| KINS(9) | Kinematics Modules | KINS(9) |
kins - kinematics definitions for LinuxCNC
For additional information, see the Documents 'Advanced Topics':
Kinematics
5-Axis Kinematics
Switchable Kinematics
loadrt trivkins (use for most cartesian machines)
loadrt corexykins
loadrt genhexkins
loadrt genserkins
loadrt lineardeltakins (see separate manpage)
loadrt maxkins
loadrt pentakins
loadrt pumakins
loadrt rosekins
loadrt rotarydeltakins
loadrt rotatekins
loadrt scarakins
loadrt tripodkins
loadrt xyzab_tdr_kins
loadrt xyzac-trt-kins
loadrt xyzbc-trt-kins
loadrt 5axiskins
Rather than exporting HAL pins and functions, these components provide the forward and inverse kinematics definitions for LinuxCNC.
Joint numbers are assigned sequentially according to the axis letters specified with the coordinates= parameter.
If the coordinates= parameter is omitted, joint numbers are assigned sequentially to every known axis letter ("xyzabcuvw").
x==joint0, y==joint1, z==joint2
a==joint3, b==joint4, c==joint5
u==joint6, v==joint7, w==joint8
The default kinematics type is KINEMATICS_IDENTITY. GUIs may provide special features for configurations using this default kinematics type. For instance, the AXIS GUI automatically handles joint and world mode operations so that the distinctions between joints and axes are not visible to the operator. This is feasible since there is an exact correspondence between a joint number and its matching axis letter.
Use kinstype=B (KINEMATICS_BOTH) for configurations that need to move joints independently (joint mode) or as coordinated (teleop) movements in world coordinates.
When using the axis gui with KINEMATICS_BOTH, the '$' key is used to toggle between joint and teleop (world) modes.
An axis letter may be used more than once (duplicated) to assign multiple joints to a single axis coordinate letter.
The above example illustrates a gantry configuration that uses duplicated coordinate letters to indicate that two joints (joint1 and joint2) move a single axis (y). Using kinstype=B allows the configuration to be toggled between joint and world modes of operation. Homing configuration options are available to synchronize the final homing move for selected joints -- see the documentation for Homing Configuration.
NOTES for duplicated coordinates:
When duplicated coordinate letters are used, specifying KINEMATICS_BOTH (kinstype=B) allows a gui to support jogging of each individual joint in joint mode. Caution is required for machines where the movement of a single joint (in a set specified by a duplicated coordinate letter) can lead to gantry racking or other unwanted outcomes. When the kinstype= parameter is omitted, operation defaults to KINEMATICS_IDENTITY (kinstype=1) and a gui may allow jogging based upon a selected axis coordinate letter (or by a keyboard key) before homing is completed and the machine is still in joint mode. The joint selected will depend upon the gui implementation but typically only one of the multiple joints in the set will jog. Consequently, specifying KINEMATICS_BOTH is recommended as it enables support for unambiguous, independent jogging of each individual joint. Machines that implement homing for all joints (including the provisions for synchronizing the final homing move for multiple joints) may be homed at machine startup and automatically switch to world mode where per-coordinate jogging is available.
Gives six degrees of freedom in position and orientation (XYZABC). The location of base and platform joints is defined by HAL parameters. The forward kinematics iteration is controlled by HAL pins. (See switchkins documentation for more info)
Kinematics that can model a general serial-link manipulator with up to 6 angular joints. (See switchkins documentation for more info)
The kinematics use Denavit-Hartenberg definition for the joint and links. The DH definitions are the ones used by John J Craig in "Introduction to Robotics: Mechanics and Control" The parameters for the manipulator are defined by HAL pins. Note that this uses a convention sometimes known as "Modified DH Parameters" and this must be borne in mind when setting up the system. https://w.wiki/NcY
Kinematics for Chris Radek's tabletop 5 axis mill named 'max' with tilting head (B axis) and horizintal rotary mounted to the table (C axis). Provides UVW motion in the rotated coordinate system. The source file, maxkins.c, may be a useful starting point for other 5-axis systems.
Gives five degrees of freedom in position and orientation (XYZAB). The location of base and effector joints is defined by HAL parameters. The forward kinematics iteration is controlled by HAL pins.
Kinematics for a puma-style robot with 6 joints
a transverse, longitudinal, and rotary joint (3 joints)
Rotary delta robot (3 Joints)
The X and Y axes are rotated 45 degrees compared to the joints 0 and 1.
(See switchkins documentation for more info)
The joints represent the distance of the controlled point from three predefined locations (the motors), giving three degrees of freedom in position (XYZ)
Tilting table (A) and horizontal rotary mounted to table (C axis) (5 Joints 0:x,1:y,2:z,3:a,4:c) with provisions to switch between xyzac and trivkins kinematic types. The joint mapping can be altered with the coordinates parameter in the same way as supported by trivkins. (See switchkins documentation for more info)
(5 Joints 0:x,1:y,2:z,3:b,4:c) with provisions to switch between xyzbc and trivkins kinematic types. The joint mapping can be altered with the coordinates parameter in the same way as supported by trivkins. (See switchkins documentation for more info)
XYZBCW -- the W coordinate values (typically used for tool motion) are incorporated into XYZ positioning. (Only 5 joints are needed by the kinematics module but an additional joint is needed to display W values). (See switchkins documentation for more info)
By default, 5axiskins uses coordinates XYZBCW assigned consecutively to joints 0..5. The module coordinates parameter may be used to assign multiple joints to an axis letter and/or to assign joints to additional coordinates A,U,V with a one-to-one correspondence to the assigned joints. Example: XYZBCWYV (8 joints total numbered 0..7) uses two joints for Y (joints 1,6) and adds an additional coordinate V that has a one-to-one relation to joint 7.
Note: These kinematics may be used with the vismach 5axisgui providing that the joint-letter assignments agree with the default ordering expected by it (XYZBCW -> joints 0..5)
Kinematics section in the LinuxCNC documentation
The HAL component userkins.comp is a template for making kinematic modules using the halcompile tool. The unmodified template supports an identity xyz configuration that uses 3 joints. See userkins(9) for more info.
| 2014-12-22 | LinuxCNC Documentation |