| 1. |
- Almlöf, Erik, 1985-
(författare)
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Exploring societal impacts of self-driving public transport using four-step transport models
- 2022
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- During the last decade, self-driving technology has become increasingly visible in the news, with the vision that people would enter vehicles that drive themselves, and that people could instead rest, read the newspaper, or have a meeting. However, these visions have mainly focused on the potential for car usage, even though public transport could benefit greatly from self-driving technology. For bus traffic, the bus driver accounts for half of the cost of driving, and savings on personnel costs could, for example, be reinvested in expanded public transport service or used to lower taxes.At the same time, more research has shown potential problems linked to self-driving technology, for example that more comfortable driving would lead to more traffic, which in turn would lead to increased emissions, higher noise levels in cities or further focus on car-centric infrastructure. For public transport, the driver's role in creating safety and acting as problem solvers has also been emphasized - who should I ask for directions if there is no knowledgeable driver on board?Various methods have previously been used to explore the social effects of self-driving technology and in this dissertation I have used so-called "four-stage models", more specifically the Swedish transport model Sampers. Four-stage models have been used for 50 years to evaluate effects on the transport system from e.g. infrastructure changes, but these models face new challenges, handling vehicles that drive by themselves. In my research, I have adjusted the model to simulate self-driving technology and investigated what effects this has on, for example, traffic volumes and emissions.In the three articles that are part of the dissertation, I have four main conclusions:Self-driving technology can mean large savings in costs for public transport, primarily for bus traffic but also to some extent for rail traffic. In addition, a smoother driving behaviour would mean more comfortable travel, which would increase the attractiveness of public transport. In addition, public transport not limited by, for example, driver schedules or current commercial conditions, could develop new types of services, such as on-demand public transport.Four-stage models have previously been used to model the transport system and have been shown to have good results, at least at an overall level. Within my research, I have made some adaptations of these models to mimic self-driving technology, but the models in their current form cannot consider, for example, vehicle sharing.It is important to point out that bus and train drivers currently perform many tasks that are not directly related to the driving of the vehicle, such as answering questions, maintaining social order among passengers and taking care of faults that occur during the trip. Today, self-driving technology cannot fulfil these roles.Self-driving technology for public transport would affect people's accessibility, driving style for vehicles, safety on board, how we plan traffic and the people who currently work as drivers. In fact, a multitude of societal effects have been identified, affecting all areas of transport. In addition, the effects are generally not similar across geographies, time units or for different actors, which further emphasizes that the total effect is not easy to summarize.
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| 2. |
- Andreolli, Raphael, et al.
(författare)
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A review on real vehicle usage modelling of driverless multipurpose vehicles in vehicle routing problems
- 2023
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Ingår i: Proceedings of the International Conference on Engineering Design, ICED 2023. - : Cambridge University Press (CUP). ; , s. 385-394
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Konferensbidrag (refereegranskat)abstract
- Real vehicle usage rarely matches the predictions made during early phases of vehicle development and sales processes at commercial road vehicle manufacturers. The automotive industry needs multidisciplinary vehicle design methods to predict real-world vehicle operations by considering the vehicle level and the transport system level simultaneously, in a more holistic approach. The aim of this study was to analyse how realistic vehicle usage of driverless multipurpose vehicles can be modelled in Vehicle Routing Problems (VRPs) by conducting a systematic literature review. We found that real vehicle usage modelling of driverless multipurpose vehicles in VRPs mainly depended on the following elements: VRP variant, energy consumption model, energy consumption rate class, number of vehicle-specific design variables and transport system-level factors. Furthermore, we identified in the literature five classes of energy consumption rate edge behaviour in VRPs. These findings can support decision-making in the modelling process to select the most suitable combination of elements, and their level of detail for the overall modelling aim and purpose.
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| 3. |
- Andreolli, Raphael, et al.
(författare)
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Energy Consumption Evaluation of Emerging and Current Vehicle Fleets in Urban Logistics
- 2024
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Ingår i: 10th Transportation Research Arena, Dublin, Ireland, 15-18 April 2024.
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Driverless multipurpose vehicles (DMVs) are an emerging vehicle concept for urban heavy-duty transport. However, little is known about their effect on urban road transport systems. Thus, the aim of this study is to analyse the total fleet energy consumption of DMVs for specific transport operations in urban logistics compared to heavy- duty battery and combustion vehicles. A novel electric vehicle routing problem was used to simulate in total 96 case-studies of operations with varying network and vehicle fleet properties. We found that the combustion vehicle fleets consumed significantly more energy for the same operation compared to the electric vehicle fleets. Although the DMV fleet and battery electric vehicle fleet showcased similar energy consumption for most case-studies, there were several operations where the DMV fleet consumed less energy and required a smaller fleet size. This study highlights the potential benefits of DMV fleets in urban logistics operations in terms of reducing total fleet energy consumption and fleet size.
