Achieving the highest precision of industrial robots – Metrology and Quality News

Robots, once manufactured, must be calibrated for accuracy and specific alignment according to their design. This is a critical process. So when the Advanced Manufacturing Technology Development Center (AMTDC) designed and developed two robots that needed to have the design, accuracy and tolerances of the constructions checked. After traditional calibration methods, including fixed cubes and dial devices, failed to deliver the results they were looking for, AMTDC turned to the expert team at API Services. Using API’s Robotic Metrology (RMS) solution, API Services was able to perform fourteen types of tests in accordance with ISO 9283, calibrate and compensate for all errors, and determine robot behavior accuracy and repeatability values ​​for the joints under different conditions of acceleration and speed.

AMTDC is a center of excellence on machine tools and production technologies supported by the Department of Heavy Industry (DHI), Government of India, in collaboration with Indian machine tool manufacturers under the initiative “Improving Competitiveness in India’s Capital Goods Sector”. AMTDC is one of a kind in India, embodying the concept of industry-university collaboration. It is housed in the IIT Madras Research Park, a nodal infrastructure for university-industry interaction under one roof, to offer solutions for the development of advanced technologies in the capital goods manufacturing sector with the collaboration of industrial partners.

AMTDC has designed and developed two robots weighing six kilograms and ten kilograms, respectively. Being brand new, the robot models had to be precision checked against the design. AMTDC first tried to manage this process internally, calibrating the robots with traditional methods, including a stable cube device and dial gauges. These processes, however, did not obtain readings accurate enough for the positional accuracy and repeatability that AMTDC needed to verify their releases. They were looking for a professional service provider who could provide them with the exact measurements needed.

As an industry leader in robotic calibration products and services, API Services was contacted by AMTDC and, after consultation, quickly understood the challenge. The API team came on site and configured the API RMS at AMTDC’s lab. The configuration included Radian Pro Laser Tracker, SmartTrack Sensor (STS), and the proprietary robot measurement software programs API developed for this solution. With the STS mounted directly to each robot’s end effector, Radian Pro was able to track each robot’s motion along its pre-determined path, automatically taking precise position measurements and feeding that data back into the software. The software presents measured values ​​on digital DH Kinematic or Volumetric Error Compensation (VEC) models of the robot’s working environment. The software analyzes the planned trajectory and the recorded actual values ​​of Radian and STS to determine any deviations. Corrections for these deviations can be uploaded directly to the robot controller, allowing for on-the-fly improvement in robot position accuracy and performance.

For AMTDC, API services calibrated and compensated for robot performance errors, driving the robots to the highest possible precision AMTDC desired in their specifications. The API also captured robot behavior accuracy and repeatability values ​​for robot joints under different speed and acceleration conditions. And these tests were carried out for the fourteen performance characteristics as stated in the ISO 9283 standard for calibration and performance testing of robots.

AMTDC, IIT Madras, has contracted the globally local team of Rea Metrologists API Services in India to calibrate their robots and provide accuracy values ​​as per AMTDC’s design. API successfully addressed their concerns with their RMS setup. RMS provides the complete toolkit needed to verify robot performance accuracy to ISO 9283. It provides a single, seamless solution for improving and optimizing robotic process performance. The measured results can be documented in detail and used to compensate for errors.

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Mavis R. Bernier