| 1. |
- Albinsson, Anton, 1989, et al.
(författare)
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Friction utilization for tyre-road friction estimation on snow: an experimental study
- 2017
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Ingår i: 13th International Symposium on Advanced Vehicle Control, AVEC'16. - 9781315265285 ; , s. 541-546
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Konferensbidrag (refereegranskat)abstract
- Friction estimation using effect-based approaches are challenging during normal driving due to the large tyre excitation needed for an accurate estimate. The required excitation level varies for different tyres, road surfaces, road conditions and tyre models used in the estimator. Previous research has investigated the required friction utilization on different surfaces but due to the small sample sizes it is hard to draw any general conclusions. This paper investigates the tyre excitation required to estimate the tyre-road friction coefficient with a generic estimator for 76 different tyres on snow for five different tyre models and for different levels of measurement noise.
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| 2. |
- Gao, Y., et al.
(författare)
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Implementation of a modified hamiltonian algorithm for control allocation
- 2017
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Ingår i: Proceedings of the 13th International Symposium on dvanced Vehicle Control, AVEC 2016. - 9781315265285 ; 2017, s. 157-162
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Konferensbidrag (refereegranskat)abstract
- This paper is motivated by the problem of terminal understeer of a road vehicle. A relevant scenario is where a vehicle enters a curve at excessive speed and the control objective is to apply automatic chassis control to prevent the vehicle from drifting out of the lane. In a previous study, the optimization problem was formulated as the minimization of maximum path off-tracking; the optimal response approximates to that of a friction-limited particle model, leading to a parabolic path reference (PPR) with the target mass-centre acceleration vector fixed in the global frame. The present paper considers in greater detail how the acceleration target is realized on an experimental vehicle. The approach is based on a recently developed model-based control method – the Modified Hamiltonian Algorithm (MHA). Simulations with a full vehicle (CarMaker) model are carried out, and test-track experiments are conducted to test the controller and validate the simulations. Results show that transient effects such as actuator delays and rate limits can have a significant effect on performance. On the other hand, the controller appears robust to factors such as tyre wear and uncertainty in vehicle parameters, and closely approximates the particle reference once these transient effects are accounted for. Since the control architecture is adaptive to track a changing acceleration reference, these conclusions are likely to be valid across a wider range of scenarios.
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| 3. |
- Gil Gómez, Gaspar, et al.
(författare)
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Validation of a Moving Base Driving Simulator for Subjective Assessments of Steering Feel and Handling
- 2017
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Ingår i: 13th International Symposium on Advanced Vehicle Control. - : CRC Press/Balkema. - 9781315265285 ; , s. 431-436
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Konferensbidrag (refereegranskat)abstract
- Moving Base Driving Simulators (MBDS) have a large potential to increase effectiveness in vehicle dynamics development. MBDS can reduce dependency on vehicle-prototypes by allowing subjective assessments (SA) of models. Little is, however, known about the relation of SA in MBDS and in physical ve- hicles. This paper aims to increase this knowledge, and proposes and implements a methodology to validate MBDS for SA of steering feel and handling. Firstly, vehicle models were generated from Kinematics & Com- pliance measurements of real vehicles. These models were validated versus objective tests, with steering ro- bots, of the physical vehicles. These vehicles and their MBDS-models were assessed by expert drivers, using a scanned-test track in the MBDS. Comparison of the SA in both environments enabled the MBDS validation. Promising results, with higher SA accuracy for handling than for steering feel, indicates that the major im- provement effort should focus on the steering model and its simulation in the MBDS.
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| 4. |
- Jonasson, Mats, et al.
(författare)
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Steering redundancy for self-driving vehicles using differential braking
- 2017
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Ingår i: Advanced Vehicle Control AVEC’16 - Proceedings of the 13th International Symposium on Advanced Vehicle Control AVEC’16. - : CRC Press/Balkema. - 9781315265285 ; , s. 23-30
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Konferensbidrag (refereegranskat)abstract
- This paper describes how differential braking can be used to turn a vehicle in the context of providing fail-operational control for self-driving vehicles. A vehicle model is developed with differential brake and steering inputs. The model is used to explain the bounds of curvature that differential braking provides and it is then validated with measurements in a test vehicle. Particular focus is paid on wheel suspension effects that significantly influence the obtained curvature. Finally, a model based controller is developed to control the curvature by differential braking. The controller is designed to compensate for the wheel angle disturbance that is introduced as a result of the control event.
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| 5. |
- Yang, D., et al.
(författare)
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Evaluation of an evasive manoeuvre assistance system at imminent side collisions
- 2017
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Ingår i: Advanced Vehicle Control AVEC’16 - Proceedings of the 13th International Symposium on Advanced Vehicle Control AVEC’16. - : CRC Press/Balkema. - 9781315265285 ; , s. 55-60
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Konferensbidrag (refereegranskat)abstract
- In this paper, the performance of an Evasive Manoeuvre Assistance System is evaluated on the test track, where an imminent half-overlapping side collision scenario is reconstructed. The control function here aims to reduce the steering effort for an emergency swerve in front of obstacle and to ease the following recovery into the driver perceived safe zone. This is realized by combined differential braking and steering torque overlay, which improves the agreement between steering input and vehicle response. Preliminary test results have shown that the function has a great potential to reduce collision risk at the presence of suddenly appeared obstacle in front.
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| 6. |
- Zhang, Dong, et al.
(författare)
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A novel control mediation approach to active rollover prevention
- 2017
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Ingår i: Proceedings of the 13th International Symposium on Advanced Vehicle Control. - : CRC Press. - 9781315265285 ; , s. 203-208
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Konferensbidrag (refereegranskat)abstract
- This paper considers a novel approach to active rollover prevention, incorporating online estimation of the driver’s intended path. The problem is formulated as one of minimizing lateral deviation from the intended path subject to friction and rollover limits. A recently published control allocation and moderation method is developed to be applicable to the rollover problem in such a way that speed is optimally reduced. Furthermore, a new Time-To-Rollover (TTR) metric, based on driving intention prediction, is incorporated into the system concept. Finally, mediation provides a general approach to designing a cooperative system, coordinating between the human driver and the onboard autonomous safety system to reduce the sensitivity of vehicle response to any sudden or emergency driver actions.
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