Model-Based Development

Transcription

1 MODPROD Workshop 2014 Model-Based Development Examples of how Optimal Control can Support Design and Evaluation Lars Eriksson Division of Vehicular Systems Department of Electrical Engieering Linköping University

2 The Application Big Toys for Big Boys 2

3 The Application Short Loading Cycle Pick up gravel Reverse and lift Stop Drive and lift Empty bucket Back and lower Stop Drive Fill Bucket -How to drive optimally? 3

4 Outline Wheel loader application How to operate the wheel loader optimally Modeling for control and optimal control Formulating and solving the optimal control problem Numerical optimal control Design problems and trade-offs Solving fuel and time optimal driving Design case Stiff converter Design case Intelligent braking Design case Where to park load receiver? Conclusions 4

5 Wheel loader model Sub systems : 1- Driveline Controls: Fuel injection, Brake torque signal. 2- Lifting system Controls: Bucket lift acceleration. 3- Steering system Controls: Derivative of steering angle. States: Engine speed, Intake manifold pressure, Vehicle speed. States: Bucket height, Bucket lift speed. States: Vehicle position, Heading angle, Steering angle.

6 Wheel loader model = torque Braking acceleration Bucket Fuel b ab mf U U U Controls : = speed Lift height Lift speed Vehicle distance Travelled speed Engine V H V S bucket bucket ice States : ω

7 Diesel engine model P = P + load trac P lift

8 Lift system and constraints

9 Torque converter η tc = φ ψ 1 φ ψ φ 1 φ 1 2 T.C. studied (one delivers 15 % more torque) Remove the discontinuities (efficient numerical optimization)

10 Vehicle speed and position

11 Steering system and vehicle position P steer Derivative of dδ = Ustr dt dθ V = dt R dx = V cos( θ ) dt dy = Vsin( θ ) dt steering angle U 2 str Constraints during steering U str, min Continuous steering angle U str U str,max Minimum turning radius L R min = R δ 2tan( ) 2

12 Outline Wheel loader application How to operate the wheel loader optimally Modeling for control and optimal control Formulating and solving the optimal control problem Numerical optimal control Design problems and trade-offs Solving fuel and time optimal driving Design case Stiff converter Design case Intelligent braking Design case Where to park load receiver? Conclusions 12

13 How to drive optimally? Lift transport section (and complete cycle) Minimum Time Minimum Fuel

14 Short loading cycle One complete cycle - Fork lift application Wheel loader optimal transients in the short loading cycle. Vaheed Nezhadali, Lars Eriksson. Submitted to the 19th IFAC World Congress 2014, South Africa.

15 Optimal Control Problem Complete cycle Fork lift application

16 PROPT tool and model implementation

17 Outline Wheel loader application How to operate the wheel loader optimally Modeling for control and optimal control Formulating and solving the optimal control problem Numerical optimal control Design problems and trade-offs Comparing fuel and time optimal driving Design case Stiff converter Design case Intelligent braking Design case Where to park load receiver? Conclusions 17

18 How to drive optimally? Only lift transport section Minimum Time Minimum Fuel

19 Time and fuel optimal solutions, trajectories Min T : acceleration» lifting» acceleration» lifting Min Fuel: - Avoiding high engine speeds. - Simultaneous acceleration and lifting

20 Break down of energy and losses Min Fuel Min T Trac%on Li+ing Engine acc. T.C losses G.B losses Trac%on Li+ing Engine acc. T.C losses G.B losses

21 Torque converter selection η tc = φ ψ 1 φ ψ φ 1 φ 1 2 T.C. studied (one delivers 15 % more torque)

22 Trade-off between fuel and time optimal Stiff torque converter is better Good to know Fuel optimal cycle to 50 % shorter cycle only 5 % fuel cost Time optimal cycle to only 5 % longer cycle 30 % fuel saving

23 Intelligent Braking Torque Converter vs Service Brakes Easy driving Switch to reverse Use engine and torque converter to brake Innovation Switch to reverse Control service brakes - How much is saved?

24 Intelligent Braking Torque Converter vs Service Brakes Intelligent braking is - More efficient - Faster Optimal Control of Wheel Loader Operation in the Short Loading Cycle Using Two Braking Alternatives. Vaheed Nezhadali, and Lars Eriksson. In: IEEE VPPC The 9th IEEE Vehicle Power and Propulsion Conference. Beijing, China.

25 Break down of energy and losses (Half of short loading cycle) To compare: - Cycle time. - Fuel consumption. - Course of events. - Proportion of consumed energy. Optimal lifting and Path Profiles for a Wheel Loader Considering Engine and Turbo Limitations. Vaheed Nezhadali, and Lars Eriksson. In: Optimization and Optimal Control in Automotive Systems, In Lecture Notes in Control Sciences, Editors: L. del Re, I. Kolmanovsky, M. Steinbuch and H. Waschl. Springer.

