. To mitigate the said issue, and properly address the design of cushion, a simulated
ergonomic analysis has been performed as described in the present paper, prior qualification and ergonomic
tests. The simulation has been iterated so to achieve an optimal design in shape, material and stiffness
of the cushion
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