Tutorial 16: Motion-Path and Blend-Curves

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Tutorial 16: Motion-Path and Blend-Curves

Motion-Path and Blend-Curve

The Objective

Add and edit a Blend-Curve

Add and edit a Motion-Path FB

Learn about motion continuity and curvature continuity

Apply the Motion-Path FB and Blend-Curve to Pick & Place motion of a two degrees-of-freedom SCARA type robot.


Motion Properties of a Point that moves on the XY-Plane (Mechanism-Plane).

If we move a Point with a general motion on the Mechanism-Plane, we can think of its:

A.Path on the Plane

B.Motion - position, velocity and acceleration - along the path

In MechDesigner, we can define the motion of a Point on the Mechanism-Plane in two different ways. We can use:

Piggyback Sliders : we design horizontal and vertical motions. We apply them to Sliders. The combined motions define the motion on the Mechanism-Plane.

Motion-Path : where we sketch the path for the Point, and give the motion of the Point along the Path.

Some design problems are easier to do with Piggyback Sliders and others with a Motion-Path.

Procedures: Add Piggyback Sliders and Add Motion-Path FB

Piggyback Sliders

1.Design two motions, one to be the X–axis motion and the other the Y–axis motion of the Mechanism-Plane (see Note)

2.Add X–Slider: Make this move in the X–axis direction of the model; apply the X-axis motion.

3.Add Y–Slider: Slides parallel with the Y–axis of X–Slider; apply the Y-axis motion. Its motion is a combination of the X-axis and Y-axis motions.

Note: The Slider directions are usually in the X–axis and Y–axis directions. However, this is not necessary. The direction of each slider should suit your design requirements.

Motion Properties of Piggyback Sliders:

A.The shape of the path of a Point on the Y-axis Slider is a combination of the X–axis and Y–axis motions.

To show the path, add a Trace-Point to a Point on the Y–Slider.

B.The magnitude of the velocity and acceleration values of the Trace-Point are a combination of the X–axis and Y–axis motions.

You can measure their magnitude of the combined motions with a Point-Data FB. You can also show them in the graphic-area if you edit the Point with the Point Properties dialog-box.

Motion-Path FB

1.Define the shape of a path, explicitly, with sketch-elements.  

2.Add a Motion-Point to the path, with the Motion-Path FB.

3.Design the motion along the path, and use a Motion FB to apply the motion to the Motion-Point.

Motion Properties of Point along a Path

A.The shape is given by the shape of the sketch-path.

B.The magnitude of the motion is a combination of the Motion and the shape of the sketch-path.

You can measure the Magnitude, X–axis and Y–axis motions with a Point-Data FB.

GST-Icon-FB-MotionPathUse the Blend-Curve and the Motion-Path FB

About the Motion-Path and Blend-Curve

Motion-Path FB - Basic

Blend-Curve and Motion-Path FB - Basic

Comparison of XY Piggyback Sliders and Blend-Curve