26 Free Load Receiver Placement Increased freedom Position Orientation

27 Trajectory from loading point to load receiver (Half short loading cycle) Same trajectory for Min M f and Min T cycles Optimal lifting and Path Profiles for a Wheel Loader Considering Engine and Turbo Limitations. Vaheed Nezhadali, and Lars Eriksson. In: Optimization and Optimal Control in Automotive Systems, In Lecture Notes in Control Sciences, Editors: L. del Re, I. Kolmanovsky, M. Steinbuch and H. Waschl. Springer.

28 Optimal trajectories in the complete short loading cycle (Different load receiver orientation, delayed lifting) Same to/from Same min T /min Mf Different to/from Different min T/min mf Towards load receiver: Solid line Towards loading point: Dashed line Wheel loader optimal transients in the short loading cycle. Vaheed Nezhadali, Lars Eriksson. Submitted to the 19th IFAC World Congress 2014, South Africa.

29 Outline Wheel loader application How to operate the wheel loader optimally Modeling for control and optimal control Formulating and solving the optimal control problem Numerical optimal control Design problems and trade-offs Comparing fuel and time optimal driving Design case Stiff converter Design case Intelligent braking Design case Where to park load receiver? Conclusions 29

30 Summary and Conclusions A model for the wheel loader has been developed. Lifting, steering and driveline dynamics were included. Formulated and solved several optimal control problems. The complete short loading cycle was described by boundary conditions. Multiple phases introduced to avoid discontinuities in gearbox gear ratio. Calculated the optimal trajectory of WL in the short loading cycle. Investigated the trade-off between fuel consumption and cycle duration when: - Torque converter selection. - Torque converter is used for braking instead of mechanical brakes. - Load receiver oriantation is changed from the optimal. - Load lifting is delayed into later phases of the cycle. - Turbocharger effects are included in the diesel engine model.

31 Publications 1- Parallel Multiple-Shooting and Collocation Optimization with OpenModelica. Bernhard Bachmann, Lennart Ochel, Vitalij Ruge, Mahder Gebremedhin, Peter Fritzson, Vaheed Nezhadali, Lars Eriksson, and Martin Sivertsson (2012). In: Modelica th International Modelica Conference. Munich, Germany. 2 - Modeling and Optimal Control of a Wheel Loader in the Lift-Transport Section of the Short Loading Cycle. Vaheed Nezhadali, and Lars Eriksson. In: 7th IFAC Symposium on Advances in Automotive Control. Tokyo, Japan. 3 - Optimal Control of Wheel Loader Operation in the Short Loading Cycle Using Two Braking Alternatives. Vaheed Nezhadali, and Lars Eriksson. In: IEEE VPPC The 9th IEEE Vehicle Power and Propulsion Conference. Beijing, China. 4 - Optimal lifting and Path Profiles for a Wheel Loader Considering Engine and Turbo Limitations. Vaheed Nezhadali, and Lars Eriksson. In: Optimization and Optimal Control in Automotive Systems, In Lecture Notes in Control Sciences, Editors: L. del Re, I. Kolmanovsky, M. Steinbuch and H. Waschl. Springer. 5- Turbocharger Dynamics Influence on Optimal Control of Diesel Engine Powered Systems. Vaheed Nezhadali, Martin Sivertsson and Lars Eriksson In: SAE World Congress 2014, Detroit, USA. 6 - Wheel loader optimal transients in the short loading cycle. Vaheed Nezhadali, Lars Eriksson. (Submitted to the 19th IFAC World Congress 2014, South Africa).

32 Model-Based Development Examples of how Optimal Control can Support Design and Evaluation Lars Eriksson, Special Thanks to: Vaheed Nezhadali, PhD Student, Vehicular Systems, LiU Anders Froberg, PhD, Volvo CE Jonas Larsson, PhD, Volvo CE

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34 Time Optimal Transients (Complete short loading cycle) Normal lifting V.S. Delayed lifting ( θ 5 =free) θ 5 =free V.S θ 5 =180 (normal lifting) Wheel loader optimal transients in the short loading cycle. Vaheed Nezhadali, Lars Eriksson. Submitted to the 19th IFAC World Congress 2014, South Africa.

35 Wheel loader optimal transients in the short loading cycle. Vaheed Nezhadali, Lars Eriksson. Submitted to the 19th IFAC World Congress 2014, South Africa. Trade-off between fuel consumption and cycle time (Complete short loading cycle)

36 Turbocharger Dynamics Influence on Optimal Control of Diesel Engine Powered Systems. Vaheed Nezhadali, Martin Sivertsson and Lars Eriksson. In: SAE World Congress 2014, Detroit, USA. Turbocharger effects on engine operation (Half of short loading cycle)

37 Turbocharger effects on cycle time and fuel consumption Short loading cycles of different travelling distance Short loading cycles of same travelling distance, varied duration Turbocharger Dynamics Influence on Optimal Control of Diesel Engine Powered Systems. Vaheed Nezhadali, Martin Sivertsson and Lars Eriksson. In: SAE World Congress 2014, Detroit, USA.