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RPAT

RPAT Repetitive Position Accuracy Testing

We now use a specially developed positional accuracy testing hardware and software package for testing every robot we refurbish. Each robot is put through a rigorous repeatability test at load, and each test is documented. Digital gauges with SPC outputs record various taught positions and their deviations where they are analyzed by the software. Every robot we ship must pass extensive RPAT tests, and includes highly detailed reports of each test performed. Repetitive Positioning Accuracy Tester

Robots are rated based on their maximum payload, maximum reach and their repetitive positioning accuracy. Repetitive position accuracy is the allowable tolerance of a robots ability to repeatedly return to a taught position in its work envelope.

The Repetitive Positioning Accuracy tester checks the repeatability accuracy of the robot manipulator in the X, Y, and Z direction. The Repetitive Positioning Accuracy tester uses three digital dial indicators to send the actual position of the manipulator compared to the taught position. The digital dial indicators used depends on the accuracy required for a particular manipulator. The dial indicators can be floor mounted, magnetic stand mounted, or movable base mounted, depending on the user’s application, floor space restraints and size of the robot being tested. The Repetitive Positioning Accuracy tester is designed to:

Verify Manipulator Positioning Accuracy after Rebuild
Troubleshoot Repeatability issues during Production
Track Axis wear during Preventive Maintenance Program

Verify Positioning Accuracy after Rebuild

The Positioning Accuracy Tester verifies that the robot manipulator meets the manufactures specification when the robot was originally manufactured.

Troubleshoot Repeatability Issues

The most common cause of repeatability issues are worn or loose RV and / or Harmonic drive. When a Rotary Vector or Harmonic drive fail it is easily identified and replaced, but when a rotary vector or harmonic drive begins to wear the backlash increases causing repeatability issues. The Repetitive Positioning Accuracy tester helps identify the correct axis causing the issue, and used in conjunction with the Drive Deflection Calculator program the worn drive is quickly and easily identified and replaced.

Repetitive Positioning Accuracy Software

The custom software allows for rapid set-up and execution of the Repetitive Positioning Accuracy test. The database includes over 1000+ robot manufacturer’s manipulators / controllers (Motoman, Fanuc, and ABB - to name a few) and their respective tolerances in millimeters, microns and inches. If the required manipulator is not in the database it can easily be added for future use. The touch results can be viewed in real time on the quick view screen (shown below) or in the real time chart. The results can be viewed in a 2 or 3 dimensional graph and can be rotated to any direction. There are two types of reports than can be viewed and printed. They are the Summary report and the Detailed Analysis Report.

Quick View The quick view screen shows the metered difference of the taught position and actual position with tolerance limits. The difference in the two positions can be viewed in inches, millimeters and microns. The actual value is show in a view box below each meter..

Real Time Chart The real time chart allows the viewing of the data as they happen. The data can be viewed in millimeters, microns or inches. The chart can be viewed with (show to the left) or without a tolerance grid.

Plot Graph The graph plots all touch data. The data can be viewed in millimeters, microns or inches. Each touch direction (X, Y and Z) can also be view individual. When your mouse is hovered over any data point on the graph a box will appear showing the value of that point. The graph can be viewed in 2D or 3D. The default is 2D. The 3D view can be rotated for different angle views. Double click on any point in the graph and a zoom screen will appear which shows the point that was clicked and the two data points before and the two data points after .

Reports There are two types of reports produced by this software. The first is a Summary Report and the second is a Detailed Analysis Report. The Summary report shows the basic touch information (total number of touches, how many touches were out of tolerance, the largest positive touch and the largest negative touch and the average of all touches). It also includes a graph which can be viewed and printed in 3D the rotated. The Detailed Analysis Report is completely customizable. The report shows the results of every touch. It also highlights the touches that were out of range (color based on how far out of range). The report has a summary section, result section, graph section, and a recommendation section.