Validation of a calibration technique for 6-DOF instrumented spatial linkages

• Published in: Journal of biomechanics Vol. 40; no. 7; pp. 1455 - 1466
• Main Authors: Gatti, Gianluca, Danieli, Guido
• Format: Journal Article
• Language: English
• Published: United States Elsevier Ltd 01-01-2007; Elsevier Limited
• Subjects: Accuracy; Algorithms; Biomechanical Phenomena - instrumentation; Calibration; Colleges & universities; Conventions; Design; Goniometer; Humans; Instrumented spatial linkage; Kinematics; Knee Joint - physiology; Knee kinematics; Models, Biological; Physical Medicine and Rehabilitation; Knee kinematics; Instrumented spatial linkage; Calibration; Goniometer
• ISSN: 0021-9290; 1873-2380
• DOI: 10.1016/j.jbiomech.2006.06.021

Abstract This paper presents a practical and effective approach to the calibration of instrumented spatial linkages for biomechanical applications. A 6-DOF mechanical linkage with rotational transducers is designed and in-house manufactured for this purpose. In order to assess the validity of the proposed calibration technique and to distinguish between geometrical and electrical parameters uncertainties, high-precision optical encoders are used and calibration is addressed from a kinematic point of view only. The proposed technique is based on a closed-loop method, in which the end segments of the linkage are connected to each other by revolute joints. A parametrical model of the system is formulated using a standard link-to-link transformation matrices approach. Continuous data collection is carried out and a recursive identification of kinematic parameters is implemented by the use of an extended Kalman filter algorithm. Results shows that the proposed technique, despites its simplicity, is effective in improving the accuracy of the system up to its theoretically computed resolution, which limits the performance of the real system.