A general NMPC framework for a diesel engine air path
This paper presents the formulation of a parameterised nonlinear model predictive control (NMPC) scheme to be applied on a diesel engine air path. The most important feature of the proposed controller is that it uses no structural properties of the system model. Therefore, the proposed NMPC scheme can be applied to any nonlinear system, leading to a general framework for a diesel engine air path. Moreover, the computational burden is substantially reduced due to an optimisation problem of low dimension obtained by means of the parameterised approach. Simulation results and an experimental validation are presented in order to emphasise the controller's efficiency and the real-time implementability
A. Murilo, M. Alamir and P. Ortner. A General NMPC Framework for a Diesel Engine Air Path. International Journal of Control, Volume 87, No 10, pp 2194-2207, 2014.[download]
Identification of a class of nonlinear relationships: Application to the identification of emission models in Diesel engines
In this paper, a novel identification framework is proposed to capture a class of nonlinear dynamic relationships that link several input signals (and their past values) to a single output. The class of relationships is the one in which the single output to be identified may be any monotonic nonlinear function of a linear regressor that may be built up with the input signals and their past values. This obviously recalls the known Wiener identification structure with differences that are underlined in dynamic model of emissions (including NOx and Particulate Mater (PM)) of a diesel engine. The nice feature of the proposed approach lies in the fact that the underlying optimization problem to be solved is a constrained Quadratic Programming (QP) problem and this, despite the nonlinear character of the identified relationship.
M. Alamir, D. Alberer and L. Del Re. Identification of a Class of Nonlinear Dynamic Relationships: Application to the Identification of Emission Models in Diesel Engines. International Journal of Engine Research. (special issue, Vol 15, pages 898-905, 2014).[download]
Experimental evaluation of a hybrid MPC strategy for vehicle start-up with an Automated Manual Transmission
In this paper, an experimental evaluation is pre- sented for a Model Predictive Control (MPC) algorithm control- ling powertrains dynamics in vehicles with Automated Manual Transmissions (AMTs). This model based control enables on- line optimization by using sub-optimal solutions directly linked to the accelerator pedal position. Transmission stability con- straints are explicitly handled as well as saturations on the control inputs. This MPC control is tested on line during vehicle start-up in a mild hybrid city car demonstrator equipped with a natural gas engine. A comparison with a PI-based control is made to show the convenience of the proposed MPC control
Amari, R., P. Tona and M. Alamir. Experimental evaluation of a hybrid MPC strategy for vehicle start-up with an Automated Manual Transmission. Proceedings of the European Control Conference (ECC'09), Budapest, 2009.
Unified MPC strategy for idle-speed control, vehicle start-up and gearing applied to an Automated Manual Transmission
A real-time Model Predictive Control (MPC) is proposed for controlling the behavior of an Automated Manual Transmission (AMT). The underlying formulation shows a unified approach that handles different modes: idle-speed control, vehicle start-up, gearing up and down. Sub-optimal solutions are computed on line using an adaptive reduced dimensional parametrization that is directly linked to the accelerator pedal position. Transmission stability constraints are explicitly handled as well as saturations on the control inputs. The proposed control is tested both in simulation and on line in a city car demonstrator equipped with a natural gas engine.
Amari R., Alamir M. and Tona P. Unified MPC strategy for idle speed control, vehicle start-up and gearing applied to an Automated Manual Trasmission. Proceedings of the IFAC World Congress, South Korea (2008).[download]
On the Use of Parameterized NMPC in Real-Time Automotive Control
Automotive control applications are very challenging due to the presence of constraints, nonlinearities and the restricted amount of computation time and em- bedded facilities. Nevertheless, the need for optimal trade-off and efficient coupling between the available constrained actuators makes Nonlinear Model Predictive Con- trol (NMPC) conceptually appealing. From a practical point of view however, this control strategy, at least in its basic form, involves heavy computations that are often incompatible with fast and embedded applications. Addressing this issue is becom- ing an active research topics in the worldwide NMPC community. The recent years witnessed an increasing amount of dedicated theories, implementation hints and software. The Control Parametrization Approach (CPA) is one option to address the problem. The present chapter positions this approach in the layout of existing alter- natives, underlines its advantages and weaknesses. Moreover, its efficiency is shown through two real-world examples from the automotive industry, namely:
- the control of a diesel engine air path and
- the Automated Manual Transmission (AMT)-control problem.
In the first example, the CPA is applied to the BMW M47TUE Diesel engine avail- able at Johannes Kepler University, Linz while in the second, a real world SMART hybrid demo car available at IFP is used. It is shown that for both examples, a suit- ably designed CPA can be used to solve the corresponding constrained problem while requiring few milliseconds of computation time per sampling period.
Alamir, M., A. Murilo, R. Amari, P. Tona, R. Furhapter and P. Ortner, On the use of parameterized NMPC in real-time automotive control. In Automotive Model Predictive Control. L. Del Re (Ed). Lecture Notes in Control and Information Sciences, Springer-Verlag, (2009). [download]
Method of controlling the closing phase of a clutch of an automated automobile transmission system
A method of controlling an automobile clutch in an automated transmission system with a CMPC control is disclosed having application to vehicle clutch control in an AMT system. The driver's request is translated in terms of sliding velocity ωsl. Constraints on the engine and clutch actuators are defined to respect their operating limits, and driving quality constraints are defined to guarantee comfort during the clutch engagement phase. In order to meet these quality constraints, a reference trajectory is defined for ωsl as a function of the clutch engagement time. An analytical expression allowing real-time calculation of a set of control trajectories with a CMPC control law is then defined from the expression of this reference trajectory. The trajectory respecting the constraints on the actuators is selected from among all these control trajectories. Finally, the clutch is controlled with the selected control trajectory.
A phenomenological model for torque transmissibility during dry clutch engagement
We propose a phenomenological model of clutch torque transmissibility, valid for clutch engagement during vehicle start-up and applicable to both manual transmissions and automated manual transmissions, which can be identified via on-board measurement available in most production vehi- cles. The model is based on the identification of a nonlinear characteristic that relates the transmissibility of engine torque to the mainshaft to the clutch actuator position and the clutch slip speed. To smooth the effect of neglected dependencies on torque transmissibility and obtain a non-linear characteristic with very low dispersion, the engine torque set-point is also included in the model. An empirical estimation of load torque during start-up, dependent on slip speed and engine torque set-point, completes the model and improves its accuracy. The model has been identified and validated on two prototype vehicles with very different features: a small city car with an electrically-actuated automated manual transmission and a big executive car with an hydraulic-actuated manual transmission. This diversity should guarantee the generality of the model in a clutch control context. An application example is given at the end of the paper to show the usefulness of the model: an alternative analysis, based on power computation, of the conditions that have to be respected to avoid oscillations at clutch engagement.
Amari, R.; P. Tona and M. Alamir. A phenomenological model for torque transmissibility. during dry clutch engagement. Proceedings of the IEEE Multi conference on Systems and Control, Saint Petersburg, Russia, 2009.
Diagnosis and on-line parameter estimation of automotive electronic throttle control systems.
In this paper, a recently developed graphical signatures generation tool is used for diagnosis and on-line parametric estimation of automotive electronic throttle control (ETC) system. The underlying diagnosis problem corresponds to variations affecting four system’s parameters. It is shown that this diagnosis method enables detection, isolation and parameter estimation even under simul- taneous faults occurrence outperforming existing works on the same problem
Youssef, B.; Alamir, M. Diagnosis and On-line parametric estimation of automotive electronic throttle control system. Proceedings of the IFAC World Congress, Praha, Czech Republic, July (2005). [download]