Walking Scenarios Research Articles

Luminance and saliency have impact on pedestrians’ fixation distribution during natural walking: Evidence from mobile eye-tracker

The general environmental factors that influence fixation distribution as part of pedestrian visual behaviour under natural conditions are unclear. Relative luminance and saliency are considered the parameters for predicting image-based fixation; however, they are not confirmed by evidence from the natural walking scenario. Field experiments using mobile eye-tracking glasses device were conducted on 16 participants in four commercial streets during day and night. Fixation data along with processed images extracted from eye-tracking glass video were analysed to investigate if relative luminance or saliency correlates with fixation distribution while walking. The results show that fixations within a 10° viewing angle were distributed in bright and more salient areas in the field of vision. Statistical analyses found a stronger positive correlation in saliency than in relative luminance and at night-time rather than under daylight. The correlation found between relative luminance/saliency and fixation distribution suggests that relative luminance/saliency may attract the visual attention of pedestrians. It will be beneficial for practical applications via a better visual environment, including lighting and guiding facilities for pedestrians, especially at night.

Geographical accessibility and spatial coverage modelling of public health care network in rural and remote India.

BackgroundLong distances to facilities, topographical constraints, inadequate service capacity of institutions and insufficient/ rudimentary road & transportation network culminate into unprecedented barriers to access. These barriers gets exacerbated in presence of external factors like conflict and political disruptions. Thus, this study was conducted in rural, remote and fragile region in India measuring geographical accessibility and modelling spatial coverage of public healthcare network.MethodsVector and raster based approaches were used to discern accessibility for various packages of service delivery. Alternative scenarios derived from local experiences were modelled using health facility, population and ancillary data. Based on that, a raster surface of travel time between facilities and population was developed by incorporating terrain, physical barriers, topography and travelling modes and speeds through various land-cover classes. Concomitantly, spatial coverage was modelled to delineate catchment areas. Further, underserved population and zonal statistics were assessed in an interactive modelling approach to ascertain spatial relationship between population, travel time and zonal boundaries. Finally, raster surface of travel time was re-modelled for the conflict situation in villages vulnerable to obstruction of access due to disturbed security scenario.ResultsEuclidean buffers revealed 11% villages without ambulatory & immunization care within 2 km radius. Similarly, for 5 km radius, 11% and 12% villages were bereft of delivery and inpatient care. Travel time accessibility analysis divulged walking scenario exhibiting lowest level of accessibility. Enabling motorized travel improved accessibility measures, with highest degree of accessibility for privately owned vehicle (motorcycle and cars). Differential results were found between packages of services where ambulatory & immunization care was relatively accessible by walking; whereas, delivery and inpatient care had a staggering average of three hours walking time. Even with best scenario, around 2/3rd population remained unserved for all package of services. Moreover, 90% villages in conflict zone grapples with inaccessibility when the scenario of heightened border tensions was considered.ConclusionsOur study demonstrated the application of GIS technique to facilitate evidence backed planning at granular level. Regardless of the scenario, the analysis divulged inaccessibility to delivery and inpatient care to be most pronounced and majority of population to be unserved. It was suggested to have concerted efforts to bolster already existing facilities and adapt systems approach to exploit synergies of inter-sectoral development.

Alteration of brain dynamics during dual‐task overground walking

When walking in our natural environment, we often solve additional cognitive tasks. This increases the demand of resources needed for both the cognitive and motor systems, resulting in Cognitive-Motor Interference (CMI). A large portion of neurophysiological investigations on CMI took place in static settings, emphasizing the experimental rigor but overshadowing the ecological validity. As a more ecologically valid alternative to treadmill and desktop-based setups to investigate CMI, we developed a dual-task walking scenario in virtual reality (VR) combined with Mobile Brain/Body Imaging (MoBI). We aimed at investigating how brain dynamics are modulated by dual-task overground walking with an additional task in the visual domain. Participants performed a visual discrimination task in VR while standing (single-task) and walking overground (dual-task). Even though walking had no impact on the performance in the visual discrimination task, a P3 amplitude reduction along with changes in power spectral densities (PSDs) were observed for discriminating visual stimuli during dual-task walking. These results reflect an impact of walking on the parallel processing of visual stimuli even when the cognitive task is particularly easy. This standardized and easy to modify VR paradigm helps to systematically study CMI, allowing researchers to control for the impact of additional task complexity of tasks in different sensory modalities. Future investigations implementing an improved virtual design with more challenging cognitive and motor tasks will have to investigate the roles of both cognition and motion, allowing for a better understanding of the functional architecture of attention reallocation between cognitive and motor systems during active behavior.

