An extensible ball bar for evaluation of robots' positioning performance

Vira, Naren; Lau, K.

doi:10.1002/rob.4620040606

Cited by 13 publications

(3 citation statements)

References 4 publications

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“…While the telescopic ballbar nowadays is a standard tool for accuracy assessment and calibration of (the XYZ part) of CMMs and machine tools and is very popular for the calibration of parallel robots (Ota et al , 2000), its use in industrial serial robots, though proposed more than two decades ago (Vira and Lau, 1987), remains very limited (for example, Karlsson and Brogårdh (2001), used it but in combination of an inclinometer). Indeed, the software that comes with the popular telescopic bar manufactured by Renishaw is specifically developed for use on a machine in which the circular motion is generated by the simultaneous movement of two orthogonal linear axes, and a defined test sequence should be followed.…”

Section: Accuracy Assessment Of Industrial Robotsmentioning

confidence: 99%

Assessment of the positioning performance of an industrial robot

Slamani

Nubiola²,

Bonev³

2012

Industrial Robot: An International Journal

112

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PurposeThe purpose of this paper is to investigate the use of a laser tracker, a laser interferometer system and a telescopic ballbar for assessing the positioning performance of a six‐axis industrial serial robot. The paper also aims to illustrate the limitations of these three metrology instruments for the assessment of robot positioning performance and to demonstrate the inadequacy of simplistic performance tests.Design/methodology/approachSpecific test methods in the case of the laser interferometer system and the telescopic ballbar are proposed. Measurements are analyzed in accordance to the ISO 9283 norm.FindingsIt is found that, in static conditions and after a relatively short warm‐up, the unidirectional position repeatability of the non‐calibrated industrial robot under study (an ABB IRB 1600) is better than 37 μm, the unidirectional orientation repeatability is at worst 87 μrad, the linear position accuracy is better than 650 μm, and the rotation accuracy is at worst 2.8 mrad (mainly because of the sixth robot axis). It was also found that the dynamic (radial) errors due to vibrations can be up to approximately ±250 μm along a small circular path at TCP speed of 700 mm/s.Practical implicationsIt is pointed out that the use of a laser tracker (or any other large range portable 3D measurement system) is questionable for assessing – let alone analyzing in depth – the unidirectional position repeatability of some of today's industrial robots. It is also demonstrated that the laser interferometer system can be used for measuring linear errors along a linear path of motion as well as angular errors about axes orthogonal to the path of motion. Finally, it is shown that the telescopic ballbar is an excellent, comparably low‐cost, high‐precision tool for assessing the static and dynamic positioning performance of industrial robots and its use in robotics should be further developed.Originality/valueThis work is the first to detail the use of three metrology equipments for assessing the positioning performance of an industrial robot. Experimental results are presented and discussed. Some guidelines for optimizing the positioning performance of an industrial robot are provided.

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Section: Accuracy Assessment Of Industrial Robotsmentioning

confidence: 99%

Assessment of the positioning performance of an industrial robot

Slamani

Nubiola²,

Bonev³

2012

Industrial Robot: An International Journal

112

View full text Add to dashboard Cite

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“…The 3D end-effector measurements required by their calibration methods described in [8,70] are deduced using a touch probe and a reference artifact. In [71][72][73][74][75], the authors utilize a telescoping ballbar to acquire measurements for robot calibration processes. A vision-based 3D position measuring device with limited range is employed in [76] and [77] to calibrate a robot.…”

Section: Introductionmentioning

confidence: 99%

Computationally efficient and robust kinematic calibration methodologies and their application to industrial robots

Messay

Ordóñez

Marcil³

2016

Robotics and Computer-Integrated Manufacturing

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Robot kinematic calibration is the process of enhancing the positioning accuracy of a given manipulator and must be performed after robot manufacture and assembly or during periodical maintenance. This dissertation presents new computationally efficient and robust kinematic calibration algorithms for industrial robots that make use of partial measurements. These include a calibration method that requires the supply of Cartesian coordinates of the calibration points (3DCAL) and another calibration technique that only requires the radial measurements from the calibration points to some reference (1DCAL). Neither method requires orientation measurements nor the explicit knowledge of the whereabout of a reference frame. Contrary to most other similar works, both methods make use of a simplified version of the original Denavit-Hartenberg (DH) kinematic model. The simplified DH(-) model has not only proven to be robust and effective in calibrating industrial manipulators but it is also favored from a computational efficiency viewpoint since it consists of comparatively fewer error parameters. We present a conceptual approach I also would like to thank the director of Yaskawa Motoman Robotics, Inc. Mr. Wade Hickle, Senior Engineer Mr. Eric Marcil and Chief Engineer Mr. George Sutton for their guidance and for making the much needed materials available to me. I appreciate Dr. John Loomis and Dr. Ruihua Liu for participating in my committee. Thanks go to Mr. Tom Schenck of Measurement Specialties, Inc. for allowing me to conduct experiments in his workplace. Finally, I would like to give my special thanks to my dearest friends for all their help and encouragement. vi

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“…Today, the telescopic ballbar is the most common metrology tool for assessing and calibrating the accuracy (the XYZ part) of CMMs and machine tools, and is very popular for calibrating parallel robots [10]. However, its use in industrial serial robots, though proposed more than two decades ago [11], remains very limited (for example, it was used in [12], but in combination with an inclinometer, and in [13] with a reference angular encoder to characterise a six-axis serial robot). In fact, the software that comes with the popular telescopic bar manufactured by Renishaw was specifically developed for use on a machine in which the circular motion is generated by the simultaneous movement of two orthogonal linear axes, and requires that a defined test sequence be followed.…”

Section: Introductionmentioning

confidence: 99%

Effect of Servo Systems on the Contouring Errors in Industrial Robots

Slamani

Nubiola

Bonev

2012

Transactions of the Canadian Society for Mechanical Engineering

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Two important aspects of the performance of a servo system, tracking errors and contour errors, significantly affect the accuracy of industrial robots under high-speed motion. Careful tuning of the control parameters in a servo system is essential, if the risk of severe structural vibration and a large contouring error is to be avoided. In this paper, we present an overview of a method to diagnose contouring errors caused by the servo control system of an ABB IRB 1600 industrial robot by measuring the robot’s motion accuracy in a Cartesian circular shape using a double ballbar (DBB) measurement instrument. Tests were carried out at different TCP (tool centre-point) speed and trajectory radii to investigate the main sources of errors that affect circular contouring accuracy. Results show that radius size errors and out-of-roundness are significant. A simple experimental model based on statistical tests was also developed to represent and predict the radius size error. The model was evaluated by comparing its prediction capability in several experiments. An excellent error prediction capability was observed.

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An extensible ball bar for evaluation of robots' positioning performance

Cited by 13 publications

References 4 publications

Assessment of the positioning performance of an industrial robot

Assessment of the positioning performance of an industrial robot

Computationally efficient and robust kinematic calibration methodologies and their application to industrial robots

Effect of Servo Systems on the Contouring Errors in Industrial Robots

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