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Nielsen, Lars
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Publications (10 of 86) Show all publications
Kharrazi, S., Nielsen, L. & Frisk, E. (2023). Generation of Mission-Based Driving Cycles Using Behavioral Models Parameterized for Different Driver Categories. SAE technical paper series
Open this publication in new window or tab >>Generation of Mission-Based Driving Cycles Using Behavioral Models Parameterized for Different Driver Categories
2023 (English)In: SAE technical paper series, ISSN 0148-7191, , p. 11Article in journal (Refereed) Published
Abstract [en]

A methodology for the generation of representative driving cycles is proposed and evaluated. The proposed method combines traffic simulation and driving behavior modeling to generate mission-based driving cycles. Extensions to the existing behavioral model in a traffic simulation tool are suggested and parameterized for different driver categories to capture the effects of road geometry and variances between drivers. The evaluation results illustrate that the developed extensions significantly improve the match between driving data and the driving cycles generated by traffic simulation. Using model extensions parameterized for different driver categories, instead of only one average driver, provides the possibility to represent different driving behaviors and further improve the realism of the resulting driving cycles.

Place, publisher, year, edition, pages
SAE International, 2023. p. 11
National Category
Vehicle Engineering
Identifiers
urn:nbn:se:liu:diva-194735 (URN)10.4271/2023-01-5033 (DOI)
Note

Thea rticle is a non-event SAE technical paper

Available from: 2023-06-09 Created: 2023-06-09 Last updated: 2023-09-13Bibliographically approved
Fors, V., Olofsson, B. & Nielsen, L. (2021). Autonomous Wary Collision Avoidance. IEEE Transactions on Intelligent Vehicles, 6(2), 353-365
Open this publication in new window or tab >>Autonomous Wary Collision Avoidance
2021 (English)In: IEEE Transactions on Intelligent Vehicles, ISSN 2379-8858, Vol. 6, no 2, p. 353-365Article in journal (Refereed) Published
Abstract [en]

Handling of critical situations is an important part in the architecture of an autonomous vehicle. A controller for autonomous collision avoidance is developed based on a wary strategy that assumes the least tireroad friction for which the maneuver is still feasible. Should the friction be greater, the controller makes use of this and performs better. The controller uses an acceleration-vector reference obtained from optimal control of a friction-limited particle, whose applicability is verified by using numerical optimization on a full vehicle model. By employing an analytical tire model of the tireroad friction limit, to determine slip references for steering and body-slip control, the result is a controller where the computation of its output is explicit and independent of the actual tire-road friction. When evaluated in real-time on a high-fidelity simulation model, the developed controller performs close to that achieved by offline numerical optimization.

Place, publisher, year, edition, pages
Institute of Electrical and Electronics Engineers (IEEE), 2021
Keywords
Autonomous vehicles, obstacle avoidance, control design, optimal control, vehicle dynamics, vehicle safety
National Category
Engineering and Technology Control Engineering
Identifiers
urn:nbn:se:liu:diva-170507 (URN)10.1109/TIV.2020.3029853 (DOI)000710540200019 ()
Funder
ELLIIT - The Linköping‐Lund Initiative on IT and Mobile CommunicationsWallenberg AI, Autonomous Systems and Software Program (WASP)
Note

Funding: Wallenberg AI, Autonomous Systems, and Software Program (WASP) - Knut and AliceWallenberg Foundation

Available from: 2020-10-13 Created: 2020-10-13 Last updated: 2021-11-08Bibliographically approved
Mohseni, F., Frisk, E. & Nielsen, L. (2021). Distributed Cooperative MPC for Autonomous Driving in Different Traffic Scenarios. IEEE Transactions on Intelligent Vehicles, 6(2), 299-309
Open this publication in new window or tab >>Distributed Cooperative MPC for Autonomous Driving in Different Traffic Scenarios
2021 (English)In: IEEE Transactions on Intelligent Vehicles, ISSN 2379-8904, Vol. 6, no 2, p. 299-309Article in journal (Refereed) Published
Abstract [en]

