3. THE VIRTUAL SYSTEM Flashcards
Overview of modelling techniques
What is the Mechatronic system level simulation
Model the (multi-domain) interaction between the different (controlled) sub-systems to evaluate the system behavior
How does the V-design cycle looks like?
How could we validate the decisions in engineering?
Classically and numerically
What are the advantages of ussing numerical tools?
Practical organization of the V-Cycle, how do the different teams works?. Attention to the parallel work!
What are the different modeling tools?
-
1D/lumped parameter simulation: * Physics based: Connect
‘blocks’ with physically relevant quantities (SIMULINK) - Rigid multibody simulation:A mechanical system consists of multiple bodies connected by joints.
- Basic geometric and inertial information is required
- 1D tools do not handle these simulations well!
Different modeling Tools- Discretized partial differential equations (PDE)?
Different modeling tools- Flexible Model Simulation?
Model simulation costs?
What is the discrete element simulation
What is the modeling workflow
???
Important to split ‘solver’ from ‘design environment’???
Lumped parameter simulation for mechatronic systems
What are the 1D/lumped parameter
simulation modeling tool?
Physics based: Connect ‘blocks’ with physically relevant quantities: Simulink-Modelica
1/D Lumped parameter
What is the difference between Acausal and Causal
- 1D/Lumped parameter simulation- Why does matlab and simulink are stil use?
Characteristics of the Bond graph modeling
Modeling the bond graph, conditions
When to use the bond graph
Conclucion Bond Graph
The Finite Element Method in Structural Dynamics
How to begin with the FEM approach?
-Attention with the hooks law for linear elastic deformation.
-Equations of motion of an elastic body
-Take the PDE partial differential equations–>Equations of motion (kinematics)
Approach of the structural dynamics in FEM
Mesh!: Discretization of the problem domain and selection of a trial function:Subdivision of the problem domain in non-overlapping elements with simple geometry
-Always try to simplify the geometry
What are the resulting equations?
Assemble the contribution from all element
Stiffness matrix
The mass matrix
And the ressulting equations–>Equilibrium - motion - linearized
Be aware of Convergence, what is this, when does it happens?
What is the Multi-Point Constraints (MPC)
Its another kind of interface—same mesh
What are the limitations of the linear FEA
In linear analysis the stiffness of the system stays constant!
Why is the multibody simulation and why does we use them?, and what are the ingridients (RIGID)
-Interaction between various mechanicalcomponents (bodies) in a single system
What are the stesp for the multibody simulation (RIGID)
How do we describe the behavior of Rigid Bodies for simulations, what about its orientation and position? (RIGID)
First, we need to describe the kinematics and dynamics.
Moreover, We need to describe the position and orientation of a body unambiguously to perform reliable analysis.
Both, kinematics and dynamics are generalized
In order to handle these descriptions we need to be able to work with generalized degrees-offreedom and generalized coordinates q rather than just Cartesian coordinates x
What are the considerations with FLEXIBLE BODY KINEMATICS
Describe body motion as a superposition of:
* Rigid body motion
* Local flexible deformation
-Take only into account the most relevant deformation modes of a component and take them into account through their modal participation factors
-Apply model order reduction. a large number of nodal DOF’s is replaced by a set of nodes.
How to simulate Flexible MBS: connection points (joints)?
Use of spiders, to divide the load!!
Linear model order reduction
What are the different types of models and which domains?
State space model
Second-order model
Linear model order reduction
Explain the Component mode synthesis, for wich problems is this the best mehtod ?
Attachment modes
Constraint modes
Inertia-relief modes
Normal modes – free-free
Parametric Model Order Reduction
- What can the parameterization be in structures?
What are the steps of the PMOR: affine decompositionParametric Model Ord
What are the steps of the PMOR: affine decomposition
Modeling the actuators
How to modeling actuators? and what can you do if you are not interested in the internal or detailed behaiviour of the actuators?
Be aware, you can use electrical models or lumped models or FEM
Modeling actuators
What are the important aspects when modeling electrical machines?
-Frequency dependence due to skin/proximity effect
-Temperature dependence of resistance
-Parasitic Effects
Modeling actuators
What are the CONCLUSIONS ON ACTUATOR MODELLING–>Model fidelity and computational loads
̶ Finite Element Modelling/Analysis (FEM/FEA)
̶ Lumped parameter electrical/thermal models
̶ Equivalent circuits
̶ Simple saturation, rate limiter or transfer function-
Modeling actuators: Power Electronics
What are the attention point when modeling the power electronics?
Modelling actuators: SENSORS
Important points when modelling SENSORS, what should be modeled?—-MAIN CONCLUCSIONS
What to model?
- Noise, e.g. with white noise source
- Accuracy, e.g. with normal Gauss distribution
- Quantisation as consequence of ADC
- Saturation / range limits
Hybrid modeling
What is PHYSICS BASED MODELLING modeling
Modelling using first principles and physical insights, e.g. Newton’s laws, Kirchhoff laws
Hybrid modeling
What is DATA DRIVEN MODELLING
Advantages
- No expert knowledge required
- Can handle complex phenomena
Disadvantages
- Often not explainable
- Poor extrapolation capabilities
- Requires (a lot of) data
Hybrid modeling
What is Hibrid Modeling
