Adams Basic Package > Adams View > View Command Language > constraint > constraint modify joint rackpin

constraint modify joint rackpin

Allows modification of an existing rack-and-pinion joint.

Format:

 
constraint modify joint rackpin
joint_name =
an existing joint
new_joint_name =
a new joint
adams_id =
integer
comments =
string
i_marker_name =
an existing marker
j_marker_name =
an existing marker
diameter_of_pitch =
real number

Example:

:
constraint modify joint rackpin &
joint_name =
JOINT__1 &
new_joint_name =
JOINT__2 &
adams_id =
2 &
comments =
"comment string" &
i_marker_name =
marker_1 &
j_marker_name=
marker_2 &
diameter_of_pitch =
0.22

Description:

 
Parameter
Value Type
Description
joint_name
An Existing Joint
Specifies the joint to modify.
new_joint_name
A New Joint
Specifies the name of the new joint.
adams_id
Adams_id
Specifies an integer used to identify this element in the Adams data file.
comments
String
Specifies comments for the object being created or modified.
i_marker_name
An Existing Marker
Specifies a marker on the first of two parts connected by this joint.
j_marker_name
An Existing Marker
Specifies a marker on the second of two parts connected by this joint.
diameter_of_pitch
Length
Specifies the pitch diameter of the pinion gear of a rack-and-pinion joint.

Extended Definition:

1. For a rack-and-pinion joint, the x-axis of the pinion must be parallel to and pointed in the same direction as the z (translational) axis of the rack. The separation between the two axes should be one-half the pitch diameter of the pinion. The rack-and-pinion joint itself does not enforce the position and orientation it requires, but the chain of both parts and joints that connects markers I and J should enforce the position and orientation. A common approach for enforcing the position and the orientation is to support the rack with a translational joint and to support the pinion with a revolute joint.
2. You may identify a joint by typing its name or by picking it from the screen. If the joint is not visible on the screen, you must type the name. You may also find it convenient to type the name even if the joint is displayed. If you created the joint by reading an Adams data set or graphics file, the joint name is the letters JOI followed by the Adams data set joint ID number. The name of Adams JOINT/101 is JOI101, for example. If you created the joint during preprocessing, you gave it a name at that time. If a joint is available by default, you may identify it by entering its name only. If it is not, you must enter its full name. To identify a joint under a model, for instance, you may need to enter the model name as well. For example, you may specify joint 'lower_pivot' in model 'links' by entering ".links.lower_pivot". You must separate multiple joint names by commas. If the joint is visible in one of your views, you may identify it by picking on any of the graphics associated with it. You need not separate multiple joint picks by commas.
3. Normally, entity names like the joint name are composed of alphabetic, numeric, or '_' (underscore) characters, and start with an alphabetic or '_' character. They may be any length. For more information, see Using Extended Names. By enclosing the name in double quotes, you may use other printable characters, or start the name with a numeral. If a name contains characters, or starts with a numeral, you must always quote the name when entering it. Note that you can specify the parentage of an entity (for example, what part "owns" a marker or a geometry element) when you CREATE it by changing the name. If you enter just the entity name, then the default parent will be assigned by Adams View. If you type in the full name, then you may over ride the default parent. In most cases, when creating an entity, Adams View will provide a default name. The default name that Adams View provides will specify the parentage that it has assumed. You may, or course, delete this name and use your own. The form of a full name is:
"...._NAME.GRAND_PARENT_NAME.PARENT_NAME.ENTITY_NAME"
The number of levels used varies from case to case and the parentage must exist before an entity can be assigned to it.
4. When you use the FILE ADAMS_DATA_SET WRITE command, Adams View writes an Adams data file for your model. Adams requires that each modeling element be identified by a unique integer identifier. If you use this parameter to specify a non-zero identifier, Adams View will use it in the corresponding statement in the Adams data file. You may also enter zero as an identifier, either explicitly or by default. The next time you write an Adams file, Adams View will replace the zero with a unique, internally-generated identifier. Adams View will permanently store this identifier with the element just as if you had entered it yourself. Normally, you would let all identifiers default to zero, and Adams View would generate the identifiers for you. You are never required to enter a non-zero identifier. You only need to specify it if, for some reason, you wish to control the Adams file output.
5. When an Adams Solver data file (.adm) is read into Adams View, all comments associated with a statement (from the end of the previous statement through the end of the current statement) are stored with the object. Comments in the data file can be associated with model. These comments must follow the title statement and be followed by the comment 'END OF MODEL COMMENTS'. This string must be uppercase. When an Adams Solver data file is written, the comments for an object are written before the statement corresponding to the object.
6. The pitch diameter relates the rotational motion of the pinion to the translational motion of the rack. When the pinion turns in the positive direction around the z-axis of the I marker, a positive pitch diameter moves the rack in the positive direction along the z-axis of the J marker and a negative pitch diameter moves the rack in the negative direction along the z-axis of the J marker.
7. A rack-and-pinion joint is a five-degree-of-freedom joint that constrains the rotational and translational displacement of the I marker as it rolls along the z-axis of the J marker. The I marker is at the center of the pinion, and the J marker is in the rack.
 
Tip:  
1. If you type a "?", AdamsAdams View will list the joints available by default.
2. Use the joint_name parameter to identify the existing joint to affect with this command.
3. You may use the new_joint_name later to refer to this joint. Adams View will not allow you to have two joints with the same full name, so you must provide a unique name.
4. Adams View connects one part at the I marker to the other at the J marker.