A cooperative control approach for autonomous vehicles is developed in order to perform different complex traffic maneuvers, e.g., double lane-switching or intersection situations. The problem is formulated as a distributed optimal control problem for a system of multiple autonomous vehicles and then solved using a nonlinear Model Predictive Control (MPC) technique, where the distributed approach is used to make the problem computationally feasible in real-time. To provide safety, a collision avoidance constraint is introduced, also in a distributed way. In the proposed method, each vehicle computes its own control inputs using estimated states of neighboring vehicles. In addition, a compatibility constraint is defined that takes collision avoidance into account but also ensures that each vehicle does not deviate significantly from what is expected by neighboring vehicles. The method allows us to construct a cost function for several different traffic scenarios. The asymptotic convergence of the system to the desired destination is proven, in the absence of uncertainty and disturbances, for a sufficiently small MPC control horizon. Simulation results show that the distributed algorithm scales well with increasing number of vehicles.

Place, publisher, year, edition, pages
IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC, 2021
Keywords
Autonomous vehicles, Collision avoidance, Trajectory, Safety, Convergence, Control design, Optimal control, Cooperative Vehicle Systems, Model Predictive Control
National Category
Control Engineering Vehicle Engineering
Identifiers
urn:nbn:se:liu:diva-172226 (URN)10.1109/TIV.2020.3025484 (DOI)000710540200014 ()
Note

Funding: Linnaeus Center CADICS - Swedish Research Council; Knut and Alice Wallenberg FoundationKnut & Alice Wallenberg Foundation

Available from: 2020-12-28 Created: 2020-12-28 Last updated: 2021-12-28
Fors, V., Anistratov, P., Olofsson, B. & Nielsen, L. (2021). Predictive Force-Centric Emergency Collision Avoidance. Journal of Dynamic Systems Measurement, and Control, 143(8), Article ID 081005.
Open this publication in new window or tab >>Predictive Force-Centric Emergency Collision Avoidance
2021 (English)In: Journal of Dynamic Systems Measurement, and Control, ISSN 0022-0434, E-ISSN 1528-9028, Vol. 143, no 8, article id 081005Article in journal (Refereed) Published
Abstract [en]

A controller for critical vehicle maneuvering is proposed that avoids obstacles and keeps the vehicle on the road while achieving heavy braking. It operates at the limit of friction and is structured in two main steps: a motion-planning step based on receding-horizon planning to obtain acceleration-vector references, and a low-level controller for following these acceleration references and transforming them into actuator commands. The controller is evaluated in a number of challenging scenarios and results in a well behaved vehicle with respect to, e.g., the steering angle, the body slip, and the path. It is also demonstrated that the controller successfully balances braking and avoidance such that it really takes advantage of the braking possibilities. Specifically, for a moving obstacle, it makes use of a widening gap to perform more braking, which is a clear advantage of the online replanning capability if the obstacle should be a moving human or animal. Finally, real-time capabilities are demonstrated. In conclusion, the controller performs well, both from a functional perspective and from a real-time perspective.

Place, publisher, year, edition, pages
ASME, 2021
National Category
Electrical Engineering, Electronic Engineering, Information Engineering
Identifiers
urn:nbn:se:liu:diva-174796 (URN)10.1115/1.4050403 (DOI)000668220800008 ()
Note

Funding: ELLIIT Strategic Area for ICT research - Swedish Government; Wallenberg AI, Autonomous Systems and Software Program (WASP) - Knut and Alice Wallenberg Foundation

Available from: 2021-04-01 Created: 2021-04-01 Last updated: 2022-04-01
Olofsson, B. & Nielsen, L. (2021). Using Crash Databases to Predict Effectiveness of New Autonomous Vehicle Maneuvers for Lane-Departure Injury Reduction. IEEE transactions on intelligent transportation systems (Print), 22(6), 3479-3490
Open this publication in new window or tab >>Using Crash Databases to Predict Effectiveness of New Autonomous Vehicle Maneuvers for Lane-Departure Injury Reduction
2021 (English)In: IEEE transactions on intelligent transportation systems (Print), ISSN 1524-9050, E-ISSN 1558-0016, Vol. 22, no 6, p. 3479-3490Article in journal (Refereed) Published
Abstract [en]

Autonomous vehicle functions in safety-critical situations show promise in reducing the risk and saving lives in accidents compared to existing safety systems. Consequently, it is from many perspectives advantageous to be able to quantify the potential benefits of new autonomous systems for vehicle maneuvers at-the-limit of tire friction. Here, to estimate the potential in terms of saved lives and reduced degree of injuries in accidents for new, not yet existing systems, a framework has been developed by combining available historic data, in the form of crash databases, and statistical methods with comparative calculations of vehicle behavior using numerical optimization rather than simulation. The framework performs effectively, it gives interesting insights into the relation between more traditional active yaw control and optimal autonomous lane-keeping control, and it clearly demonstrates the potential of saved lives by using autonomous vehicle maneuvers.

