The XiL-Framework is based on long-term research at IPEK – Institute of Product Engineering dating back to 1996 and integrates consequently simulation and experiment in the product engineering process. It is considered a framework suitable for the continuous, holistic, customer oriented synthesis and validation of modern vehicles with complex functionality with respect to environmental interactions.171F
172
Therefore, the physical test bench employed in this work was conceived in accordance with the XiL-framework. In this section, the placement of the framework in the engineering process, as well as a description of its elements, is presented.
2.3.1 The Product Engineering Process
According to ALBERS172F
173, the product engineering process can be described as a
continuous interaction of three systems: the operation system, the system of objectives and the system of objects, also called the system triple of product engineering. Furthermore, ALBERS173F
174 also states that discussing human knowledge and process
aspects of the system triple approach reveals the necessity of specifying the role of the operation system within the co-evolutionary and iterative process of complex product engineering. Therefore, the Advanced System Triple Approach174F
175 (c.f. Fig.
2.19) is introduced in order to describe the two central activities of product engineering: the combination of analyzing objectives and synthesizing objects (creation) and the combination of analyzing objects and synthesizing objectives (validation).
Figure 2.19: Advanced System Triple Approach ( from ALBERS ET AL.175F
176)
170 Zell 1997
171 Busoniu et al. 2010
172 Albers et al. 2008, Düser 2010 and Albers / Düser 2011 173 Albers 2010
174 Albers et al. 2010 175 Albers et al. 2012b 176 Albers et al. 2013e
ALBERS176F
177 proposes the integrated product engineering Model – iPeM as a suitable
meta-model of the product engineering process mainly because of its high flexibility and generality. The meta-model is divided into “Activities of Product Engineering” (also called macro-activities), the “Activities of Problem Solving” (also called micro- activities), the “Phase Model”, the “System of Resources” and the system triple of objects, objectives and the operation system. Within the iPeM, the balance between the system of objectives and the system of objects is achieved through validation, which is considered the central macro-activity in the product engineering process. This balance, thus validation, is of great importance for the success of the engineering process as only thereby can knowledge be generated, as opposed to the simple comparison between objects and objectives. This knowledge is used to solidify and expand the system of objectives and allows a successful synthesis in case of a goal- oriented return of knowledge in other activities. A graphical representation of the iPeM is depicted in Fig. 2.20.
Figure 2.20: Integrated Product Engineering Model – iPeM ( ALBERS177)
2.3.2 XiL-Framework in the Context of Product Engineering
Within the development process, the application of the XiL-Framework mainly addresses the interaction of the activities “Modeling of principle solution & embodiment” and “Validation”. Furthermore, the activity „Project planning” allows an application-related realization of the framework.176 The framework represents a
continuously useable and process applicable approach as part of the “Operation 177 Albers 2010 Sy stem of Obj e ctive s Sy stem of Obje cts Sy s tem of Resources Operating System Phase Model Activities of Problem Solving
Activities of Product Engineering S P A L T E N Project Planning Profile Detection Idea Detection Modeling of Principle Solution & Embodiment
Validation
Production System Eng. Production Market Launch Analysis of Utilization Analysis of Decommission time today
System” of product engineering, which allows the analyzing of the three interacting systems “Driver”, “Vehicle” and “Environment” with a changing focus.177F
178Therefore, the
XiL-Framework constitutes a holistic and integrated development and validation framework for powertrain systems. The “X” represents the “System Under Development (SUD)” and can be located in any of the systems “Driver”, “Vehicle” or “Environment”.178F
179 The SUD can be of a physical, virtual or a combined physical/virtual
nature and can be conceived from a very abstract or highly concrete manner.179F
180 For
this reason, different layers in the XiL-Framework are introduced.
For the system “vehicle” these layers are the element-in-the-loop-layer, the subsystem and the vehicle-in-the-loop-layer (c.f. Fig. 2.21). On each layer the behavior of the rest vehicle is reproduced, either virtually or physically, and connected to the “driver” and the “environment” systems in order to reproduce their effects on the SUD as closely to reality as possible.
The “Driver” and “Environment” systems and the rest vehicle simulation can also be implemented on different scaling levels, which have to be determined according to the application at hand.
Figure 2.21: IPEK X-in-the-Loop-Framework180F
181
178 Albers et al. 2012a
179 In the context of this work the SUD is considered to be in the system “Vehicle”. Albers et al. 2013e
consider the cases where the SUD is located in any of the remaining systems.
180 Albers et al. 2014
181 Albers et al. 2008, Albers et al. 2012a and Albers et al. 2013e
Sy s te m „ Env iron m e nt“ Sy s te m „ Dr iv e r“ WSP-in-the-Loop
e.g. friction systems, software code, …
Rest-Vehicle-Model X-in-the-Loop
Model-in-the-Loop Hardware-in-the-Loop
virtual physical
System „Vehicle“
Driving Maneuvers and Test Cases
Road Test Roller Test Bench Vehicle-in-the-Loop Complete Vehicle
Subsystem-in-the-Loop
Level 1 (e.g. powertrain) …
Level i-1 (e.g. gearbox with clutch)
3
Motivation and Research Objectives
In this chapter, the motivation for a RL based active damping of clutch judder vibrations and the definition of the research objectives of this work are presented. First, the research gap regarding the suppression of clutch judder is derived from the disadvantages and shortcomings of state of the art in the field and the suitability of a RL based solution to close this gap is evaluated.