LMMV Robot Modules
General Kinematic Description
Two robot modules (a standard and an enhanced version) have been added to control modular Cartesian robots that are built using the Adept Linear Modules. Both of these robot modules can be configured to support from 1 to 4 joints consisting of any combination of X/Y/Z/Theta axes.
Module Specifications
Minimum V+ Compatibility:
V+ 12.0B2 or later
Device Module File Name:
lm
elm (enhanced linear module)
Device Module Identification Number:
32 (lm)
33 (elm)
Default Startup Message:
LMMV X/Y/Z/Theta Robot Module (lm) Enhanced LMMV X/Y/Z/Theta Robot Module (elm)
Additional License requirements:
None (lm)
Kinematic License (elm)
Default Joint Configuration and Mapping
This robot normally contains four joints and four motors. By default, the joints and motors are mapped as followed
Servo Board
Joint
Motor
Board
Channel
1
1
1
1
2
2
1
2
3
3
1
3
4
4
1
4
4
1
6
Although the robot does not contain five motors, the fifth motor channel is utilized for implementing dual-encoder loop feedback for the Theta axis.
Robot Option Word (bit numbers start with bit #1):
Bit
Default
Description
2
Off
For the elm module, if this bit is on, linear and backlash compensation is enabled for all four joints of the robot. In this mode, executing a HERE or WHERE will return the current, commanded joint set points rather than the instantaneously converted encoder values. For the lm module, a configuration error is generated if this bit is on.
- Robot Model and Robot Serial Number, Default: 0, 0
Specific L
ink DescriptionsThese robot modules control a mechanism with up to a four degrees of freedom, which consist of three orthogonal, linear axes (XYZ) followed by a revolute axis (theta). The four axes of motion are defined as follows:
Joint 1 is a linear axis that moves in the world X direction. A positive displacement of the joint moves the robot in the positive world X direction.
Joint 2 is a linear axis that moves in the world Y direction. A positive displacement of the joint moves the robot in the positive world Y direction.
Joint 3 is a linear axis that moves in the world Z direction. A positive displacement of the joint moves the robot in the negative world Z direction.
Joint 4 is a revolute axis (theta) about the world Z direction. A positive rotation of the joint turns the robot's end effector in a negative direction relative to the world Z axis. The axis of rotation of joint 4 defines the nominal Z axis of the robot's tool frame of reference. That is, if a NULLtool is defined, the Z axis of the tool frame will be colinear with the axis of rotation of joint 4 and will be pointed in the direction of the negative Z axis.
As with all robot modules, the standard V+ BASE and TOOL transformations can be used in combination with the geometric model to specify and compute the end point of the robot relative to the world coordinate frame.
Variations in Axis Configuration
This module can be configured to control any combination of the four axes, from any single joint on up to all four axes.
Link Dimensions (Geometric Dimensional Constants)
There are no dimensional constants that can be specified for this device than the tool offset distance. The only geometric constraints of are that the base linear axes must be mutually perpendicular. It immaterial whether the mechanical drive axes that implement the mechanism are intersecting or offset from one another. In fact, the origin of the coordinate system can be arbitrarily defined to be any point relative the axis drives, so long as it is consistently defined from one working to the next.
Interpretation of Cartesian Rotations
During program-generated straight-line motions, the first Cartesian rotation speed controls the rate at which joint 4 (theta) rotates, and the speed should be set to be consistent with the joint-interpolated speed for the axis. If the theta axis is not configured, the first Cartesian speed should be set to zero. The second and third Cartesian angles are not utilized and their speeds should likewise be set to zero.
Coupling Between Robot Joints and Motors
Both the "lm" and "elm" modules support coupling between the Z and theta joints to allow coupled wrist axes to be properly controlled. In addition, the "elm" module includes a coupling matrix that provides skew compensation for errors in the orthogonality of the X and Y axes. In both cases, a 2-by-2 linear coupling matrix is provided to describe the coupling relationship.
Robot Configuration Control Program Instructions
The following robot configuration-control program instructions do not have any effect upon the operation of mechanisms controlled by this module:
ABOVE, BELOW, FLIP, NOFLIP, LEFTY, RIGHTY
Additional Restrictions & Notes
By default, each of the joints is configured with sample SPEC data. However, most likely, the sample SPEC data will not be appropriate for the linear modules that the customer has selected. Therefore, prior to powering on the linear modules, SPEC should always be executed to configure the robot module with the proper SPEC data.
To assist in identify the SPEC data in use, these modules include a 15-character ID string for each joint.
Please submit comments to: techpubs@adept.com
Last modified on: 01/23/2006
Copyright © 2006 by Adept Technology, Inc.
All rights reserved.