Place, publisher, year, edition, pages
Institute of Electrical and Electronics Engineers (IEEE), 2021
National Category
Control Engineering Transport Systems and Logistics
Identifiers
urn:nbn:se:liu:diva-172144 (URN)10.1109/TITS.2020.2983553 (DOI)000658360600021 ()2-s2.0-85083464559 (Scopus ID)
Funder
Wallenberg AI, Autonomous Systems and Software Program (WASP)ELLIIT - The Linköping‐Lund Initiative on IT and Mobile Communications
Note

Funding: Wallenberg AI, Autonomous Systems and Software Program (WASP) - Knut and Alice Wallenberg Foundation; ELLIIT Strategic Research Area - Swedish Government

Available from: 2020-12-27 Created: 2020-12-27 Last updated: 2021-09-29Bibliographically approved
Fors, V., Olofsson, B. & Nielsen, L. (2020). Attainable force volumes of optimal autonomous at-the-limit vehicle manoeuvres. Vehicle System Dynamics, 58(7), 1101-1122
Open this publication in new window or tab >>Attainable force volumes of optimal autonomous at-the-limit vehicle manoeuvres
2020 (English)In: Vehicle System Dynamics, ISSN 0042-3114, E-ISSN 1744-5159, Vol. 58, no 7, p. 1101-1122Article in journal (Refereed) Published
Abstract [en]

With new developments in sensor technology, a new generation of vehicle dynamics controllers is developing, where the braking and steering strategies use more information, e.g. knowledge of road borders. The basis for vehicle-safety systems is how the forces from tyre–road interaction is vectored to achieve optimal total force and moment on the vehicle. To study this, the concept of attainable forces previously proposed in literature is adopted, and here a new visualisation technique is devised. It combines the novel concept of attainable force volumes with an interpretation of how the optimal solution develops within this volume. A specific finding is that for lane-keeping it is important to maximise the force in a certain direction, rather than to control the direction of the force vector, even though these two strategies are equivalent for the friction-limited particle model previously used in some literature for lane-keeping control design. More specifically, it is shown that the optimal behaviour develops on the boundary surface of the attainable force volume. Applied to lane-keeping control, this observation indicates a set of control principles similar to those analytically obtained for friction-limited particle models in earlier research, but result in vehicle behaviour close to the globally optimal solution also for more complex models and scenarios.

Place, publisher, year, edition, pages
Taylor & Francis, 2020
Keywords
Active safety, force vectoring, vehicle dynamics control, tyre–road interaction, vehicle manoeuvre strategy
National Category
Vehicle Engineering
Identifiers
urn:nbn:se:liu:diva-156638 (URN)10.1080/00423114.2019.1608363 (DOI)000470461700001 ()2-s2.0-85064738528 (Scopus ID)
Note

Funding agencies: Swedish Government; Wallenberg AI, Autonomous Systems and Software Program (WASP) - Knut and Alice Wallenberg Foundation

Available from: 2019-05-02 Created: 2019-05-02 Last updated: 2020-10-22Bibliographically approved
Anistratov, P., Olofsson, B., Burdakov, O. & Nielsen, L. (2020). Autonomous-Vehicle Maneuver Planning Using Segmentation and the Alternating Augmented Lagrangian Method. In: Rolf Findeisen, Sandra Hirche, Klaus Janschek, Martin Mönnigmann (Ed.), 21th IFAC World Congress Proceedings: . Paper presented at The 21st IFAC World Congress (Virtual), Berlin, Germany, July 12-17, 2020 (pp. 15558-15565). Elsevier, 53
Open this publication in new window or tab >>Autonomous-Vehicle Maneuver Planning Using Segmentation and the Alternating Augmented Lagrangian Method
2020 (English)In: 21th IFAC World Congress Proceedings / [ed] Rolf Findeisen, Sandra Hirche, Klaus Janschek, Martin Mönnigmann, Elsevier, 2020, Vol. 53, p. 15558-15565Conference paper, Published paper (Refereed)
Abstract [en]