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| 4. |
- Zhang, Wenliang
(författare)
-
Exploiting over-actuation for improved active safety of autonomous electric vehicles
- 2022
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The increasing demand for road vehicles has led to challenging road safety and environmental issues. The deployment of active safety systems and autonomous vehicles can contribute to safer roads by assisting or replacing human drivers in the task of maintaining vehicle control in critical conditions: e.g., an obstacle-avoidance manoeuvre. Road vehicle electrification can bring about environmental benefits and at the same time enable the development of over-actuated vehicle platforms. Over-actuation can be explored together with active safety and automated driving systems in order to enhance vehicle safety. On the other hand, to achieve their best possible performance, such safety and automated systems require the knowledge of vehicle states such as sideslip angle as well as reliable trajectories. However, measuring such crucial states can be overly expensive on production vehicles.The studies presented in this thesis aim to explore how over-actuation can improve path-following and yaw-stability performance of autonomous electric vehicles in critical manoeuvres and investigate the associated state estimation and trajectory planning problems.To achieve these goals, this thesis focuses on five aspects. First, it explores vehicle dynamics modelling by introducing vehicle and tyre models of various levels of complexity. In particular, the camber effect on lateral tyre forces was modelled using a simple, yet effective, component, which allows for individual camber control of each wheel. Second, it addresses the state estimation problem by designing and evaluating three moving horizon estimation (MHE) based estimators and an unscented Kalman filter. The evaluation in three critical manoeuvres showed that the estimator MHE outperformed the other algorithms, with improved convergence rate, accuracy and response to external disturbances and modelling errors, due to its consideration of a sequence of most recent measurements and process noises. Third, trajectory planning is studied through optimal control formulations and by examining the effect of model complexity in critical driving scenarios. It was shown that the advanced double-track planner with load transfer and the Magic Formula tyre model was desired to achieve more consistent trajectory planning and tracking performance as well as smaller peak yaw rate and sideslip angle. Fourth, the path following and yaw stability problem is tackled in the model predictive control framework and by exploring various over-actuation configurations -- active front steering (AFS), torque vectoring (TV) and active camber (AC). The results in safety-critical conditions showed that AFS + TV improved yaw stability, path following and passing velocity compared to AFS, and AFS + AC performed better than AFS + TV. The integrated control of AFS + TV + AC further enhanced vehicle safety and was more robust to reference trajectory variations, as a result of its more effective actuator and tyre utilisation. Finally, this work details the framework for optimal control implementation, which facilitates efficient computing, smooth parameter tuning and results analysis, as well as sustainable code development.The research presented in this thesis has contributed to the modelling, formulation and control of autonomous electric vehicles by exploiting over-actuation for enhanced vehicle safety. It has been shown that over-actuation control strategies can be a promising solution for improving active safety, and thus they contribute to a safer and more sustainable future transport.
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| 5. |
- Almlöf, Erik, 1985-
(författare)
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Beyond Technology : Understanding societal impacts of implementing self-driving vehicle systems on road transport
- 2024
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- During the last decade, self-driving vehicles have become a major topic of interest, promising to transform transport by making travel safer and more efficient. However, as we move closer to making these vehicles a reality, it has become clear that introducing them into society might not be as straightforward as once thought, and there are growing doubts about the benefits they are supposed to offer.In this thesis, I investigate the societal impacts of self-driving vehicles by exploring four aspects: reasons for researching self-driving vehicles, how these vehicles could be implemented, the societal impacts of fully implementing self-driving vehicles, and their relationship to sustainability goals.I find that the motivation for researching this topic is often opaque, and the existence of the technology itself is used as a justification for more research. Furthermore, most research into realising self-driving vehicles focuses on purely technical aspects such as designing better algorithms. However, I show that many challenges remain connected to the sociotechnical intertwinement of self-driving vehicles. For instance, I illustrate how they will interact with pedestrians and how services using self-driving vehicles would be practically organised.Additionally, self-driving vehicles are likely to impact many aspects of society, such as congestion, accessibility, and economic factors. However, I demonstrate that no single framework successfully captures all the identified societal impacts, which are likely to depend on diverse factors such as geographical variations.The impacts further affect sustainability, where new challenges are likely to emerge. I show that while current tools to govern the transport system are still relevant, a comprehensive approach is needed to ensure that policymakers make well-considered decisions. In conclusion, I call for a more balanced view of self-driving vehicles. Introducing this new technology requires careful planning and governance to ensure that self-driving vehicle systems genuinely enhance our quality of life and help build a sustainable future.
