RealFlow provides four individual nodes for different applications. They can be found under:
Edit > Add > Object >MultiServo>> MultiServo > [ MultiServo type ]
A MultiServo system always consists of at least two elements: two rigid bodies linked via a MultiServo node. This is already the entire setup and the objects can be either passive or active, have different shapes or size or are absolutely identical. It is up to you. In the following descriptions we will only discuss a two-body system, because it is much easier to understand, but everything said here is also valid for three or more objects. In this system we have body A with active rigid body dynamics properties and body B in passive mode. Object B is located in the scene's origin. Normally, all targets refer to object B's local system, but in this special case we can use the world coordinate system for convenience.
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The target position is the point in space the objects want to reach. A body's target velocity, on the other hand, is the speed the bodies want to acquire. All target position and velocity settings are made under the MultiServo's “Target” panel and there you have to specify three values for X, Y and Z. The following table shows you the different meanings of the “Target” values:
MultiServo Position Linear | The target distance the object should cover in metres. |
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MultiServo Position Angular | The targeted amount of degrees the object should cover. |
MultiServo Velocity Linear | The target velocity the object should achieve given in metres per second. |
MultiServo Velocity Angular | The target rotation speed the object should achieve, given in degrees per second. |
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So, the main question is which force/torque or power you finally need to accelerate the engine? Of course, there is a physically correct method to calculate these values using masses, frictions and velocities, but we recommend starting with these values:
Force Total mass of the linked objects * 100Power Force * 10Brake force Force * 10Brake power Power * 10
When you simulate, Caronte starts up in order to produce the change you want with the conditions you set. However, once the goal is achieved, it is necessary to stop and not go beyond it. This is why our motor also needs values for force and power to break (with the same meaning you saw before, but now the target is just to stop producing the change).
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- Add a basic object to the scene in your 3D program (cube, sphere etc.). This object will serve as a proxy for a more complex body, for example a fully featured car. The basic object should perform all the motions you want to see later in RealFlow. The object's motion can be stored in an animation path and exported as an SD file.
- Import the SD file into RealFlow and put the object (e.g. the car rig) at the exact initial position of the imported object.
- Add a “MultiServo Position Linear” node between the proxy object (“Rigids B”) and the object you want to move (“Object A”). The “Target” values are [ 0,0,0 ]. This means that both objects will perform exactly the same motion, because the main object will follow the proxy node, as it will try to keep its relative position in relation to the proxy: the relative positions between these nodes will remain the same, though the linked objects can move. Hide the proxy object and simulate the scene.
If the proxy object and the body you want to move (here, the car) should also have the same orientation, you must also add a “MultiServo Position Angular” node.
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