Segmenting a motion-planning problem into smaller subproblems could be beneficial in terms of computational complexity. This observation is used as a basis for a new sub-maneuver decomposition approach investigated in this paper in the context of optimal evasive maneuvers for autonomous ground vehicles. The recently published alternating augmented Lagrangianmethod is adopted and leveraged on, which turns out to fit the problem formulation with several attractive properties of the solution procedure. The decomposition is based on moving the coupling constraints between the sub-maneuvers into a separate coordination problem, which is possible to solve analytically. The remaining constraints and the objective function are decomposed into subproblems, one for each segment, which means that parallel computation is possible and benecial. The method is implemented and evaluated in a safety-critical double lane-change scenario. By using the solution of a low-complexity initialization problem and applying warm-start techniques in the optimization, a solution is possible to obtain after just a few alternating iterations using the developed approach. The resulting computational time is lower than solving one optimization problem for the full maneuver.

Place, publisher, year, edition, pages
Elsevier, 2020
Series
IFAC PapersOnline, E-ISSN 2405-8963
Keywords
trajectory and path planning, motion planning, optimal control, problem decomposition, vehicle safety maneuvers
National Category
Vehicle Engineering Robotics Computational Mathematics
Identifiers
urn:nbn:se:liu:diva-171784 (URN)10.1016/j.ifacol.2020.12.2400 (DOI)000652593600372 ()
Conference
The 21st IFAC World Congress (Virtual), Berlin, Germany, July 12-17, 2020
Funder
Wallenberg AI, Autonomous Systems and Software Program (WASP)
Note

Funding: Wallenberg AI, Autonomous Systems and Software Program (WASP) - Knut and Alice Wallenberg Foundation

Available from: 2020-12-06 Created: 2020-12-06 Last updated: 2021-09-22Bibliographically approved
Fors, V., Gao, Y., Olofsson, B., Gordon, T. & Nielsen, L. (2020). Real-Time Minimum-Time Lane Change Using the Modified Hamiltonian Algorithm. In: Matthijs Klomp, Fredrik Bruzelius, Jens Nielsen, Angela Hillemyr (Ed.), Advances in Dynamics of Vehicles on Roads and Tracks: . Paper presented at 26th Symposium of the International Association of Vehicle System Dynamics (pp. 1457-1465). SPRINGER INTERNATIONAL PUBLISHING AG
Open this publication in new window or tab >>Real-Time Minimum-Time Lane Change Using the Modified Hamiltonian Algorithm
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2020 (English)In: Advances in Dynamics of Vehicles on Roads and Tracks / [ed] Matthijs Klomp, Fredrik Bruzelius, Jens Nielsen, Angela Hillemyr, SPRINGER INTERNATIONAL PUBLISHING AG , 2020, p. 1457-1465Conference paper, Published paper (Refereed)
Abstract [en]

A minimum-time lane change maneuver is executed under friction-limited conditions using (1) the Modified Hamiltonian Algorithm (MHA) suitable for real-time control and (2) numerical optimization for comparison. A key variable is the switching time of the acceleration reference in MHA. Considering that MHA is based on an approximate vehicle model to target real-time control, it cannot exactly match the ideal reference as obtained from offline optimization; this paper shows that incorporation of a limited-jerk condition successfully predicts the switching time and that the desired lane position is reached in near minimum time.