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| 6. |
- Almlöf, Erik, 1985-, et al.
(författare)
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Frameworks for assessing societal impacts of automated driving technology
- 2022
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Ingår i: Transportation planning and technology (Print). - : Taylor & Francis. - 0308-1060 .- 1029-0354. ; 45:7, s. 545-572
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Tidskriftsartikel (refereegranskat)abstract
- Numerous studies have studied the impacts of automated driving (AD) technology on e.g. accident rates or CO2 emissions using various frameworks. In this paper we present an overview of previous frameworks used for societal impacts and review their advantages and limitations. Additionally, we introduce the Total Impact Assessment (TIA) framework developed by the Swedish Transport Administration and use this framework to evaluate three scenarios for AD bus services in Stockholm. We conclude that the reviewed frameworks cover different aspects of AD technology, and that e.g. cybersecurity and biodiversity are areas largely neglected. Furthermore, most frameworks assume effects to be homogenous, when there may be large variation in e.g. perceived security. The TIA framework does not manage to include all societal aspects of AD technology, but has great benefits and manages to provide important insights of the societal impacts of AD technology, especially how effects may wary for different actors.
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| 7. |
- Almlöf, Erik, 1985-, et al.
(författare)
-
Frameworks for assessing societal impacts of self-driving technology
-
Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- Numerous studies have studied the impacts of self-driving technology on e.g. accident rates or CO2 emissions using various frameworks. In this paper we present an overview of previous frameworks used for societal impacts, and review their advantages and limitations. Additionally, we introduce the Total Impact Assessment (TIA) framework developed by the Swedish Transport Administration and use this framework to evaluate three scenarios for self-driving bus services in Stockholm. We conclude that the reviewed frameworks cover different aspects of self-driving technology, and that e.g. cybersecurity and biodiversity are areas neglected by most frameworks. Furthermore, most frameworks assume effects to be homogenous, when there may be large variation in e.g. perceived security. The TIA framework does not manage to include all societal aspects of self-driving technology, but has great benefits and manages to provide important insights of the societal impacts of self-driving technology, especially how effects may wary for different actors.
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| 8. |
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| 9. |
- Almlöf, Erik, 1985-, et al.
(författare)
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Will leisure trips be more affected than work trips by autonomous technology? : Modelling self-driving public transport and cars in Stockholm, Sweden
- 2022
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Ingår i: Transportation Research Part A. - : Elsevier BV. - 0965-8564 .- 1879-2375. ; 165, s. 1-19
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Tidskriftsartikel (refereegranskat)abstract
- Self-driving technology may lead to a paradigm shift for the transport industry with shared cars available to every-one. However, this vision has increasingly been challenged as too optimistic and unsubstantiated. In this study we explore societal impacts of using this technology for both cars and public transport and investigate differences depending on geography and trip purpose. Four scenarios were designed through workshops with 130 transport experts, modelled using a conventional four-step model for Stockholm, Sweden and evaluated in terms of changes to mode choice, number of trips and person kilometres.We find larger increases for non-commuting trips, i.e. service and leisure trips, than for commuting trips, questioning the view of the 'productive work trip' as self-driving technology's main impact on society. As these trips are primarily made outside of rush hours, this may lead to a changed transport system. Geographic differences are substantial and heavily dependent on the cost model for car alternatives, even indicating a reduction in car travel in rural areas if private ownership would be replaced by shared cars. Furthermore, walking and cycling levels decreased in all scenarios while enhancing public transport using self-driving technology had a limited impact on ridership.These results show that the impacts of self-driving technology may have varied societal impacts even within a region and may lead to increased car travel, especially off-peak. These conclusions stress the need for policies that are sensitive to both geography and time.
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| 10. |
- Almlöf, Erik, 1985-, et al.
