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

Dec 5, 2017, 5:32:33 PM (18 months ago)



  • Burt-Research/KinematicsJointRangesConversionFactors

    v3 v4  
    11= Kinematics, Transmission Ratios, and Joint Ranges =
     3== Kinematics ==
     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.
    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.
     12=== D-H parameters ===
    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.