High accurate robotic drilling with external sensor and compliance model-based compensation

Abstract

High accurate absolute robot positioning is a requirement, and still a challenge, in many applications, such as drilling in the aerospace industry. The accuracy is affected due to many sources of errors from robot model, tool calibration, sensor and product uncertainties. While model-based error compensation cannot reach the desired accuracy, sensor-based compensation appears as the practical solution to increase the robot positioning accuracy. A structured analysis of the error sources in robotic manufacturing processes can facilitate error identification and further compensation. This paper describes an error source breaking down approach for analyzing robotic manufacturing processes. Moreover, an external sensor-based compensation is proposed for error reduction and error identification. Comparison with a compliance model-based compensation is performed. The proposed approach is applied to a robotic drilling process for aircraft manufacturing, considered a general and real industrial application. Further validation through experimentation is performed. The validation revealed a clear improvement in robot positioning accuracy and the benefits of the proposed error source structure for analysis

Using locally adjustable hand-eye calibrations to reduce robot localization error

“…9b. A similar error reduction was reported in [20,27,28], but it was achieved by using real-time feedback from external sensors. Other techniques based on interpolation do not need dynamic tracking of robot movement (similar to our approach), but they reduced only position error [31,32].…”

“…Active control based on external sensors was also used for automated welding of aerospace components [19]. Localization error in accurate robotic drilling was reduced to 0.1 mm and 0.2° using an external sensor and compliance compensation [20]. Even as these active control techniques (as well as other passive or hybrid compliance strategies [21][22][23]) enable the completion of tasks requiring high accuracy, they could still benefit from reduced localization error.…”

Simulation and Experimental Research on Robot Drilling

“…Wong et al [3] presented the vision guided error measurement system in a robot for surgical drilling. The robot used lasers to maintain its position throughout the process.…”

Automatic Motion Generation for Robotic Milling Optimizing Stiffness with Sample-Based Planning

“…In one of our last publications, an error source structure for the identification and model-based compensation of errors in robotic manufacturing has been proposed using the Product, Process and Resource model (PPR) [8]. A comparison between sensor-based and compliance model-based compensation for robotic drilling has been presented [8]. This model has been extended in this publication into an architecture for optimizing robot machining motions optimizing robot stiffness.…”

“…In conjunction with the identification of limitations, several researchers have also experimentally determined error sources [6] and proposed strategies for improving robotic machining accuracy through modular compensation [7], which could be a way for increasing the robot accuracy and its accurate programmability. In one of our last publications, an error source structure for the identification and model-based compensation of errors in robotic manufacturing has been proposed using the Product, Process and Resource model (PPR) [8]. A comparison between sensor-based and compliance model-based compensation for robotic drilling has been presented [8].…”