S. Besnard

Bio: S. Besnard is an academic researcher from Centre national de la recherche scientifique. The author has contributed to research in topics: Calibration (statistics) & Parallel manipulator. The author has an hindex of 1, co-authored 1 publications receiving 107 citations.

Identifiable parameters for parallel robots kinematic calibration

Abstract: Presents a numerical method for the determination of the identifiable parameters of parallel robots. The special case of Stewart-Gough 6 degrees-of-freedom parallel robots is studied for classical and self calibration methods, but this method can be generalized to any kind of parallel robot. The method is based on QR decomposition of the observation matrix of the calibration system. Numerical relations between the parameters which are identified and those which are not identifiable can be obtained for each method.

Geometric error measurement and compensation of machines : an update

Abstract: For measuring machines and machine tools, geometrical accuracy is a key performance criterion. While numerical compensation is well established for CMMs, it is increasingly used on machine tools in addition to mechanical accuracy. This paper is an update on the CIRP keynote paper by Sartori and Zhang from 1995 [Sartori S, Zhang GX (1995) Geometric error measurement and compensation of machines, Annals of the CIRP 44(2):599–609]. Since then, numerical error compensation has gained immense importance for precision machining. This paper reviews the fundamentals of numerical error compensation and the available methods for measuring the geometrical errors of a machine. It discusses the uncertainties involved in different mapping methods and their application characteristics. Furthermore, the challenges for the use of numerical compensation for manufacturing machines are specified. Based on technology and market development, this work aims at giving a perspective for the role of numerical compensation in the future.

Simplifying the kinematic calibration of parallel mechanisms using vision-based metrology

Abstract: In this paper, a vision-based measuring device is proposed and experimentally demonstrated to be an accurate, flexible, and low-cost tool for the kinematic calibration of parallel mechanisms. The accuracy and ease of use of the proposed vision sensor are outlined, with the suppression of the need for an accurate calibration target, and adequacy to the kinematic calibration process is investigated. In particular, identifiability conditions with the use of such an exteroceptive sensor are derived, considering the calibration with inverse or implicit models. Extensive results are given, with the evaluation of the measuring device and the calibration of an H4 robot. Using the full-pose measurement, an experimental analysis of the optimal calibration model is achieved, with study of the kinematic behavior of the mechanism. The efficiency of the provided method is thus evaluated, and the applicability of vision-based measuring devices to the context of kinematic calibration of parallel mechanisms is discussed.

A new calibration method for parallel kinematics machine tools using orientation constraint

Abstract: This paper considers the problem of improving the accuracy of parallel kinematics machine tools through a low-cost and effective calibration method. A novel orientation constraint of keeping two attitude angles of the end-effector constant is presented to derive the calibration algorithm with special insight on the effect of using various combinations of two angles. The orientation constraint of the selected combination is realized physically through leveling a commercial biaxial inclinometer installed on the end-effector. Benefits of the proposed method include exempting the needs for precise pose (position and orientation) measurement and for mechanical fixtures, as well as rendering the independence of the measuring range and angular positioning accuracy of the inclinometer. Simulation based on the geometry of the Stewart platform of XJ-HEXA shows the position and orientation accuracy can reach 0.1 mm and 0.01° after calibration, when using an inclinometer with the repeatability of 0.001° and measuring the leg lengths with the precision of 0.002 mm at 80 configurations. Experiments on XJ-HEXA further verify the effectiveness of the proposed method.

Experimental results on kinematic calibration of parallel manipulators using a partial pose measurement device

Abstract: This paper presents kinematic calibration of parallel manipulators with partial pose measurements, using a device that measures a rotation of the end-effect or along with its position. The device contains a linear variable differential transformer, a biaxial inclinometer, and a rotary sensor. The device is designed in a modular fashion, and links of different lengths can be used. Two additional kinematic parameters required for the measurement device are discussed, kinematic relations are derived, and cost function is established to perform calibration with the proposed device. The study is performed for a six-degree-of-freedom fully parallel HexaSlide mechanism (HSM). Experimental results show significant improvement in the accuracy of the HSM.