(författare)
-
Will leisure trips be more affected than work trips by autonomous technology? Modelling self-driving public transport and cars in Stockholm, Sweden
-
Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- Self-driving technology may lead to a paradigm shift for the transport industry with shared cars available to everyone. However, this vision has increasingly been challenged as too optimistic and unsubstantiated. In this study we explore societal impacts of using this technology for both cars and public transport and investigate differences depending on geography and trip purpose. Four scenarios were designed through workshops with 130 transport experts, modelled using a conventional four-step model for Stockholm, Sweden and evaluated in terms of changes to mode choice, number of trips and person kilometres. We find larger increases for non-commuting trips, i.e. service and leisure trips, than for commuting trips, questioning the view of the ‘productive work trip’ as self-driving technology’s main impact on society. As these trips are primarily made outside of rush hours, this may lead to a changed transport system. Geographic differences are substantial and heavily dependent on the cost model for car alternatives, even indicating a reduction in car travel in rural areas if private ownership would be replaced by shared cars. Furthermore, walking and cycling levels decreased in all scenarios while enhancing public transport using self-driving technology has a limited impact on ridership. These results show that the impacts of self-driving technology may have varied societal impacts even within a region and may lead to increased car travel, especially off-peak. These conclusions stress the need for policies that are sensitive to both geography and time.
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| 11. |
- Li, Yiquan, et al.
(författare)
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Model-Based Coordinated Steering and Braking Control for a Collision Avoidance Driver Assist Function
- 2023
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Ingår i: WCX SAE World Congress Experience. - : SAE International.
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Konferensbidrag (refereegranskat)abstract
- ADAS (Advanced Driver Assistance System) functions can help the driver avoid accidents or mitigate their effect when they occur, and are pre-cursors to full autonomous driving (SAE defined as Level 4+). The main goal of this work is to develop a Model-Based system to actuate the Evasive Maneuver Assist (EMA) function. A typical scenario is the situation in which longitudinal Autonomous Emergency Braking (AEB) is too late and the driver has to adopt an evasive maneuver to avoid an object suddenly appearing on the road ahead. At this time, EMA can help improve the driver’s steering and braking operation in a coordinated way. The vehicle maneuverability and response performance will be enhanced when the driver is facing the collision. The function will additionally let the vehicle steer in a predetermined optimized trajectory based on a yaw rate set point and stabilize the vehicle. The EMA function is introduced with some analysis of benchmarking data. Benchmarking has shown different strategies from several OEMs (Original Equipment Manufacturers) and suppliers, in which the discipline of how they want the vehicle performance to behave and where improvements could be found. Functional requirement and performance metrics of EMA function are created. The performance metrics are based on objective and subjective evaluation. Frequency analysis is used to develop transfer functions to understand actuator effects, and Model-Based Design (MBD) is employed to subsequently develop the controller function using co-simulation between Matlab/Simulink and VI-CarRealtime. Results and analysis are presented at key vehicle speeds where intervention could be necessary. The final part introduces driving simulator tests after the development of the function. The measured signal results could be compared with simulation results and driver’s performance without EMA. Eventually, a questionnaire survey was made to define a direction for further improvement. Additional ideas are presented for more advanced work.
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| 12. |
- Palmberg, Robin, 1992-, et al.
(författare)
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Towards a better understanding of the health impacts of one’s movement in space and time
- 2022
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Ingår i: Journal of Literature and Science. - : Informa UK Limited. - 1754-646X. ; , s. 1-24
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Tidskriftsartikel (refereegranskat)abstract
- To better understand the interactions between physical built environment conditions and one’s well-being, we created a passive data collector for travellers and made the first step towards an explanatory model based on psychophysiological relations. By measuring biometric information from select trial participants we showed how different controlled factors are affecting the heart rate of the participants. A regression model with the impact factors such as speed, location, time and activity (accelerometer data) reveals how the factors relate to each other and how they correlate with the recorded individual’s heart rates throughout the observed period. For examples, the results show that the increase in movement speed is not linearly correlated with the heart rate. One’s heart rate would increase significantly when the individual reaches brisk walking and running speed, but not before nor after. Early morning and early evening time slots were the time where the observed individuals have the highest heart rates, which may correlate to individuals’ commute activities. Heart rates at the office would be lower than at home, which might correlate to more physical activities in the household.
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| 13. |
- Parseh, Masoumeh, 1989-, et al.
