A moving part can look convincing in an animation and still fail to perform its intended task in a simulation. For molecular modelers testing a nano-device, that difference matters: a gripper may need to close around a target, but an imposed motion that is too fast can leave the system with no successful grasp to study.
The Simulate animation in SAMSON runs a multiple-step simulation at each animation frame. It can be combined with other animations that control atom positions, making it useful for testing a moving or constrained system rather than simply replaying a fixed trajectory.
First check the motion, not just the pose
A useful question is: how far does the moving part travel, and over how much time? The documentation’s nano-gripper example gives a concrete warning. Its actuated blue part moves 1.7 nm in 2.5 ps. Dividing distance by time gives an average speed of 0.68 nm/ps, or 680 m/s. At that rate, the gripper fails to grasp the cylinder.
This calculation is simple, but it changes how to interpret an animation. A series of plausible-looking positions does not by itself show that the system has had a suitable simulation at each stage of the motion. When a grasp fails, check the imposed movement and its timing before concluding that the design or target interaction is necessarily the problem. The example does not establish a universal speed limit; it shows why the motion schedule is part of the test.
Set up the animation sequence deliberately
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Add the Simulate effect by double-clicking it in the Animation panel of the Animator. Its keyframe is placed at the current frame, and you can move that keyframe if needed.
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Check the order of animations. The Animator executes animations from top to bottom, so place Simulate after the animations that generate the starting positions for the simulation. If the order is wrong, the simulation may not begin from the positions you intended.
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Inspect the simulation settings. In the Inspector for the Simulate animation, you can change the number of steps per frame and the step size for the simulator’s state updater. These settings determine how the simulation is carried out across animation frames, so review them as part of the setup rather than treating the animation as a simple visual effect.
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When you want to save the resulting trajectory, combine the simulation with the Record path animation. The recorded path can then be used with Play path or Play reverse path.
Turn a failed grasp into a useful test
A failed grasp is still informative if the setup makes the cause easier to examine. Start by calculating the average speed of the actuated part from its displacement and the time available. Then verify that the starting-position animations run before Simulate, and review the step count and step size in the Inspector. Adjust the motion schedule or simulation settings as appropriate for the question you are testing, and record the trajectory if you need to inspect or replay the result.
These checks do not guarantee that a gripper will grasp its target. They help separate a possible timing or setup issue from other explanations, and make it easier to compare simulation runs on a consistent basis.
For details on adding and configuring the animation, see the Simulate documentation.
Note: SAMSON and all SAMSON Extensions are free for non-commercial use. Get SAMSON.