>> For the most part, the robot tends to jog in a straight line, but drift in >> sort of a curve in at least one direction.
>Drift sounds like a measurement problem although it may also be something >adding up somewhere, integrating speed to get position or similar. >> Sometimes the kinematics solve to joint angles that are impossible, and the >> robot faults for "over speed" from trying to go to positions > 10000 degrees. >This seems like a problem with the kinematics but maybe a measurement error >could do this to. The only thing I am sure of in regards to the kinematics is that they are not correct. I am at a loss for how to fix it. We have tried a number of methods to come up with the proper D-H parameters for our robot arm. First, we tried to learn more about D-H parameters and what they correspond to, to better understand how to calculate them for our robot arm. We cross-referenced the Puma 560 CAD model with the defined D-H parameters, in an attempt to see where the numbers were coming from in relation to the robot. We then tried to measure the CAD model of our robot to get the same dimensions to use as D-H parameters. I think we came close, but were still off by enough that the robot would veer off path and/or try to jump to huge joint angles that are impossible to reach (>10000 degrees) We found this educational robot control package that includes a calculator for D-H parameters: www.tekkotsu.org/Kinematics.html We put our measurements into the calculator and used the output as our genserkins D-H parameters. Again, the robot was close, but would veer off course and eventually try to jump to huge joint angles and fault for over speed. Throughout this process, we have used RoboAnalyzer www.roboanalyzer.com/ and MRPT www.mrpt.org/ as visualizers of our D-H parameters.
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