Field Expansion with Multiplexing Prism Glasses Improves Pedestrian Detection for Acquired Monocular Vision.

PurposePatients with acquired monocular vision (AMV) lose vision in the temporal crescent on the side of the blind eye. This visual field loss affects patients’ ability to detect potential hazards in the blind field. Mounting a base-in multiplexing prism (MxP) on the nasal side of the seeing eye can provide true field expansion and enable detection of potential collision hazards. We evaluated the efficacy of the MxP glasses in a virtual reality walking environment.MethodsA three-dimensional printed clip-on MxP holder that can be adjusted for an individual user's facial parameters was developed. Virtual reality walking scenarios were designed to evaluate the effect of MxP field expansion on the detection of a pedestrian approaching from different initial bearing angles and courses. The pedestrian detection rates and response times of 10 participants with simulated AMV (normally sighted participants with one eye patched) and three patients with AMV were measured.ResultsThe MxP provided true field expansion of about 25°. Participants performed significantly better with the MxP than without the MxP in the pedestrian detection task on their blind field, while their seeing field performance was not significantly different.ConclusionsThe MxP glasses for patients with AMV improved the detection of potential collision hazards in the blind field.Translational RelevanceThe MxP with an adjustable clip-on holder may help patients with AMV to decrease the risk of collision with other pedestrians.

An Energy-Efficient and Reliable Scheduling Strategy for Dynamic WBANs With Channel Periodicity Exploitation

In dynamic scenarios such as walking, wireless body area networks (WBANs) have unique dynamic features, for instance, the sensor nodes placed on the limbs have approximately periodic link qualities. To realize energy-efficient and reliable communication in dynamic WBANs, this paper focuses on designing a scheduling strategy, that exploits the dynamic channel periodicity. In walking scenarios, we first construct a WBAN testbed, then conduct experiments to show the channel periodicity between the sensor nodes deployed at different positions and quantify the correlation between the received signal strength indication (RSSI) and the acceleration signals. Next, we propose a gait cycle detection algorithm to detect the periodic motion and calculate the acceleration periodicity and phase. Then, we propose a channel periodicity based scheduling (CPBS) strategy that exploits the periodic fluctuations of link qualities, to improve energy efficiency and reliability. With the CPBS strategy, the transmission time is allocated according to the motion state and the rate requirement of each sensor node, which can avoid channel collision. Finally, we evaluate the performance of the CPBS strategy in both periodic and realistic (approximately 23% of the time for aperiodic movements) scenarios. The results show that, compared to stochastic scheduling (SS) strategy, the proposed CPBS strategy can save 17.61% and 13.56% energy consumption in periodic and realistic scenarios, respectively. In addition, the packet loss rate (PLR) can be made as low as zero in both scenarios. Therefore, the proposed CPBS strategy can achieve energy-efficient and reliable communication in dynamic WBANs.

Wearable skin-like optoelectronic systems with suppression of motion artifacts for cuff-less continuous blood pressure monitor.

According to the statistics of the World Health Organization, an estimated 17.9 million people die from cardiovascular diseases each year, representing 31% of all global deaths. Continuous non-invasive arterial pressure (CNAP) is essential for the management of cardiovascular diseases. However, it is difficult to achieve long-term CNAP monitoring with the daily use of current devices due to irritation of the skin as well as the lack of motion artifacts suppression. Here, we report a high-performance skin-like optoelectronic system integrated with ultra-thin flexible circuits to monitor CNAP. We introduce a theoretical model via the virtual work principle for predicting the precise blood pressure and suppressing motion artifacts, and propose optical difference in the frequency domain for stable optical measurements in terms of skin-like devices. We compare the results with the blood pressure acquired by invasive (intra-arterial) blood pressure monitoring for >1500 min in total on 44 subjects in an intensive care unit. The maximum absolute errors of diastolic and systolic blood pressure were ±7/±10 mm Hg, respectively, in immobilized, and ±10/±14 mm Hg, respectively, in walking scenarios. These strategies provide advanced blood pressure monitoring techniques, which would directly address an unmet clinical need or daily use for a highly vulnerable population.

