This paper investigates the fundamentals of motion planning for minimizing motion sickness in transportation systems of higher automation levels. The optimum velocity profile is sought for a predefined road path from a specific starting point to a final one within specific and given boundaries and constraints in order to minimize the motion sickness and the journey time. An empirical approach based on British standard is used to evaluate motion sickness. The trade-off between minimizing motion sickness and journey time is investigated through multi-objective optimization by altering the weighting factors. The correlation between sickness and journey time is represented as a Pareto front because of their conflicting relation. The compromise between the two components is quantified along the curve, while the severity of the sickness is determined using frequency analysis. In addition, three case studies are developed to investigate the effect of driving style, vehicle speed, and road width, which can be considered among the main factors affecting motion sickness. According to the results, the driving style has higher impact on both motion sickness and journey time compared to the vehicle speed and the road width. The benefit of higher vehicle speed gives shorter journey time while maintaining relatively lower illness rating compared with lower vehicle speed. The effect of the road width is negligible on both sickness and journey time when travelling on a longer road. The results pave the path for the development of vehicular technologies to implement for real-world driving from the outcomes of this paper.

Various vibration isolators using negative stiffness elements have been proposed in order to improve ride comfort of passengers in vehicles. In this paper, five different ones are compared. Four of them have been already propped, while the fifth one is novel, based on the KDamping concept, which has proven efficient in other applications. After optimising each one with respect to static and dynamic factors of ride comfort, three types of analysis are performed. In the first type, the models are simulated for the optimum solutions, for two more excitations which correspond to the response of the vehicle's body while driving over road profiles of Class B and C. In the second type, the models are simulated for different seated passengers. While in the third type, based on the Pareto theory, three solutions are finally selected for each model, and their transmissibility from seat to head (STHT) is compared. The main conclusion is that the isolator using the KDamping concept has proven its adaptability and universality for different excitations corresponding to different road classes and for different seated passengers, minimising the resonance frequency around 0.56 Hz and providing the most compact and comfortable optimum design solutions among all the other models.

In the transition from partial to high automation, occupants will no longer be actively involved in driving. This will allow the use of travel time for work or leisure, where high comfort levels preventing motion sickness are required. In this paper, an optimal trajectory planning algorithm is presented in order to minimise motion sickness in automated vehicles. A predefined path is provided as an input to the algorithm, to generate an optimal path with limited lateral deviation and the corresponding optimal velocity profile, for the minimisation of motion sickness. An optimal control problem is formulated with a cost function combining both motion sickness and travel time. For a sickening curvy road, the algorithm reduced the motion sickness dose value (MSDV) up to 52% depending on the allowed lateral deviation and the weighting on travel time. The efficacy of the proposed algorithm has been evaluated via human-in-the-loop experiments using a moving-base driving simulator. Motion cueing parameters were selected to optimally transmit the sickening stimuli resulting in close to full vibration transmission above 0.2 Hz. During the experiment, the participants were asked to rate their experience based on the standard MIsery SCore ratings. According to these, sickness levels were reduced on average by 65% with reduced motion sickness in all 16 participants.

A seat that provides good vibration isolation is of prime importance for passenger’s safety and health. The main conflict in seat suspensions implies that the increasing initial deformation of the system (increase in “static discomfort”) leads to better isolation of accelerations (increase in “dynamic comfort”). Many researchers have focused on overcoming or at least suppressing this conflict between load support capacity and vibration isolation by modeling new suspension systems, such as the so-called negative suspension systems. However, apart from the modeling of new suspension systems, optimization is an important part in designing a seat and finding the best compromise between these two objectives. Thus, in this work, four types of seat suspension systems with embedded negative stiffness elements are implemented and optimized in order to be benchmarked. Three of them have already been tested either in passenger or in an off-road vehicle seat. All the vibration isolators are optimized with genetic algorithms in respect to static and dynamic factors of ride comfort by applying constraints oriented to the objectives and the design of the structure. The optimization is implemented for two excitations, which correspond to a vehicle driving over road profiles of Classes A and B, and the common solutions are outlined.