Changes between Version 3 and Version 4 of Burt-Research/KinematicsJointRangesConversionFactors


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Timestamp:
Dec 5, 2017, 5:32:33 PM (18 months ago)
Author:
al
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  • Burt-Research/KinematicsJointRangesConversionFactors

    v3 v4  
    11= Kinematics, Transmission Ratios, and Joint Ranges =
    22
     3== Kinematics ==
     4
     5* The robot has 3 joints: J1, J2, and J3, shown below. J1 rotates about Z0, J2 rotates about Z1, and J3 rotates about Z2.
     6* J3 is able to change between left- and right-hand configurations, denoted J3L and J3R, respectively.
     7* J1 and J2 are part of a cable differential system.
     8
    39A good introduction to coordinate frames, transformations and kinematics is beyond the scope of this document. There are several good introductory robotics books available. We recommend Spong, M.; Hutchinson, S.; Vidyasagar, M. Robot Modeling and Control; 2006 John Wiley & Sons as we use the variant of the Denavit-Hartenberg (D-H)  method that is from this book to establish the coordinate frames.
     10
     11
     12=== D-H parameters ===
    413
    514D-H frames are defined roughly as shown in Figure 1 when the robot is in its zero position (NOT the robot’s home position). Note that the joint range of Joint 3 (Table 2) prevents BURT from actually reaching this position. Frames 0 and 1 are located at the intersection of the J1 and J2 axes. Frame 2 is coincident to the J3 axis. The frame 3 origin is coincident to the center of the haptic ball when it points straight up. The D-H parameters do not change between left- and right-handed configurations. However, the configuration files do contain separate world-to-base transforms for each configuration. These transforms define the origin of the world frame to be at the user’s sternum, 540 mm from the X1-Z1 plane along Z0. The diagram shows the locations of the world origin in left-handed and right-handed robot configurations. A positive joint motion is based on the right hand rule for each axis.