Compressed-time kinematics-simulation with ASOM v7
Optimization of the simulation of kinematic assembly groups for car bodies (hatches, hoods, doors, convertible roof systems) in the conceptual design phase, using highly interactive “multi-variant compressed-time simulations” in the kinematics software ASOM v7.
Dipl.-Ing. Eliseo Milonia, info-key GmbH & Co. KG, Wuppertal
In this lecture, it will be shown by way of an interactive presentation with the kinematics synthesis software ASOM v7, how kinematic solution variants (e.g. for hatches, hoods, convertible roof systems, etc.) can be developed even in an early design phase, and how all solution variants developed in this way can stay accessible for later modifications with minimal effort. The following novel features implemented in ASOM v7 are, among others, of importance in this context and are presented in detail interactively:
- The simultaneous handling of multiple solutions and variants (under consideration of e.g. different inclinations, optional snow/wind loads, different temperatures, different manual force points of action, alternative drives, etc.) with almost no additional effort, since, e.g. for later modifications, all variants can be modified together (otherwise it would be necessary to individually modify, at least partially, dozens of variants, one after the other).
- The possibility for the user to predefine kinematic, kinetostatic and ergonomic conditions (conditions for manual forces, positions, gas spring design/ mounting, etc.) that have to be met with great precision.
- The integration of these approaches into a compressed-time simulation philosophy, where all results and effects of changes in the specified inputs are always computed immediately for the whole course of the motion, and are visualized in an open and intuitive way.
Introduction of the used example: Modified Door Handle
- At least two (or three) desired positions: 1. closed, 2. pre-opened, 3. open
- Specific maximal motor and manual forces for different environmental conditions (winter / summer etc.)
- Area restrictions
- Ergonomic conditions
- Mounting restrictions
Definition: When the movement of a kinematic system is simulated, the simulation duration is the actual physical duration of the simulated movement.
In a Compressed-time Simulation, the whole duration of the simulation (the complete simulated movement) is computed in a very small fraction of that physical duration after each system modification.
The computation is carried out in no more time than the simulation duration.
This way, the simulation can be played back in real time. To see changes in properties of the whole movement after you change the system, you need to wait until the whole simulation is computed.
The computation is carried out in a very small fraction of the simulation duration (ideally a small fraction of a second).
This way, changes in properties of the whole movement can be observed in real time, when changes are made to the system.
Real-time Simulation, example video
Compressed-time Simulation, example video
Interactive Synthesis Techniques
- Kinematics Synthesis: Immediate creation of solutions for the desired motion conditions. Multiple desired points or positions can be specified. Syntheses can also be built on moving objects (e.g. on a part of another synthesis).
- Energy Storage Synthesis: Find solutions with a desired energy storage (e.g. a gas spring).
- Force Synthesis: Desired forces can be specified for arbitrary simulation times. Depending on the degrees of freedom in the force characteristics of the necessary energy storage, either one or two conditions can be placed.
Interactive Synthesis Techniques, example video
Multiple Cases in One Simulation
If you don’t want to simulate only a very few selected system cases or system variants, the number of necessary cases can add up very quickly.
In the following example there are eight primary cases (2 x 2 x 2).
- Two alternative drive positions (2 cases)
- Alternatively with or without tension spring (2 cases)
- Alternatively with or without needed breakout force (2 cases)
The number of necessary cases can easily grow even higher and thus quickly become hard to manage. Supplementary cases for our example (typical requirements in car manufacturing):
- Direction of movement (2 cases: forward/backwards)
- Alternatively with or without additional torsion spring (2 cases)
- Different ambient temperatures (3 cases)
- Different points of action for manual force (2 cases)
Total number of cases: 192 (2 x 2 x 2 x 2 x 2 x 3 x 2)
Multiple Cases in One Simulation, example video
Keeping partial solutions during subsequent adjustments
Modifications can be made without the danger of destroying or losing important partial solutions or features after they are achieved. This comprises:
- Achieved positions (ending as well as intermediary). This aspect is illustrated in the following video.
- Furthermore, the Compressed-time Simulation makes it possible to keep features like
- Specified forces at specified simulation times
- Fulfilled area restrictions
- Fulfilled collision conditions
- Keeping predefined parameters in e.g. energy storages.
Keeping partial solutions during subsequent adjustments, example video
Including customer-specific know-how
Such as …
- A Collision (with or without offset)
- Current Collision state
- Collision state over whole simulation (Compressed-time Simulation)
- An Instant center of rotation
- A Specific force (e.g. maximum spring force)
- A Guarantee that the four-bar joints A1 and B1 stay in 'Area1'
Including customer-specific know-how, example video
Compressed-time-Simulation in ASOM v7 (at a glance)
- Get solutions for all cases in one simulation (here 8 cases)
- … with Interactive Synthesis Techniques
- … while modifying the project without losing previously found partial solutions and synthesis conditions
- … over the complete simulation time
- … including customer-specific know-how
Automotive Circle, Conference, Simulation 2016,
The virtual product and process development chain, from press plant to paint shop
Bad Nauheim, 05./06. Oktober 2016