On the Edge: Motion Simulation

8 Sep, 2006 By: Russell Brook

Discover Solid Edge's Motion Simulation tools for animation.

The Solid Edge Motion Simulation feature provides the capability to explode, render and animate your designs, allowing you to create dynamic photorealistic animations and motion simulations using existing Solid Edge 3D models.

This first of a two-part article looks at the Motion Simulation feature. Next month, I'll discuss how the Explode, Render and Animation commands combine with Motion Simulation to create animation files to communicate designs outside of your engineering department, create training and maintenance materials as well as shop floor documentation and more.

Full Motion Simulation Using the new motion simulation tools in Solid Edge, you can create fast, accurate and realistic conceptual motion studies during your design phase, animating designs to demonstrate and communicate product functionality in real time. Solid Edge provides capabilities that let you quickly and easily define motion relationships between gears, pulleys and hydraulic cylinders while applying motors to generate movement.

Gears act like enhanced assembly relationships. They work by determining a relationship (or ratio) between adjacent parts, such as gears and pulleys (rotation to rotation). Gears efficiently solve motion between related components without the need to define physical contact relationships. They can describe rotary-to-rotary (gears), rotary-to-linear (rack and pinion) or linear-to-linear (telescopic or hydraulic cylinder) relationships.

Motors complement gear relationships by driving a gear through its range of motion -- rotary or linear. Usually you only need one motor to drive a gear train, although multiple motors can be used for more complicated designs. After applying a motor to the driving gear, the gears themselves solve the rest of the motion. Motors provide properties include direction, speed and travel.

A dedicated timeline automatically captures events created by gears and motors and provides total control over your motion simulation.

Setting up a motion simulation is quick and easy. Just follow three simple exercises to discover the basic steps for adding gear relationships and setting up the motors required to generate your motion studies.

Setting Up the Exercise
If you want to use your own models for this exercise, jump to Exercise 1 -- Adding Gear Relationship.

The principles in this exercise are easily applied to many scenarios. I used the Solid Edge Engineers Reference (included in Solid Edge Classic) to quickly generate a set of paired spur gears. Select the Engineers Reference via the EdgeBar and double click Spur Gears (figure 1).

Figure 1. Access the Engineers Reference via the EdgeBar.

Accept the default settings. Before selecting the Create button, click on the Calculate button. Take note of the number of gear teeth for each of the gears. It should be 21 for the spur and 43 for the gear (figure 2). Click Create.

Figure 2. Note the number of teeth for the pinion and the gear. Use these to determine the accurate gear ratio later.

Both gears are generated automatically but must be positioned. Create an assembly sketch consisting of two vertical lines 112mm apart. Use a planar alignment to align the top faces of the gears. Axial align the gears so the center of the gear is aligned to the assembly sketch lines (figure 3). Be sure that the rotational lock is NOT applied; the gears need to be free to rotate. You are now ready to start the exercises.

Figure 3. Use an axial alignment to align the gear centers with the assembly sketch as shown.

Exercise 1 -- Adding Gear Relationship
Gears are a special type of assembly relationship; they not only position your parts, they also let you add additional parameters that define how the gear operates, such as their ratio.

Start by selecting the spur gear and choosing the Add Relationship button from the SmartStep ribbon bar (figure 4). Click the small drop down arrow to see all the assembly relationship options. Select the Gear relationship option.

Figure 4. Add relationships and select the Gear option.

There are three main gear types: Rotation to Rotation, which is used for circular gears; Rotation to Linear, which can be a applied to a rack and pinion; and Linear to Linear, used for hydraulic cylinders or assemblies with a telescopic action. For this exercise choose Rotation to Rotation (figure 5).

Figure 5. Solid Edge gear types.

The Solid Edge SmartStep appears. With the gear relationship type set to Rotation to Rotation, the drop-down list becomes active to let you select either Ratio or Teeth. Select the Teeth option in the combo box and enter 21 and 43 (if you are using your own models, choose parameters to suite your model). The gear ratio is automatically calculated based on the number of teeth (figure 6).

Figure 6. The Gear SmartStep ribbon bar lets you enter the gear parameters.

Follow the prompts in the SmartStep ribbon bar. Start by selecting the center of the spur gear and leave the direction at the default setting.

Then select the center of the gear, make sure you set the direction in the opposite direction to the spur to get realistic operation (figure 7).

Figure 7. Apply the gear relationship to both the spur and the gear.

You have now set up the gear relationship. To test it, select the Move Part icon from the main toolbar and drag the spur around the z-axis (figure 8).

Figure 8. Test the gear relationship by dragging the spur around its z-axis.

You can automate the gears. To automate the gear movement, you need a motion generator or motor. Exercise 2 explains how to apply them.

Exercise 2 -- Add a Motor
To apply a motor, simply select the Add Motor command from the main toolbar (figure 9).

Figure 9. Select the Add Motor command.

Then select the center cylinder of the spur gear for the location of the motor (figure 10).

Figure 10. Choose the center of the spur gear to position the motor.

Leave the default settings of rotation for the type and 120 degrees for the duration (figure 11).

Figure 11. Motor SmartStep lets you choose the type and duration/distance a motor drives the mechanism.

Exercise 3 -- Motion Simulation
Once you have defined the gear relationships and the motors, you're ready to automate your design. Start by choosing the Simulate Motor command under the Motor Command icon. The Motion Simulation Timeline automatically displays (figure 12). All events and object have been captured. For this exercise, press the Run button to set your gears in motion. Simply drag the motion duration, and for more complex mechanisms, just add more gears as necessary, while maintaining full control over timing and duration. You can also capture your motion study by saving it as an AVI. (More on this feature next month.)

Figure 12. The Motion Timeline captures motion events and lets you easily adjust your motion study and gear settings.

These simple exercises are designed to familiarize you with the fundamentals of Motion Simulation. You are now equipped to explore the many possibilities of generating more complex motion studies.

In next month's article, I'll explain how to explode, render and animate your designs. You'll also learn how to combine the techniques discussed in this article to create impressive full motion movies using exploding assemblies, motion, rendering and animation. See you On the Edge next month.

About the Author: Russell Brook

Russell Brook

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