Experimental investigation on vibration sensitivity of an indoor glass footbridge to walking conditions

For decades, the vibration performance of pedestrian structures, like footbridges and floors, has attracted the attention of researchers. According to the literature, specific vibration performances must be satisfied, depending on the class of use, structural typology and material composition of a given pedestrian system. Additional design issues, however, may derive from the presence of structural components that can be susceptible to unfavourable ambient conditions and/or time or extreme loads, including progressive degradation of material properties. This is the case for glass structures, where mostly slender load-bearing elements (with high span-to-thickness ratio) are used in combination with complementary materials (i.e., for bonding) that are often characterized by time/temperature/ambient-dependent behaviour. The relatively high span-to-thickness ratio generally manifests itself in structural masses that can be small, compared to the occupants. Human-Structure Interaction (HSI) phenomena, in this regard, may be relevant and require dedicated studies. In this paper, the dynamic performance of an existing indoor suspension glass footbridge is taken into account and explored via Operational Modal Analysis (OMA) techniques. A wide range of loading configurations (i.e., walking scenarios) are of technical interest and thus taken into account for the case-study system. These include variations in the imposed human-induced vibrations, such as the movement features, number of occupants (combined standing/walking persons), ambient conditions, size effects and mechanical restraints. Sensitivity of measured accelerations, fundamental frequencies and damping ratios for the occupied system is then discussed.

3-D Space Visualization System Using Ultrasonic Sensors as an Assistive Device for the Blind.

This study proposes a new assistive device for the blind that uses more than one-dimensional data to draw objects. The study aims to convert three-dimensional (3-D) spatial information into sound information using 6-axis and ultrasonic sensors, and to draw a 3-D depiction of the space ahead for the user. Fourteen participants were involved in testing, wherein 4 were visually impaired. Moreover, the male to female ratio was 7:3, with the average age of participants at 28.8 years. An initial sound recognition experiment was designed to assess the device’s accuracy through participant use. Recognition rates were 70% for normal participants and 88% for the blind participants. Additional experiments expanded the environmental conditions by requiring participants to discern the distances of 10 objects, positioned at both high and low locations. Two different scenarios were employed: stationary and walking scenarios. The stationary distance measurement participants scored an average of 96 points, while the walking participants averaged 81 points. Under the given conditions, this study found that its assistive device for the visually impaired can draw a 3-D space with 88.5% accuracy. This probability promises a basic level of utility that can assist those with visual impairment in controlled environments, such as hospitals and homes.

A High-Fidelity Wearable System for Measuring Lower-Limb Kinetics and Kinematics

There are many important challenges in gait analysis, which has many applications in healthcare, rehabilitation, therapy, and exercise training. However, gait analysis is typically performed in a gait laboratory, which is inaccessible to the general population and is not available in natural gait environments (e.g., outdoors). In this paper, we discuss the development of a high-fidelity, cost-effective, wireless sensor network to address the challenge of efficient gait monitoring in real-world walking scenarios. The sensor network is designed in a modular way to capture plantar forces and knee angle, angular velocity, and angular acceleration. A force module called a smart insole is designed to measure the plantar forces. The module is comprised of force sensitive resistors (FSRs) and a signal conditioning circuit. Various signal conditioning techniques, including a novel technique called transfrequency, are investigated to provide a linear mapping for FSR measurements and to provide data acquisition fidelity. The motion module includes a low-cost inertial measurement unit (IMU) augmented with a Kalman filter to provide filtered knee kinematics. A qualitative evaluation of the sensor network communication module is achieved by considering the internal communication protocols between the modules and the external wireless transmission protocol used to deliver data to an end-point terminal PC. Experiments are conducted to validate the motion and force modules. Then, the overall, integrated system is compared to gold standard laboratory results, demonstrating a successful application for gait identification. The results show that the sensor network accurately captures important gait parameters and features.

An Efficient Data Delivery Scheme in WBAN to Deal with Shadow Effect due to Postural Mobility

The body movement and change in posture exhibit high mobility in sensor nodes which causes shadowing in the Wireless Body Area Network (WBAN). Due to this, the connectivity between the nodes in WBAN is affected which further causes failure in data delivery. This article presents a MAC protocol in WBAN to deal with the problem of data delivery due to body movement and postural mobility. It uses an Improved Initial Centroid K-means clustering technique for classification of various human body postures followed by back propagation neural network as a classifier to recognize human body posture. This article proposes a posture aware dynamic data delivery (PA-DDD) protocol to deliver data dynamically. The PA-DDD protocol can be used under varying speed walking scenario. The simulation results show that it prolongs the network lifetime and is energy efficient.

