Device Building

Designing a V5 MechanismThis section describes the basic tasks in creating an V5 mechanism.

Joint Taxonomy in a V5 MechanismCreating a V5 Mechanism

Creating Joints in a V5 MechanismDefining a Fixed Part in a V5 MechanismDefining Commands for a V5 Mechanism

Editing Joints for a V5 MechanismDefining Home Positions for a V5 Mechanism

Defining a Home Position TimetableUsing the Update Command

Creating a V5 Mechanism with a Joint Axis CommandDefining Travel Limits

Defining Tool Tips

Designing a V5 Mechanism file:///C:/Program Files (x86)/Dassault Systemes/B19doc/English/onli...

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Joint Taxonomy in a V5 MechanismDevice Building lets you define and edit 11 different joint types.

The table below describes the joint types and their characteristics. Note that only the joints that are assigned a command can bemanipulated.

In addition to the methods of joint creation described on this table, Device Building supports creating joints by selecting frames. These joints can be revolute, prismatic, cylindrical, spherical, planar or rigid.

GRAPHIC REPRESENTATION JOINT TYPE DEGREES OF FREEDOM COMMAND TYPE DIRECT MANIPULATION

Revolute 1 Rotation Angle YES / Left-mouse button

Prismatic 1 Translation Length YES / Left-mouse button

Cylindrical 1 Rotation1 TranslationAngle or Length YES / Left-mouse button

Length + Angle NO

Spherical 3 Rotations _ NO

Planar 2 Translations1 Rotation _ NO

Rigid _ _ NO

Roll Curve 1 Rotation1Translation Length NO

Slide Curve 2 Rotations1 Translation _ NO

Point Curve 3 Rotations1 Translation Length NO

Point Surface 2 Translations3 Rotations _ NO

Universal Joint 2 Rotations _ NO

All joint types that can be created in DMU Kinematics, while not available as part of Device Building, are supported in Delmiasimulations. In addition to the joint types listed above, additional supported joints are: screw, CV, gear, rack, cable, etc.


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Creating a V5 MechanismThis procedure shows how to create a mechanism and define the joint axis.

Open the rods.CATProduct document from the samples directory.

Create the Mechanism

Make sure you are in Design mode. If not, select the root product in the tree and select Edit > Representations > Design Mode.1.

Click New Mechanism .

The Mechanism is identified in the specification tree.

2.

Define the Joint AxisIn this section, you select two lines and two planes that define the joint axis.

Select Line 1 in the geometry area. In our example select a cylinder as shown:

The dialog box is automatically updated with your selection.

1.

Select Line 2 in the geometry area. Select a second cylinder.

The dialog box Current selection area is automatically updated.

2.


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Select a plane for each rod.

In the dialog box, the Current selection: Plane 1 and Plane 2 fields are updated.

The Revolute Joint is created and the specification tree is updated.

3.

Click OK to confirm the Revolute Joint creation.4.

Proceed in the same manner to create the other joints.5.

Remember to define at least one command and a fixed part within your mechanism.

You can also create a new mechanism by selecting Insert > New Mechanism from the menu bar.


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Creating Joints in a V5 MechanismThis procedure shows how to create joints in a V5 mechanism.

Open the rods+3joints.CATProduct document.

You can create 11 joint types as shown in the following table:

Revolute Roll Curve

Prismatic Slide Curve

Cylindrical Point Curve

Spherical Point Surface

Planar Universal

Rigid

In addition to these joint types, there is a method of creating joints using frames that relies on Joint Axis .

When you create a joint, you can define the mechanism within the same dialog box. Remember, though, that you can create a

mechanism independently from its joints by selecting Insert > New Mechanism from the menu bar or clicking New Mechanism .

Click Revolute Joint from the Kinematic Joints toolbar (Revolute Joint is the default joint type).1.

Click the arrow within the icon and undock the Kinematic Joints toolbar.2.

Select the joint type of your choice. For instance, click Rigid Joint .

The Joint Creation : Rigid dialog box is displayed.

The term "rigid" corresponds to "fully restricted" in the standard kinematic terminology.

3.