(författare)
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Motion planning for autonomous vehicles with the inclusion of post-impact motions for minimising collision risk
- 2022
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Ingår i: Vehicle System Dynamics. - : Informa UK Limited. - 0042-3114 .- 1744-5159. ; , s. 1-27
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Tidskriftsartikel (refereegranskat)abstract
- The introduction of more automation into our vehicles is increasing our ability to avoid or mitigate the effects of collisions. Early systems could brake when a likely collision was detected, while more advanced systems will be able to steer to avoid or reconfigure a collision during the same circumstances. This paper addresses how the post-impact motion of an impacted vehicle could be included in the decision-making process of severity minimisation motion planning. A framework is proposed that builds on previous work by the authors, combining models from motion planning, vehicle dynamics, and accident reconstruction. This framework can be configured for different contexts by adjusting its cost function according to relevant risks. Simulations of the unified system are carried out and analysed from the perspective of vehicle model complexity and collision parameters sensitivity. Additionally, effects are highlighted concerning different modelling decisions, with respect to vehicle dynamics models and collision models, that are important to consider in further research.
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| 14. |
- Parseh, Masoumeh, 1989-, et al.
(författare)
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Motion Planning for Autonomous Vehicles with the Inclusion of Post-impact Motions for Minimizing Collision Risk
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- The introduction of more automation into our vehicles is increasing our ability to avoid or mitigate the effects of collisions. Early systems could brake when a likely collision was detected, while more advanced systems will be able to steer to avoid or reconfigure a collision during the same circumstances. This paper addresses how the post-impact motion of an impacted vehicle could be included in the decision making process of severity minimization motion planning. A framework is proposed that builds on previous work by the authors, combining models from motion planning, vehicle dynamics and accident reconstruction. This framework can be configured for different contexts by adjusting its cost function according to relevant risks. Simulations of the unified system are carried out and analysed from the perspective of vehicle model complexity and collision parameters sensitivity. Additionally, effects are highlighted concerning different modeling decisions, with respect to vehicle dynamics models and collision models, that are important to consider in further research.
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| 15. |
- Parseh, Masoumeh, 1989-, et al.
(författare)
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Pre-Crash Vehicle Control and Manoeuvre Planning: A Step Towards Minimizing Collision Severity for Highly Automated Vehicles
- 2019
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Ingår i: 2019 IEEE International Conference of Vehicular Electronics and Safety (ICVES). - : Institute of Electrical and Electronics Engineers (IEEE).
-
Konferensbidrag (refereegranskat)abstract
- This paper addresses the control of a highly automated vehicle in a traffic scenario, where colliding with other traffic agents is unavoidable. Such a critical situation could be the result of a fault in the vehicle, late obstacle detection or the presence of an aggressive driver. We provide an approach that allows the vehicle’s control system to choose the manoeuvre that is likely to lead to the least severe injuries to vehicle occupants.The approach involves the off-line solving of an optimal control problem to create a set of trajectories based on controlling the steering angle rate and the braking rate at the vehicle’s limits. Occupant injury severity prediction, based on accident data with the focus on impact location, is used by a real-time collision control algorithm to choose a trajectory from the pre-computed optimal set. A simulation set-up is presented to illustrate the idea of the collision control algorithm in a simple scenario involving dynamic traffic agents.
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| 16. |
- Pérez, Javier, et al.
(författare)
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On-line learning applied to spiking neural network for antilock braking systems
- 2023
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Ingår i: Neurocomputing. - : Elsevier. - 0925-2312 .- 1872-8286. ; 559
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Tidskriftsartikel (refereegranskat)abstract
- Computationally replicating the behaviour of the cerebral cortex to perform the control tasks of daily life in a human being is a challenge today. First, it is necessary to know the structure and connections between the el- ements of the neural network that perform movement control. Next, a mathematical neural model that adequately resembles biological neurons has to be developed. Finally, a suitable learning model that allows adapting neural network response to changing conditions in the environment is also required. Spiking Neural Networks (SNN) are currently the closest approximation to biological neural networks. SNNs make use of temporal spike trains to deal with inputs and outputs, thus allowing a faster and more complex computation. In this paper, a controller based on an SNN is proposed to perform the control of an anti-lock braking system (ABS) in vehicles. To this end, two neural networks are used to regulate the braking force. The first one is devoted to estimating the optimal slip while the second one is in charge of setting the optimal braking pressure. The latter resembles biological reflex arcs to ensure stability during operation. This neural structure is used to control the fast regulation cycles that occur during ABS operation. Furthermore, an algorithm has been developed to train the network while driving. On-line learning is proposed to update the response of the controller. Hence, to cope with real conditions, a control algorithm based on neural networks that learn by making use of neural plasticity, similar to what occurs in biological systems, has been implemented. Neural connections are modulated using Spike-Timing-Dependent Plasticity (STDP) by means of a supervised learning structure using the slip error as input. Road-type detection has been included in the same neural structure. To validate and to evaluate the performance of the proposed algorithm, simulations as well as experiments in a real vehicle were carried out. The algorithm proved to be able to adapt to changes in adhesion conditions rapidly. This way, the capability of spiking neural networks to perform the full control logic of the ABS has been verified.
