Coupled-Axis XYZ-Theta Robot Module

Coupled-Axis XYZ-Theta Robot Module

This robot module controls a mechanism with four degrees-of-freedom that consists of three orthogonal, linear axes (XYZ) followed by a revolute axis (theta). As compared to the general XYZtheta robot module, this module does not allow any joints to be disabled, but it does allow the Z and theta axes to be coupled and does include compensation for skew between the X and Y axes.

Refer to the “Software Configuration” chapter in the AdeptMotion VME User’s Guide, and chapter 3 of this manual, for installation instructions.

Module Specifications

Minimum V+ Compatibility
V+ 11.2R or later.

Device Module File Name
CAR

Device Module Identification Number

The following identification number is displayed with the robot serial and model number after the system boots up, and whenever the ID monitor command is issued: 22

Default Startup Message

The following startup message is displayed just after the system boots up:

Cartesian Robot Module

Default joint configuration and mapping (split-axis enabled)

The robot contains four joints and four motors. By default, the joints and motors are mapped as follows

Joint

Axis

Type

Motor

Board/Channel

1

1 (X)

Primary

1

1/1

2

2 (Y)

Primary

2

1/2

3

3 (Z)

Primary

3

1/3

4

4 (theta)

Primary

4

1/4

Additional 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.

Robot Option Word (bit numbers start with bit #1)

Bit        Default            Description
   9         Off                   If on, motor limit-stop testing will be enabled.
                                    (Joint limit-stop testing is always enabled.)

Robot Model and Robot Serial Number, Default: 0, 0.

Axis Configuration

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 NULL tool is defined, the Z axis of the tool frame will be collinear with the axis of rotation of joint 4 and will be pointed in the direction of the negative world 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.

Maximum operating range of rotational joints

Joint 4: -359.9° to +359.9°

Variations in Axis Configuration

This module controls all four axes as defined above and cannot be re-configured for any other number of axes.

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 Adept SmartMotion Developer's Guide for a description of this parameter.

Other Dimensional Constants

There are no dimensional constants that can be specified for this device other than the tool offset distance. The only geometric constraint of importance is that the Z joint must move perpendicularly to the plane defined by the X and Y joints. It is immaterial whether the mechanical drive axes that implement the mechanism are intersecting or offset from one another. In fact, the origin of the world coordinate system can be arbitrarily defined to be any point relative to the axis drives, so long as it is consistently defined from one working session to the next.

Figure 16.1. Link Definitions and Dimensions for CAR Device

Interpretations of Cartesian Rotation

During program-generated straight-line motions, the first Cartesian rotation speed controls the rate at which joint 4 rotates, and the speed should be set to be consistent with the joint-interpolated speed for joint 4. No other Cartesian rotational speeds are applicable.

Coupling Between Robot Joints and Motors

A 2-by-2 coupling matrix is provided to define the relationship between the motion of the X and Y joints and the motion of motors 1 and 2. This coupling matrix can be used to correct for any non-perpendicularity (skewing) between the X and Y joints.

A second 2-by-2 coupling matrix is provided to define the relationship between the motion of the Z and theta joints and the motion of motors 3 and 4. This coupling matrix permits this kinematic module to be used with robots that have mechanical coupling between the Z and theta drive trains.

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

(See the V+ Language Reference Guide for more information on these instructions.)

Additional Restrictions

None.