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Objective motion cueing tuning for vehicle dynamics evaluation in winter conditions
KTH, School of Engineering Sciences (SCI), Centres, VinnExcellence Center for ECO2 Vehicle design. KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Vehicle engineering and technical acoustics.ORCID iD: 0000-0002-9259-6432
2024 (English)Licentiate thesis, comprehensive summary (Other academic)
Abstract [en]

Vehicle manufacturers strive for an increasingly efficient and faster development process. Although computer-aided engineering has made significant progress toward a fully virtual development process, a challenge remains in integrating human subjective feedback to fully close the virtual development loop. Subjective assessment of ride and driving characteristics are still very important traits of a passenger car. Moving-base driving simulators have the ability to introduce the human into the virtual development loop, thus enabling subjective assessment of virtual vehicle models. Such an introduction has the potential to significantly speed up the development process and at the same time save resources by avoiding physical testing and providing informed decisions in the early phase of vehicle development cycles. The challenge to do so lies in the possibility to evaluate a vehicle in a driving simulator, which is highly dependent on the motion cueing.

Motion cueing algorithms are used to map the vehicle motion into the confined workspace of a driving simulator. As of today, these algorithms are still often tuned and evaluated subjectively. The challenge with this approach is that it does not guarantee the fidelity of the cueing and it needs physical vehicles to be compared with. This work thus focuses on the objective development and evaluation of motion cueing, which potentially could enable high fidelity motion cueing in the early stages of the vehicle development process, when prototypes are not available. This is very important for winter testing since the testing is challenging with regards to ambient conditions, the limited testing season and the increasing need to speed up the development process.

The goal of this work is to move towards an objective approach to cueing evaluation based on physical models combining vehicle model, simulator, and human. Therefore, this thesis presents an objective methodology to motion cueing evaluation and development. Based on the state-of-the-art review, this work addresses the need for simple linear models to evaluate the fidelity of motion cueing algorithms. The linear model is applied to the problem of positioning the longitudinal axis of rotation of the simulator cabin and shows promising results when compared to time series-based optimisation and subjective assessment. Furthermore, using the same model to improve the motion cueing by introducing tilt coordination shows that even though the immersion is improved, the tilt coordination changes the perceived vehicle characteristics. To objectively evaluate different yaw cueing strategies in winter conditions, a more detailed human model is introduced that extends the state-of-the-art vestibular organ models by introducing gaze stabilisation using a model of the vestibulo-collic reflex. The cueing evaluation indicates the potential of separating slip angle feedback from the high-pass filtering of motion cues, as well as the advantage of using the vehicle’s motion as a target for cueing optimisation rather than the human vestibular response in winter handling evaluation.

By addressing the inherent skewing of vehicle characteristics in motion cueing and suggesting improvements to the evaluation and cueing strategies, this work contributes to the possibility of virtually evaluating the vehicle dynamic characteristics in driving simulators under winter conditions.

Place, publisher, year, edition, pages
Stockholm: KTH Royal Institute of Technology, 2024. , p. 49
Series
TRITA-SCI-FOU ; 2024:24
Keywords [en]
Motion cueing, objective methods, driving simulator, subjective assessment, motion perception
National Category
Vehicle Engineering
Research subject
Vehicle and Maritime Engineering
Identifiers
URN: urn:nbn:se:kth:diva-346493ISBN: 978-91-8040-923-0 (print)OAI: oai:DiVA.org:kth-346493DiVA, id: diva2:1858388
Presentation
2024-06-13, Munin, Teknikringen 8, Stockholm, 10:00 (English)
Opponent
Supervisors
Funder
Vinnova, 2016-05195TrenOp, Transport Research Environment with Novel PerspectivesAvailable from: 2024-05-20 Created: 2024-05-16 Last updated: 2024-06-10Bibliographically approved
List of papers
1. Enhancing perception of vehicle motion by objective positioning of the longitudinal axis of rotation in driving simulators
Open this publication in new window or tab >>Enhancing perception of vehicle motion by objective positioning of the longitudinal axis of rotation in driving simulators
(English)Manuscript (preprint) (Other academic)
Abstract [en]

The automotive industry is heading towards a more objective approach to vehicle testing, but subjective evaluation is still an important part of the development process. Subjective evaluation in physical testing has environmental implications and is dependent on ambient conditions. A more repeatable, faster, safer, and more cost-effective tool for subjective evaluation is to use moving base driving simulators. The motion cueing algorithms (MCA) maps the movement of the vehicle into the limited space of the simulator. The choice of reference point, i.e., where on the vehicle to sample the motion to feed to the MCA and the alignment of the axis of rotation of the simulator cabin is still an open topic. This paper investigates the choice of reference point and corresponding simulator longitudinal axis of rotation in roll using two methods. The first method uses a linearised model of the combined system of vehicle, simulator, and vestibular models. The second method, to position the cabin longitudinal axis of rotation, is based on offline optimisation. The linear model can capture important characteristics of the specific forces and rotations that are fed to the driver through the motion cueing algorithms and offers a method to objectively analyse and potentially tune the motion cueing. The analysis is further complemented with a subjective evaluation of corresponding settings. The results from the linear model, the offline optimisation and the subjective evaluation shows that a reference point at the driver’s head has a clear advantage over the full frequency range compared to a reference point in the chassis roll axis and that the positioning of the cabin longitudinal axis of rotation has a significant effect on the perceived vehicle characteristics. 