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| 17. |
- Raj, Rishabh, et al.
(författare)
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Performance Mapping of a Linear Induction Machine for Hyperloop Applications
- 2022
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Ingår i: 2022 International Conference on Electrical Machines, ICEM 2022. - : Institute of Electrical and Electronics Engineers (IEEE). ; , s. 427-433
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Konferensbidrag (refereegranskat)abstract
- In the future, faster-electrified means of transportation are a necessity for more sustainable technologies. The use of Linear Induction Machines (LIM) poses an important propulsion option for high-speed transportation, particularly in hyperloop applications. Such types of high-power linear machines are complex to design and needs development without compromising too much on efficiency. The reason for the low efficiency of LIMs is high rotor losses and large airgap. Furthermore, a need to estimate the efficiency map during the runtime is necessary as high losses under constrained environments of pressure and temperature leads to significant changes in the total efficiency. Currently, LIM manufacturers do not usually provide efficiency maps with respect to an entire range of torque and speed. Thus, a design methodology and temperature-dependent efficiency maps are proposed for LIM. In accordance with the design requirements of the hyperloop pod in its entirety, a maximum speed of approximately 150km/h is achieved.
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| 18. |
- Vaddadi, Bhavana, Ph.D. Student, et al.
(författare)
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Measuring system level effects of Corporate MaaS : A case study in Sweden
- 2019
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Ingår i: Towards human scale cities -open and happy. ; , s. 68-
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Mobility as a Service (MaaS) integrates different elements of transportation, which mainly are: ticket & payment integration, mobility modes integration and ICT integration. It plays an important role as it is expected to enable the shift from private car use to shared and sustainable transport modes. Corporate Mobility as a Service (CMaaS) is a version of MaaS, which enables mobility within as well as to and from, a work site for the employees. CMaaS fulfils all the above-mentioned characteristics of MaaS. It may also consist of different service packages which could either be free and/ or paid. CMaaS is a new concept and its implementation is limited. The expected benefits of CMaaS are both to support a shift toward sustainable transportation and to be the first step towards more general MaaS solutions. In this paper, we study the effects of CMaaS from economic, environmental and societal aspects on individual, organizational and social levels. The case study of the implementation of CMaaS at a company with 13000 employees located in a city 30 km outside of Stockholm, Sweden, is used in this study. The estate spans over three-square kilometres, and the facilities are spread over the area with distances between the buildings of up to 5kms. The service provides internal taxis, small shuttle buses and e-bikes to aid the employees to get around the estate during the working day. It also offers a commuter bus service to and from Stockholm City. The evaluation is based on data collected through three surveys with more than 400 respondents, complemented with operational data. The analysis is ongoing and will be completed during the spring. Preliminary results show that CMaaS have supported the shift towards the use of e-bikes in favour of motorized modes which has positive effects on e.g. health and emissions.
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| 19. |
- Zhang, Wenliang, et al.
(författare)
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Evaluating Model Predictive Path Following and Yaw Stability Controllers for Over-Actuated Autonomous Electric Vehicles
- 2020
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Ingår i: IEEE Transactions on Vehicular Technology. - : IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC. - 0018-9545 .- 1939-9359. ; 69:11, s. 12807-12821
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Tidskriftsartikel (refereegranskat)abstract
- Active safety systems are of significant importance for autonomous vehicles operating in safety-critical situations like an obstacle-avoidance manoeuvre with high vehicle speed or poor road condition. However, a conventional electronic stability control system, may not always yield desired path following and yaw stability performance in such circumstances merely through brake intervention. This paper pursues a detailed investigation on utilising model predictive control (MPC) and torque vectoring for path following and yaw stability control of over-actuated autonomous electric vehicles (AEVs) in dangerous double lane change manoeuvre. The control problem of the AEV is formulated based on MPC by utilising active front steering and torque vectoring, and constraints are imposed explicitly on yaw rate and sideslip angle to ensure yaw stability. Four MPC-based controllers are designed based on double-track vehicle models. Specifically, they include two one-level controllers, i.e. one with torque vectoring and one with equal torque allocation, and two two-level controllers, i.e. one with optimisation-based torque allocation and one with rule-based allocation. These controllers are assessed extensively, with respect to passing velocity, tracking accuracy, tyre utilisation and robustness. The effect of horizon length on the control performance and computational efficiency is also investigated.
