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MECHATRONIC DESIGN METHODS AND SOFTWARE IN MECHANICAL ENGINEERING


The dynamic motion behaviour of complex mechanical structures can be improved by use of mechatronic design concepts and methods. Thus the mechanical parts of the mechatronic system are extended by actuators, sensors and modern digital online information processing systems. To determine and to optimize the functional features of the entire mechatronic system as well as the constructive layout, geometrical, physical-topological, and mathematical system models should be taken into account at an early stage in the design process before expensive test beds are mounted. To achieve optimal design results many a realistic system model of the mechatronic products has to be assembled, modified, analysed, and assessed in an iterative optimization process. To speed up this design process, a fast and efficient determination of dynamic models and analysis results (e.g., simulation data, frequency response). In the following, we want to present a solution to simplify and accelerate the design process of mechanical parts of a mechatronic systems especially for design engineers working in a visual manner.

On the basis of a geometric system model, physical-topological system models have to be derived in a first model transformation process which will be described in detail in the following. Here we want to demonstrate the determination of MBS models (Multi-Body System Models) from geometric models based on predefined solution-element objects. This transformation process is realized by a tool coupling between CAMeL and I-DEAS. In the second model transformation, process the mathematical equations are usually computed in explicit non-linear state-space representation form by discipline-specific formalisms (e.g., in mechanics by a Lagrange formalism). Undefined system parameters of the entire dynamic model and especially controller parameters (steering and feedback) have to be derived by means of methods from control theory (e.g., numerical parameter optimization, pole placement). For the assessment of the functional behaviour, analysis models (e.g., time domain data) are generally derived via an analysis process (e.g., time-domain analysis process). On the basis of the analysis results experienced, engineers will have to decide whether and which modifications have to be made in the next iteration step (e.g., state-space controller instead of PID controller, modification of the geometric model, etc.).

Model Transformation Process The entire transformation process of a newly created assembly-solution-object is subdivided into the transformation process of the assembly-, the part-, and the connection objects. The transformation processes of the part-solution objects are already defined. If more than one predefined transformation process is available, the design engineer has to choose a sensible MBS model. The connection objects result in MBS joint objects between two rigid bodies depending on the defined relative degrees of freedom. The transformation process of the assembly-solution objects can be seen as nearly a one-by-one process, because assembly objects describe the topology of the entire system model.

Fig:- Role of engineer in mechatronics

REALIZATION OF THE SOLUTION-ELEMENT-OBJECTS

The CAD/CAE/CAM system I-DEAS particularly supports the fast and efficient graphical construction and modification of new three-dimensional mechanical components, such as assembly solution-element objects based on a given part- and assembly solution-element catalogue. The mechatronic development system CAMeL supports the physical modeling and the analysis and optimization of the dynamic system behaviour of the entire mechatronic system model. For a general implementation of the solution-element objects presented, the model data structure and the processes have basically to be extended and modified in CAMeL and IDEAS. CAMeL is an open development system (Rutz, 1995) and is completely developed at MLaP. The commercial software system I-DEAS is not meant to be extended by external software developers. Thus a prototypical realization applied with an attractive example (milling machine) will prove the advantage of this idea.

MECHANICAL ISSUES A mechatronic system can be characterized synthetically by versatility and flexibility as two main aspects whose integration gives mechatronic behaviour of modern systems.

Versatility is mainly related to operation capability and performance that are needed for mechanical activity of a mechatronic system. Flexibility is mainly related to regulation capability and performance that are needed for controlled actions of a mechatronic system.

Thus, mechanical issues in mechatronic systems are related to versatility mainly in terms of Kinematics and Dynamics of a load movement, Mechanics of interactions (like contact and grasp), Dynamics of Multibody Systems. However, the mechanical attention is always linked to aspects of the mechatronic design and indeed, simulation of mechanical actions is usually performed by taking into account also models for the controlled actuation.

Thus, the role of Mechanical Engineering in Mechatronics can be understood according to two main aspects, namely the mechanical design and operation, and the mechanical interaction with environment in performing system tasks.

Those mechanical aspects both for design and operation aims are studied by looking at traditional disciplines for machinery but even at specific novel disciplines.

Thus, Kinematics and Dynamics of load movement are studied to analyse and investigate on the motion of mechatronic systems and load body during the operation performing or not a task.

Particular attention is usually directed to mechanical aspects of the motion in the system and load as due to the flexibility and control of the operation of the system. In addition the task is studied by looking both at kinematic and dynamic features of the motion and related actions against the environment and within the mechatronic system yet. The particular attention to motion issues is also motivated by the attention to safety and security issues both for the system and human operators that can be in the operation area of the system.

Mechanics of interaction is interesting in evaluating situations with mechanical contacts and force transmissions between the system parts or its extremity and environment or task object. It is fundamental to size the system actions according to the task requirements and specific analysis of the corresponding mechanics is necessary to achieve desired goals and proper working of the overall system.


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