Place, publisher, year, edition, pages
SPRINGER INTERNATIONAL PUBLISHING AG, 2020
Series
Lecture Notes in Mechanical Engineering, ISSN 2195-4356, E-ISSN 2195-4364
Keywords
Control allocation, Friction-limited control, Active safety, Vehicle dynamics, Time-optimal control, Stability control
National Category
Electrical Engineering, Electronic Engineering, Information Engineering
Identifiers
urn:nbn:se:liu:diva-164570 (URN)10.1007/978-3-030-38077-9_167 (DOI)000675429300166 ()9783030380762 (ISBN)9783030380779 (ISBN)
Conference
26th Symposium of the International Association of Vehicle System Dynamics
Available from: 2020-03-26 Created: 2020-03-26 Last updated: 2021-08-27
Fors, V., Olofsson, B. & Nielsen, L. (2019). Formulation and interpretation of optimal braking and steering patterns towards autonomous safety-critical manoeuvres. Vehicle System Dynamics, 57(8), 1206-1223
Open this publication in new window or tab >>Formulation and interpretation of optimal braking and steering patterns towards autonomous safety-critical manoeuvres
2019 (English)In: Vehicle System Dynamics, ISSN 0042-3114, E-ISSN 1744-5159, Vol. 57, no 8, p. 1206-1223Article in journal (Refereed) Published
Abstract [en]

Stability control of a vehicle in autonomous safety-critical at-the-limit manoeuvres is analysed from the perspective of lane keeping or lane changing, rather than that of yaw control as in traditional ESC systems. An optimal control formulation is developed, where the optimisation criterion is a linear combination of the initial and final velocity of the manoeuvre. Varying the interpolation parameter in this formulation turns out to result in an interesting family of optimal braking and steering patterns in stabilising manoeuvres. The two different strategies of optimal lane-keeping control and optimal yaw control are shown to be embedded in the formulation and result from the boundary values of the parameter. The results provide new insights and have the potential to be used for future safety systems that adapt the level of braking to the situation at hand, which is demonstrated through examples of how to exploit theresults.

Place, publisher, year, edition, pages
Taylor & Francis, 2019
Keywords
Vehicle stability, yaw control, lane keeping, lane change, avoidance manoeuvre, at-the-limit
National Category
Vehicle Engineering
Identifiers
urn:nbn:se:liu:diva-152896 (URN)10.1080/00423114.2018.1549331 (DOI)000470891200008 ()
Funder
Knut and Alice Wallenberg Foundation
Note

Funding agencies: Swedish Government (Sveriges Regering); Wallenberg AI, Autonomous Systems and Software Program (WASP) (Knut och Alice Wallenbergs Stiftelse) - Knut and Alice Wallenberg Foundation

Available from: 2018-11-27 Created: 2018-11-27 Last updated: 2020-10-22Bibliographically approved
Fors, V., Olofsson, B. & Nielsen, L. (2019). Yaw-Moment Control At-the-Limit of Friction Using Individual Front-Wheel Steering and Four-Wheel Braking. In: : . Paper presented at 9th IFAC Symposium on Advances in Automotive Control (AAC) (pp. 458-464). , 52(5)
Open this publication in new window or tab >>Yaw-Moment Control At-the-Limit of Friction Using Individual Front-Wheel Steering and Four-Wheel Braking
2019 (English)Conference paper, Published paper (Refereed)
Abstract [en]

A simplified combined-slip model that only considers the extreme case at the friction limit is suggested and used in a closed-loop controller for autonomous vehicle handling in at-the-limit maneuvers. In the development of the controller it is assumed that the front wheels are individually steered, but it is demonstrated in a left-hand turn scenario that with a simple adaptation, the method is still applicable for a vehicle with equal front-wheel angles.

Series
IFAC-PapersOnLine, ISSN 2405-8963 ; 5
Keywords
tire modeling, chassis control, yaw control, departure prevention, optimal control
National Category
Electrical Engineering, Electronic Engineering, Information Engineering
Identifiers
urn:nbn:se:liu:diva-160480 (URN)10.1016/j.ifacol.2019.09.073 (DOI)000486629500074 ()
Conference
9th IFAC Symposium on Advances in Automotive Control (AAC)
Funder
ELLIIT - The Linköping‐Lund Initiative on IT and Mobile CommunicationsWallenberg AI, Autonomous Systems and Software Program (WASP)
Note

Swedish Government; Wallenberg AI, Autonomous Systems and Software Program (WASP) - Knut and AliceWallenberg Foundation

Available from: 2019-10-08 Created: 2019-10-08 Last updated: 2020-12-11
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