Indoor particle inhalability of a stationary and moving manikin

Understanding particle inhalation caused by human activity is vital for developing estimates of inhalation exposure in indoor environments. This study used Computational Fluid Dynamics to compare nasal aspiration efficiency of a stationary manikin in uniform airflow and a moving manikin in stagnant air. The model was a full-scale body with detailed facial features at the nose. The stationary manikin case adopted a constant freestream velocities of 0.2 m/s and 0.4 m/s representing typical office wind environments; while the moving manikin case considered a walking speed of 0.4 m/s as a comparison case, followed with additional higher walking speeds (0.8 m/s and 1.6 m/s) to investigate realistic walking scenarios. Inhalation rates through the nose included light and medium breathing at 15 and 27 L per minute.The aspiration efficiency (AE) was used to quantify the nasal particle inhalability from an upstream release source. In order to evaluate the inhalability for the moving manikin, a 3-dimensional particle source was created and validated with a 2-dimensional particle source, which was common in studies for stationary manikins. Discrepancies in aspiration efficiencies were quantified between using 2- and 3-dimensional particle sources. The particle inhalability for a moving manikin was estimated for three particle sizes and three walking speeds. The inhalability of a walking manikin was found higher than a stationary manikin facing the wind, less relevant to particle sizes but more related to walking speeds. This study quantified the particle inhalability for moving manikins to characterise a more comprehensive scenario for modelling human respiration and developing estimations of particle exposure.

Malaysian Urban Residents’ Readiness to Reduce Car Usage and their Perception on Non-Motorised Facilities.

The research in this paper tries to establish the readiness of urban residents’ in Malaysia to minimize the car usage and their inclination to use non-motorised transport, such as cycling and walking, as alternatives to using a car for commuting. This study also tries to measure the perception of the residents regarding the existing scenario of walking and cycling infrastructure facilities provided in their cities. The data used in the study was collected through a survey in three cities, namely-Shah Alam, Batu Pahat, and Putrajaya, as a representation of the main cities in Malaysia. The results produced suggested- the majority of the population was not ready to give up travelling via car and take up cycling and walking in lieu of it. The causes listed for “refusal” of reducing the car usage included hot weather, surrounding safety concerns and undesirable pedestrian and cycling infrastructure conditions. The research explored that attitude, lifestyle and high level of dependency on cars are crucial factors dictating the travel behaviour, which is the reason why residents refuse to shift to sustainable and environment friendly options of travel. The research also suggests that these three cities need to improve and uplift their walking and cycling infrastructure facilities, especially in terms of provision of cover and shade, connectivity, design and maintenance and cleanliness to motivate the urban residents to minimize usage of the cars and take up walking and cycling instead.

Time series classification using a modified LSTM approach from accelerometer-based data: A comparative study for gait cycle detection

BackgroundGait event detection (GED) is an important aspect in identifying and interpret a user’s gait to assess gait abnormalities and design intelligent assistive devices. Research questionThere is a need to develop robust GED models that can accurately detect various gait instances in different scenarios and environments. MethodsThis paper presents a novel method of detecting heel strikes (HS) and toe offs (TO) during the user’s gait cycle using a modified Long Short-Term Memory (LSTM) networks approach. The method was tested on a database from Movement Analysis in Real-world Environments using Accelerometers (MAREA) (n = 20 healthy subjects) that consisted of walking and running in indoor and outdoor environments with accelerometers positioned on waist, wrist and both ankles. Modifications include oversampling, composite accelerations and optimizing the LSTM network architecture were made. ResultsPerformance of our modified model was found to be better than six state-of-the-art GED algorithms, with a median F1 score of 0.98 for Heel Strikes and 0.98 for Toe Offs in the scenario of steady walking in an indoor environment, and a median F1 score of 0.94 for Heel Strikes and 0.68 for Toe-offs in the scenario of walking and running in an outdoor environment. SignificanceThis paper highlights the potential of the single proposed model to be an alternative to the six GED models in gait detection under various conditions.

