Advanced Techniques of Industrial Robot Programming

Industrial Robotics: Programming, Simulation and Applications, 2006

KSME Journal, 1992

For the implementation of industrial robots in a elM environment, it is necessary to be able to position their end•effectors to an abstractly defined cartesian position with desired accuracy. In other words, it is necessary to find accurate actuator command values corresponding to given goal positions which are expressed with respect to a certain coordinate frame. If the teaching•by• doing method is used, very accurate actuator command values are obtained from transducer readings. For the case when the goal poitions are mathematically expressed, however, the actuator command values for the goal positions must be calculated using robot kinematics. It is, however, well known that the position errors in the order of IOmm is not unusual while many industrial robots have the repeatability in the order of O.1mm. In here, the position error is referred to as the difference between the specified goal position and the position where a robot is actually controlled. To reduce the position errors, many researchers proposed calibration mel:hods which are based on robot kinematic identification. However, those methods are quite complex and require an accurate position measuring device. In this paper, a new method which does not require the accurate kinematic identification, is introduced. In this method, the accurate actuator command values are calculated using the nominal kinematic model which is appropriatly altered based on the available encoder readings of the several reference frames. To demonstrate the simplicity and the effectiveness of the method, computer simulations as well as experimental studies are performed and their results are discussed.

Robotics and Computer-Integrated Manufacturing, 2015

The paper deals with geometric calibration of industrial robots and focuses on reduction of the measurement noise impact by means of proper selection of the manipulator configurations in calibration experiments. Particular attention is paid to the enhancement of measurement and optimization techniques employed in geometric parameter identification. The developed method implements a complete and irreducible geometric model for serial manipulator, which takes into account different sources of errors (link lengths, joint offsets, etc). In contrast to other works, a new industry-oriented performance measure is proposed for optimal measurement configuration selection that improves the existing techniques via using the direct measurement data only. This new approach is aimed at finding the calibration configurations that ensure the best robot positioning accuracy after geometric error compensation. Experimental study of heavy industrial robot KUKA KR-270 illustrates the benefits of the developed pose strategy technique and the corresponding accuracy improvement.

Journal of the Brazilian Society of Mechanical Sciences and Engineering, 2011

Theoretical and Practical Aspects of Robot Calibration with Experimental Verification One of the greatest challenges in today's industrial robotics is the development of off-line programming systems that allow drastic reduction in robots' reprogramming time, improving productivity. The article purpose is to pave the way to the construction of generic calibration systems easily adapted to any type of robot, regardless their application, such as modular robots and robot controllers specifically designed for non-standard applications. A computer system was built for developing and implementing a calibration system that involves the joint work of computer and measurement systems. Each step of this system's development is presented together with its theoretical basis. With the development of a remote maneuvering system based on ABB S3 controller experimental tests have been carried out using an IRB2000 robot and a measurement arm (ITG ROMER) with 0.087 mm of position measurement accuracy. The robot model used by its controller was identified and the robot was calibrated and evaluated in different workspaces resulting in an average accuracy improvement from 1.5 mm to 0.3 mm.

The work reported here is concerned with methods used to provide partial pose data for robot calibration tests. Rather than focussing on traditional, precision measurement techniques, the paper discusses calibration using end point motion constraints of various kinds. The preferred method consists of using a wire potentiometer attached to the robot tool by means of two specially designed fixtures. Suitable modeling of the measurement system as well as the internal kinematics of the manipulator allows simulation of the calibration process. Experimental results obtained in the calibration of an industrial manipulator is presented, and means to make the complete calibration process automatic is discussed.

Sensors, 2013

Identification of robot kinematic errors during the calibration process often requires accurate full pose measurements (position and orientation) of robot end-effectors in Cartesian space. This paper proposes a new method of full pose measurement of robot end-effectors for calibration. This method is based on an analysis of the features of a set of target points (placed on a rotating end-effector) on a circular trajectory. The accurate measurement is validated by computational simulation results from the Puma robot. Moreover, experimental calibration and validation results for the Hyundai HA-06 robot prove the effectiveness, correctness, and reliability of the proposed method. This method can be applied to robots that have entirely revolute joints or to robots for which only the last joint is revolute.

New Technologies - Trends, Innovations and Research, 2012

The paper focuses on the calibration of serial industrial robots using partial pose measurements. In contrast to other works, the developed advanced robot calibration technique is suitable for geometrical and elastostatic calibration. The main attention is paid to the model parameters identification accuracy. To reduce the impact of measurement errors, it is proposed to use directly position measurements of several points instead of computing orientation of the endeffector. The proposed approach allows us to avoid the problem of non-homogeneity of the least-square objective, which arises in the classical identification technique with the full-pose information. The developed technique does not require any normalization and can be efficiently applied both for geometric and elastostatic identification. The advantages of a new approach are confirmed by comparison analysis that deals with the efficiency evaluation of different identification strategies. The obtained results have been successfully applied to the elastostatic parameters identification of the industrial robot employed in a machining work-cell for aerospace industry.

International Journal of Computer Integrated Manufacturing, 2001

Accurate use of robots in an off-line programming mode is only possible through a proper calibration procedure. In this procedure, the end-effector is made to move along a set of known spatial poses where the positional errors are to be measured and employed in mathematical models. The models are subsequently solved for the manipulator dimensions (geometric parameters) using suitable regression techniques.

Advances in Mechanical Engineering

Robot kinematic calibration used to be carried out with the partial pose measurements (position only) of dimension 3 in industry, while full pose measurements (orientation and position) of dimension 6 sometimes could be considered to improve the calibration performance. This paper investigates the effects of measurement dimensions on robot calibration accuracy. It compares the resulting robot accuracies in both partial pose and full pose cases after calibrating three structural types of robot manipulators such as a serial manipulator (Hyundai HA-06 robot), a single closed-chain manipulator (Hyundai HX-165 robot), and a multiple closed-chain manipulator (Hyundai HP-160 robot). These comparative studies show when the full-pose based calibration need to be considered and how much it contributes the improvement of robot accuracy to the different structural type of robot manipulators.