Keywords
Motion cueing, objective methods, driving simulator, subjective assessment, motion perception
National Category
Vehicle Engineering
Research subject
Vehicle and Maritime Engineering
Identifiers
urn:nbn:se:kth:diva-346043 (URN)
Funder
TrenOp, Transport Research Environment with Novel PerspectivesVinnova, 2016-05195
Note

QC 20240502

Available from: 2024-04-30 Created: 2024-04-30 Last updated: 2024-05-19Bibliographically approved
2. Motion cueing for winter test conditions
Open this publication in new window or tab >>Motion cueing for winter test conditions
2022 (English)In: IAVSD 2021: Advances in Dynamics of Vehicles on Roads and Tracks II, Springer Science and Business Media Deutschland GmbH , 2022, p. 888-901Conference paper, Published paper (Refereed)
Abstract [en]

This paper investigates the tuning of motion cues in dynamic driving simulators for EPAS (Electronic power assisted steering) tuning in winter conditions. The study investigates the differences in frequency content of the vehicle states yaw rate and lateral acceleration between dry and winter EPAS tuning. Based on the results from this investigation, which shows an increased spectral density of low frequency content in both yaw rate and lateral acceleration, coordinated tilt is added to the motion cueing, to give the driver low frequency lateral acceleration feedback. The tilt coordination filter is tuned using offline optimisation based on logged data. The resulting MCA is evaluated objectively using a linear model of a driving simulator and subjectively through driving around a winter test track with six test drivers. The test is conducted using a pairwise comparison of two different settings, one setting without and another with added tilt coordination. Objective metrics shows reduction in lateral false cues, increased correlation between actual vehicle acceleration and simulator acceleration and an increased spectral density below 0.30 Hz. The pairwise comparison and the commentary feedback shows potential in adding tilt coordination with more drivers favouring tilt coordination, however statistical significance cannot be reached due to the low number of drivers.

Place, publisher, year, edition, pages
Springer Science and Business Media Deutschland GmbH, 2022
Series
Lecture Notes in Mechanical Engineering, ISSN 2195-4356, E-ISSN 2195-4364
Keywords
Driving simulator, Motion cueing, Tilt Coordination, Vehicle dynamics, Winter test
National Category
Vehicle Engineering
Identifiers
urn:nbn:se:kth:diva-309472 (URN)10.1007/978-3-031-07305-2_82 (DOI)2-s2.0-85136965410 (Scopus ID)
Conference
27th Symposium of the International Association of Vehicle System Dynamics, IAVSD 2021, Virtual/Online, 17-19 August 2021
Funder
Vinnova
Note

QC 20230626

Available from: 2022-03-03 Created: 2022-03-03 Last updated: 2024-05-19Bibliographically approved
3. Driver gaze model for motion cueing yaw feedback optimisation
Open this publication in new window or tab >>Driver gaze model for motion cueing yaw feedback optimisation
2023 (English)In: 28th Symposium on Dynamics of Vehicles on Roads and Tracks, 2023Conference paper, Published paper (Refereed)
Abstract [en]

Driving simulators are increasingly important in vehicle development, benefiting from hardware and motion cueing algorithm (MCA) advancements. However, current state-of-the-art MCAs are optimising with regards to a vehicle fixed vestibular system, ignoring active and passive head movements during manoeuvres. Research shows that drivers actively move their heads to focus their gaze and passively stabilising it during involuntary trunk movements, resulting in significant differences between vehicle and head yaw angles. Humans isolate trunk and head movement in the range of 0.1-1.0 Hz, suggesting neck-driven gaze stabilisation. This behaviour is not accounted for in current MCAs, warranting an investigation. This study develops a driver gaze model to enhance motion cueing strategies and compares it to existing methods. Findings indicate significant discrepancies between vehicle and estimated head yaw rate in winter testing with high slip angles, and that omitting vestibular models and separating the slip angle in the yaw feedback improves the motion cueing with regards to induced head movements. Further, the results shows that there is a clear relationship between motion cueing, visual feedback, and induced driver head movement. In conclusion, driver gaze models can improve motion cueing strategies in driving simulators, and thus the study highlights the need for considering driver gaze behaviour and provides insights for tuning and optimising MCAs.

Keywords
Motion cueing, Driving simulator, Head gaze.
National Category
Vehicle Engineering
Research subject
Vehicle and Maritime Engineering
Identifiers
urn:nbn:se:kth:diva-346042 (URN)
Conference
IAVSD2023, 28th Symposium on Dynamics of Vehicles on Roads and Tracks, Aug 21-25, Ottawa, Canada (2023). 
Funder
Vinnova, 2016-05195TrenOp, Transport Research Environment with Novel Perspectives
Note

QC 20240521

Available from: 2024-04-30 Created: 2024-04-30 Last updated: 2024-05-21Bibliographically approved

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Hvitfeldt, Henrik

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