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| 20. |
- Zhang, Wenliang, et al.
(författare)
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Integrated control of motion actuators for enhancing path following and yaw stability of over-actuated autonomous vehicles
- 2023
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Ingår i: Energies. - : MDPI. - 1996-1073. ; 16:12
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Tidskriftsartikel (refereegranskat)abstract
- Advanced active safety systems play a crucial role in ensuring the safe driving of vehicles in critical conditions such as an obstacle avoidance manoeuvre. However, conventional techniques relying mainly on braking interventions may not result in the desired vehicle response in such situations. Over-actuation through the control of individual motion actuators could potentially improve the safety performance of vehicles. This study evaluates various configurations of motion actuators for path following and yaw stability control of vehicles in critical driving scenarios. The configurations include active front steering (S), active front steering + torque vectoring (ST), active front steering + active camber (SC) and active front steering + torque vectoring + active camber (STC). The evaluation is achieved based on a nonlinear model predictive control formulation, which considers yaw stability and the physical limits of motion actuators. This problem formulation uses a double-track vehicle model, combined with the Dugoff tyre model and its variant with the camber effect, to model the vehicle dynamics. The actuator configurations are evaluated regarding the passing velocity, tracking accuracy, safety distance and robustness to reference trajectory variation. The results indicate that the integrated control of STC performs the best among all the four configurations while S performs the worst. Furthermore, SC is generally superior to ST.
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| 21. |
- Zhao, Lin, 1995-, et al.
(författare)
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A Survey of Teleoperation : Driving Feedback
- 2023
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Ingår i: IV 2023. - : Institute of Electrical and Electronics Engineers (IEEE).
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Konferensbidrag (refereegranskat)abstract
- Teleoperation can be regarded as an effectivebackup system for self-driving vehicles, which could take overvehicle control in some special scenarios that the automatedvehicles could not handle. However, there are still many challengesin teleoperation, such as low situation awareness. Thiscould potentially be dangerous in some extreme situations.However, it could be effectively improved by providing suitabledriving feedbacks. Hence, this article provides a timely andcomprehensive review of existing and possible driving feedbacktechniques in teleoperation. They are presented from the pointof view of video feedback, steering force feedback, motioncueingfeedback, audio and vibration feedback, and other nonconventionalfeedback modes. Then, the current challenges,future trends and opportunities in teleoperation are presentedand discussed.
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| 22. |
- Zhao, Lin, 1995-, et al.
(författare)
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Driving Experience and Behavior Change in Remote Driving : An Explorative Experimental Study
- 2024
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Ingår i: IEEE Transactions on Intelligent Vehicles. - : Institute of Electrical and Electronics Engineers (IEEE). - 2379-8858 .- 2379-8904. ; 9:2, s. 3754-3767
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Tidskriftsartikel (refereegranskat)abstract
- Remote driving plays an essential role in coordinating automated vehicles in some challenging situations. Due to the changed driving environment, the experiences and behaviors of remote drivers would undergo some changes compared to conventional drivers. To study this, a continuous real-life and remote driving experiment is conducted under different driving conditions. In addition, the effect of steering force feedback (SFF) on the driving experience is also investigated. In order to achieve this, three types of SFF modes are compared. According to the results, no SFF significantly worsens the driving experience in both remote and real-life driving. Additionally, less force and returnability on steering wheel are needed in remote driving, and the steering force amplitude appears to influence the steering velocity of remote drivers. Furthermore, there is an increase in lane following deviation during remote driving. Remote drivers are also prone to driving at lower speeds and have a higher steering reversal rate. They also give larger steering angle inputs when crossing the cones in a slalom manoeuvre and cause the car to experience larger lateral acceleration. These findings provide indications on how to design SFF and how driving behavior and experience change in remote driving.
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| 23. |
- Zhao, Lin, 1995-, et al.
(författare)
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Influence of sound, vibration, and motion-cueing feedback on driving experience and behaviour in real-life teleoperation
- 2023
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Driving feedback is an important way of providing remotedrivers with physical world information during teleoperation. In thisstudy, a teleoperation experiment is conducted to explore how sound,vibration and motion-cueing feedback influence the drivers’ driving experience and behaviour. To this end, four types of driving feedback modesare used as variables to investigate this, including no feedback, motioncueing feedback, sound and vibration feedback, and a combination ofsound, vibration, and motion-cueing feedback. A prototype of teleoperation platform is first built, which includes a teleoperated vehicle anda driving station capable of generating sound, vibration, and motioncueing feedback. Then, the scenario with disturbances is built to investigate how the driving behaviour changes under various driving feedbackmodes. Both subjective and objective assessments are used in this study.For driving experience, the driving feeling, such as presence feeling, roadsurface feeling, etc, are explored. For driving behaviour, the throttle reversal rate is investigated. Furthermore, the relationship between throttle reversal rate and driving experience is studied. The results show thatthe combined feedback mode could provide drivers with the highest rateddriving experience; the motion-cueing feedback could provide better roadsurface feeling while the sound and vibration feedback could provide better speed feeling. The throttle reversal rate with motion-cueing feedbackis higher than without it, which may be caused by the increased roadsurface feeling provided by motion cues.