Select the parts either in the geometry area or in the specification tree.4.


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Your selection is shown in the Joint Creation: Rigid dialog box.

Click OK to confirm your operation.

The rigid joint is identified in the specification tree.

5.

For more information, please refer to Joint Taxonomy and Creating a Mechanism.


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Defining a Fixed Part for a V5 MechanismThis task describes how to define a fixed part.

Open the rods+4joints+cmd.CATProduct document from the samples directory.

Click Fixed Part from the toolbar or select Insert > Fixed Part... from the menu bar. The New Fixed Part dialog box is

displayed.

1.

Select the Fixed Part either in the geometry area or in the specification tree.2.

The fixed part is automatically defined and is identified in the specification tree.

You can use Undo at any time to modify your selection.

3.


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Defining Commands for a V5 MechanismThis task describes how to define a command on a cylindrical joint after its creation.

You can define a command either during joint creation or after joint creation.

Open the rods+4joints.CATProduct document. You created a mechanism in previous tasks.

Double-click Joint 4 in the specification tree. The Joint Edition dialog box is displayed.1.

Explore the options by checking Driven angle. The mechanism corresponds accordingly.

2.

Click OK to confirm your operation. The command is identified in the specification tree.3.

You can also create the command while creating a joint.


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Editing Joints for a V5 MechanismThis task describes how to edit the properties of a joint. Editing the properties of a joint includes:

modifying the joint name

activating or deactivating its command

Open the rods+4joints.CATProduct document from the samples directory.

Double-click the joint to be edited in the specification tree, i.e. Joint 1 as shown in the example below.

The Joint Edition dialog box is displayed.

1.

In the Joint name field, enter a meaningful name, i.e., Revolute 1-3.2.

Check the Driven angle command.

3.

Click OK to confirm your operation. The joint is updated and identified in the specification tree under its new name.4.


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Note that you can edit the mechanism name. Double-click the mechanism in the specification tree, enter a new name in the MechanismEdition dialog box displayed, and click OK.


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Defining Home Positions for a V5 MechanismDevice Building allows you to define one or more standard configurations (or home positions) for a mechanism. Each home position ischaracterized by a unique name and a set of command values. Home positions are typically used to define the desired states of amechanism; for example, the open and closed configurations of a gripper. This procedure describes several methods that you can useto define home positions for a mechanism.

See also: Mechanical Specifications.

Open the DRESSUP.CATProduct document.1.

Click Home Positions . The Home Position Viewer dialog box is displayed.

2.

Click New. The Home Position Editor dialog box is displayed with the standard jog controls in the upper section and a text

entry field in the lower section. The jog controls are used to specify the desired set of command values for the home position,

while the text entry field is used to specify its name.

3.

For the first home position, enter a value of 90 degrees (1.57 radians) in the numeric field for Command.1 and enter the

string "Home1" in the Home Position Name: field. Click OK.

4.


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Home1 has been added to the list of home positions for the mechanism.

5.

Define a second home position named "Home2". Use the slider bar to set the value of Command.1 to approximately -45

degrees (-0.785 radians). Click OK.

6.


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In the Home Position Viewer, double click on each home position. This has the effect of immediately moving the mechanism to

the specified coordinates.

7.

In the Home Position Viewer, select Home2 and click Modify. Move the mouse into the geometry area near the joint labeled

Joint.3. Use the manipulator to change the value of Command.1 to approximately -90 degrees (-1.57 radians). Click OK.

8.

Click Close on the Home Position Viewer.9.

For additional information on entering command values, see Jogging a Mechanism.


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Defining a Home Position TimetableDevice Building allows the user to define the elapsed time for a mechanism to move between each of its home positions. The set of allsuch time values is stored in a timetable. This information is typically used in simulation contexts when commanding a mechanism tomove from one configuration to another; for example, opening and closing a gripper.

This procedure describes how to define a home position timetable for a mechanism.


The previous task should be completed and loaded or open the sample document named rods+homes.CATProduct.

Click Timetable . The Timetable Editor dialog box is displayed. Notice that default time values are zero.

1.

Select the cell corresponding to row Home1 and column Home2. Enter a value of 10 seconds. This value represents the time

required to move from Home1 to Home2.

