Jochen Vleugels

Ergonomic design of an EEG headset using 3D anthropometry

Although EEG experiments over the past decades have shown numerous applications for brain-computer interfacing (BCI), there is a need for user-friendly BCI devices that can be used in real-world situations. 3D anthropometry and statistical shape modeling have been shown to improve the fit of devices such as helmets and respirators, and thus they might also be suitable to design BCI headgear that better fits the size and shape variation of the human head. In this paper, a new design method for BCI devices is proposed and evaluated. A one-size-fits-all BCI headset frame is designed on the basis of three digital mannequins derived from a shape model of the human head. To verify the design, the geometric fit, stability and repeatability of the prototype were compared to an EEG cap and a commercial BCI headset in a preliminary experiment. Most design specifications were met, and all the results were found to be similar to those of the commercial headset. Therefore, the suggested design method is a feasible alternative to traditional anthropometric design for BCI headsets and similar headgear.

Cold-induced vasoconstriction for preventing onycholysis during cancer treatment

Chemotherapy induced nail toxicity is observed in up to 88 % of cancer patients. Onycholysis, a severe form of nail toxicity in which the nail is detached from the nail bed, is observed in 0 % to 44 % of cancer patients undergoing a taxanes based chemotherapy. The use of ice gloves may reduce incidence rates for chemotherapy induced onycholysis, but cause cold and pain. In this research it was hypothesized that the use of local active cooling would reduce blood flow in the distal phalanxes, whilst inducing less discomfort as compared to an ice glove.

Thickness of Compressed Hair Layer: A Pilot Study in a Manikin

Recent advancements in 3D anthropometry enable to link a subject’s 1D measurements to its 3D shape to achieve better fit, functionality, comfort and/or safety. Statistical shape models of the human head retrieved from medical images (CT or MRI) allow for such parameterized models, with a recently proven accuracy of 1.6 mm with only four scalp parameters. This induces opportunities for better sizing systems and mass customization of head mounted products. Due to the nature of medical images, hair is never present in these models. Head shapes constructed from conventional optical 3D scans however do capture the presence of hair. In current optical 3D scans, subjects wear a swimming cap, hairnet or wig cap to flatten and compress the hair layer and prevent artifacts, interferences and misinterpretations during scanning due to the presence of hair. Thus models based on medical images provide parameterized scalp models with proven accuracy. This might be required for the design of certain head mounted wearables were sensors/actuators should make proper contact with the scalp through the hair. However, many other products to be designed for closely fitting the human head will rest on a (flattened) layer of hair. Thus in these situations it might be required to take account of the flattened and compressed hair layer in the design process. Up till now, knowledge of the compressed hair layer geometry is rarely needed in the field of industrial design with only anecdotic numbers available. The uprising of accurate parameter driven 3D models of the human head and entailed applications will induce the need for further accurate quantification thereof. Firstly, we present two a method to assess the thickness of the flattened and compressed hair layer by capturing hair thickness at a given point with a linear dial gauge. Secondly, we present another method to quantify the hair layer from points measured on scalp and hair layer. From this geometric information one can also deduce whether and to what extend the parametric scalp model approximates the head model with hair layer with the same accuracy as it approximates the scalp. Effect of hair thickness was evaluated by measuring a manikin with and without wigs and caps that flattened and compressed the wigs. All experiments were thus conducted in vitro, but both methods can be transferred without burdens to in vivo experiments. A hair thickness between 1.3 ± 0.4 mm was observed with the first method and 1.5 ± 1.3 mm with the second method. A small number of measurements indicate that the head form with flattened and compressed hair is predicted by the parametric scalp model with the same accuracy as it predicts the scalp form. These pilot results indicated that for the design of head mounted products that rest on the flattened hair layer, a margin of at least 1.5 mm should be taken into account for eventual variations in hair thickness. For the design of (personalized) head mounted products, already established parameterized scalp models can be used without loss of accuracy towards the presence of a flattened hair layer. Further large scale and in vivo studies are required to confirm and fine-tune these results.

A Test Setting to Enhance Bobsled Performance at Start Phase

This paper focuses on a test setting that could be used to enhance performance of bobsleigh teams. The collaboration of the teams plays an important role to maximize the performance during bobsleigh runs. We introduce a method to log forces at the start of the run. The setting is validated for 10 runs of nine pilot and brakeman duos. Runs with synchronized force peaks exhibit slight improvements in start speed (0.07 m/s) and start time (52 ms). These improvements are not significant. We provide recommendations for an improved test setting that could be used to collect data to retrieve those factors that mostly influence athletes’ performance in starting bobsleigh runs.

Latent Heat Loss of a Virtual Thermal Manikin for Evaluating the Thermal Performance of Bicycle Helmets

Thermal performance of three bicycle helmets for latent heat loss was evaluated through a virtual testing methodology using Computational fluid dynamics (CFD) simulations. The virtual thermal manikin was prescribed with a constant sweat rate of 2 g/h and a constant sweat film thickness of 0.3 mm. The simulations were carried out at 6 m/s until convergence was achieved. The results from steady state simulations show heat loss of 158 W from manikin without helmet and approximately 135 W with helmets. However, the thermal performance of helmets with a sweating manikin has been reduced from 89–93% to 84–87%. These results imply that evaporative/latent heat loss plays a significant role in thermal performance of helmets. Therefore, thermal performance tests for helmets should also include testing of helmets for evaporative heat loss.