Role of T Cell-To-Dendritic Cell Chemoattraction in T Cell Priming Initiation in the Lymph Node: An Agent-Based Modeling Study.

The adaptive immune response is initiated in lymph nodes by contact between antigen-bearing dendritic cells (DCs) and antigen-specific T cells. A selected number of naïve T cells that recognize a specific antigen may proliferate into expanded clones, differentiate, and acquire an effector phenotype. Despite growing experimental knowledge, certain mechanistic aspects of T cell behavior in lymph nodes remain poorly understood. Computational modeling approaches may help in addressing such gaps. Here we introduce an agent-based model describing T cell movements and their interactions with DCs, leading to activation and expansion of cognate T cell clones, in a two-dimensional representation of the lymph node paracortex. The primary objective was to test the putative role of T cell chemotaxis toward DCs, and quantitatively assess the impact of chemotaxis with respect to T cell priming efficacy. Firstly, we evaluated whether chemotaxis of naïve T cells toward a nearest DC may accelerate the scanning process, by quantifying, through simulations, the number of unique T cell—DC contact events. We demonstrate that, in the presence of naïve T cell-to-DC chemoattraction, a higher total number of contacts occurs, as compared to a T cell random walk scenario. However, the forming swarm of naïve T cells, as these cells get attracted to the neighborhood of a DC, may then physically restrict access of additional T cells to the DC, leading to an actual decrease in the cumulative number of unique contacts between naïve T cells and DCs. Secondly, we investigated the potential role of chemotaxis in maintaining cognate T cell clone expansion. The time course of cognate T cells number in the system was used as a quantitative characteristic of the expansion. Model-based simulations indicate that inclusion of chemotaxis, which is selective for already activated (but not naïve) antigen-specific T cells, may strongly accelerate the time of immune response occurrence, which subsequently increases the overall amplitude of the T cell clone expansion process.

The attentional cost of movement in multiple sclerosis.

Individuals living with multiple sclerosis frequently have impairments in mobility. These impairments are more pronounced when they engage in a cognitively demanding mobility tasks (i.e., walking and talking, obstacle clearance, etc). Based in part on the attentional capacity model of movement, these impairments are suggested to result from greater attentional demands. Yet, this model has not been directly tested in neurological populations. The objective of the study was to determine whether individuals with multiple sclerosis have greater attentional cost of movement across a range of tasks. This study tested probe reaction times of 20 individuals with multiple sclerosis and 26 healthy controls in five different movement tasks. The tasks were specifically chosen to challenge the perceptual-motor system based on variations in static and dynamic balance requirements. Participants were asked to verbally respond as quickly as possible to randomly presented audio probes during motor performance. Task order was randomized, and average probe reaction time was calculated for each task. The results showed tasks requiring dynamic stability had greater probe reaction times in both healthy controls and individuals with multiple sclerosis. Furthermore, individuals with multiple sclerosis had longer probe reaction times across all tasks compared to healthy controls. Yet, there was no relationship between probe reaction times and performance during a complex walking scenario. The results indicate the attentional capacity model may be inadequate to explain cognitive-motor interaction in people with multiple sclerosis. Future studies should address the theoretical framework of cognitive-motor interaction, which may influence the design of interventions aimed at improving performance in individuals with MS.

Objective measures of rollator user stability and device loading during different walking scenarios

Walking aids are widely used by older adults, however, alarmingly, their use has been linked to increased falls-risk, yet clinicians have no objective way of assessing user stability. This work aims to demonstrate the application of a novel methodology to investigate how the type of walking task, the amount of body weight supported by the device (i.e., device loading), and task performance strategy affect stability of rollator users. In this context, ten users performed six walking tasks with an instrumented rollator. The combined stability margin “SM” was calculated, which considers user and rollator as a combined system. A Friedman Test was used to investigate the effects of task on SM and a least-squares regression model was applied to investigate the relationship between device loading and SM. In addition, the effects of task performance strategy on SM were explored. As a result, it was found that: the minimum SM for straight line walking was higher than for more complex tasks (p<0.05); an increase in device loading was associated with an increase in SM (p<0.05); stepping up a kerb with at least 1 rollator wheel in ground contact at all times resulted in higher SM than lifting all four wheels simultaneously. Hence, we conclude that training should not be limited to straight line walking but should include various everyday tasks. Within person, SM informs on which tasks need practicing, and which strategy facilitates stability, thereby enabling person-specific guidance/training. The relevance of this work lies in an increase in walking aid users, and the costs arising from fall-related injuries.