2.

Complete the timetable as follows:

3.

Click OK.4.


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Using the Update CommandThis procedure shows you how to use Update Positions to synchronize the assembly model and the kinematic model. This

command is typically used to impose the various joint constraints on a mechanism, after performing some operations on the assemblycomponent of the mechanism.

Open the rods_with_joints.CATProduct document.

Updating a mechanism

Move the Rod.2. and Rod.1 parts in this model:

Point to the compass manipulation handle.

Drag and drop the compass onto Rod.1 in the geometry area and move it away from Rod.4.

Move Rod.2 in a similar manner.

1.

Reposition the 3D compass as it was. Select View > Reset compass.

2.

Click Update Positions . The Update Mechanism dialog box is displayed.

3.

Click OK to confirm your operation. The mechanism is updated and the parts are returned to their original locations.4.


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Now, move Rod.2 and Rod.1 in the same way. Reset the compass.

5.

Click .6.

Check the "Take current positions for Rigid Joints" option. This option allows you to define the rigid joint offsets in terms of

the current positions of the mechanism.

The mechanism is updated as shown below.

7.


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Now simulate the mechanism. Please refer to Jogging a Mechanism.

The current position has been kept for Joint.2 (Rigid, Rod.4, Rod.1).

8.

Deleting an assembly constraint

If you need information about this particular constraint, double-click Coincidence.2 (Rod.3, Rod.4) in the specification tree to

display the Constraint Definition dialog box. Click OK.

1.

Right-click Coincidence.2 (Rod.3, Rod.4) in the specification tree. 2.


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Select Delete from the contextual menu displayed.

3.

Click . The Update Mechanism dialog box appears.

4.

Click OK. The joints within the mechanism are updated. Joint.1 (Revolute, Rod.3, Rod.4) is converted into a Cylindrical joint as

shown below.

Revolute:

Cylindrical:

5.


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Creating a V5 Mechanism with Joint AxisThis procedure describes how to create a mechanism with a joint axis.

Open the rods.CATProduct document. Use Defining Frames of Interest to put design tags on two of the rods in the place on thegeometry where you wish to create a joint.

Click Joint Axis from the Kinematics Joints toolbar. A joint creation dialog box appears.

1.

Select the New Mechanism button if you do not already have a mechanism created.2.

Select the relevant design tags on each product for axis 1 and axis 2.3.

Click OK to confirm your operation and the mechanism is created.

4.


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Defining Travel Limits

This task describes how to define travel limits for commands within a mechanism. The limits are used during jogging/simulation of adevice or mechanism.

The travel limits for robots within the robot catalog are specified by the robot manufacturer. In certain cases, users may wish to entermodified limits, e.g., to avoid a collision. These modified limits are called soft limits; the original limits are called hard limits. If a userenters soft limits, those limits become the lower and upper limits for a specific device; if the user does not enter any soft limits, thelower and upper limits are the hard limits.

Limits can be specified using mathematical expressions or numeric values. So that values can be defined as a relationship to other jointtravel limits, mathematical expressions can be used.

In addition to limits, users can also create a caution zone. Caution zones exist only in the world of CAM software; they are not definedwithin the robot controller. The purpose of a caution zone is to keep a margin so that a downloaded program will not exceed the limitafter calibration or minor changes in the real world.

This arc represents a robot's travel limits. The green area represents the normal travel limits; the gold / yellow area represents thecaution zone and the red area shows the range of soft to hard limits. The white line represents the soft limit while the black linerepresents the hard limit.This zone can be defined by a percentage or a value with respect to the soft limits.


To see how the command works with a device you have created yourself, use the rods+4joints+cmd.CATProductdocument, after you have defined a mechanism for it.

To see how the command works with a robot from the robot library, use BodySide_Robot.CATProcess, and double click onthe robot in the PPR tree. This will put the robot into Device Building.

You can access the sample file regardless of your configuration. However, access to the Standard Robot Library product depends onwhether you also have purchased this add-on to Device Building's configurations.

Select the device.1.

Click Travel Limits . The dialog box appears.2.