Multi-patch B-Spline Statistical Shape Models for CAD-Compatible Digital Human Modeling

Parametric 3D human body models are valuable tools for ergonomic product design and statistical shape modelling (SSM) is a powerful technique to build realistic body models from a database of 3D scans. Like the underlying 3D scans, body models built from SSMs are typically represented with triangle meshes. Unfortunately, triangle meshes are not well supported by CAD software where spline geometry dominates. Therefore, we propose a methodology to convert databases of pre-corresponded triangle meshes into multi-patch B-spline SSMs. An evaluation on four 3D scan databases shows that our method is able to generate accurate and water-tight models while preserving inter-subject correspondences by construction. In addition, we demonstrate that such SSMs can be used to generate design manikins which can be readily used in SolidWorks for designing well conforming product parts.

A Cryotherapeutic Device for Preventing Nail Toxicity During Chemotherapy: Comparison of Three Cooling Strategies

Onycholysis is a form of nail toxicity where the nail detaches from the nail bed. This medical condition is reported to appear with up to 44% of the patients undergoing a taxanes based chemotherapy. Frozen gloves can be effective in preventing nail toxicity as they enable cold-induced vasoconstriction (CIVC), or reduction of blood flow, and therefore limits the transport of chemotherapeutic agents towards the nail bed. Unfortunately, the use of frozen gloves also results in cold-induced vasodilation (CIVD), which increases blood flow and reduces the effectiveness of the preventive treatment. Moreover, the gloves induce pain and additional distress during a cancer treatment. The objective of this article is to examine the usefulness of an active local cooling device for controlling blood flow in the fingertips and reducing CIVD, while limiting pain and discomfort. Three different cooling strategies are evaluated for comparing their cooling effectiveness.

Determining Comfortable Pressure Ranges for Wearable EEG Headsets

Measuring and interpretation of brain wave signals through electroencephalography (EEG) is an emerging technology. The technique is traditionally applied in a clinical setting with EEG caps and conductive gels to ensure proper contact through a subject’s hair, and anticipate inter-subject anthropometric variations. Development of dry electrodes offers the potential to develop wearable EEG headsets. Such devices could induce medical and commercial applications. In this paper, we evaluate a prototype EEG headset that actively places electrodes at standardized positions on the subject’s head, where each electrode is applied with equal pressure. The system is designed for use with dry electrodes. Our research delivers a better understanding on the link between general level of comfort and possible useful clear data signals, that can be used in brain computer interfaces (BCI). The present study is confined to the impact of adjustable electrodes pressure on level of user comfort only. Levels of discomfort are assessed in twelve participants, wearing an EEG headset with controllable electrode pressure exerted at 14 locations. Of-the-shelf dry electrodes are used. In a first session, evenly distributed pressure is increased and afterwards decreased in fixed time intervals, going from 10 kPa to 30 kPa and vice versa with steps of 2 kPa. In a second session, a subject specific acceptable pressure level is retrieved from the data of the first session and constantly applied for 30 min. During this intervention, level of discomfort is assessed in a VAS-scale. Additional observation and surveys yields insights on user experience in wearing a pressure exerting EEG headset.

Custom Made Cycling Jerseys Prediction Based on Kinect Analysis for Improved Performance

Human factors of cycling jerseys allow supporting the performance of cyclists in terms of aerodynamics, biomechanics and physical comfort. Within this research, it is aimed to evaluate three contactless methods for predicting body measurements that allows selecting the size of a cycling jersey. The accuracy of 2D images, 3D markers and a 3D scan technique are compared to hand measurements. With respect to shoulder width, RSME is 2.8 cm for 2D images, 15.1 cm for markers and 8.5 cm for the full body scanner. The results suggest that 2D images may be a useful, low-cost and accurate method for predicting body size measurements of cycling clothing. A careful selection of body sizes or a combination thereof, can aid to enhance the accuracy of a contactless body size prediction for selecting the appropriate cycling jersey size.

A 3D Printed Thermal Manikin Head for Evaluating Helmets for Convective and Radiative Heat Loss

Thermal performance of three bicycle helmets for radiative and convective heat loss was evaluated through heat loss experiments in a wind tunnel. A 3D printed thermal manikin head of a 50th percentile western male population was developed. Thermal performance of a helmet was quantified by comparing the manikin head heat losses with and without helmet. Experiments were performed for two air velocities: 1.6 m/s and 6 m/s. An infrared heat lamp positioned above the manikin simulated the effect of solar load. The results from the experiments showed a convective cooling efficiency between 89% and 96% for open helmets and between 78% and 83% for closed helmets. The radiative heat gain ranged from 3.5 W to 4.5 W for open helmets and 5 W to 8 W for closed helmets.