XZ Stacker Robot Module
This robot module controls a mechanism with two degrees of freedom – a linear joint (X) followed by a joint that provides vertical motion (Z). The XZ robot module can operate with either a rotary Z axis or a linear Z axis. In the linear mode, joint 2 moves directly up and down. In the rotary mode, joint 2 rotates about a horizontal axis, and the robot’s tool is assumed to be always maintained in a downward direction by a simple pivot and gravity arrangement. Consequently, this robot produces motions that are equivalent to an X/Z Cartesian robot. (See the Axis Configuration section below.)
Refer to the "Software Configuration" chapter in the AdeptMotion VME Developer’s Guide or the SmartMotion Developer's Guide, and this document, for installation instructions.
Module Specifications
Minimum V+ compatibility: 11.1
(This module is not available for V+ 11.0 or earlier.)
V+ License Requirements: "Kinematics License"
If you install a module for which you do not have a license, an "*Option not installed*" message will be displayed when you restart your system.
Device module name: XZ
Device module identification number: 23
This number is displayed with the robot serial and model number after the system boots up, and whenever the ID monitor command is issued.
Default startup message: "X/Z Stacker Robot"
The startup message is displayed just after the system boots up.
Default joint configuration and mapping (split-axis enabled):
Joint
Axis
Type
Motor
Board/Channel
1
1 (X)
Primary
1
1/1
2
2 (Z)
Primary
2
1/2
1
1 (X’)
>>Split
3
1/3
2
2 (Z’)
>>Split
4
1/4
Joint configuration and mapping with split-axis disabled:
Joint
Axis
Type
Motor
Board/Channel
1
1 (X)
Primary
1
1/1
2
2 (Z)
Primary
2
1/2
With multiple robots, it will be necessary to correct the joint configuration from the SPEC.V2 program to avoid conflicts.
Robot Option Word
Default robot option word value: 1 (split-axis control enabled, rotary joint 2)
Bit 1: Split-axis option
In this module, the robot option word enables the split-axis option (see appendix A). Turning on bit 1 (the least significant bit, mask value 1) enables the split-axis option. On this module, the split-axis operates on two joints, Joint 1 and Joint 2.
Bit 4: Linear joint 2
In V+ 11.1K1 (and later), the XZ robot module can operate with either a rotary joint controlling the Z axis, or a linear Z axis. The selection of the type of Z axis is controlled by bit 4 (counting from 1), mask value 8. If this bit is set, the Z axis is implemented with a linear joint, otherwise the Z axis is implemented with a rotary axis.
Note: If a linear Z axis is configured, the two link dimensions accessible via SPEC are ignored.
Axis Configuration
The two axes of motion for this mechanism are defined as follows:
1. 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.
2. Joint 2 is either a rotary or a linear axis.
When configured as a rotary axis:
Joint 2 is a revolute axis that rotates about an axis that is parallel to the world Y axis.
• A positive change in joint angle corresponds to a negative rotation about an axis parallel to the world Y axis.
• When joint 2 is positioned at zero degrees, its link will be horizontal and will point in the direction of the positive world X axis.
• When joint 2 is positioned at 90 degrees, its link points up in the direction of the world Z axis.
When configured as a linear axis:
Joint 2 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.
Independent of the positions of joints 1 and 2, the orientation of the tool mounting flange always points down (assuming a NULL BASE and TOOL). That is, the positive Z axis of the tool mounting flange always points in the world -Z direction.
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.
Maximum operating range of rotational joints
In the rotary configuration, joint 2 is limited to a range of less than 360 degrees.
In the linear configuration, there are no rotational joints.
Variations in Axis Configuration
This module must always have both joints configured.
Link Dimensions (Geometric Dimensional Constants)
Tool Z-offset distance
The Tool Z-offset distance defines the distance from the center of the wrist to the tool mounting flange. See the AdeptMotion VME User’s Guide for a description of this parameter.
Other Dimensional Constants
There are two dimensional constants that are utilized by this module. The first constant specifies the height of the axis of rotation of joint 2 above the world X-Y plane. The second constant specifies the length of the joint 2 link. This link length is measured from the center of rotation of joint 2 to the pivot point for the gripper.
Link Dimension Parameters for X /Z Robot
Parameter
Units
Value
1
height of axis of rotation of joint 2 (s1)
mm
2
length of link 2 (a2)
mm
Interpretations of Cartesian Rotation
Since the orientation is fixed, the program control Cartesian rotation parameters are not utilized, and their speeds should be set to zero.
Coupling Between Robot Joints and Motors
This module does not allow the motors for the two axes to couple. However, both joints can be optionally configured to be powered by a pair of motors operating under split-axis-control. When the first robot option bit is set (1), both joints are put into split-axis-control mode. In this mode, the first and third motors operate joint 1 and the second and fourth motors operate joint 2.
Robot Configuration Control Program Instructions
The following robot configuration control program instructions are utilized to specify the range of motion for joint 2:
FLIP, NOFLIP
For each world location, an XZ device can achieve the location in two configurations: one with the arm of the rotational link pointed in the positive X direction, and one with the arm pointed in the negative X direction. V+ will move to the required tool-tip position in the current configuration, and will only change configuration if a configuration-change instruction (FLIP, NOFLIP) is used. Moving from one configuration to the other requires the arm to move through either its +90 or -90 degree position (straight up or straight down). See Figure2.
The FLIP and NOFLIP instructions can be used to request a change in the robot configuration during the next move. When the robot is in a NOFLIP configuration, joint 2 is between -90 and +90 degrees and its link will generally point in the world +X direction. In the FLIP'ed configuration, this link will generally point in the world -X direction. The robot can only change configuration during a joint-interpolated move.
The following robot configuration control program instructions do not have any effect upon the operation of mechanisms controlled by this module:
LEFTY, RIGHTY, ABOVE, BELOW
(See the V+ Language Reference Guide for more information on these instructions.)
Additional Restrictions
None.
Special Features
This module supports split-axis mode for joints 1 and 2.
(See Appendix A.)
Please submit comments to: techpubs@adept.com
Last modified on: 02/13/2007
Copyright © 2007 by Adept Technology, Inc.
All rights reserved.