Alter the upper and lower joint limits using specific numeric values or a mathematical expression.

Mathematical Expression: An arithmetic statement that contains pre-defined functions and/or operators. For details, see

Operators and Functions.

Rules for Constant and Variable joint limits:

Specific numeric values imply that the joint limit is a constant.The units assumed during entry of constant joint limits are the current dialog units such asdegrees in the example for Joint 1 above.

1.

3.


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By contrast, a mathematical expression implies that the joint limit is a variable function.Such expressions are used when typically the joint limits for one joint are functions of other jointcurrent values. In the example above, the Joint 3 limits are a variable function of the Joint 2current value.

Mathematical expressions MUST always be started with an "=" sign. This informs the system thatthe following text is a variable joint limit.

If a mathematical expression is entered without the starting "=" sign then theexpression will be automatically prefixed and saved with an "=" sign on entering OKfor the "Modify Command Limits" dialog.

The units assumed within a mathematical expression are by definition always radians andmillimeters. Hence, for example, degree values specified in mathematical expressions, such as"=90+dof(2)" with 90 is to be 90 degrees, must be multiplied by the built in constant RAD so theexpression should be entered as "=90*RAD+dof(2)".

2.

(Optional) Alter the caution zone limit by using the spinners.

You can choose to define the caution zone in terms of absolute values or in terms of a percentage of the joint limits.

The caution zone, whether specified in percentage terms or in absolute values, cannot be greater than 50% of the total hard

limits range. If you attempt to set a range exceeding 50% of hard limits range for any joint, you will get a warning message,

and previous caution zone values of all the joints will be retained.

4.

Click OK.

To return to the hard limits set by the robot manufacturer, press the Reset button. The caution zone will return tozero, and any soft limits previously entered for any of the joints will return to the manufacturer's specifications. Ifthe limits have not been altered, the Reset button will appeared grayed out, as shown on the image above.

5.

Operators, Functions, and Constants for Mathematical Expressions

Operators Math Functions; abs SASA, acos, asin, atan SASS= acosr, asinr, atanr SSSA+ cos, sin, tan RANGE- cosr, sinr, tnr INRANGE* exp SASASA/ Int SASASS^ sqrt SASSSA1% floor, ceil SASSSA2( log, log10 RAMP)

Operators Usage

;Separator for expressions. Useful in case ofmultiple expressions for a nono-commandjoint.

, Arguments separator in a function.= Assignment+ Unary plus / binary addition- Unary minus / binary subtraction* Binary multiplication/ Binary division^ Exponent% Modulo operator( Opening parenthesis) Closing parenthesis

Math Usageabs(x) Returns absolute valueacos(x), asin(x),atan(x) Returns arc cos, sin, tan in degrees

acosr(x),asinr(x), atanr(x) Returns arc cos, sin, tan in radians

cos(x), sin(x),tan(x) Returns cos, sin, tan in degrees


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cosr(x), sinr(x),tnr(x) Returns cos, sin, tan in radians

exp(x) Returns e raised to power xint(x) Returns integer value resulting from truncationsqrt(x) Returns square rootfloor(x), ceil(x) Returns floor, ceiling of xlog(x), log10(x) Returns natural logarithm, logarithm base 10

Constant Name Value Used for ConversionPI 3.14159RAD 0.0174533 (to convert degrees to radians)DEG 57.29578 (to convert radians to degrees)


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Defining Tool TipsThis task describes how to define tool tips on a mechanism.

The tool tips are the parts of the device that are supposed to be in contact with the product for a given home position. The tool tipsare excluded from the clash analysis in tools like DPM Body-in-White's weldgun search.

Click Define Tool Tips .1.

Select the product. The dialog box below appears.

2.

From the pulldown menu, select the home position for which you will define the tool tips. The default value is All Positions,

although if you have home positions defined, you may select among those.

3.

On the part geometry, select the part that is a tool tip.

In some cases, such as weld guns, the parts may have two or more tips. You can select as many parts as areapplicable, one at a time.

The part name appears in the dialog box.

4.

When you have selected all the parts that make up the tool tip, click OK.5.


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Device Building