Conservative random walks in confining potentials

Lévy walks are continuous time random walks with spatio-temporal coupling of jump lengths and waiting times, often used to model superdiffusive spreading processes such as animals searching for food, tracer motion in weakly chaotic systems, or even the dynamics in quantum systems such as cold atoms. In the simplest version Lévy walks move with a finite speed. Here, we present an extension of the Lévy walk scenario for the case when external force fields influence the motion. The resulting motion is a combination of the response to the deterministic force acting on the particle, changing its velocity according to the principle of total energy conservation, and random velocity reversals governed by the distribution of waiting times. For the fact that the motion stays conservative, that is, on a constant energy surface, our scenario is fundamentally different from thermal motion in the same external potentials. In particular, we present results for the velocity and position distributions for single well potentials of different steepness. The observed dynamics with its continuous velocity changes enriches the theory of Lévy walk processes and will be of use in a variety of systems, for which the particles are externally confined.

Willingness to Pay for Improved Household Solid Waste Collection in Blantyre, Malawi

Insufficient staff, inappropriate collection vehicles, limited operating budgets and growing, hard to reach populations mean that solid waste management remains limited in most developing countries; Malawi is no exception. We estimated the willingness to pay (WTP) for two hypothetical solid waste collection services. Additionally, we tested the impact of the WTP question positioning relative to environmental perceptions on respondents’ WTP. The first scenario involved a five minute walk to a disposal facility; the second scenario involved a 30 min walk. Additionally, the order of the question was randomized within the questionnaire. A WTP value of K1780 was found for the five minute walk scenario when the question was placed first, and K2138 when placed after revealing the respondent’s perceptions on the environment. In the 30 min walk scenario, WTP was K945 when placed first and K1139 when placed after revealing the respondent’s perceptions on the environment. The estimated values indicate that there is both a willingness to pay for solid waste services and that there are at least two options that would be acceptable to the community; a pilot scale implementation would be required to validate the hypothetical values, especially given the dependency on problem framing. Community financing should be considered as a sustainable approach to solid waste management in underserved areas.

Temporal correlation model‐based transmission power control in wireless body area network

Researchers have encountered many challenges in developing communication system in wireless body area networks (WBANs). These challenges include the dynamic characteristics of WBAN channels, limited energy resources, and strict requirements, such as high reliability and low latency. To achieve highly reliable and energy-efficient communication in the WBAN, temporal correlation model-based transmission power control (TCM-TPC) is proposed. In this method, the channel condition is firstly determined based on a long-term mean channel gain and the last known channel gain using a temporal correlation model. The channel is estimated as a conditional distribution of channel gains. After that, the transmit output power is selected from the estimated channel to satisfy a pre-defined outage probability. Performance of the proposed TCM-TPC method was evaluated on a network simulator for a walking scenario. The evaluation results showed that the TCM-TPC had up to 1.48% of packet loss, while other TPC methods had up to 6.86% of packet loss. Furthermore, for a high data rate application, the TCM-TPC showed the lowest energy consumption for all sensor nodes.

Robust vibration serviceability assessment of footbridges subjected to pedestrian excitation: strategy and applications

The present paper proposes a strategy for the robust vibration serviceability assessment of footbridges. The response of the footbridge to vertical walking loading is predicted by simulating continuous flows of pedestrians on the structure. In the calculations, both variability in the walking characteristics and human-structure interaction effects are accounted for. Uncertainty in the modal parameters of the footbridge is considered in a multi-interval approach. The resulting range in predicted response levels is subsequently compared to vibration comfort criteria. A case study serves as illustration of the procedure. First, the response of the footbridge is evaluated in a multi-interval assessment showing how the predicted vibration levels are affected by uncertainties. The multi-interval approach allows understanding how uncertainties in the modal parameters of the structure affects the response. Second, the procedure is applied for the design of Tuned Mass Dampers (TMD). The TMD parameters are tuned by solving an optimisation problem such that an effective reduction of the accelerations under realistic walking scenarios is ensured. The total TMD mass is minimised, considered as the determining factor for the cost of the TMD. A higher TMD mass is needed to satisfy the vibration serviceability constraints for higher levels of uncertainty, showing the trade-off between cost and robustness.