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| 24. |
- Zhao, Lin, 1995-, et al.
(författare)
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Study of different steering feedback models influence during remote driving
- 2021
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Ingår i: Proceedings of the 27th IAVSD Symposium on Dynamics of Vehicles on Roads and Tracks. - Cham : Springer International Publishing.
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Konferensbidrag (refereegranskat)abstract
- Steering feedback is one essential aspect to provide real world information, and can influence driving performance during remote driving. In this work, the classical feedback models based on physical characteristics (Physical Model) and modular characteristics (Modular Model) of the steering system are constructed separately, and the influences of it on the remote drivers are studied. Objective and subjective measurement methods are separately used for evaluating the performance of the feedback models. In the subjective assessment, a multi-level assessment method is used for studying the influence of steering models on driver’s intuitive feeling. In the objective assessment, lane following accuracy, steering reversal rates, vehicle speed, time consumption, and throttle engagement are studied for different feedback models and scenarios. Moreover, the human biological information of electroencephalogram and heart rate variability are measured for studying the workload differences. The results showed that the physical model gave drivers a better steering characteristic feel and confidence in remote driving while the modular model could provide better real world feel. Returnability was an important parameter in remote driving, and the level of feedback force and returnability speed could be lower in remote driving compared to real car driving. It was also found that drivers had a higher workload in remote driving compared to real car driving.
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| 25. |
- Zhao, Lin, 1995-
(författare)
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Teleoperation and the influence of driving feedback on drivers’ behaviour and experience
- 2023
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Automated vehicles (AVs) have been developing at a rapid pace over the past few years. However, many difficulties still remain for achieving full Level-5 AVs. This signifies that AVs still require human operators to intervene or assist, such as taking over control of AVs or selecting their routes. Therefore, teleoperation can be seen as a subsystem of AVs that can remotely control and supervise a vehicle when needed. However, teleoperated driving conditions are largely different from real-life driving, so remote drivers may experience different driving feedback. In such a situation, therefore, the driving behaviour and performance of remote drivers can also be impacted. The following three studies were conducted to investigate these points.First, a seamless comparative study was carried out between teleoperated and real-life driving. Driving behaviour and performance were compared in two scenarios: slalom and lane following. Significant differences in driving behaviour and performance between them were found in the study. The lane following deviation during teleoperated driving is much greater than that of real-life driving. In addition, remote drivers are more likely to drive slower and make more steering corrections in lane following manoeuvres.Second, three types of steering force feedback (SFF) modes were compared separately in both teleoperated and real-life driving to investigate the effect of SFF on driving experience. The three SFF modes consist of Physical model-based steering force Feedback (PsF), Modular model-based steering force Feedback (MsF), and No steering force Feedback (NsF). The difference between PsF and MsF is that the main forces come from different sources, namely the estimated tyre force and steering motor current, respectively. As expected, the experimental results indicate that NsF would significantly reduce the driving experience in both driving conditions. In addition, remote drivers were found to require reduced steering feedback force and returnability.Finally, the influence of motion-cueing, sound, and vibration feedback on driving behaviour and experience was studied in a virtual teleoperation platform based on the IPG CarMaker environment. The prototype of a teleoperated driving station (TDS) with motion-cueing, sound, and vibration feedback was first developed to study human factors in teleoperated driving. Then, the low-speed disturbance scenario and high-speed dynamic scenario were used separately to investigate how these factors affect driving. Experimental results indicate that sound and vibration feedback can be an important factor in speed control by providing remote drivers a sense of speed. In the low-speed disturbance scenario, motion-cueing feedback can help with road surface perception and improve the driving experience. However, it did not significantly improve driving performance in the high-speed dynamic scenario.The research conducted reveals how driving behaviour may change in teleoperated driving and how different driving feedback influences it. These results could provide guidance for improving teleoperated driving in future research and serve as a guide for policymaking related to teleoperation.
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