| 1. |
- Berntorp, Karl
(författare)
-
Particle Filter for Combined Wheel-Slip and Vehicle-Motion Estimation
- 2015
-
Ingår i: 2015 American Control Conference (ACC). - 0743-1619 .- 2378-5861. - 9781479917730 - 9781479986842 ; , s. 5414-5419
-
Konferensbidrag (refereegranskat)abstract
- The vehicle-estimation problem is approached by fusing measurements from wheel encoders, an inertial measurement unit, and (optionally) a global positioning system in a Rao-Blackwellized particle filter. In total 14 states are estimated, including key variables in active safety systems, such as longitudinal velocity, roll angle, and wheel slip for all four wheels. The method only relies on kinematic relationships. We present experimental data for one test scenario, using a Volkswagen Golf equipped with state-of-the-art sensors for determining ground truth. We report highly promising results, even for periods of combined aggressive cornering and braking.
|
|
| 2. |
- Hosseini, Seyed Mehrdad, 1977, et al.
(författare)
-
Adaptive forward collision warning algorithm for automotive applications
- 2016
-
Ingår i: American Control Conference. - 0743-1619. - 9781467386821 ; 2016-July, s. 5982-5987
-
Konferensbidrag (refereegranskat)abstract
- This paper proposes an adaptive collision warning algorithm (CWA) that supports the driver by issuing early warnings for collision avoidance without noticeably increasing the risk of false alarms in real traffic. This algorithm can also detect when an emergency intervention is necessary. Compared to existing CWAs, the proposed solution in this paper triggers alarms by solving a linear convex program using traffic data, road’s constraints and bicycle model dynamics, and by incorporating an adaptive (speed-dependent) warning threshold. A collision threat is detected by determining feasible steering trajectories without altering the vehicle’s longitudinal velocity.
|
|
| 3. |
- Hult, Robert, 1984, et al.
(författare)
-
An approximate solution to the optimal coordination problem for autonomous vehicles at intersections
- 2015
-
Ingår i: American Control Conference. - 0743-1619. - 9781479917730 ; 2015, s. 763-768
-
Konferensbidrag (refereegranskat)abstract
- In this paper, we address the problem of optimal and safe coordination of autonomous vehicles through a traffic intersection. We state the problem as a finite time, constrained optimal control problem, a combinatorial optimization problem that is difficult to solve in real-time. A low complexity computational scheme is proposed, based on a hierarchical decomposition of the original optimal control formulation, where a central coordination problem is solved together with a number of local optimal control problems for each vehicle. We show how the proposed decomposition allows a reduction of the complexity of the central problem, provided that approximated parametric solutions of the local problems are available beforehand. We derive conditions for the construction of the parametric approximations and demonstrate the method with a numerical example.
|
|
| 4. |
- Klintberg, Anton, 1989, et al.
(författare)
-
Theoretical bounds on the accuracy of state and parameter estimation for batteries
- 2017
-
Ingår i: American Control Conference. - 0743-1619. ; , s. 4035-4041
-
Konferensbidrag (refereegranskat)abstract
- Today it is standard to use equivalent circuit models to describe the dynamic behavior of Li-ion vehicle batteries. The parameters and states change with operating point and are therefore continuously estimated using bayesian observers, though without knowing to what degree the performance can be improved. Posterior Cramér-Rao Lower Bounds (CRLBs) can be used to theoretically quantify the optimal accuracy of bayesian estimators. In this paper we apply this to a second-order nonlinear equivalent-circuit model of a lithium-ion battery. It is shown, by numerical calculations, how the posterior Cramér-Rao Lower Bounds depend on the amplitude and frequency of the current, and on the slope of the Open Circuit Voltage (OCV) curve. Furthermore, it is investigated how much the accuracy is reduced in combined estimation of the states and the resistance compared to when the resistance is perfectly known. More importantly, it is also shown that the Mean Square Errors (MSE) of an Extended Kalman Filter (EKF) are close to the posterior CRLBs, which means that, under the investigated circumstances, it is not possible to significantly reduce the MSEs by replacing the EKF by any other observer.
|
|
| 5. |
- Murgovski, Nikolce, 1980, et al.
(författare)
-
Convex relaxations in the optimal control of electrified vehicles
- 2015
-
Ingår i: American Control Conference. - 0743-1619. - 9781479986842 ; 2015-July, s. 2292-2298
-
Konferensbidrag (refereegranskat)abstract
- When controlling the energy flow in electrified powertrains by means of convex optimization, the typically non-convex set of the original formulation needs to be relaxed to a convex super-set. In this paper we show that when using the backward simulation approach, where vehicle velocity is equal to the reference velocity, the global optimum of the original non-convex problem can be obtained by solving the relaxed convex problem. When vehicle velocity is kept as a state in the problem, in the so called forward simulation approach, we provide a condition for which, when satisfied, an agreement will be achieved between the solutions of the relaxed and the original problem.
|
|
| 6. |
- Nilsson, Julia, 1986, et al.
(författare)
-
Longitudinal and lateral control for automated lane change maneuvers
- 2015
-
Ingår i: American Control Conference. - 0743-1619. - 9781479986842 ; 2015-July, s. 1399-1404
-
Konferensbidrag (refereegranskat)abstract
- This paper considers the trajectory planning problem of a vehicle system for automated lane change maneuvers. By considering a lane change maneuver as primarily a longitudinal planning problem, the proposed trajectory planning algorithm determines whether there exists a longitudinal trajectory which allows the ego vehicle to safely position itself in a gap between surrounding vehicles in the target lane. If such a longitudinal trajectory exists, the algorithm plans the corresponding lateral trajectory. The lane change trajectory planning problem is thereby reduced to solving low-complexitymodel predictive control problems resulting in loosely coupled longitudinal and lateral motion trajectories. Simulation results demonstrate the ability of the proposed algorithm to generate smooth collision-free trajectories for lane change maneuvers.
|
|
| 7. |
- Nilsson, Magnus, et al.
(författare)
-
ADMM applied to energy management of ancillary systems in trucks
- 2015
-
Ingår i: American Control Conference. - 0743-1619. - 9781479986842 ; 2015-July, s. 3459-3466
-
Konferensbidrag (refereegranskat)abstract
- This paper investigates how recently endorsed methods in distributed optimization can be exploited in the energy-management problem for heavy trucks, with focus on improved control of ancillary systems. The justification for investigating this is because it may offer higher modularity and integrity to the development process of vehicle models. This paper assumes an indirect approach for solving the optimal control problem. For simplicity, a multi-level control hierarchy is also assumed, where prediction and integer decisions are planned at a higher level, while real-time decisions take place at a lower level. This allows the higher level to deliver an estimate of optimal costates to the lower level. Convex models of ancillary components allow the problem to be formulated as a second-order cone program at the lower level, which can be reformulated as an exchange problem suitable for distributed control. The exchange problem is solved using the alternating direction method of multipliers with proximal message passing, which returns a solution with the same fuel economy as that from dynamic programming. Convergence properties are briefly discussed, where the most notable conclusion is that warm start gives a significant improvement on the convergence rate, supporting practical feasibility of the distributed approach.
|
|
