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Unread 28-01-2007, 16:53
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Re: Simulating Motion with Physical Dynamics

Quote:
Originally Posted by worldbringer View Post
That's cool.

How do you define the motion within the program? Do you, for example, describe the arm's angle as a function of time? Or does the program understand how motors work, and you input the motor's speed or power?
The physical simulator has four basic properties that can be applied to parts and assemblies -- gravity, linear spring, linear motor and rotary motor.

Gravity behavies as you might expect. You can vary the magnitude and direction.

Linear springs are defined by a free length and a spring force. The program seems to try to differentiate between compression and tension springs automagically and has mixed success. Unfortunately, there's no way to account for a spring's physical characteristics -- compressed length, particularly.

Linear and rotary motors are defined by speed of motion rather than the physical characteristics as well. Also, their operation is unaffected by other circumstances. For example, a rotary motor can be set to operate at a speed of 45*/sec -- but it doesn't slow or speed up based upon load.

The dynamics modeling is great for determining how motion will play out given a limited set of variables -- but it can by no means be used to determine gearing or load bearing capacity.
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